gcc/c-family/c.opt

   1 ; Options for the C, ObjC, C++ and ObjC++ front ends.
   2 ; Copyright (C) 2003-2023 Free Software Foundation, Inc.
   3 ;
   4 ; This file is part of GCC.
   5 ;
   6 ; GCC is free software; you can redistribute it and/or modify it under
   7 ; the terms of the GNU General Public License as published by the Free
   8 ; Software Foundation; either version 3, or (at your option) any later
   9 ; version.
  10 ;
  11 ; GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 ; WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 ; FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 ; for more details.
  15 ;
  16 ; You should have received a copy of the GNU General Public License
  17 ; along with GCC; see the file COPYING3.  If not see
  18 ; <http://www.gnu.org/licenses/>.
  19
  20 ; See the GCC internals manual for a description of this file's format.
  21
  22 ; Please try to keep this file in ASCII collating order.
  23
  24 Language
  25 C
  26
  27 Language
  28 ObjC
  29
  30 Language
  31 C++
  32
  33 Language
  34 ObjC++
  35
  36 -all-warnings
  37 C ObjC C++ ObjC++ Warning Alias(Wall)
  38
  39 -ansi
  40 C ObjC C++ ObjC++ Alias(ansi)
  41
  42 -assert
  43 C ObjC C++ ObjC++ Separate Alias(A) MissingArgError(assertion missing after %qs)
  44
  45 -assert=
  46 C ObjC C++ ObjC++ Joined Alias(A) MissingArgError(assertion missing after %qs)
  47
  48 -comments
  49 C ObjC C++ ObjC++ Alias(C)
  50
  51 -comments-in-macros
  52 C ObjC C++ ObjC++ Alias(CC)
  53
  54 -define-macro
  55 C ObjC C++ ObjC++ Separate Alias(D) MissingArgError(macro name missing after %qs)
  56
  57 -define-macro=
  58 C ObjC C++ ObjC++ Joined Alias(D) MissingArgError(macro name missing after %qs)
  59
  60 -dependencies
  61 C ObjC C++ ObjC++ Alias(M)
  62
  63 -dump
  64 C ObjC C++ ObjC++ Separate Alias(d)
  65
  66 -dump=
  67 C ObjC C++ ObjC++ Joined Alias(d)
  68
  69 -imacros
  70 C ObjC C++ ObjC++ Separate Alias(imacros) MissingArgError(missing filename after %qs)
  71
  72 -imacros=
  73 C ObjC C++ ObjC++ Joined Alias(imacros) MissingArgError(missing filename after %qs)
  74
  75 -include
  76 C ObjC C++ ObjC++ Separate Alias(include) MissingArgError(missing filename after %qs)
  77
  78 -include=
  79 C ObjC C++ ObjC++ Joined Alias(include) MissingArgError(missing filename after %qs)
  80
  81 -include-barrier
  82 C ObjC C++ ObjC++ Alias(I, -)
  83
  84 -include-directory
  85 C ObjC C++ ObjC++ Separate Alias(I) MissingArgError(missing path after %qs)
  86
  87 -include-directory=
  88 C ObjC C++ ObjC++ Joined Alias(I) MissingArgError(missing path after %qs)
  89
  90 -include-directory-after
  91 C ObjC C++ ObjC++ Separate Alias(idirafter) MissingArgError(missing path after %qs)
  92
  93 -include-directory-after=
  94 C ObjC C++ ObjC++ Joined Alias(idirafter) MissingArgError(missing path after %qs)
  95
  96 -include-prefix
  97 C ObjC C++ ObjC++ Separate Alias(iprefix)
  98
  99 -include-prefix=
 100 C ObjC C++ ObjC++ JoinedOrMissing Alias(iprefix)
 101
 102 -include-with-prefix
 103 C ObjC C++ ObjC++ Separate Alias(iwithprefix)
 104
 105 -include-with-prefix=
 106 C ObjC C++ ObjC++ JoinedOrMissing Alias(iwithprefix)
 107
 108 -include-with-prefix-after
 109 C ObjC C++ ObjC++ Separate Alias(iwithprefix)
 110
 111 -include-with-prefix-after=
 112 C ObjC C++ ObjC++ JoinedOrMissing Alias(iwithprefix)
 113
 114 -include-with-prefix-before
 115 C ObjC C++ ObjC++ Separate Alias(iwithprefixbefore)
 116
 117 -include-with-prefix-before=
 118 C ObjC C++ ObjC++ JoinedOrMissing Alias(iwithprefixbefore)
 119
 120 -no-integrated-cpp
 121 Driver Alias(no-integrated-cpp)
 122
 123 -no-line-commands
 124 C ObjC C++ ObjC++ Alias(P)
 125
 126 -no-standard-includes
 127 C ObjC C++ ObjC++ Alias(nostdinc)
 128
 129 -no-warnings
 130 C ObjC C++ ObjC++ Alias(w)
 131
 132 -output
 133 C ObjC C++ ObjC++ Separate Alias(o)
 134
 135 -output=
 136 C ObjC C++ ObjC++ Joined Alias(o)
 137
 138 -output-pch
 139 C ObjC C++ ObjC++ Separate
 140
 141 -pedantic
 142 C ObjC C++ ObjC++ Alias(pedantic)
 143
 144 -preprocess
 145 C ObjC C++ ObjC++ Undocumented Alias(E)
 146
 147 -print-missing-file-dependencies
 148 C ObjC C++ ObjC++ Alias(MG)
 149
 150 -trace-includes
 151 C ObjC C++ ObjC++ Alias(H)
 152
 153 -traditional
 154 Driver Alias(traditional)
 155
 156 -traditional-cpp
 157 C ObjC C++ ObjC++ Alias(traditional-cpp)
 158
 159 -trigraphs
 160 C ObjC C++ ObjC++ Alias(trigraphs)
 161
 162 -undefine-macro
 163 C ObjC C++ ObjC++ Separate Alias(U) MissingArgError(macro name missing after %qs)
 164
 165 -undefine-macro=
 166 C ObjC C++ ObjC++ Joined Alias(U) MissingArgError(macro name missing after %qs)
 167
 168 -user-dependencies
 169 C ObjC C++ ObjC++ Alias(MM)
 170
 171 -verbose
 172 Common C ObjC C++ ObjC++ Alias(v)
 173
 174 -write-dependencies
 175 C ObjC C++ ObjC++ NoDriverArg Separate Alias(MD) MissingArgError(missing filename after %qs)
 176
 177 -write-user-dependencies
 178 C ObjC C++ ObjC++ NoDriverArg Separate Alias(MMD) MissingArgError(missing filename after %qs)
 179
 180 A
 181 C ObjC C++ ObjC++ Joined Separate MissingArgError(assertion missing after %qs)
 182 -A<question>=<answer>   Assert the <answer> to <question>.  Putting '-' before <question> disables the <answer> to <question>.
 183
 184 C
 185 C ObjC C++ ObjC++
 186 Do not discard comments.
 187
 188 CC
 189 C ObjC C++ ObjC++
 190 Do not discard comments in macro expansions.
 191
 192 D
 193 C ObjC C++ ObjC++ Joined Separate MissingArgError(macro name missing after %qs)
 194 -D<macro>[=<val>]       Define a <macro> with <val> as its value.  If just <macro> is given, <val> is taken to be 1.
 195
 196 E
 197 C ObjC C++ ObjC++ Undocumented Var(flag_preprocess_only)
 198
 199 F
 200 Driver C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
 201 -F <dir>        Add <dir> to the end of the main framework include path.
 202
 203 fgimple
 204 C Var(flag_gimple) Init(0)
 205 Enable parsing GIMPLE.
 206
 207 H
 208 C ObjC C++ ObjC++
 209 Print the name of header files as they are used.
 210
 211 I
 212 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
 213 -I <dir>        Add <dir> to the end of the main include path.
 214
 215 M
 216 C ObjC C++ ObjC++
 217 Generate make dependencies.
 218
 219 MD
 220 C ObjC C++ ObjC++ NoDriverArg Separate MissingArgError(missing filename after %qs)
 221 Generate make dependencies and compile.
 222
 223 MF
 224 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing filename after %qs)
 225 -MF <file>      Write dependency output to the given file.
 226
 227 MG
 228 C ObjC C++ ObjC++
 229 Treat missing header files as generated files.
 230
 231 MM
 232 C ObjC C++ ObjC++
 233 Like -M but ignore system header files.
 234
 235 MMD
 236 C ObjC C++ ObjC++ NoDriverArg Separate MissingArgError(missing filename after %qs)
 237 Like -MD but ignore system header files.
 238
 239 Mmodules
 240 C++
 241 Generate C++ Module dependency information.
 242
 243 Mno-modules
 244 C++
 245 ; undocumented
 246
 247 MP
 248 C ObjC C++ ObjC++
 249 Generate phony targets for all headers.
 250
 251 MQ
 252 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing makefile target after %qs)
 253 -MQ <target>    Add a target that may require quoting.
 254
 255 MT
 256 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing makefile target after %qs)
 257 -MT <target>    Add a target that does not require quoting.
 258
 259 fdeps-format=
 260 C ObjC C++ ObjC++ NoDriverArg Joined MissingArgError(missing format after %qs)
 261 Structured format for output dependency information.  Supported (\"p1689r5\").
 262
 263 fdeps-file=
 264 C ObjC C++ ObjC++ NoDriverArg Joined MissingArgError(missing output path after %qs)
 265 File for output dependency information.
 266
 267 fdeps-target=
 268 C ObjC C++ ObjC++ NoDriverArg Joined MissingArgError(missing path after %qs)
 269 -fdeps-target=obj.o Output file for the compile step.
 270
 271 P
 272 C ObjC C++ ObjC++
 273 Do not generate #line directives.
 274
 275 U
 276 C ObjC C++ ObjC++ Joined Separate MissingArgError(macro name missing after %qs)
 277 -U<macro>       Undefine <macro>.
 278
 279 WNSObject-attribute
 280 C ObjC C++ ObjC++ LTO Var(warn_nsobject_attribute) Warning Init(1)
 281 Warn if the NSObject attribute is applied to a non-typedef.
 282
 283 Wabi
 284 C ObjC C++ ObjC++ LTO Var(warn_abi) Warning
 285 Warn about things that will change when compiling with an ABI-compliant compiler.
 286
 287 Wabi=
 288 C ObjC C++ ObjC++ LTO Joined RejectNegative UInteger Warning
 289 Warn about things that change between the current -fabi-version and the specified version.
 290
 291 Wabi-tag
 292 C++ ObjC++ Var(warn_abi_tag) Warning
 293 Warn if a subobject has an abi_tag attribute that the complete object type does not have.
 294
 295 Wpsabi
 296 C ObjC C++ ObjC++ LTO Var(warn_psabi) Init(1) Warning Undocumented LangEnabledBy(C ObjC C++ ObjC++,Wabi)
 297
 298 Wabsolute-value
 299 C ObjC Var(warn_absolute_value) Warning EnabledBy(Wextra)
 300 Warn on suspicious calls of standard functions computing absolute values.
 301
 302 Waddress
 303 C ObjC C++ ObjC++ Var(warn_address) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 304 Warn about suspicious uses of memory addresses.
 305
 306 Enum
 307 Name(warn_aligned_new_level) Type(int) UnknownError(argument %qs to %<-Waligned-new%> not recognized)
 308
 309 EnumValue
 310 Enum(warn_aligned_new_level) String(none) Value(0)
 311
 312 EnumValue
 313 Enum(warn_aligned_new_level) String(global) Value(1)
 314
 315 EnumValue
 316 Enum(warn_aligned_new_level) String(all) Value(2)
 317
 318 Waligned-new
 319 C++ ObjC++ Alias(Waligned-new=,global,none)
 320 Warn about 'new' of type with extended alignment without -faligned-new.
 321
 322 Waligned-new=
 323 C++ ObjC++ Var(warn_aligned_new) Enum(warn_aligned_new_level) Joined RejectNegative Warning LangEnabledBy(C++ ObjC++,Wall,1,0)
 324 -Waligned-new=[none|global|all] Warn even if 'new' uses a class member allocation function.
 325
 326 Wall
 327 C ObjC C++ ObjC++ Warning
 328 Enable most warning messages.
 329
 330 Walloca
 331 C ObjC C++ ObjC++ Var(warn_alloca) Warning
 332 Warn on any use of alloca.
 333
 334 Walloc-size
 335 C ObjC Var(warn_alloc_size) Warning LangEnabledBy(C ObjC, Wextra)
 336 Warn when allocating insufficient storage for the target type of the assigned pointer.
 337
 338 Walloc-size-larger-than=
 339 C ObjC C++ LTO ObjC++ Var(warn_alloc_size_limit) Joined Host_Wide_Int ByteSize Warning Init(HOST_WIDE_INT_MAX)
 340 -Walloc-size-larger-than=<bytes>        Warn for calls to allocation functions that
 341 attempt to allocate objects larger than the specified number of bytes.
 342
 343 Wno-alloc-size-larger-than
 344 C ObjC C++ LTO ObjC++ Alias(Walloc-size-larger-than=,18446744073709551615EiB,none) Warning
 345 Disable Walloc-size-larger-than= warning.  Equivalent to Walloc-size-larger-than=<SIZE_MAX> or larger.
 346
 347 Walloc-zero
 348 C ObjC C++ ObjC++ Var(warn_alloc_zero) Warning
 349 Warn for calls to allocation functions that specify zero bytes.
 350
 351 Walloca-larger-than=
 352 C ObjC C++ LTO ObjC++ Var(warn_alloca_limit) Warning Joined Host_Wide_Int ByteSize Init(HOST_WIDE_INT_MAX)
 353 -Walloca-larger-than=<number>   Warn on unbounded uses of
 354 alloca, and on bounded uses of alloca whose bound can be larger than
 355 <number> bytes.
 356
 357 Wno-alloca-larger-than
 358 C ObjC C++ LTO ObjC++ Alias(Walloca-larger-than=,18446744073709551615EiB,none) Warning
 359 Disable Walloca-larger-than= warning.  Equivalent to Walloca-larger-than=<SIZE_MAX> or larger.
 360
 361 Warray-bounds=
 362 LangEnabledBy(C ObjC C++ LTO ObjC++,Wall,1,0)
 363 ; in common.opt
 364
 365 Warray-compare
 366 C ObjC C++ ObjC++ Var(warn_array_compare) Warning LangEnabledBy(C ObjC C++ ObjC++, Wall)
 367 Warn about comparisons between two operands of array type.
 368
 369 Warray-parameter
 370 C ObjC C++ ObjC++ Warning Alias(Warray-parameter=, 2, 0)
 371 Warn about mismatched declarations of array parameters and unsafe accesses to them.
 372
 373 Warray-parameter=
 374 C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_array_parameter) IntegerRange(0, 2) LangEnabledBy(C ObjC C++ ObjC++,Wall, 2, 0) Warning
 375 Warn about mismatched declarations of array parameters and unsafe accesses to them.
 376
 377 Wzero-length-bounds
 378 C ObjC C++ ObjC++ Var(warn_zero_length_bounds) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 379 Warn about accesses to interior zero-length array members.
 380
 381 Wassign-intercept
 382 ObjC ObjC++ Var(warn_assign_intercept) Warning
 383 Warn whenever an Objective-C assignment is being intercepted by the garbage collector.
 384
 385 Wbad-function-cast
 386 C ObjC Var(warn_bad_function_cast) Warning
 387 Warn about casting functions to incompatible types.
 388
 389 Wbidi-chars
 390 C ObjC C++ ObjC++ Warning Alias(Wbidi-chars=,any,none)
 391 ;
 392
 393 Wbidi-chars=
 394 C ObjC C++ ObjC++ RejectNegative Joined Warning CPP(cpp_warn_bidirectional) CppReason(CPP_W_BIDIRECTIONAL) Var(warn_bidirectional) Init(bidirectional_unpaired) Enum(cpp_bidirectional_level) EnumSet
 395 -Wbidi-chars=[none|unpaired|any|ucn] Warn about UTF-8 bidirectional control characters.
 396
 397 ; Required for these enum values.
 398 SourceInclude
 399 cpplib.h
 400
 401 Enum
 402 Name(cpp_bidirectional_level) Type(int) UnknownError(argument %qs to %<-Wbidi-chars%> not recognized)
 403
 404 EnumValue
 405 Enum(cpp_bidirectional_level) String(none) Value(bidirectional_none) Set(1)
 406
 407 EnumValue
 408 Enum(cpp_bidirectional_level) String(unpaired) Value(bidirectional_unpaired) Set(1)
 409
 410 EnumValue
 411 Enum(cpp_bidirectional_level) String(any) Value(bidirectional_any) Set(1)
 412
 413 EnumValue
 414 Enum(cpp_bidirectional_level) String(ucn) Value(bidirectional_ucn) Set(2)
 415
 416 Wbool-compare
 417 C ObjC C++ ObjC++ Var(warn_bool_compare) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 418 Warn about boolean expression compared with an integer value different from true/false.
 419
 420 Wbool-operation
 421 C ObjC C++ ObjC++ Var(warn_bool_op) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 422 Warn about certain operations on boolean expressions.
 423
 424 Wframe-address
 425 C ObjC C++ ObjC++ Var(warn_frame_address) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 426 Warn when __builtin_frame_address or __builtin_return_address is used unsafely.
 427
 428 Wbuiltin-declaration-mismatch
 429 C ObjC C++ ObjC++ Var(warn_builtin_declaration_mismatch) Init(1) Warning
 430 Warn when a built-in function is declared with the wrong signature.
 431
 432 Wbuiltin-macro-redefined
 433 C ObjC C++ ObjC++ CPP(warn_builtin_macro_redefined) CppReason(CPP_W_BUILTIN_MACRO_REDEFINED) Var(cpp_warn_builtin_macro_redefined) Init(1) Warning
 434 Warn when a built-in preprocessor macro is undefined or redefined.
 435
 436 Wc11-c23-compat
 437 C ObjC CPP(cpp_warn_c11_c2x_compat) CppReason(CPP_W_C11_C2X_COMPAT) Var(warn_c11_c2x_compat) Init(-1) Warning
 438 Warn about features not present in ISO C11, but present in ISO C23.
 439
 440 Wc11-c2x-compat
 441 C ObjC Alias(Wc11-c23-compat)
 442 Deprecated in favor of -Wc11-c23-compat.
 443
 444 Wc90-c99-compat
 445 C ObjC CPP(cpp_warn_c90_c99_compat) CppReason(CPP_W_C90_C99_COMPAT) Var(warn_c90_c99_compat) Init(-1) Warning
 446 Warn about features not present in ISO C90, but present in ISO C99.
 447
 448 Wc99-c11-compat
 449 C ObjC Var(warn_c99_c11_compat) Init(-1) Warning
 450 Warn about features not present in ISO C99, but present in ISO C11.
 451
 452 Wc++-compat
 453 C ObjC Var(warn_cxx_compat) CPP(warn_cxx_operator_names) CppReason(CPP_W_CXX_OPERATOR_NAMES) Init(0) Warning
 454 Warn about C constructs that are not in the common subset of C and C++.
 455
 456 Wc++0x-compat
 457 C++ ObjC++ Warning Alias(Wc++11-compat) Undocumented
 458
 459 Wc++11-compat
 460 C++ ObjC++ Var(warn_cxx11_compat) Warning LangEnabledBy(C++ ObjC++,Wall) Init(0) CPP(cpp_warn_cxx11_compat) CppReason(CPP_W_CXX11_COMPAT)
 461 Warn about C++ constructs whose meaning differs between ISO C++ 1998 and ISO C++ 2011.
 462
 463 Wc++14-compat
 464 C++ ObjC++ Var(warn_cxx14_compat) Warning LangEnabledBy(C++ ObjC++,Wall)
 465 Warn about C++ constructs whose meaning differs between ISO C++ 2011 and ISO C++ 2014.
 466
 467 Wc++1z-compat
 468 C++ ObjC++ Warning Alias(Wc++17-compat) Undocumented
 469
 470 Wc++17-compat
 471 C++ ObjC++ Var(warn_cxx17_compat) Warning LangEnabledBy(C++ ObjC++,Wall)
 472 Warn about C++ constructs whose meaning differs between ISO C++ 2014 and ISO C++ 2017.
 473
 474 Wc++2a-compat
 475 C++ ObjC++ Warning Alias(Wc++20-compat) Undocumented
 476
 477 Wc++20-compat
 478 C++ ObjC++ Var(warn_cxx20_compat) Warning LangEnabledBy(C++ ObjC++,Wall) Init(0) CPP(cpp_warn_cxx20_compat) CppReason(CPP_W_CXX20_COMPAT)
 479 Warn about C++ constructs whose meaning differs between ISO C++ 2017 and ISO C++ 2020.
 480
 481 Wc++11-extensions
 482 C++ ObjC++ Var(warn_cxx11_extensions) Warning Init(1)
 483 Warn about C++11 constructs in code compiled with an older standard.
 484
 485 Wc++14-extensions
 486 C++ ObjC++ Var(warn_cxx14_extensions) Warning Init(1)
 487 Warn about C++14 constructs in code compiled with an older standard.
 488
 489 Wc++17-extensions
 490 C++ ObjC++ Var(warn_cxx17_extensions) Warning Init(1)
 491 Warn about C++17 constructs in code compiled with an older standard.
 492
 493 Wc++20-extensions
 494 C++ ObjC++ Var(warn_cxx20_extensions) Warning Init(1)
 495 Warn about C++20 constructs in code compiled with an older standard.
 496
 497 Wc++23-extensions
 498 C++ ObjC++ Var(warn_cxx23_extensions) Warning Init(1)
 499 Warn about C++23 constructs in code compiled with an older standard.
 500
 501 Wcast-function-type
 502 C ObjC C++ ObjC++ Var(warn_cast_function_type) Warning EnabledBy(Wextra)
 503 Warn about casts between incompatible function types.
 504
 505 Wcast-qual
 506 C ObjC C++ ObjC++ Var(warn_cast_qual) Warning
 507 Warn about casts which discard qualifiers.
 508
 509 Wcatch-value
 510 C++ ObjC++ Warning Alias(Wcatch-value=, 1, 0)
 511 Warn about catch handlers of non-reference type.
 512
 513 Wcatch-value=
 514 C++ ObjC++ Var(warn_catch_value) Warning Joined RejectNegative UInteger LangEnabledBy(C++ ObjC++,Wall, 1, 0) IntegerRange(0, 3)
 515 Warn about catch handlers of non-reference type.
 516
 517 Wchanges-meaning
 518 C++ ObjC++ Var(warn_changes_meaning) Warning Init(1)
 519 Complain about a name being declared as a class member after a previous use of the same name.
 520
 521 Wchar-subscripts
 522 C ObjC C++ ObjC++ Var(warn_char_subscripts) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 523 Warn about subscripts whose type is \"char\".
 524
 525 Wchkp
 526 C ObjC C++ ObjC++ Warning WarnRemoved
 527 Removed in GCC 9.  This switch has no effect.
 528
 529 Wclobbered
 530 C ObjC C++ ObjC++ Var(warn_clobbered) Warning EnabledBy(Wextra)
 531 Warn about variables that might be changed by \"longjmp\" or \"vfork\".
 532
 533 Wcomma-subscript
 534 C++ ObjC++ Var(warn_comma_subscript) Warning
 535 Warn about uses of a comma operator within a subscripting expression.
 536
 537 Wcomment
 538 C ObjC C++ ObjC++ CPP(warn_comments) CppReason(CPP_W_COMMENTS) Var(cpp_warn_comment) Init(0) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 539 Warn about possibly nested block comments, and C++ comments spanning more than one physical line.
 540
 541 Wcomments
 542 C ObjC C++ ObjC++ Warning Alias(Wcomment)
 543 Synonym for -Wcomment.
 544
 545 Wconditionally-supported
 546 C++ ObjC++ Var(warn_conditionally_supported) Warning
 547 Warn for conditionally-supported constructs.
 548
 549 Wconversion
 550 C ObjC C++ ObjC++ Var(warn_conversion) Warning
 551 Warn for implicit type conversions that may change a value.
 552
 553 Wconversion-null
 554 C++ ObjC++ Var(warn_conversion_null) Init(1) Warning
 555 Warn for converting NULL from/to a non-pointer type.
 556
 557 Wcpp
 558 C ObjC C++ ObjC++ CppReason(CPP_W_WARNING_DIRECTIVE)
 559 ; Documented in common.opt
 560
 561 Wctad-maybe-unsupported
 562 C++ ObjC++ Var(warn_ctad_maybe_unsupported) Warning
 563 Warn when performing class template argument deduction on a type with no
 564 deduction guides.
 565
 566 Wctor-dtor-privacy
 567 C++ ObjC++ Var(warn_ctor_dtor_privacy) Warning
 568 Warn when all constructors and destructors are private.
 569
 570 Wdangling-else
 571 C ObjC C++ ObjC++ Var(warn_dangling_else) Warning LangEnabledBy(C ObjC C++ ObjC++,Wparentheses)
 572 Warn about dangling else.
 573
 574 Wdangling-pointer
 575 C ObjC C++ LTO ObjC++ Alias(Wdangling-pointer=, 2, 0) Warning
 576 Warn for uses of pointers to auto variables whose lifetime has ended.
 577
 578 Wdangling-pointer=
 579 C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_dangling_pointer) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall, 2, 0) IntegerRange(0, 2)
 580 Warn for uses of pointers to auto variables whose lifetime has ended.
 581
 582 Wdangling-reference
 583 C++ ObjC++ Var(warn_dangling_reference) Warning LangEnabledBy(C++ ObjC++, Wall)
 584 Warn when a reference is bound to a temporary whose lifetime has ended.
 585
 586 Wdate-time
 587 C ObjC C++ ObjC++ CPP(warn_date_time) CppReason(CPP_W_DATE_TIME) Var(cpp_warn_date_time) Init(0) Warning
 588 Warn about __TIME__, __DATE__ and __TIMESTAMP__ usage.
 589
 590 Wdeclaration-after-statement
 591 C ObjC Var(warn_declaration_after_statement) Init(-1) Warning
 592 Warn when a declaration is found after a statement.
 593
 594 Wdelete-incomplete
 595 C++ ObjC++ Var(warn_delete_incomplete) Init(1) Warning
 596 Warn when deleting a pointer to incomplete type.
 597
 598 Wdelete-non-virtual-dtor
 599 C++ ObjC++ Var(warn_delnonvdtor) Warning LangEnabledBy(C++ ObjC++,Wall || Weffc++)
 600 Warn about deleting polymorphic objects with non-virtual destructors.
 601
 602 Wdeprecated
 603 C C++ ObjC ObjC++ CPP(cpp_warn_deprecated) CppReason(CPP_W_DEPRECATED)
 604 ; Documented in common.opt
 605
 606 Wdeprecated-copy
 607 C++ ObjC++ Var(warn_deprecated_copy) Warning LangEnabledBy(C++ ObjC++, Wextra)
 608 Mark implicitly-declared copy operations as deprecated if the class has a
 609 user-provided copy operation.
 610
 611 Wdeprecated-copy-dtor
 612 C++ ObjC++ Var(warn_deprecated_copy, 2) Warning
 613 Mark implicitly-declared copy operations as deprecated if the class has a
 614 user-provided copy operation or destructor.
 615
 616 Wdeprecated-enum-enum-conversion
 617 C++ ObjC++ Var(warn_deprecated_enum_enum_conv) Warning
 618 Warn about deprecated arithmetic conversions on operands of enumeration types.
 619
 620 Wdeprecated-enum-float-conversion
 621 C++ ObjC++ Var(warn_deprecated_enum_float_conv) Warning
 622 Warn about deprecated arithmetic conversions on operands where one is of enumeration
 623 type and the other is of a floating-point type.
 624
 625 Wdesignated-init
 626 C ObjC Var(warn_designated_init) Init(1) Warning
 627 Warn about positional initialization of structs requiring designated initializers.
 628
 629 Wdiscarded-array-qualifiers
 630 C ObjC Var(warn_discarded_array_qualifiers) Init(1) Warning
 631 Warn if qualifiers on arrays which are pointer targets are discarded.
 632
 633 Wdiscarded-qualifiers
 634 C ObjC Var(warn_discarded_qualifiers) Init(1) Warning
 635 Warn if type qualifiers on pointers are discarded.
 636
 637 Wdiv-by-zero
 638 C ObjC C++ ObjC++ Var(warn_div_by_zero) Init(1) Warning
 639 Warn about compile-time integer division by zero.
 640
 641 Wduplicated-branches
 642 C ObjC C++ ObjC++ Var(warn_duplicated_branches) Init(0) Warning
 643 Warn about duplicated branches in if-else statements.
 644
 645 Wduplicated-cond
 646 C ObjC C++ ObjC++ Var(warn_duplicated_cond) Init(0) Warning
 647 Warn about duplicated conditions in an if-else-if chain.
 648
 649 Weffc++
 650 C++ ObjC++ Var(warn_ecpp) Warning
 651 Warn about violations of Effective C++ style rules.
 652
 653 Wempty-body
 654 C ObjC C++ ObjC++ Var(warn_empty_body) Warning EnabledBy(Wextra)
 655 Warn about an empty body in an if or else statement.
 656
 657 Wendif-labels
 658 C ObjC C++ ObjC++ CPP(warn_endif_labels) CppReason(CPP_W_ENDIF_LABELS) Var(cpp_warn_endif_labels) Init(1) Warning LangEnabledBy(C ObjC C++ ObjC++,Wpedantic)
 659 Warn about stray tokens after #else and #endif.
 660
 661 Wenum-compare
 662 C ObjC C++ ObjC++ Var(warn_enum_compare) Init(-1) Warning LangEnabledBy(C ObjC,Wall || Wc++-compat)
 663 Warn about comparison of different enum types.
 664
 665 Wenum-conversion
 666 C ObjC C++ ObjC++ Var(warn_enum_conversion) Init(0) Warning LangEnabledBy(C ObjC,Wextra)
 667 Warn about implicit conversion of enum types.
 668
 669 Wenum-int-mismatch
 670 C ObjC Var(warn_enum_int_mismatch) Warning LangEnabledBy(C ObjC,Wall || Wc++-compat)
 671 Warn about enum/integer type mismatches.
 672
 673 Werror
 674 C ObjC C++ ObjC++
 675 ; Documented in common.opt
 676
 677 Werror-implicit-function-declaration
 678 C ObjC RejectNegative Warning Alias(Werror=, implicit-function-declaration)
 679 This switch is deprecated; use -Werror=implicit-function-declaration instead.
 680
 681 Wexceptions
 682 C++ ObjC++ Var(warn_exceptions) Init(1) Warning
 683 Warn when an exception handler is shadowed by another handler.
 684
 685 Wextra
 686 C ObjC C++ ObjC++ Warning
 687 ; in common.opt
 688
 689 Wextra-semi
 690 C++ ObjC++ Var(warn_extra_semi) Warning
 691 Warn about semicolon after in-class function definition.
 692
 693 Wfloat-conversion
 694 C ObjC C++ ObjC++ Var(warn_float_conversion) Warning LangEnabledBy(C ObjC C++ ObjC++,Wconversion)
 695 Warn for implicit type conversions that cause loss of floating point precision.
 696
 697 Wfloat-equal
 698 C ObjC C++ ObjC++ Var(warn_float_equal) Warning
 699 Warn if testing floating point numbers for equality.
 700
 701 Wformat
 702 C ObjC C++ ObjC++ Warning Alias(Wformat=, 1, 0)
 703 Warn about printf/scanf/strftime/strfmon format string anomalies.
 704
 705 Wformat-contains-nul
 706 C ObjC C++ ObjC++ Var(warn_format_contains_nul) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 1, 0)
 707 Warn about format strings that contain NUL bytes.
 708
 709 Wformat-diag
 710 C ObjC C++ ObjC++ Var(warn_format_diag) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 1, 0)
 711 Warn about GCC format strings with strings unsuitable for diagnostics.
 712
 713 Wformat-extra-args
 714 C ObjC C++ ObjC++ Var(warn_format_extra_args) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 1, 0)
 715 Warn if passing too many arguments to a function for its format string.
 716
 717 Wformat-nonliteral
 718 C ObjC C++ ObjC++ Var(warn_format_nonliteral) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 2, 0)
 719 Warn about format strings that are not literals.
 720
 721 Wformat-overflow
 722 C ObjC C++ LTO ObjC++ Warning Alias(Wformat-overflow=, 1, 0) IntegerRange(0, 2)
 723 Warn about function calls with format strings that write past the end
 724 of the destination region.  Same as -Wformat-overflow=1.
 725
 726 Wformat-security
 727 C ObjC C++ ObjC++ Var(warn_format_security) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 2, 0)
 728 Warn about possible security problems with format functions.
 729
 730 Wformat-signedness
 731 C ObjC C++ ObjC++ Var(warn_format_signedness) Warning
 732 Warn about sign differences with format functions.
 733
 734 Wformat-truncation
 735 C ObjC C++ LTO ObjC++ Warning Alias(Wformat-truncation=, 1, 0)
 736 Warn about calls to snprintf and similar functions that truncate output.
 737 Same as -Wformat-truncation=1.
 738
 739 Wformat-y2k
 740 C ObjC C++ ObjC++ Var(warn_format_y2k) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=,warn_format >= 2, 0)
 741 Warn about strftime formats yielding 2-digit years.
 742
 743 Wformat-zero-length
 744 C ObjC C++ ObjC++ Var(warn_format_zero_length) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=,warn_format >= 1, 0)
 745 Warn about zero-length formats.
 746
 747 Wformat=
 748 C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_format) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall, 1, 0) IntegerRange(0, 2)
 749 Warn about printf/scanf/strftime/strfmon format string anomalies.
 750
 751 Wformat-overflow=
 752 C ObjC C++ LTO ObjC++ Joined RejectNegative UInteger Var(warn_format_overflow) Warning LangEnabledBy(C ObjC C++ LTO ObjC++,Wformat=, warn_format >= 1, 0) IntegerRange(0, 2)
 753 Warn about function calls with format strings that write past the end
 754 of the destination region.
 755
 756 Wformat-truncation=
 757 C ObjC C++ LTO ObjC++ Joined RejectNegative UInteger Var(warn_format_trunc) Warning LangEnabledBy(C ObjC C++ LTO ObjC++,Wformat=, warn_format >= 1, 0) IntegerRange(0, 2)
 758 Warn about calls to snprintf and similar functions that truncate output.
 759
 760 Wflex-array-member-not-at-end
 761 C C++ Var(warn_flex_array_member_not_at_end) Warning
 762 Warn when a structure containing a C99 flexible array member as the last
 763 field is not at the end of another structure.
 764
 765 Wif-not-aligned
 766 C ObjC C++ ObjC++ Var(warn_if_not_aligned) Init(1) Warning
 767 Warn when the field in a struct is not aligned.
 768
 769 Wignored-qualifiers
 770 C C++ Var(warn_ignored_qualifiers) Warning EnabledBy(Wextra)
 771 Warn whenever type qualifiers are ignored.
 772
 773 Wignored-attributes
 774 C C++ Var(warn_ignored_attributes) Init(1) Warning
 775 Warn whenever attributes are ignored.
 776
 777 Winaccessible-base
 778 C++ ObjC++ Var(warn_inaccessible_base) Init(1) Warning
 779 Warn when a base is inaccessible in derived due to ambiguity.
 780
 781 Wincompatible-pointer-types
 782 C ObjC Var(warn_incompatible_pointer_types) Init(1) Warning
 783 Warn when there is a conversion between pointers that have incompatible types.
 784
 785 Winfinite-recursion
 786 C ObjC C++ LTO ObjC++ Var(warn_infinite_recursion) Warning LangEnabledBy(C ObjC C++ LTO ObjC++, Wall)
 787 Warn for infinitely recursive calls.
 788
 789 Waddress-of-packed-member
 790 C ObjC C++ ObjC++ Var(warn_address_of_packed_member) Init(1) Warning
 791 Warn when the address of packed member of struct or union is taken.
 792
 793 Winit-self
 794 C ObjC C++ ObjC++ Var(warn_init_self) Warning LangEnabledBy(C++ ObjC++,Wall)
 795 Warn about variables which are initialized to themselves.
 796
 797 Winit-list-lifetime
 798 C++ ObjC++ Var(warn_init_list) Warning Init(1)
 799 Warn about uses of std::initializer_list that can result in dangling pointers.
 800
 801 Winterference-size
 802 C++ ObjC++ Var(warn_interference_size) Warning Init(1)
 803 Warn about nonsensical values of --param destructive-interference-size or
 804 constructive-interference-size.
 805
 806 Wimplicit
 807 C ObjC Var(warn_implicit) Warning LangEnabledBy(C ObjC,Wall)
 808 Warn about implicit declarations.
 809
 810 Wimplicit-fallthrough=
 811 LangEnabledBy(C ObjC C++ ObjC++,Wextra,3,0)
 812 ; in common.opt
 813
 814 Wdouble-promotion
 815 C ObjC C++ ObjC++ Var(warn_double_promotion) Warning
 816 Warn about implicit conversions from \"float\" to \"double\".
 817
 818 Wexpansion-to-defined
 819 C ObjC C++ ObjC++ CPP(warn_expansion_to_defined) CppReason(CPP_W_EXPANSION_TO_DEFINED) Var(cpp_warn_expansion_to_defined) Init(0) Warning EnabledBy(Wextra || Wpedantic)
 820 Warn if \"defined\" is used outside #if.
 821
 822 Wimplicit-function-declaration
 823 C ObjC Var(warn_implicit_function_declaration) Init(-1) Warning LangEnabledBy(C ObjC,Wimplicit)
 824 Warn about implicit function declarations.
 825
 826 Wimplicit-int
 827 C ObjC Var(warn_implicit_int) Init(-1) Warning LangEnabledBy(C ObjC,Wimplicit)
 828 Warn when a declaration does not specify a type.
 829
 830 Wimport
 831 C ObjC C++ ObjC++ Undocumented Ignore
 832
 833 Winherited-variadic-ctor
 834 C++ ObjC++ Var(warn_inh_var_ctor) Init(1) Warning
 835 Warn about C++11 inheriting constructors when the base has a variadic constructor.
 836
 837 Wint-conversion
 838 C ObjC Var(warn_int_conversion) Init(1) Warning
 839 Warn about incompatible integer to pointer and pointer to integer conversions.
 840
 841 Wint-in-bool-context
 842 C ObjC C++ ObjC++ Var(warn_int_in_bool_context) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 843 Warn for suspicious integer expressions in boolean context.
 844
 845 Wint-to-pointer-cast
 846 C ObjC C++ ObjC++ Var(warn_int_to_pointer_cast) Init(1) Warning
 847 Warn when there is a cast to a pointer from an integer of a different size.
 848
 849 Winvalid-constexpr
 850 C++ ObjC++ Var(warn_invalid_constexpr) Init(-1) Warning
 851 Warn when a function never produces a constant expression.
 852
 853 Winvalid-offsetof
 854 C++ ObjC++ Var(warn_invalid_offsetof) Init(1) Warning
 855 Warn about invalid uses of the \"offsetof\" macro.
 856
 857 Winvalid-pch
 858 C ObjC C++ ObjC++ CPP(warn_invalid_pch) CppReason(CPP_W_INVALID_PCH) Var(cpp_warn_invalid_pch) Init(0) Warning
 859 Warn about PCH files that are found but not used.
 860
 861 Winvalid-utf8
 862 C ObjC C++ ObjC++ CPP(cpp_warn_invalid_utf8) CppReason(CPP_W_INVALID_UTF8) Var(warn_invalid_utf8) Init(0) Warning
 863 Warn about invalid UTF-8 characters.
 864
 865 Wjump-misses-init
 866 C ObjC Var(warn_jump_misses_init) Warning LangEnabledby(C ObjC,Wc++-compat)
 867 Warn when a jump misses a variable initialization.
 868
 869 Wliteral-suffix
 870 C++ ObjC++ CPP(warn_literal_suffix) CppReason(CPP_W_LITERAL_SUFFIX) Var(cpp_warn_literal_suffix) Init(1) Warning
 871 Warn when a string or character literal is followed by a ud-suffix which does not begin with an underscore.
 872
 873 Wlogical-op
 874 C ObjC C++ ObjC++ Var(warn_logical_op) Init(0) Warning
 875 Warn when a logical operator is suspiciously always evaluating to true or false.
 876
 877 Wlogical-not-parentheses
 878 C ObjC C++ ObjC++ Var(warn_logical_not_paren) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 879 Warn when logical not is used on the left hand side operand of a comparison.
 880
 881 Wlong-long
 882 C ObjC C++ ObjC++ CPP(cpp_warn_long_long) CppReason(CPP_W_LONG_LONG) Var(warn_long_long) Init(-1) Warning LangEnabledBy(C ObjC,Wc90-c99-compat)
 883 Do not warn about using \"long long\" when -pedantic.
 884
 885 Wmain
 886 C ObjC C++ ObjC++ Var(warn_main) Init(-1) Warning LangEnabledBy(C ObjC,Wall, 2, 0)
 887 Warn about suspicious declarations of \"main\".
 888
 889 Wmain
 890 LangEnabledBy(C ObjC C++ ObjC++,Wpedantic, 2, 0)
 891 ;
 892
 893 Wmemset-transposed-args
 894 C ObjC C++ ObjC++ Var(warn_memset_transposed_args) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 895 Warn about suspicious calls to memset where the third argument is constant literal zero and the second is not.
 896
 897 Wmemset-elt-size
 898 C ObjC C++ ObjC++ Var(warn_memset_elt_size) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 899 Warn about suspicious calls to memset where the third argument contains the number of elements not multiplied by the element size.
 900
 901 Wmisleading-indentation
 902 C C++ Common Var(warn_misleading_indentation) Warning LangEnabledBy(C C++,Wall)
 903 Warn when the indentation of the code does not reflect the block structure.
 904
 905 Wmismatched-dealloc
 906 C ObjC C++ ObjC++ Var(warn_mismatched_alloc) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 907 Warn for deallocation calls with arguments returned from mismatched allocation
 908 functions.
 909
 910 Wmismatched-new-delete
 911 C++ ObjC++ Var(warn_mismatched_new_delete) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 912 Warn for mismatches between calls to operator new or delete and the corresponding
 913 call to the allocation or deallocation function.
 914
 915 Wmismatched-tags
 916 C++ ObjC++ Var(warn_mismatched_tags) Warning
 917 Warn when a class is redeclared or referenced using a mismatched class-key.
 918
 919 Wmissing-braces
 920 C ObjC C++ ObjC++ Var(warn_missing_braces) Warning LangEnabledBy(C ObjC,Wall)
 921 Warn about possibly missing braces around initializers.
 922
 923 Wmissing-declarations
 924 C ObjC C++ ObjC++ Var(warn_missing_declarations) Warning
 925 Warn about global functions without previous declarations.
 926
 927 Wmissing-field-initializers
 928 C ObjC C++ ObjC++ Var(warn_missing_field_initializers) Warning EnabledBy(Wextra)
 929 Warn about missing fields in struct initializers.
 930
 931 Wmissing-requires
 932 C++ ObjC++ Var(warn_missing_requires) Init(1) Warning
 933 Warn about likely missing requires keyword.
 934
 935 Wmissing-template-keyword
 936 C++ ObjC++ Var(warn_missing_template_keyword) Init(1) Warning
 937 Warn when the template keyword is missing after a member access token in a dependent member access expression if that member is a template.
 938
 939 Wmultistatement-macros
 940 C ObjC C++ ObjC++ Var(warn_multistatement_macros) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 941 Warn about unsafe macros expanding to multiple statements used as a body of a clause such as if, else, while, switch, or for.
 942
 943 Wmultiple-inheritance
 944 C++ ObjC++ Var(warn_multiple_inheritance) Warning
 945 Warn on direct multiple inheritance.
 946
 947 Wnamespaces
 948 C++ ObjC++ Var(warn_namespaces) Warning
 949 Warn on namespace definition.
 950
 951 Wnrvo
 952 C++ ObjC++ Var(warn_nrvo)
 953 Warn if the named return value optimization is not performed although it is allowed.
 954
 955 Wpacked-not-aligned
 956 C ObjC C++ ObjC++ Var(warn_packed_not_aligned) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 957 Warn when fields in a struct with the packed attribute are misaligned.
 958
 959 Wrange-loop-construct
 960 C++ ObjC++ Var(warn_range_loop_construct) Warning LangEnabledBy(C++ ObjC++,Wall)
 961 Warn when a range-based for-loop is creating unnecessary copies.
 962
 963 Wredundant-tags
 964 C++ ObjC++ Var(warn_redundant_tags) Warning
 965 Warn when a class or enumerated type is referenced using a redundant class-key.
 966
 967 Wsized-deallocation
 968 C++ ObjC++ Var(warn_sized_deallocation) Warning EnabledBy(Wextra)
 969 Warn about missing sized deallocation functions.
 970
 971 Wsizeof-pointer-div
 972 C ObjC C++ ObjC++ Var(warn_sizeof_pointer_div) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 973 Warn about suspicious divisions of two sizeof expressions that don't work correctly with pointers.
 974
 975 Wsizeof-array-div
 976 C ObjC C++ ObjC++ Var(warn_sizeof_array_div) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 977 Warn about divisions of two sizeof operators when the first one is applied
 978 to an array and the divisor does not equal the size of the array element.
 979
 980 Wsizeof-pointer-memaccess
 981 C ObjC C++ ObjC++ Var(warn_sizeof_pointer_memaccess) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 982 Warn about suspicious length parameters to certain string functions if the argument uses sizeof.
 983
 984 Wsizeof-array-argument
 985 C ObjC C++ ObjC++ Var(warn_sizeof_array_argument) Warning Init(1)
 986 Warn when sizeof is applied on a parameter declared as an array.
 987
 988 Wstring-compare
 989 C ObjC C++ LTO ObjC++ Warning Var(warn_string_compare) Warning LangEnabledBy(C ObjC C++ ObjC++, Wextra)
 990 Warn about calls to strcmp and strncmp used in equality expressions that
 991 are necessarily true or false due to the length of one and size of the other
 992 argument.
 993
 994 Wstringop-overflow
 995 C ObjC C++ LTO ObjC++ Warning Alias(Wstringop-overflow=, 2, 0)
 996 Warn about buffer overflow in string manipulation functions like memcpy
 997 and strcpy.
 998
 999 Wstringop-overflow=
1000 C ObjC C++ LTO ObjC++ Joined RejectNegative UInteger Var(warn_stringop_overflow) Init(2) Warning LangEnabledBy(C ObjC C++ LTO ObjC++, Wall, 2, 0) IntegerRange(0, 4)
1001 Under the control of Object Size type, warn about buffer overflow in string
1002 manipulation functions like memcpy and strcpy.
1003
1004 Wstringop-overread
1005 C ObjC C++ LTO ObjC++ Var(warn_stringop_overread) Init(1) Warning LangEnabledBy(C ObjC C++ LTO ObjC++, Wall)
1006 Warn about reading past the end of a source array in string manipulation functions like memchr and memcpy.
1007
1008 Wstringop-truncation
1009 C ObjC C++ LTO ObjC++ Var(warn_stringop_truncation) Warning Init (1) LangEnabledBy(C ObjC C++ LTO ObjC++, Wall)
1010 Warn about truncation in string manipulation functions like strncat and strncpy.
1011
1012 Wstrict-flex-arrays
1013 C C++ Var(warn_strict_flex_arrays) Warning
1014 Warn about inproper usages of flexible array members
1015 according to the level of -fstrict-flex-arrays.
1016
1017 Wsuggest-attribute=format
1018 C ObjC C++ ObjC++ Var(warn_suggest_attribute_format) Warning
1019 Warn about functions which might be candidates for format attributes.
1020
1021 Wsuggest-override
1022 C++ ObjC++ Var(warn_override) Warning
1023 Suggest that the override keyword be used when the declaration of a virtual
1024 function overrides another.
1025
1026 Wswitch
1027 C ObjC C++ ObjC++ Var(warn_switch) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1028 Warn about enumerated switches, with no default, missing a case.
1029
1030 Wswitch-default
1031 C ObjC C++ ObjC++ Var(warn_switch_default) Warning
1032 Warn about enumerated switches missing a \"default:\" statement.
1033
1034 Wswitch-enum
1035 C ObjC C++ ObjC++ Var(warn_switch_enum) Warning
1036 Warn about all enumerated switches missing a specific case.
1037
1038 Wswitch-bool
1039 C ObjC C++ ObjC++ Var(warn_switch_bool) Warning Init(1)
1040 Warn about switches with boolean controlling expression.
1041
1042 Wswitch-outside-range
1043 C ObjC C++ ObjC++ Var(warn_switch_outside_range) Warning Init(1)
1044 Warn about switch values that are outside of the switch's type range.
1045
1046 Wtemplates
1047 C++ ObjC++ Var(warn_templates) Warning
1048 Warn on primary template declaration.
1049
1050 Wmissing-attributes
1051 C ObjC C++ ObjC++ Var(warn_missing_attributes) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1052 Warn about declarations of entities that may be missing attributes
1053 that related entities have been declared with.
1054
1055 Wmissing-format-attribute
1056 C ObjC C++ ObjC++ Warning Alias(Wsuggest-attribute=format)
1057 ;
1058
1059 Wmissing-include-dirs
1060 C ObjC C++ ObjC++ CPP(warn_missing_include_dirs) CppReason(CPP_W_MISSING_INCLUDE_DIRS) Var(cpp_warn_missing_include_dirs) Init(0) Warning
1061 Warn about user-specified include directories that do not exist.
1062
1063 Wmissing-parameter-type
1064 C ObjC Var(warn_missing_parameter_type) Warning EnabledBy(Wextra)
1065 Warn about function parameters declared without a type specifier in K&R-style functions.
1066
1067 Wmissing-prototypes
1068 C ObjC Var(warn_missing_prototypes) Warning
1069 Warn about global functions without prototypes.
1070
1071 Wmissing-variable-declarations
1072 C ObjC Var(warn_missing_variable_declarations) Warning
1073 Warn about global variables without previous declarations.
1074
1075 Wmudflap
1076 C ObjC C++ ObjC++ WarnRemoved
1077
1078 Wmultichar
1079 C ObjC C++ ObjC++ CPP(warn_multichar) CppReason(CPP_W_MULTICHAR) Var(cpp_warn_multichar) Init(0) Warning
1080 Warn about use of multi-character character constants.
1081
1082 Wnarrowing
1083 C ObjC C++ ObjC++ Warning Var(warn_narrowing) Init(-1) LangEnabledBy(C++ ObjC++,Wall || Wc++11-compat)
1084 Warn about narrowing conversions within { } that are ill-formed in C++11.
1085
1086 Wnested-externs
1087 C ObjC Var(warn_nested_externs) Warning
1088 Warn about \"extern\" declarations not at file scope.
1089
1090 Wnoexcept
1091 C++ ObjC++ Var(warn_noexcept) Warning
1092 Warn when a noexcept expression evaluates to false even though the expression can't actually throw.
1093
1094 Wnoexcept-type
1095 C++ ObjC++ Warning Var(warn_noexcept_type) LangEnabledBy(C++ ObjC++,Wabi || Wc++17-compat)
1096 Warn if C++17 noexcept function type will change the mangled name of a symbol.
1097
1098 Wnon-template-friend
1099 C++ ObjC++ Var(warn_nontemplate_friend) Init(1) Warning
1100 Warn when non-templatized friend functions are declared within a template.
1101
1102 Wclass-conversion
1103 C++ ObjC++ Var(warn_class_conversion) Init(1) Warning
1104 Warn when a conversion function will never be called due to the type it converts to.
1105
1106 Wclass-memaccess
1107 C++ ObjC++ Var(warn_class_memaccess) Warning LangEnabledBy(C++ ObjC++, Wall)
1108 Warn for unsafe raw memory writes to objects of class types.
1109
1110 Wnon-virtual-dtor
1111 C++ ObjC++ Var(warn_nonvdtor) Warning LangEnabledBy(C++ ObjC++,Weffc++)
1112 Warn about non-virtual destructors.
1113
1114 Wnonnull
1115 C ObjC C++ LTO ObjC++ Var(warn_nonnull) Warning LangEnabledBy(C ObjC C++ LTO ObjC++,Wformat=,warn_format >= 1,0)
1116 Warn about NULL being passed to argument slots marked as requiring non-NULL.
1117
1118 Wnonnull
1119 C ObjC C++ LTO ObjC++ LangEnabledBy(C ObjC C++ LTO ObjC++,Wall)
1120 ;
1121
1122 Wnonnull-compare
1123 C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wall)
1124 ;
1125
1126 Wnormalized
1127 C ObjC C++ ObjC++ Warning Alias(Wnormalized=,nfc,none)
1128 ;
1129
1130 Wnormalized=
1131 C ObjC C++ ObjC++ RejectNegative Joined Warning CPP(warn_normalize) CppReason(CPP_W_NORMALIZE) Init(normalized_C) Var(cpp_warn_normalize) Enum(cpp_normalize_level)
1132 -Wnormalized=[none|id|nfc|nfkc] Warn about non-normalized Unicode strings.
1133
1134 ; Required for these enum values.
1135 SourceInclude
1136 cpplib.h
1137
1138 Enum
1139 Name(cpp_normalize_level) Type(int) UnknownError(argument %qs to %<-Wnormalized%> not recognized)
1140
1141 EnumValue
1142 Enum(cpp_normalize_level) String(none) Value(normalized_none)
1143
1144 EnumValue
1145 Enum(cpp_normalize_level) String(nfkc) Value(normalized_KC)
1146
1147 EnumValue
1148 Enum(cpp_normalize_level) String(id) Value(normalized_identifier_C)
1149
1150 EnumValue
1151 Enum(cpp_normalize_level) String(nfc) Value(normalized_C)
1152
1153 Wobjc-root-class
1154 ObjC ObjC++ Var(warn_objc_root_class) Warning Init(1)
1155 Warn if a class interface has no superclass.  Root classes may use an attribute
1156 to suppress this warning.
1157
1158 Wold-style-cast
1159 C++ ObjC++ Var(warn_old_style_cast) Warning
1160 Warn if a C-style cast is used in a program.
1161
1162 Wold-style-declaration
1163 C ObjC Var(warn_old_style_declaration) Warning EnabledBy(Wextra)
1164 Warn for obsolescent usage in a declaration.
1165
1166 Wold-style-definition
1167 C ObjC Var(warn_old_style_definition) Init(-1) Warning
1168 Warn if an old-style parameter definition is used.
1169
1170 Wopenacc-parallelism
1171 C C++ Var(warn_openacc_parallelism) Warning
1172 Warn about potentially suboptimal choices related to OpenACC parallelism.
1173
1174 Wopenmp-simd
1175 C C++ Var(warn_openmp_simd) Warning LangEnabledBy(C C++,Wall)
1176 Warn if a simd directive is overridden by the vectorizer cost model.
1177
1178 Woverlength-strings
1179 C ObjC C++ ObjC++ Var(warn_overlength_strings) Warning LangEnabledBy(C ObjC C++ ObjC++,Wpedantic)
1180 Warn if a string is longer than the maximum portable length specified by the standard.
1181
1182 Woverloaded-virtual
1183 C++ ObjC++ Warning Alias(Woverloaded-virtual=,2,0)
1184 Warn about overloaded virtual function names.
1185
1186 Woverloaded-virtual=
1187 C++ ObjC++ Joined UInteger IntegerRange(0,2) Var(warn_overloaded_virtual) Warning LangEnabledBy(C++ ObjC++,Wall,1,0)
1188 Warn about overloaded virtual function names.
1189
1190 Woverride-init
1191 C ObjC Var(warn_override_init) Warning EnabledBy(Wextra)
1192 Warn about overriding initializers without side effects.
1193
1194 Woverride-init-side-effects
1195 C ObjC Var(warn_override_init_side_effects) Init(1) Warning
1196 Warn about overriding initializers with side effects.
1197
1198 Wpacked-bitfield-compat
1199 C ObjC C++ ObjC++ Var(warn_packed_bitfield_compat) Init(-1) Warning
1200 Warn about packed bit-fields whose offset changed in GCC 4.4.
1201
1202 Wparentheses
1203 C ObjC C++ ObjC++ Var(warn_parentheses) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1204 Warn about possibly missing parentheses.
1205
1206 Wpedantic
1207 C ObjC C++ ObjC++ CPP(cpp_pedantic) CppReason(CPP_W_PEDANTIC) Warning
1208 ; Documented in common.opt
1209
1210 Wpessimizing-move
1211 C++ ObjC++ Var(warn_pessimizing_move) Warning LangEnabledBy(C++ ObjC++, Wall)
1212 Warn about calling std::move on a local object in a return statement preventing copy elision.
1213
1214 Wpmf-conversions
1215 C++ ObjC++ Var(warn_pmf2ptr) Init(1) Warning
1216 Warn when converting the type of pointers to member functions.
1217
1218 Wpointer-arith
1219 C ObjC C++ ObjC++ Var(warn_pointer_arith) Warning LangEnabledBy(C ObjC C++ ObjC++,Wpedantic)
1220 Warn about function pointer arithmetic.
1221
1222 Wpointer-sign
1223 C ObjC Var(warn_pointer_sign) Warning LangEnabledBy(C ObjC,Wall || Wpedantic)
1224 Warn when a pointer differs in signedness in an assignment.
1225
1226 Wpointer-compare
1227 C ObjC C++ ObjC++ Var(warn_pointer_compare) Init(1) Warning
1228 Warn when a pointer is compared with a zero character constant.
1229
1230 Wpointer-to-int-cast
1231 C ObjC Var(warn_pointer_to_int_cast) Init(1) Warning
1232 Warn when a pointer is cast to an integer of a different size.
1233
1234 Wpragmas
1235 C ObjC C++ ObjC++ Var(warn_pragmas) Init(1) Warning
1236 Warn about misuses of pragmas.
1237
1238 Wprio-ctor-dtor
1239 C ObjC C++ ObjC++ Var(warn_prio_ctor_dtor) Init(1) Warning
1240 Warn if constructor or destructors with priorities from 0 to 100 are used.
1241
1242 Wproperty-assign-default
1243 ObjC ObjC++ Var(warn_property_assign_default) Init(1) Warning
1244 Warn if a property for an Objective-C object has no assign semantics specified.
1245
1246 Wprotocol
1247 ObjC ObjC++ Var(warn_protocol) Init(1) Warning
1248 Warn if inherited methods are unimplemented.
1249
1250 Wplacement-new
1251 C++ Warning Alias(Wplacement-new=, 1, 0)
1252 Warn for placement new expressions with undefined behavior.
1253
1254 Wplacement-new=
1255 C++ Joined RejectNegative UInteger Var(warn_placement_new) Init(-1) Warning IntegerRange(0, 2)
1256 Warn for placement new expressions with undefined behavior.
1257
1258 Wredundant-decls
1259 C ObjC C++ ObjC++ Var(warn_redundant_decls) Warning
1260 Warn about multiple declarations of the same object.
1261
1262 Wredundant-move
1263 C++ ObjC++ Var(warn_redundant_move) Warning LangEnabledBy(C++ ObjC++,Wextra)
1264 Warn about redundant calls to std::move.
1265
1266 Wregister
1267 C++ ObjC++ Var(warn_register) Warning
1268 Warn about uses of register storage specifier.
1269
1270 Wreorder
1271 C++ ObjC++ Var(warn_reorder) Warning LangEnabledBy(C++ ObjC++,Wall)
1272 Warn when the compiler reorders code.
1273
1274 Wreturn-type
1275 C ObjC C++ ObjC++ Var(warn_return_type) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall) Init(-1)
1276 Warn whenever a function's return type defaults to \"int\" (C), or about inconsistent return types (C++).
1277
1278 Wscalar-storage-order
1279 C ObjC C++ ObjC++ Var(warn_scalar_storage_order) Init(1) Warning
1280 Warn on suspicious constructs involving reverse scalar storage order.
1281
1282 Wselector
1283 ObjC ObjC++ Var(warn_selector) Warning
1284 Warn if a selector has multiple methods.
1285
1286 Wself-move
1287 C++ ObjC++ Var(warn_self_move) Warning LangEnabledBy(C++ ObjC++, Wall)
1288 Warn when a value is moved to itself with std::move.
1289
1290 Wsequence-point
1291 C ObjC C++ ObjC++ Var(warn_sequence_point) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1292 Warn about possible violations of sequence point rules.
1293
1294 Wshadow-ivar
1295 ObjC ObjC++ Var(warn_shadow_ivar) EnabledBy(Wshadow) Init(1) Warning
1296 Warn if a local declaration hides an instance variable.
1297
1298 Wshift-overflow
1299 C ObjC C++ ObjC++ Warning Alias(Wshift-overflow=, 1, 0)
1300 Warn if left shift of a signed value overflows.
1301
1302 Wshift-overflow=
1303 C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_shift_overflow) Init(-1) Warning IntegerRange(0, 2)
1304 Warn if left shift of a signed value overflows.
1305
1306 Wshift-count-negative
1307 C ObjC C++ ObjC++ Var(warn_shift_count_negative) Init(1) Warning
1308 Warn if shift count is negative.
1309
1310 Wshift-count-overflow
1311 C ObjC C++ ObjC++ Var(warn_shift_count_overflow) Init(1) Warning
1312 Warn if shift count >= width of type.
1313
1314 Wshift-negative-value
1315 C ObjC C++ ObjC++ Var(warn_shift_negative_value) Init(-1) Warning
1316 Warn if left shifting a negative value.
1317
1318 Warith-conversion
1319 C ObjC C++ ObjC++ Var(warn_arith_conv) Warning
1320 Warn if conversion of the result of arithmetic might change the value even though converting the operands cannot.
1321
1322 Wsign-compare
1323 C ObjC C++ ObjC++ Var(warn_sign_compare) Warning LangEnabledBy(C++ ObjC++,Wall)
1324 Warn about signed-unsigned comparisons.
1325
1326 Wsign-compare
1327 C ObjC C++ ObjC++ EnabledBy(Wextra)
1328 ;
1329
1330 Wsign-conversion
1331 C ObjC C++ ObjC++ Var(warn_sign_conversion) Warning LangEnabledBy(C ObjC,Wconversion)
1332 Warn for implicit type conversions between signed and unsigned integers.
1333
1334 Wsign-promo
1335 C++ ObjC++ Var(warn_sign_promo) Warning
1336 Warn when overload promotes from unsigned to signed.
1337
1338 Wstrict-null-sentinel
1339 C++ ObjC++ Warning Var(warn_strict_null_sentinel)
1340 Warn about uncasted NULL used as sentinel.
1341
1342 Wstrict-prototypes
1343 C ObjC Var(warn_strict_prototypes) Warning
1344 Warn about unprototyped function declarations.
1345
1346 Wstrict-aliasing=
1347 C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wall, 3, 0) IntegerRange(0, 3)
1348 ;
1349
1350 Wstrict-overflow=
1351 C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wall, 1, 0) IntegerRange(0, 5)
1352 ;
1353
1354 Wstrict-selector-match
1355 ObjC ObjC++ Var(warn_strict_selector_match) Warning
1356 Warn if type signatures of candidate methods do not match exactly.
1357
1358 Wsync-nand
1359 C C++ Var(warn_sync_nand) Init(1) Warning
1360 Warn when __sync_fetch_and_nand and __sync_nand_and_fetch built-in functions are used.
1361
1362 Wsynth
1363 C++ ObjC++ Var(warn_synth) Warning
1364 Deprecated.  This switch has no effect.
1365
1366 Wsystem-headers
1367 C ObjC C++ ObjC++ Warning
1368 ; Documented in common.opt
1369
1370 Wtautological-compare
1371 C ObjC C++ ObjC++ Var(warn_tautological_compare) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1372 Warn if a comparison always evaluates to true or false.
1373
1374 Wterminate
1375 C++ ObjC++ Warning Var(warn_terminate) Init(1)
1376 Warn if a throw expression will always result in a call to terminate().
1377
1378 Wtraditional
1379 C ObjC CPP(cpp_warn_traditional) CppReason(CPP_W_TRADITIONAL) Var(warn_traditional) Init(0) Warning
1380 Warn about features not present in traditional C.
1381
1382 Wtraditional-conversion
1383 C ObjC Var(warn_traditional_conversion) Warning
1384 Warn of prototypes causing type conversions different from what would happen in the absence of prototype.
1385
1386 Wtrigraphs
1387 C ObjC C++ ObjC++ CPP(warn_trigraphs) CppReason(CPP_W_TRIGRAPHS) Var(cpp_warn_trigraphs) Init(2) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1388 Warn if trigraphs are encountered that might affect the meaning of the program.
1389
1390 Wundeclared-selector
1391 ObjC ObjC++ Var(warn_undeclared_selector) Warning
1392 Warn about @selector()s without previously declared methods.
1393
1394 Wundef
1395 C ObjC C++ ObjC++ CPP(warn_undef) CppReason(CPP_W_UNDEF) Var(cpp_warn_undef) Init(0) Warning
1396 Warn if an undefined macro is used in an #if directive.
1397
1398 Wunicode
1399 C ObjC C++ ObjC++ CPP(cpp_warn_unicode) CppReason(CPP_W_UNICODE) Var(warn_unicode) Init(1) Warning
1400 Warn about invalid forms of delimited or named escape sequences.
1401
1402 Wuninitialized
1403 C ObjC C++ ObjC++ LTO LangEnabledBy(C ObjC C++ ObjC++ LTO,Wall)
1404 ;
1405
1406 Wmaybe-uninitialized
1407 C ObjC C++ ObjC++ LTO LangEnabledBy(C ObjC C++ ObjC++ LTO,Wall)
1408 ;
1409
1410 Wunknown-pragmas
1411 C ObjC C++ ObjC++ Warning Var(warn_unknown_pragmas) LangEnabledBy(C ObjC C++ ObjC++,Wall, 1, 0)
1412 Warn about unrecognized pragmas.
1413
1414 Wunsuffixed-float-constants
1415 C ObjC Var(warn_unsuffixed_float_constants) Warning
1416 Warn about unsuffixed float constants.
1417
1418 Wunused
1419 C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wall)
1420 ; documented in common.opt
1421
1422 Wunused-local-typedefs
1423 C ObjC C++ ObjC++ Var(warn_unused_local_typedefs) Warning EnabledBy(Wunused)
1424 Warn when typedefs locally defined in a function are not used.
1425
1426 Wunused-macros
1427 C ObjC C++ ObjC++ CppReason(CPP_W_UNUSED_MACROS) Var(cpp_warn_unused_macros) Warning
1428 Warn about macros defined in the main file that are not used.
1429
1430 Wunused-result
1431 C ObjC C++ ObjC++ Var(warn_unused_result) Init(1) Warning
1432 Warn if a caller of a function, marked with attribute warn_unused_result, does not use its return value.
1433
1434 Wunused-variable
1435 C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wunused)
1436 ; documented in common.opt
1437
1438 Wunused-const-variable
1439 C ObjC C++ ObjC++ Warning Alias(Wunused-const-variable=, 2, 0)
1440 Warn when a const variable is unused.
1441
1442 Wunused-const-variable=
1443 C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_unused_const_variable) Warning LangEnabledBy(C ObjC,Wunused-variable, 1, 0) IntegerRange(0, 2)
1444 Warn when a const variable is unused.
1445
1446 ; Defining this option here in addition to common.opt is necessary
1447 ; in order for the default -Wall setting of -Wuse-after-free=2 to take
1448 ; effect.
1449
1450 Wuse-after-free=
1451 LangEnabledBy(C ObjC C++ LTO ObjC++, Wall,2,0)
1452 ; in common.opt
1453
1454 Wvariadic-macros
1455 C ObjC C++ ObjC++ CPP(warn_variadic_macros) CppReason(CPP_W_VARIADIC_MACROS) Var(cpp_warn_variadic_macros) Init(0) Warning LangEnabledBy(C ObjC C++ ObjC++,Wpedantic || Wtraditional)
1456 Warn about using variadic macros.
1457
1458 Wvarargs
1459 C ObjC C++ ObjC++ Warning Var(warn_varargs) Init(1)
1460 Warn about questionable usage of the macros used to retrieve variable arguments.
1461
1462 Wvexing-parse
1463 C++ ObjC++ Warning Var(warn_vexing_parse) Init(1)
1464 Warn about the most vexing parse syntactic ambiguity.
1465
1466 Wvla
1467 C ObjC C++ ObjC++ Var(warn_vla) Init(-1) Warning
1468 Warn if a variable length array is used.
1469
1470 Wvla-larger-than=
1471 C ObjC C++ LTO ObjC++ Var(warn_vla_limit) Warning Joined Host_Wide_Int ByteSize Init(HOST_WIDE_INT_MAX)
1472 -Wvla-larger-than=<number>      Warn on unbounded uses of variable-length
1473 arrays, and on bounded uses of variable-length arrays whose bound can be
1474 larger than <number> bytes.
1475
1476 Wno-vla-larger-than
1477 C ObjC C++ LTO ObjC++ Alias(Wvla-larger-than=,18446744073709551615EiB,none) Warning
1478 Disable Wvla-larger-than= warning.  Equivalent to Wvla-larger-than=<SIZE_MAX> or larger.
1479
1480 Wvla-parameter
1481 C ObjC C++ ObjC++ Var(warn_vla_parameter) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1482 Warn about mismatched declarations of VLA parameters.
1483
1484 Wvolatile
1485 C++ ObjC++ Var(warn_volatile) Warning
1486 Warn about deprecated uses of volatile qualifier.
1487
1488 Wvolatile-register-var
1489 C ObjC C++ ObjC++ Var(warn_volatile_register_var) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1490 Warn when a register variable is declared volatile.
1491
1492 Wvirtual-inheritance
1493 C++ ObjC++ Var(warn_virtual_inheritance) Warning
1494 Warn on direct virtual inheritance.
1495
1496 Wvirtual-move-assign
1497 C++ ObjC++ Var(warn_virtual_move_assign) Warning Init(1)
1498 Warn if a virtual base has a non-trivial move assignment operator.
1499
1500 Wwrite-strings
1501 C ObjC C++ ObjC++ Var(warn_write_strings) Warning
1502 In C++, nonzero means warn about deprecated conversion from string literals to 'char *'.  In C, similar warning, except that the conversion is of course not deprecated by the ISO C standard.
1503
1504 Wxor-used-as-pow
1505 C ObjC C++ ObjC++ Var(warn_xor_used_as_pow) Warning Init(1)
1506 Warn about xor operators where it appears the user meant exponentiation.
1507
1508 Wzero-as-null-pointer-constant
1509 C++ ObjC++ Var(warn_zero_as_null_pointer_constant) Warning
1510 Warn when a literal '0' is used as null pointer.
1511
1512 Wuseless-cast
1513 C ObjC C++ ObjC++ Var(warn_useless_cast) Warning
1514 Warn about useless casts.
1515
1516 Wsubobject-linkage
1517 C++ ObjC++ Var(warn_subobject_linkage) Warning Init(1)
1518 Warn if a class type has a base or a field whose type uses the anonymous namespace or depends on a type with no linkage.
1519
1520 Welaborated-enum-base
1521 C++ ObjC++ Var(warn_elaborated_enum_base) Warning Init(1)
1522 Warn if an additional enum-base is used in an elaborated-type-specifier.
1523
1524 Wduplicate-decl-specifier
1525 C ObjC Var(warn_duplicate_decl_specifier) Warning LangEnabledBy(C ObjC,Wall)
1526 Warn when a declaration has duplicate const, volatile, restrict or _Atomic specifier.
1527
1528 Wrestrict
1529 C ObjC C++ ObjC++ Var(warn_restrict) Warning LangEnabledBy(C ObjC C++ ObjC++, Wall)
1530 Warn when an argument passed to a restrict-qualified parameter aliases with
1531 another argument.
1532
1533 ansi
1534 C ObjC C++ ObjC++
1535 A synonym for -std=c89 (for C) or -std=c++98 (for C++).
1536
1537 d
1538 C ObjC C++ ObjC++ Joined
1539 ; Documented in common.opt.  FIXME - what about -dI, -dD, -dN and -dD?
1540
1541 fabi-compat-version=
1542 C++ ObjC++ Joined RejectNegative UInteger Var(flag_abi_compat_version) Init(-1)
1543 The version of the C++ ABI used for -Wabi warnings and link compatibility aliases.
1544
1545 faccess-control
1546 C++ ObjC++ Var(flag_access_control) Init(1)
1547 Enforce class member access control semantics.
1548
1549 fada-spec-parent=
1550 C ObjC C++ ObjC++ RejectNegative Joined Var(ada_specs_parent)
1551 -fada-spec-parent=unit  Dump Ada specs as child units of given parent.
1552
1553 faligned-new
1554 C++ ObjC++ Alias(faligned-new=,1,0)
1555 Support C++17 allocation of over-aligned types.
1556
1557 faligned-new=
1558 C++ ObjC++ Joined RejectNegative Var(aligned_new_threshold) UInteger Init(-1)
1559 -faligned-new=<N>       Use C++17 over-aligned type allocation for alignments greater than N.
1560
1561 fall-virtual
1562 C++ ObjC++ WarnRemoved
1563
1564 fallow-parameterless-variadic-functions
1565 C ObjC Ignore
1566 Does nothing. Preserved for backward compatibility.
1567
1568 falt-external-templates
1569 C++ ObjC++ WarnRemoved
1570 No longer supported.
1571
1572 fasm
1573 C ObjC C++ ObjC++ Var(flag_no_asm, 0)
1574 Recognize the \"asm\" keyword.
1575
1576 ; Define extra predefined macros for use in libgcc.
1577 fbuilding-libgcc
1578 C ObjC C++ ObjC++ Undocumented Var(flag_building_libgcc)
1579
1580 fbuiltin
1581 C ObjC C++ ObjC++ Var(flag_no_builtin, 0)
1582 Recognize built-in functions.
1583
1584 fbuiltin-
1585 C ObjC C++ ObjC++ Joined
1586
1587 fcanonical-system-headers
1588 C ObjC C++ ObjC++
1589 Where shorter, use canonicalized paths to systems headers.
1590
1591 fchar8_t
1592 C++ ObjC++ Var(flag_char8_t) Init(-1)
1593 Enable the char8_t fundamental type and use it as the type for UTF-8 string
1594 and character literals.
1595
1596 fcheck-pointer-bounds
1597 C ObjC C++ ObjC++ LTO WarnRemoved
1598 Removed in GCC 9.  This switch has no effect.
1599
1600 fchkp-check-incomplete-type
1601 C ObjC C++ ObjC++ LTO WarnRemoved
1602 Removed in GCC 9.  This switch has no effect.
1603
1604 fchkp-zero-input-bounds-for-main
1605 C ObjC C++ ObjC++ LTO WarnRemoved
1606 Removed in GCC 9.  This switch has no effect.
1607
1608 fchkp-first-field-has-own-bounds
1609 C ObjC C++ ObjC++ LTO WarnRemoved RejectNegative
1610 Removed in GCC 9.  This switch has no effect.
1611
1612 fchkp-narrow-bounds
1613 C ObjC C++ ObjC++ LTO WarnRemoved
1614 Removed in GCC 9.  This switch has no effect.
1615
1616 fchkp-narrow-to-innermost-array
1617 C ObjC C++ ObjC++ LTO WarnRemoved RejectNegative
1618 Removed in GCC 9.  This switch has no effect.
1619
1620 fchkp-flexible-struct-trailing-arrays
1621 C ObjC C++ ObjC++ LTO WarnRemoved
1622 Removed in GCC 9.  This switch has no effect.
1623
1624 fchkp-optimize
1625 C ObjC C++ ObjC++ LTO WarnRemoved
1626
1627 fchkp-use-fast-string-functions
1628 C ObjC C++ ObjC++ LTO WarnRemoved
1629 Removed in GCC 9.  This switch has no effect.
1630
1631 fchkp-use-nochk-string-functions
1632 C ObjC C++ ObjC++ LTO WarnRemoved
1633 Removed in GCC 9.  This switch has no effect.
1634
1635 fchkp-use-static-bounds
1636 C ObjC C++ ObjC++ LTO WarnRemoved
1637 Removed in GCC 9.  This switch has no effect.
1638
1639 fchkp-use-static-const-bounds
1640 C ObjC C++ ObjC++ LTO WarnRemoved
1641 Removed in GCC 9.  This switch has no effect.
1642
1643 fchkp-treat-zero-dynamic-size-as-infinite
1644 C ObjC C++ ObjC++ LTO WarnRemoved
1645 Removed in GCC 9.  This switch has no effect.
1646
1647 fchkp-check-read
1648 C ObjC C++ ObjC++ LTO WarnRemoved
1649 Removed in GCC 9.  This switch has no effect.
1650
1651 fchkp-check-write
1652 C ObjC C++ ObjC++ LTO WarnRemoved
1653 Removed in GCC 9.  This switch has no effect.
1654
1655 fchkp-store-bounds
1656 C ObjC C++ ObjC++ LTO WarnRemoved
1657 Removed in GCC 9.  This switch has no effect.
1658
1659 fchkp-instrument-calls
1660 C ObjC C++ ObjC++ LTO WarnRemoved
1661 Removed in GCC 9.  This switch has no effect.
1662
1663 fchkp-instrument-marked-only
1664 C ObjC C++ ObjC++ LTO WarnRemoved
1665 Removed in GCC 9.  This switch has no effect.
1666
1667 fchkp-use-wrappers
1668 C ObjC C++ ObjC++ LTO WarnRemoved
1669 Removed in GCC 9.  This switch has no effect.
1670
1671 static-libmpx
1672 Driver WarnRemoved
1673 Removed in GCC 9.  This switch has no effect.
1674
1675 static-libmpxwrappers
1676 Driver WarnRemoved
1677 Removed in GCC 9.  This switch has no effect.
1678
1679 fcilkplus
1680 C ObjC C++ ObjC++ LTO Undocumented Ignore
1681 Removed in GCC 8.  This switch has no effect.
1682
1683 fconcepts
1684 C++ ObjC++ Var(flag_concepts)
1685 Enable support for C++ concepts.
1686
1687 fconcepts-ts
1688 C++ ObjC++ Var(flag_concepts_ts) Init(0)
1689 Enable certain features present in the Concepts TS.
1690
1691 fconcepts-diagnostics-depth=
1692 C++ ObjC++ Joined RejectNegative UInteger Var(concepts_diagnostics_max_depth) Init(1)
1693 Specify maximum error replay depth during recursive diagnosis of a constraint satisfaction failure.
1694
1695 fcond-mismatch
1696 C ObjC C++ ObjC++
1697 Allow the arguments of the '?' operator to have different types.
1698
1699 fconserve-space
1700 C++ ObjC++ Ignore
1701 Does nothing.  Preserved for backward compatibility.
1702
1703 fconstant-string-class=
1704 ObjC ObjC++ Joined MissingArgError(no class name specified with %qs)
1705 -fconst-string-class=<name>     Use class <name> for constant strings.
1706
1707 fconstexpr-depth=
1708 C++ ObjC++ Joined RejectNegative UInteger Var(max_constexpr_depth) Init(512)
1709 -fconstexpr-depth=<number>      Specify maximum constexpr recursion depth.
1710
1711 fconstexpr-cache-depth=
1712 C++ ObjC++ Joined RejectNegative UInteger Var(constexpr_cache_depth) Init(8)
1713 -fconstexpr-cache-depth=<number>        Specify maximum constexpr recursion cache depth.
1714
1715 fconstexpr-fp-except
1716 C++ ObjC++ Var(flag_constexpr_fp_except) Init(0)
1717 Allow IEC559 floating point exceptions in constant expressions.
1718
1719 fconstexpr-loop-limit=
1720 C++ ObjC++ Joined RejectNegative UInteger Var(constexpr_loop_limit) Init(262144)
1721 -fconstexpr-loop-limit=<number> Specify maximum constexpr loop iteration count.
1722
1723 fconstexpr-ops-limit=
1724 C++ ObjC++ Joined RejectNegative Host_Wide_Int Var(constexpr_ops_limit) Init(33554432)
1725 -fconstexpr-ops-limit=<number>  Specify maximum number of constexpr operations during a single constexpr evaluation.
1726
1727 fcontracts
1728 C++ ObjC++ Var(flag_contracts) Init(0)
1729 Enable certain features present in drafts of C++ Contracts.
1730
1731 Enum
1732 Name(on_off) Type(int) UnknownError(argument %qs must be either %<on%> or %<off%>)
1733
1734 EnumValue
1735 Enum(on_off) String(off) Value(0)
1736
1737 EnumValue
1738 Enum(on_off) String(on) Value(1)
1739
1740 fcontract-assumption-mode=
1741 C++ Joined RejectNegative
1742 -fcontract-assumption-mode=[on|off]     Enable or disable treating axiom level contracts as assumptions (default on).
1743
1744 fcontract-build-level=
1745 C++ Joined RejectNegative
1746 -fcontract-build-level=[off|default|audit]      Specify max contract level to generate runtime checks for.
1747
1748 fcontract-strict-declarations=
1749 C++ Var(flag_contract_strict_declarations) Enum(on_off) Joined Init(0) RejectNegative
1750 -fcontract-strict-declarations=[on|off] Enable or disable warnings on generalized redeclaration of functions with contracts (default off).
1751
1752 fcontract-mode=
1753 C++ Var(flag_contract_mode) Enum(on_off) Joined Init(1) RejectNegative
1754 -fcontract-mode=[on|off]        Enable or disable all contract facilities (default on).
1755
1756 fcontract-continuation-mode=
1757 C++ Joined RejectNegative
1758 -fcontract-continuation-mode=[on|off]   Enable or disable contract continuation mode (default off).
1759
1760 fcontract-role=
1761 C++ Joined RejectNegative
1762 -fcontract-role=<name>:<semantics>      Specify the semantics for all levels in a role (default, review), or a custom contract role with given semantics (ex: opt:assume,assume,assume).
1763
1764 fcontract-semantic=
1765 C++ Joined RejectNegative
1766 -fcontract-semantic=<level>:<semantic>  Specify the concrete semantics for level.
1767
1768 fcoroutines
1769 C++ LTO Var(flag_coroutines)
1770 Enable C++ coroutines (experimental).
1771
1772 fdebug-cpp
1773 C ObjC C++ ObjC++
1774 Emit debug annotations during preprocessing.
1775
1776 fdeduce-init-list
1777 C++ ObjC++ Ignore
1778 Does nothing.  Preserved for backward compatibility.
1779
1780 fdeclone-ctor-dtor
1781 C++ ObjC++ Var(flag_declone_ctor_dtor) Init(-1)
1782 Factor complex constructors and destructors to favor space over speed.
1783
1784 fdefault-inline
1785 C++ ObjC++ Ignore
1786 Does nothing.  Preserved for backward compatibility.
1787
1788 fdiagnostics-show-template-tree
1789 C++ ObjC++ Var(flag_diagnostics_show_template_tree) Init(0)
1790 Print hierarchical comparisons when template types are mismatched.
1791
1792 fdirectives-only
1793 C ObjC C++ ObjC++
1794 Preprocess directives only.
1795
1796 fdollars-in-identifiers
1797 C ObjC C++ ObjC++
1798 Permit '$' as an identifier character.
1799
1800 fmacro-prefix-map=
1801 C ObjC C++ ObjC++ Joined RejectNegative
1802 -fmacro-prefix-map=<old>=<new>  Map one directory name to another in __FILE__, __BASE_FILE__, and __builtin_FILE().
1803
1804 fdump-ada-spec
1805 C ObjC C++ ObjC++ RejectNegative Var(flag_dump_ada_spec)
1806 Write all declarations as Ada code transitively.
1807
1808 fdump-ada-spec-slim
1809 C ObjC C++ ObjC++ RejectNegative Var(flag_dump_ada_spec_slim)
1810 Write all declarations as Ada code for the given file only.
1811
1812 felide-constructors
1813 C++ ObjC++ Var(flag_elide_constructors) Init(1)
1814
1815 felide-type
1816 C++ ObjC++ Var(flag_elide_type) Init(1)
1817 Do not elide common elements in template comparisons.
1818
1819 fenforce-eh-specs
1820 C++ ObjC++ Var(flag_enforce_eh_specs) Init(1)
1821 Generate code to check exception specifications.
1822
1823 fenum-int-equiv
1824 C++ ObjC++ WarnRemoved
1825
1826 fexec-charset=
1827 C ObjC C++ ObjC++ Joined RejectNegative
1828 -fexec-charset=<cset>   Convert all strings and character constants to character set <cset>.
1829
1830 fextended-identifiers
1831 C ObjC C++ ObjC++
1832 Permit universal character names (\\u and \\U) in identifiers.
1833
1834 finput-charset=
1835 C ObjC C++ ObjC++ Joined RejectNegative
1836 -finput-charset=<cset>  Specify the default character set for source files.
1837
1838 fextern-tls-init
1839 C++ ObjC++ Var(flag_extern_tls_init) Init(-1)
1840 Support dynamic initialization of thread-local variables in a different translation unit.
1841
1842 fexternal-templates
1843 C++ ObjC++ WarnRemoved
1844
1845 ffold-simple-inlines
1846 C++ ObjC++ Optimization Var(flag_fold_simple_inlines)
1847 Fold calls to simple inline functions.
1848
1849 ffor-scope
1850 C++ ObjC++ WarnRemoved
1851
1852 ffreestanding
1853 C ObjC C++ ObjC++
1854 Do not assume that standard C libraries and \"main\" exist.
1855
1856 fgnu-keywords
1857 C++ ObjC++ Var(flag_no_gnu_keywords, 0)
1858 Recognize GNU-defined keywords.
1859
1860 fgnu-runtime
1861 ObjC ObjC++ LTO RejectNegative Var(flag_next_runtime,0) Init(NEXT_OBJC_RUNTIME)
1862 Generate code for GNU runtime environment.
1863
1864 fgnu89-inline
1865 C ObjC Var(flag_gnu89_inline) Init(-1)
1866 Use traditional GNU semantics for inline functions.
1867
1868 fguiding-decls
1869 C++ ObjC++ WarnRemoved
1870
1871 fhandle-exceptions
1872 C++ ObjC++ Optimization Alias(fexceptions) Warn({%<-fhandle-exceptions%> has been renamed %<-fexceptions%> (and is now on by default)})
1873
1874 fhonor-std
1875 C++ ObjC++ WarnRemoved
1876
1877 fhosted
1878 C ObjC
1879 Assume normal C execution environment.
1880
1881 fhuge-objects
1882 C++ ObjC++ WarnRemoved
1883 No longer supported.
1884
1885 fimplement-inlines
1886 C++ ObjC++ Var(flag_implement_inlines) Init(1)
1887 Export functions even if they can be inlined.
1888
1889 fimplicit-constexpr
1890 C++ ObjC++ Var(flag_implicit_constexpr)
1891 Make inline functions constexpr by default.
1892
1893 fimplicit-inline-templates
1894 C++ ObjC++ Var(flag_implicit_inline_templates) Init(1)
1895 Emit implicit instantiations of inline templates.
1896
1897 fimplicit-templates
1898 C++ ObjC++ Var(flag_implicit_templates) Init(1)
1899 Emit implicit instantiations of templates.
1900
1901 fnew-inheriting-ctors
1902 C++ ObjC++ Var(flag_new_inheriting_ctors) Init(1)
1903 Implement C++17 inheriting constructor semantics.
1904
1905 ffriend-injection
1906 C++ ObjC++ WarnRemoved
1907
1908 fkeep-inline-dllexport
1909 C C++ ObjC ObjC++ Var(flag_keep_inline_dllexport) Init(1) Condition(TARGET_DLLIMPORT_DECL_ATTRIBUTES)
1910 Don't emit dllexported inline functions unless needed.
1911
1912 flabels-ok
1913 C++ ObjC++ WarnRemoved
1914
1915 flax-vector-conversions
1916 C ObjC C++ ObjC++ Var(flag_lax_vector_conversions)
1917 Allow implicit conversions between vectors with differing numbers of subparts and/or differing element types.
1918
1919 fmodules-ts
1920 C++ ObjC++ Var(flag_modules) Integer Init(0)
1921 Enable C++ modules-ts (experimental).
1922
1923 fno-modules
1924 C++ ObjC++ Undocumented RejectNegative Var(flag_modules,0) Integer
1925 ;; undocumented
1926
1927 fmodule-header
1928 C++ ObjC RejectNegative Var(flag_header_unit,0) Integer
1929 Enable C++ header module (experimental).
1930
1931 fmodule-header=
1932 C++ ObjC++ Joined RejectNegative Undocumented
1933
1934 fmodule-implicit-inline
1935 C++ ObjC++ Var(flag_module_implicit_inline,0) Integer
1936 Member functions defined within their class are inline in module purview.
1937
1938 fmodule-only
1939 C++ ObjC RejectNegative Var(flag_module_only) Integer
1940 Only emit Compiled Module Interface.
1941
1942 fmodule-mapper=
1943 C++ ObjC++ Joined RejectNegative MissingArgError(missing mapper)
1944 Mapper for module to CMI files.
1945
1946 fmodule-lazy
1947 C++ ObjC++ Var(flag_module_lazy) Init(1)
1948 Enable lazy module importing.
1949
1950 fmodule-version-ignore
1951 C++ ObjC Var(flag_module_version_ignore) Integer
1952 ; undocumented, Very dangerous, but occasionally useful
1953
1954 Winvalid-imported-macros
1955 C++ ObjC++ Var(warn_imported_macros) Warning
1956 Warn about macros that have conflicting header units definitions.
1957
1958 Wcompare-distinct-pointer-types
1959 C ObjC Var(warn_compare_distinct_pointer_types) Warning Init(1)
1960 Warn if pointers of distinct types are compared without a cast.
1961
1962 flang-info-include-translate
1963 C++ Var(note_include_translate_yes)
1964 Note #include directives translated to import declarations.
1965
1966 flang-info-include-translate-not
1967 C++ Var(note_include_translate_no)
1968 Note #include directives not translated to import declarations, and not known to be textual.
1969
1970 flang-info-include-translate=
1971 C++ Joined RejectNegative MissingArgError(missing header name)
1972 Note a #include translation of a specific header.
1973
1974 flang-info-module-cmi
1975 C++ Var(note_module_cmi_yes)
1976 Note Compiled Module Interface pathnames.
1977
1978 flang-info-module-cmi=
1979 C++ Joined RejectNegative MissingArgError(missing module name)
1980 Note Compiled Module Interface pathname of a specific module or header-unit.
1981
1982 fmax-include-depth=
1983 C ObjC C++ ObjC++ Joined RejectNegative UInteger
1984 fmax-include-depth=<number> Set the maximum depth of the nested #include.
1985
1986 fms-extensions
1987 C ObjC C++ ObjC++ Var(flag_ms_extensions)
1988 Don't warn about uses of Microsoft extensions.
1989
1990 fmudflap
1991 C ObjC C++ ObjC++ WarnRemoved
1992
1993 fmudflapth
1994 C ObjC C++ ObjC++ WarnRemoved
1995
1996 fmudflapir
1997 C ObjC C++ ObjC++ WarnRemoved
1998
1999 fname-mangling-version-
2000 C++ ObjC++ Joined WarnRemoved
2001
2002 fnew-abi
2003 C++ ObjC++ WarnRemoved
2004
2005 fnew-ttp-matching
2006 C++ ObjC++ Var(flag_new_ttp)
2007 Implement resolution of DR 150 for matching of template template arguments.
2008
2009 fnext-runtime
2010 ObjC ObjC++ LTO RejectNegative Var(flag_next_runtime)
2011 Generate code for NeXT (Apple macOS) runtime environment.
2012
2013 fnil-receivers
2014 ObjC ObjC++ Var(flag_nil_receivers) Init(1)
2015 Assume that receivers of Objective-C messages may be nil.
2016
2017 flocal-ivars
2018 ObjC ObjC++ Var(flag_local_ivars) Init(1)
2019 Allow access to instance variables as if they were local declarations within instance method implementations.
2020
2021 fivar-visibility=
2022 ObjC ObjC++ Joined RejectNegative Enum(ivar_visibility) Var(default_ivar_visibility) Init(IVAR_VISIBILITY_PROTECTED)
2023 -fvisibility=[private|protected|public|package] Set the default symbol visibility.
2024
2025 Enum
2026 Name(ivar_visibility) Type(enum ivar_visibility) UnknownError(unrecognized ivar visibility value %qs)
2027
2028 EnumValue
2029 Enum(ivar_visibility) String(private) Value(IVAR_VISIBILITY_PRIVATE)
2030
2031 EnumValue
2032 Enum(ivar_visibility) String(protected) Value(IVAR_VISIBILITY_PROTECTED)
2033
2034 EnumValue
2035 Enum(ivar_visibility) String(public) Value(IVAR_VISIBILITY_PUBLIC)
2036
2037 EnumValue
2038 Enum(ivar_visibility) String(package) Value(IVAR_VISIBILITY_PACKAGE)
2039
2040 fnonansi-builtins
2041 C++ ObjC++ Var(flag_no_nonansi_builtin, 0)
2042
2043 fnonnull-objects
2044 C++ ObjC++ WarnRemoved
2045
2046 fnothrow-opt
2047 C++ ObjC++ Optimization Var(flag_nothrow_opt)
2048 Treat a throw() exception specification as noexcept to improve code size.
2049
2050 fobjc-abi-version=
2051 ObjC ObjC++ LTO Joined RejectNegative UInteger Var(flag_objc_abi)
2052 Specify which ABI to use for Objective-C family code and meta-data generation.
2053
2054 ; Generate special '- .cxx_construct' and '- .cxx_destruct' methods
2055 ; to initialize any non-POD ivars in Objective-C++ classes.
2056 fobjc-call-cxx-cdtors
2057 ObjC++ Var(flag_objc_call_cxx_cdtors)
2058 Generate special Objective-C methods to initialize/destroy non-POD C++ ivars, if needed.
2059
2060 fobjc-direct-dispatch
2061 ObjC ObjC++ Var(flag_objc_direct_dispatch)
2062 Allow fast jumps to the message dispatcher.
2063
2064 ; Nonzero means that we will allow new ObjC exception syntax (@throw,
2065 ; @try, etc.) in source code.
2066 fobjc-exceptions
2067 ObjC ObjC++ Var(flag_objc_exceptions)
2068 Enable Objective-C exception and synchronization syntax.
2069
2070 fobjc-gc
2071 ObjC ObjC++ LTO Var(flag_objc_gc)
2072 Enable garbage collection (GC) in Objective-C/Objective-C++ programs.
2073
2074 fobjc-nilcheck
2075 ObjC ObjC++ Var(flag_objc_nilcheck,1)
2076 Enable inline checks for nil receivers with the NeXT runtime and ABI version 2.
2077
2078 ; Nonzero means that we generate NeXT setjmp based exceptions.
2079 fobjc-sjlj-exceptions
2080 ObjC ObjC++ Var(flag_objc_sjlj_exceptions) Init(-1)
2081 Enable Objective-C setjmp exception handling runtime.
2082
2083 fobjc-std=objc1
2084 ObjC ObjC++ Var(flag_objc1_only)
2085 Conform to the Objective-C 1.0 language as implemented in GCC 4.0.
2086
2087 fopenacc
2088 C ObjC C++ ObjC++ LTO Var(flag_openacc)
2089 Enable OpenACC.
2090
2091 fopenacc-dim=
2092 C ObjC C++ ObjC++ LTO Joined Var(flag_openacc_dims)
2093 Specify default OpenACC compute dimensions.
2094
2095 fopenmp
2096 C ObjC C++ ObjC++ LTO Var(flag_openmp)
2097 Enable OpenMP (implies -frecursive in Fortran).
2098
2099 fopenmp-simd
2100 C ObjC C++ ObjC++ Var(flag_openmp_simd)
2101 Enable OpenMP's SIMD directives.
2102
2103 foperator-names
2104 C++ ObjC++
2105 Recognize C++ keywords like \"compl\" and \"xor\".
2106
2107 foptional-diags
2108 C++ ObjC++ Ignore
2109 Does nothing.  Preserved for backward compatibility.
2110
2111 fpch-deps
2112 C ObjC C++ ObjC++
2113
2114 fpch-preprocess
2115 C ObjC C++ ObjC++
2116 Look for and use PCH files even when preprocessing.
2117
2118 fpermissive
2119 C++ ObjC++ Var(flag_permissive)
2120 Downgrade conformance errors to warnings.
2121
2122 fplan9-extensions
2123 C ObjC Var(flag_plan9_extensions)
2124 Enable Plan 9 language extensions.
2125
2126 fpreprocessed
2127 C ObjC C++ ObjC++
2128 Treat the input file as already preprocessed.
2129
2130 ftrack-macro-expansion
2131 C ObjC C++ ObjC++ JoinedOrMissing RejectNegative UInteger
2132 ; converted into ftrack-macro-expansion=
2133
2134 ftrack-macro-expansion=
2135 C ObjC C++ ObjC++ JoinedOrMissing RejectNegative UInteger
2136 -ftrack-macro-expansion=<0|1|2> Track locations of tokens coming from macro expansion and display them in error messages.
2137
2138 fpretty-templates
2139 C++ ObjC++ Var(flag_pretty_templates) Init(1)
2140 Do not pretty-print template specializations as the template signature followed by the arguments.
2141
2142 fprintf-return-value
2143 C ObjC C++ ObjC++ LTO Optimization Var(flag_printf_return_value) Init(1)
2144 Treat known sprintf return values as constants.
2145
2146 freplace-objc-classes
2147 ObjC ObjC++ LTO Var(flag_replace_objc_classes)
2148 Used in Fix-and-Continue mode to indicate that object files may be swapped in at runtime.
2149
2150 frepo
2151 C++ ObjC++ WarnRemoved
2152 Removed in GCC 10.  This switch has no effect.
2153
2154 frtti
2155 C++ ObjC++ Optimization Var(flag_rtti) Init(1)
2156 Generate run time type descriptor information.
2157
2158 fshort-enums
2159 C ObjC C++ ObjC++ LTO Optimization Var(flag_short_enums)
2160 Use the narrowest integer type possible for enumeration types.
2161
2162 fshort-wchar
2163 C ObjC C++ ObjC++ LTO Optimization Var(flag_short_wchar)
2164 Force the underlying type for \"wchar_t\" to be \"unsigned short\".
2165
2166 fsigned-bitfields
2167 C ObjC C++ ObjC++ Var(flag_signed_bitfields) Init(1)
2168 When \"signed\" or \"unsigned\" is not given make the bitfield signed.
2169
2170 fsigned-char
2171 C ObjC C++ ObjC++ LTO Var(flag_signed_char)
2172 Make \"char\" signed by default.
2173
2174 fsized-deallocation
2175 C++ ObjC++ Var(flag_sized_deallocation) Init(-1)
2176 Enable C++14 sized deallocation support.
2177
2178 fstrict-flex-arrays
2179 C C++ Common Alias(fstrict-flex-arrays=,3,0)
2180
2181 fstrict-flex-arrays=
2182 C C++ Common Joined RejectNegative UInteger Var(flag_strict_flex_arrays) Init(0) IntegerRange(0,3)
2183 -fstrict-flex-arrays=<level>    Control when to treat the trailing array of a structure as a flexible array member for the purposes of accessing the elements of such an array. The default is treating all trailing arrays of structures as flexible array members.
2184
2185 fsquangle
2186 C++ ObjC++ WarnRemoved
2187
2188 fsso-struct=
2189 C ObjC Joined RejectNegative Enum(sso_struct) Var(default_sso) Init(SSO_NATIVE)
2190 -fsso-struct=[big-endian|little-endian|native]  Set the default scalar storage order.
2191
2192 Enum
2193 Name(sso_struct) Type(enum scalar_storage_order_kind) UnknownError(unrecognized scalar storage order value %qs)
2194
2195 EnumValue
2196 Enum(sso_struct) String(big-endian) Value(SSO_BIG_ENDIAN)
2197
2198 EnumValue
2199 Enum(sso_struct) String(little-endian) Value(SSO_LITTLE_ENDIAN)
2200
2201 EnumValue
2202 Enum(sso_struct) String(native) Value(SSO_NATIVE)
2203
2204 fstats
2205 C++ ObjC++ Var(flag_detailed_statistics)
2206 Display statistics accumulated during compilation.
2207
2208 fstrict-enums
2209 C++ ObjC++ Optimization Var(flag_strict_enums)
2210 Assume that values of enumeration type are always within the minimum range of that type.
2211
2212 fstrict-prototype
2213 C++ ObjC++ WarnRemoved
2214
2215 fstrong-eval-order
2216 C++ ObjC++ Common Alias(fstrong-eval-order=, all, none)
2217 Follow the C++17 evaluation order requirements for assignment expressions,
2218 shift, member function calls, etc.
2219
2220 fstrong-eval-order=
2221 C++ ObjC++ Common Var(flag_strong_eval_order) Joined Enum(strong_eval_order) RejectNegative Init(-1)
2222 Follow the C++17 evaluation order requirements for assignment expressions,
2223 shift, member function calls, etc.
2224
2225 Enum
2226 Name(strong_eval_order) Type(int)
2227
2228 EnumValue
2229 Enum(strong_eval_order) String(none) Value(0)
2230
2231 EnumValue
2232 Enum(strong_eval_order) String(some) Value(1)
2233
2234 EnumValue
2235 Enum(strong_eval_order) String(all) Value(2)
2236
2237 ftemplate-backtrace-limit=
2238 C++ ObjC++ Joined RejectNegative UInteger Var(template_backtrace_limit) Init(10)
2239 Set the maximum number of template instantiation notes for a single warning or error.
2240
2241 ftemplate-depth-
2242 C++ ObjC++ Joined RejectNegative Undocumented Alias(ftemplate-depth=)
2243
2244 ftemplate-depth=
2245 C++ ObjC++ Joined RejectNegative UInteger
2246 -ftemplate-depth=<number>       Specify maximum template instantiation depth.
2247
2248 fthis-is-variable
2249 C++ ObjC++ WarnRemoved
2250
2251 fthreadsafe-statics
2252 C++ ObjC++ Optimization Var(flag_threadsafe_statics) Init(1)
2253 -fno-threadsafe-statics Do not generate thread-safe code for initializing local statics.
2254
2255 funsigned-bitfields
2256 C ObjC C++ ObjC++ Var(flag_signed_bitfields, 0)
2257 When \"signed\" or \"unsigned\" is not given make the bitfield unsigned.
2258
2259 funsigned-char
2260 C ObjC C++ ObjC++ LTO Var(flag_signed_char, 0)
2261 Make \"char\" unsigned by default.
2262
2263 fuse-cxa-atexit
2264 C++ ObjC++ Var(flag_use_cxa_atexit) Init(DEFAULT_USE_CXA_ATEXIT)
2265 Use __cxa_atexit to register destructors.
2266
2267 fuse-cxa-get-exception-ptr
2268 C++ ObjC++ Var(flag_use_cxa_get_exception_ptr) Init(2)
2269 Use __cxa_get_exception_ptr in exception handling.
2270
2271 fvisibility-inlines-hidden
2272 C++ ObjC++
2273 Marks all inlined functions and methods as having hidden visibility.
2274
2275 fvisibility-ms-compat
2276 C++ ObjC++ Var(flag_visibility_ms_compat)
2277 Changes visibility to match Microsoft Visual Studio by default.
2278
2279 fvtable-gc
2280 C++ ObjC++ WarnRemoved
2281 No longer supported.
2282
2283 fvtable-thunks
2284 C++ ObjC++ WarnRemoved
2285 No longer supported.
2286
2287 fweak
2288 C++ ObjC++ Var(flag_weak) Init(1)
2289 Emit common-like symbols as weak symbols.
2290
2291 fwide-exec-charset=
2292 C ObjC C++ ObjC++ Joined RejectNegative
2293 -fwide-exec-charset=<cset>      Convert all wide strings and character constants to character set <cset>.
2294
2295 fworking-directory
2296 C ObjC C++ ObjC++ Var(flag_working_directory) Init(-1)
2297 Generate a #line directive pointing at the current working directory.
2298
2299 fxref
2300 C++ ObjC++ WarnRemoved
2301 No longer supported.
2302
2303 fzero-link
2304 ObjC ObjC++ Var(flag_zero_link)
2305 Generate lazy class lookup (via objc_getClass()) for use in Zero-Link mode.
2306
2307 gen-decls
2308 ObjC ObjC++ Driver Var(flag_gen_declaration) RejectNegative
2309 Dump declarations to a .decl file.
2310
2311 femit-struct-debug-baseonly
2312 C ObjC C++ ObjC++
2313 -femit-struct-debug-baseonly    Aggressive reduced debug info for structs.
2314
2315 femit-struct-debug-reduced
2316 C ObjC C++ ObjC++
2317 -femit-struct-debug-reduced     Conservative reduced debug info for structs.
2318
2319 femit-struct-debug-detailed=
2320 C ObjC C++ ObjC++ Joined
2321 -femit-struct-debug-detailed=<spec-list>        Detailed reduced debug info for structs.
2322
2323 fext-numeric-literals
2324 C++ ObjC++ Var(flag_ext_numeric_literals) Init(1)
2325 Interpret imaginary, fixed-point, or other gnu number suffix as the corresponding
2326 number literal rather than a user-defined number literal.
2327
2328 idirafter
2329 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
2330 -idirafter <dir>        Add <dir> to the end of the system include path.
2331
2332 imacros
2333 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing filename after %qs)
2334 -imacros <file> Accept definition of macros in <file>.
2335
2336 imultilib
2337 C ObjC C++ ObjC++ Joined Separate
2338 -imultilib <dir>        Set <dir> to be the multilib include subdirectory.
2339
2340 include
2341 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing filename after %qs)
2342 -include <file> Include the contents of <file> before other files.
2343
2344 iprefix
2345 C ObjC C++ ObjC++ Joined Separate
2346 -iprefix <path> Specify <path> as a prefix for next two options.
2347
2348 isysroot
2349 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
2350 -isysroot <dir> Set <dir> to be the system root directory.
2351
2352 isystem
2353 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
2354 -isystem <dir>  Add <dir> to the start of the system include path.
2355
2356 iquote
2357 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
2358 -iquote <dir>   Add <dir> to the end of the quote include path.
2359
2360 iwithprefix
2361 C ObjC C++ ObjC++ Joined Separate
2362 -iwithprefix <dir>      Add <dir> to the end of the system include path.
2363
2364 iwithprefixbefore
2365 C ObjC C++ ObjC++ Joined Separate
2366 -iwithprefixbefore <dir>        Add <dir> to the end of the main include path.
2367
2368 lang-asm
2369 C Undocumented RejectDriver
2370
2371 no-integrated-cpp
2372 Driver
2373
2374 nostdinc
2375 C ObjC C++ ObjC++
2376 Do not search standard system include directories (those specified with -isystem will still be used).
2377
2378 nostdinc++
2379 C++ ObjC++
2380 Do not search standard system include directories for C++.
2381
2382 o
2383 C ObjC C++ ObjC++ Joined Separate
2384 ; Documented in common.opt
2385
2386 pedantic
2387 C ObjC C++ ObjC++ Alias(Wpedantic)
2388 ; Documented in common.opt
2389
2390 print-objc-runtime-info
2391 ObjC ObjC++
2392 Generate C header of platform-specific features.
2393
2394 remap
2395 C ObjC C++ ObjC++
2396 Remap file names when including files.
2397
2398 std=c++98
2399 C++ ObjC++
2400 Conform to the ISO 1998 C++ standard revised by the 2003 technical corrigendum.
2401
2402 std=c++03
2403 C++ ObjC++ Alias(std=c++98)
2404 Conform to the ISO 1998 C++ standard revised by the 2003 technical corrigendum.
2405
2406 std=c++11
2407 C++ ObjC++
2408 Conform to the ISO 2011 C++ standard.
2409
2410 std=c++0x
2411 C++ ObjC++ Alias(std=c++11) Undocumented
2412 Deprecated in favor of -std=c++11.
2413
2414 std=c++1y
2415 C++ ObjC++ Alias(std=c++14) Undocumented
2416 Deprecated in favor of -std=c++14.
2417
2418 std=c++14
2419 C++ ObjC++
2420 Conform to the ISO 2014 C++ standard.
2421
2422 std=c++1z
2423 C++ ObjC++ Alias(std=c++17) Undocumented
2424 Deprecated in favor of -std=c++17.
2425
2426 std=c++17
2427 C++ ObjC++
2428 Conform to the ISO 2017 C++ standard.
2429
2430 std=c++2a
2431 C++ ObjC++ Alias(std=c++20) Undocumented
2432 Conform to the ISO 2020 C++ standard (experimental and incomplete support).
2433
2434 std=c++20
2435 C++ ObjC++
2436 Conform to the ISO 2020 C++ standard (experimental and incomplete support).
2437
2438 std=c++2b
2439 C++ ObjC++ Alias(std=c++23) Undocumented
2440 Conform to the ISO 2023 C++ draft standard (experimental and incomplete support).
2441
2442 std=c++23
2443 C++ ObjC++
2444 Conform to the ISO 2023 C++ draft standard (experimental and incomplete support).
2445
2446 std=c++2c
2447 C++ ObjC++ Alias(std=c++26)
2448 Conform to the ISO 2026 C++ draft standard (experimental and incomplete support).
2449
2450 std=c++26
2451 C++ ObjC++ Undocumented
2452 Conform to the ISO 2026 C++ draft standard (experimental and incomplete support).
2453
2454 std=c11
2455 C ObjC
2456 Conform to the ISO 2011 C standard.
2457
2458 std=c1x
2459 C ObjC Alias(std=c11)
2460 Deprecated in favor of -std=c11.
2461
2462 std=c17
2463 C ObjC
2464 Conform to the ISO 2017 C standard (published in 2018).
2465
2466 std=c18
2467 C ObjC Alias(std=c17)
2468 Conform to the ISO 2017 C standard (published in 2018).
2469
2470 std=c23
2471 C ObjC
2472 Conform to the ISO 2023 C standard draft (expected to be published in 2024) (experimental and incomplete support).
2473
2474 std=c2x
2475 C ObjC Alias(std=c23)
2476 Deprecated in favor of -std=c23.
2477
2478 std=c89
2479 C ObjC Alias(std=c90)
2480 Conform to the ISO 1990 C standard.
2481
2482 std=c90
2483 C ObjC
2484 Conform to the ISO 1990 C standard.
2485
2486 std=c99
2487 C ObjC
2488 Conform to the ISO 1999 C standard.
2489
2490 std=c9x
2491 C ObjC Alias(std=c99)
2492 Deprecated in favor of -std=c99.
2493
2494 std=gnu++98
2495 C++ ObjC++
2496 Conform to the ISO 1998 C++ standard revised by the 2003 technical
2497 corrigendum with GNU extensions.
2498
2499 std=gnu++03
2500 C++ ObjC++ Alias(std=gnu++98)
2501 Conform to the ISO 1998 C++ standard revised by the 2003 technical
2502 corrigendum with GNU extensions.
2503
2504 std=gnu++11
2505 C++ ObjC++
2506 Conform to the ISO 2011 C++ standard with GNU extensions.
2507
2508 std=gnu++0x
2509 C++ ObjC++ Alias(std=gnu++11) Undocumented
2510 Deprecated in favor of -std=gnu++11.
2511
2512 std=gnu++1y
2513 C++ ObjC++ Alias(std=gnu++14) Undocumented
2514 Deprecated in favor of -std=gnu++14.
2515
2516 std=gnu++14
2517 C++ ObjC++
2518 Conform to the ISO 2014 C++ standard with GNU extensions.
2519
2520 std=gnu++1z
2521 C++ ObjC++ Alias(std=gnu++17) Undocumented
2522 Deprecated in favor of -std=gnu++17.
2523
2524 std=gnu++17
2525 C++ ObjC++
2526 Conform to the ISO 2017 C++ standard with GNU extensions.
2527
2528 std=gnu++2a
2529 C++ ObjC++ Alias(std=gnu++20) Undocumented
2530 Conform to the ISO 2020 C++ standard with GNU extensions (experimental and incomplete support).
2531
2532 std=gnu++20
2533 C++ ObjC++
2534 Conform to the ISO 2020 C++ standard with GNU extensions (experimental and incomplete support).
2535
2536 std=gnu++2b
2537 C++ ObjC++ Alias(std=gnu++23) Undocumented
2538 Conform to the ISO 2023 C++ draft standard with GNU extensions (experimental and incomplete support).
2539
2540 std=gnu++23
2541 C++ ObjC++
2542 Conform to the ISO 2023 C++ draft standard with GNU extensions (experimental and incomplete support).
2543
2544 std=gnu++2c
2545 C++ ObjC++ Alias(std=gnu++26)
2546 Conform to the ISO 2026 C++ draft standard with GNU extensions (experimental and incomplete support).
2547
2548 std=gnu++26
2549 C++ ObjC++ Undocumented
2550 Conform to the ISO 2026 C++ draft standard with GNU extensions (experimental and incomplete support).
2551
2552 std=gnu11
2553 C ObjC
2554 Conform to the ISO 2011 C standard with GNU extensions.
2555
2556 std=gnu1x
2557 C ObjC Alias(std=gnu11)
2558 Deprecated in favor of -std=gnu11.
2559
2560 std=gnu17
2561 C ObjC
2562 Conform to the ISO 2017 C standard (published in 2018) with GNU extensions.
2563
2564 std=gnu18
2565 C ObjC Alias(std=gnu17)
2566 Conform to the ISO 2017 C standard (published in 2018) with GNU extensions.
2567
2568 std=gnu23
2569 C ObjC
2570 Conform to the ISO 2023 C standard draft (expected to be published in 2024) with GNU extensions (experimental and incomplete support).
2571
2572 std=gnu2x
2573 C ObjC Alias(std=gnu23)
2574 Deprecated in favor of -std=gnu23.
2575
2576 std=gnu89
2577 C ObjC Alias(std=gnu90)
2578 Conform to the ISO 1990 C standard with GNU extensions.
2579
2580 std=gnu90
2581 C ObjC
2582 Conform to the ISO 1990 C standard with GNU extensions.
2583
2584 std=gnu99
2585 C ObjC
2586 Conform to the ISO 1999 C standard with GNU extensions.
2587
2588 std=gnu9x
2589 C ObjC Alias(std=gnu99)
2590 Deprecated in favor of -std=gnu99.
2591
2592 std=iso9899:1990
2593 C ObjC Alias(std=c90)
2594 Conform to the ISO 1990 C standard.
2595
2596 std=iso9899:199409
2597 C ObjC
2598 Conform to the ISO 1990 C standard as amended in 1994.
2599
2600 std=iso9899:1999
2601 C ObjC Alias(std=c99)
2602 Conform to the ISO 1999 C standard.
2603
2604 std=iso9899:199x
2605 C ObjC Alias(std=c99)
2606 Deprecated in favor of -std=iso9899:1999.
2607
2608 std=iso9899:2011
2609 C ObjC Alias(std=c11)
2610 Conform to the ISO 2011 C standard.
2611
2612 std=iso9899:2017
2613 C ObjC Alias(std=c17)
2614 Conform to the ISO 2017 C standard (published in 2018).
2615
2616 std=iso9899:2018
2617 C ObjC Alias(std=c17)
2618 Conform to the ISO 2017 C standard (published in 2018).
2619
2620 std=iso9899:2024
2621 C ObjC Alias(std=c23)
2622 Conform to the ISO 2023 C standard draft (expected to be published in 2024) (experimental and incomplete support).
2623
2624 stdlib=
2625 Driver C++ ObjC++ Common Condition(ENABLE_STDLIB_OPTION) Var(flag_stdlib_kind) Joined Enum(stdlib_kind) RejectNegative Init(1)
2626 -stdlib=[libstdc++|libc++]      The standard library to be used for C++ headers
2627 and runtime.
2628
2629 Enum
2630 Name(stdlib_kind) Type(int)
2631
2632 EnumValue
2633 Enum(stdlib_kind) String(libstdc++) Value(1)
2634
2635 EnumValue
2636 Enum(stdlib_kind) String(libc++) Value(2)
2637
2638 traditional
2639 Driver
2640
2641 traditional-cpp
2642 C ObjC C++ ObjC++
2643 Enable traditional preprocessing.
2644
2645 trigraphs
2646 C ObjC C++ ObjC++
2647 -trigraphs      Support ISO C trigraphs.
2648
2649 undef
2650 C ObjC C++ ObjC++ Var(flag_undef)
2651 Do not predefine system-specific and GCC-specific macros.
2652
2653 v
2654 C ObjC C++ ObjC++
2655 ; Documented in common.opt
2656
2657 w
2658 C ObjC C++ ObjC++
2659 ; Documented in common.opt
2660
2661 ; This comment is to ensure we retain the blank line above.