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Commit | Line | Data |
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0a3b29ad | 1 | *** Changes in GCC 3.4: |
2 | ||
e89e69ce | 3 | * Changes in GCC 3.4 are described in 'gcc-3.4/changes.html' |
220b71ed | 4 | |
2437a99c | 5 | *** Changes in GCC 3.3: |
6 | ||
7 | * The "new X = 3" extension has been removed; you must now use "new X(3)". | |
8 | ||
0fe26a86 | 9 | * G++ no longer allows in-class initializations of static data members |
10 | that do not have arithmetic or enumeration type. For example: | |
11 | ||
9031d10b | 12 | struct S { |
0fe26a86 | 13 | static const char* const p = "abc"; |
14 | }; | |
15 | ||
9031d10b | 16 | is no longer accepted. |
0fe26a86 | 17 | |
18 | Use the standards-conformant form: | |
19 | ||
9031d10b | 20 | struct S { |
0fe26a86 | 21 | static const char* const p; |
22 | }; | |
23 | ||
24 | const char* const S::p = "abc"; | |
25 | ||
26 | instead. | |
27 | ||
28 | (ISO C++ is even stricter; it does not allow in-class | |
29 | initializations of floating-point types.) | |
30 | ||
5698e0d0 | 31 | *** Changes in GCC 3.1: |
32 | ||
eaf45f93 | 33 | * -fhonor-std and -fno-honor-std have been removed. -fno-honor-std was |
34 | a workaround to allow std compliant code to work with the non-std | |
35 | compliant libstdc++-v2. libstdc++-v3 is std compliant. | |
36 | ||
90b81f5b | 37 | * The C++ ABI has been fixed so that `void (A::*)() const' is mangled as |
38 | "M1AKFvvE", rather than "MK1AFvvE" as before. This change only affects | |
39 | pointer to cv-qualified member function types. | |
40 | ||
5bc45500 | 41 | * The C++ ABI has been changed to correctly handle this code: |
9031d10b | 42 | |
5bc45500 | 43 | struct A { |
44 | void operator delete[] (void *, size_t); | |
45 | }; | |
46 | ||
9031d10b | 47 | struct B : public A { |
5bc45500 | 48 | }; |
49 | ||
50 | new B[10]; | |
51 | ||
52 | The amount of storage allocated for the array will be greater than | |
53 | it was in 3.0, in order to store the number of elements in the | |
54 | array, so that the correct size can be passed to `operator delete[]' | |
9031d10b | 55 | when the array is deleted. Previously, the value passed to |
5bc45500 | 56 | `operator delete[]' was unpredictable. |
57 | ||
58 | This change will only affect code that declares a two-argument | |
59 | `operator delete[]' with a second parameter of type `size_t' | |
9031d10b | 60 | in a base class, and does not override that definition in a |
5bc45500 | 61 | derived class. |
62 | ||
63 | * The C++ ABI has been changed so that: | |
64 | ||
9031d10b | 65 | struct A { |
5bc45500 | 66 | void operator delete[] (void *, size_t); |
67 | void operator delete[] (void *); | |
68 | }; | |
69 | ||
4109ca29 | 70 | does not cause unnecessary storage to be allocated when an array of |
5bc45500 | 71 | `A' objects is allocated. |
72 | ||
73 | This change will only affect code that declares both of these | |
74 | forms of `operator delete[]', and declared the two-argument form | |
75 | before the one-argument form. | |
76 | ||
ce95a955 | 77 | * The C++ ABI has been changed so that when a parameter is passed by value, |
78 | any cleanup for that parameter is performed in the caller, as specified | |
35ce493b | 79 | by the ia64 C++ ABI, rather than the called function as before. As a |
80 | result, classes with a non-trivial destructor but a trivial copy | |
81 | constructor will be passed and returned by invisible reference, rather | |
82 | than by bitwise copy as before. | |
ce95a955 | 83 | |
f6c5e5b7 | 84 | * G++ now supports the "named return value optimization": for code like |
85 | ||
86 | A f () { | |
87 | A a; | |
88 | ... | |
89 | return a; | |
90 | } | |
91 | ||
92 | G++ will allocate 'a' in the return value slot, so that the return | |
93 | becomes a no-op. For this to work, all return statements in the function | |
94 | must return the same variable. | |
95 | ||
5698e0d0 | 96 | *** Changes in GCC 3.0: |
55c9fda9 | 97 | |
970e58dd | 98 | * Support for guiding declarations has been removed. |
99 | ||
55c9fda9 | 100 | * G++ now supports importing member functions from base classes with a |
101 | using-declaration. | |
102 | ||
103 | * G++ now enforces access control for nested types. | |
6999e4fc | 104 | |
f0b92dfb | 105 | * In some obscure cases, functions with the same type could have the |
106 | same mangled name. This bug caused compiler crashes, link-time clashes, | |
13585af5 | 107 | and debugger crashes. Fixing this bug required breaking ABI |
f0b92dfb | 108 | compatibility for the functions involved. The functions in questions |
109 | are those whose types involve non-type template arguments whose | |
110 | mangled representations require more than one digit. | |
111 | ||
9031d10b | 112 | * Support for assignment to `this' has been removed. This idiom |
3da16ddc | 113 | was used in the very early days of C++, before users were allowed |
114 | to overload `operator new'; it is no longer allowed by the C++ | |
115 | standard. | |
116 | ||
1076ef16 | 117 | * Support for signatures, a G++ extension, have been removed. |
118 | ||
6999e4fc | 119 | * Certain invalid conversions that were previously accepted will now |
120 | be rejected. For example, assigning function pointers of one type | |
121 | to function pointers of another type now requires a cast, whereas | |
122 | previously g++ would sometimes accept the code even without the | |
123 | cast. | |
124 | ||
125 | * G++ previously allowed `sizeof (X::Y)' where Y was a non-static | |
126 | member of X, even if the `sizeof' expression occurred outside | |
9031d10b | 127 | of a non-static member function of X (or one of its derived classes, |
6999e4fc | 128 | or a member-initializer for X or one of its derived classes.) This |
129 | extension has been removed. | |
130 | ||
9031d10b | 131 | * G++ no longer allows you to overload the conditional operator (i.e., |
6999e4fc | 132 | the `?:' operator.) |
133 | ||
351c3a61 | 134 | * The "named return value" extension: |
9031d10b | 135 | |
351c3a61 | 136 | int f () return r { r = 3; } |
137 | ||
138 | has been deprecated, and will be removed in a future version of G++. | |
139 | ||
5c4e0454 | 140 | *** Changes in GCC 2.95: |
caa99b15 | 141 | |
142 | * Messages about non-conformant code that we can still handle ("pedwarns") | |
143 | are now errors by default, rather than warnings. This can be reverted | |
144 | with -fpermissive, and is overridden by -pedantic or -pedantic-errors. | |
145 | ||
5c4e0454 | 146 | * String constants are now of type `const char[n]', rather than `char[n]'. |
147 | This can be reverted with -fno-const-strings. | |
148 | ||
149 | * References to functions are now supported. | |
150 | ||
151 | * Lookup of class members during class definition now works in all cases. | |
152 | ||
153 | * In overload resolution, type conversion operators are now properly | |
154 | treated as always coming from the most derived class. | |
155 | ||
156 | * C9x-style restricted pointers are supported, using the `__restrict' | |
157 | keyword. | |
158 | ||
159 | * You can now use -fno-implicit-inline-templates to suppress writing out | |
160 | implicit instantiations of inline templates. Normally we do write them | |
161 | out, even with -fno-implicit-templates, so that optimization doesn't | |
162 | affect which instantiations are needed. | |
163 | ||
164 | * -fstrict-prototype now also suppresses implicit declarations. | |
165 | ||
166 | * Many obsolete options have been removed: -fall-virtual, -fmemoize-lookups, | |
167 | -fsave-memoized, +e?, -fenum-int-equivalence, -fno-nonnull-objects. | |
168 | ||
169 | * Unused virtual functions can be discarded on some targets by specifying | |
170 | -ffunction-sections -fvtable-gc to the compiler and --gc-sections to the | |
5d89bd6f | 171 | linker. Unfortunately, this only works on GNU/Linux if you're linking |
5c4e0454 | 172 | statically. |
173 | ||
174 | * Lots of bugs stomped. | |
175 | ||
5c8b4cb9 | 176 | *** Changes in EGCS 1.1: |
a23a393d | 177 | |
9031d10b | 178 | * Namespaces are fully supported. The library has not yet been converted |
434b0d19 | 179 | to use namespace std, however, and the old std-faking code is still on by |
180 | default. To turn it off, you can use -fhonor-std. | |
181 | ||
3fd9acd7 | 182 | * Massive template improvements: |
183 | + member template classes are supported. | |
184 | + template friends are supported. | |
185 | + template template parameters are supported. | |
186 | + local classes in templates are supported. | |
187 | + lots of bugs fixed. | |
a23a393d | 188 | |
189 | * operator new now throws bad_alloc where appropriate. | |
190 | ||
434b0d19 | 191 | * Exception handling is now thread safe, and supports nested exceptions and |
192 | placement delete. Exception handling overhead on x86 is much lower with | |
193 | GNU as 2.9. | |
3fd9acd7 | 194 | |
195 | * protected virtual inheritance is now supported. | |
196 | ||
197 | * Loops are optimized better; we now move the test to the end in most | |
198 | cases, like the C frontend does. | |
199 | ||
200 | * For class D derived from B which has a member 'int i', &D::i is now of | |
201 | type 'int B::*' instead of 'int D::*'. | |
202 | ||
434b0d19 | 203 | * An _experimental_ new ABI for g++ can be turned on with -fnew-abi. The |
204 | current features of this are more efficient allocation of base classes | |
205 | (including the empty base optimization), and more compact mangling of C++ | |
206 | symbol names (which can be turned on separately with -fsquangle). This | |
207 | ABI is subject to change without notice, so don't use it for anything | |
208 | that you don't want to rebuild with every release of the compiler. | |
209 | ||
3071a55c | 210 | As with all ABI-changing flags, this flag is for experts only, as all |
211 | code (including the library code in libgcc and libstdc++) must be | |
212 | compiled with the same ABI. | |
213 | ||
a23a393d | 214 | *** Changes in EGCS 1.0: |
1423c9c0 | 215 | |
b6684166 | 216 | * A public review copy of the December 1996 Draft of the ISO/ANSI C++ |
217 | standard is now available. See | |
1423c9c0 | 218 | |
219 | http://www.cygnus.com/misc/wp/ | |
220 | ||
221 | for more information. | |
222 | ||
4600a21b | 223 | * g++ now uses a new implementation of templates. The basic idea is that |
224 | now templates are minimally parsed when seen and then expanded later. | |
225 | This allows conformant early name binding and instantiation controls, | |
226 | since instantiations no longer have to go through the parser. | |
227 | ||
228 | What you get: | |
229 | ||
230 | + Inlining of template functions works without any extra effort or | |
231 | modifications. | |
4600a21b | 232 | + Instantiations of class templates and methods defined in the class |
233 | body are deferred until they are actually needed (unless | |
234 | -fexternal-templates is specified). | |
4600a21b | 235 | + Nested types in class templates work. |
4600a21b | 236 | + Static data member templates work. |
4600a21b | 237 | + Member function templates are now supported. |
4600a21b | 238 | + Partial specialization of class templates is now supported. |
b1cfe2be | 239 | + Explicit specification of template parameters to function templates |
240 | is now supported. | |
4600a21b | 241 | |
172b2e47 | 242 | Things you may need to fix in your code: |
4600a21b | 243 | |
172b2e47 | 244 | + Syntax errors in templates that are never instantiated will now be |
245 | diagnosed. | |
4600a21b | 246 | + Types and class templates used in templates must be declared |
247 | first, or the compiler will assume they are not types, and fail. | |
4600a21b | 248 | + Similarly, nested types of template type parameters must be tagged |
172b2e47 | 249 | with the 'typename' keyword, except in base lists. In many cases, |
250 | but not all, the compiler will tell you where you need to add | |
251 | 'typename'. For more information, see | |
4600a21b | 252 | |
653e5405 | 253 | http://www.cygnus.com/misc/wp/dec96pub/template.html#temp.res |
4600a21b | 254 | |
9031d10b | 255 | + Guiding declarations are no longer supported. Function declarations, |
b1cfe2be | 256 | including friend declarations, do not refer to template instantiations. |
257 | You can restore the old behavior with -fguiding-decls until you fix | |
258 | your code. | |
259 | ||
4600a21b | 260 | Other features: |
261 | ||
262 | + Default function arguments in templates will not be evaluated (or | |
263 | checked for semantic validity) unless they are needed. Default | |
264 | arguments in class bodies will not be parsed until the class | |
265 | definition is complete. | |
4600a21b | 266 | + The -ftemplate-depth-NN flag can be used to increase the maximum |
172b2e47 | 267 | recursive template instantiation depth, which defaults to 17. If you |
268 | need to use this flag, the compiler will tell you. | |
b1cfe2be | 269 | + Explicit instantiation of template constructors and destructors is |
270 | now supported. For instance: | |
271 | ||
653e5405 | 272 | template A<int>::A(const A&); |
4600a21b | 273 | |
274 | Still not supported: | |
275 | ||
172b2e47 | 276 | + Member class templates. |
172b2e47 | 277 | + Template friends. |
4600a21b | 278 | |
279 | * Exception handling support has been significantly improved and is on by | |
b6684166 | 280 | default. The compiler supports two mechanisms for walking back up the |
281 | call stack; one relies on static information about how registers are | |
282 | saved, and causes no runtime overhead for code that does not throw | |
283 | exceptions. The other mechanism uses setjmp and longjmp equivalents, and | |
284 | can result in quite a bit of runtime overhead. You can determine which | |
285 | mechanism is the default for your target by compiling a testcase that | |
286 | uses exceptions and doing an 'nm' on the object file; if it uses __throw, | |
287 | it's using the first mechanism. If it uses __sjthrow, it's using the | |
288 | second. | |
289 | ||
290 | You can turn EH support off with -fno-exceptions. | |
4600a21b | 291 | |
172b2e47 | 292 | * RTTI support has been rewritten to work properly and is now on by default. |
293 | This means code that uses virtual functions will have a modest space | |
294 | overhead. You can use the -fno-rtti flag to disable RTTI support. | |
4600a21b | 295 | |
296 | * On ELF systems, duplicate copies of symbols with 'initialized common' | |
297 | linkage (such as template instantiations, vtables, and extern inlines) | |
298 | will now be discarded by the GNU linker, so you don't need to use -frepo. | |
299 | This support requires GNU ld from binutils 2.8 or later. | |
3b1b1722 | 300 | |
172b2e47 | 301 | * The overload resolution code has been rewritten to conform to the latest |
302 | C++ Working Paper. Built-in operators are now considered as candidates | |
303 | in operator overload resolution. Function template overloading chooses | |
304 | the more specialized template, and handles base classes in type deduction | |
305 | and guiding declarations properly. In this release the old code can | |
306 | still be selected with -fno-ansi-overloading, although this is not | |
307 | supported and will be removed in a future release. | |
308 | ||
309 | * Standard usage syntax for the std namespace is supported; std is treated | |
310 | as an alias for global scope. General namespaces are still not supported. | |
b7032dd4 | 311 | |
4600a21b | 312 | * New flags: |
313 | ||
b6684166 | 314 | + New warning -Wno-pmf-conversion (don't warn about |
315 | converting from a bound member function pointer to function | |
316 | pointer). | |
4600a21b | 317 | |
9031d10b | 318 | + A flag -Weffc++ has been added for violations of some of the style |
4600a21b | 319 | guidelines in Scott Meyers' _Effective C++_ books. |
320 | ||
321 | + -Woverloaded-virtual now warns if a virtual function in a base | |
322 | class is hidden in a derived class, rather than warning about | |
323 | virtual functions being overloaded (even if all of the inherited | |
324 | signatures are overridden) as it did before. | |
325 | ||
326 | + -Wall no longer implies -W. The new warning flag, -Wsign-compare, | |
653e5405 | 327 | included in -Wall, warns about dangerous comparisons of signed and |
328 | unsigned values. Only the flag is new; it was previously part of | |
329 | -W. | |
4600a21b | 330 | |
331 | + The new flag, -fno-weak, disables the use of weak symbols. | |
d6c1e77c | 332 | |
172b2e47 | 333 | * Synthesized methods are now emitted in any translation units that need |
334 | an out-of-line copy. They are no longer affected by #pragma interface | |
335 | or #pragma implementation. | |
336 | ||
337 | * __FUNCTION__ and __PRETTY_FUNCTION__ are now treated as variables by the | |
338 | parser; previously they were treated as string constants. So code like | |
9031d10b | 339 | `printf (__FUNCTION__ ": foo")' must be rewritten to |
172b2e47 | 340 | `printf ("%s: foo", __FUNCTION__)'. This is necessary for templates. |
341 | ||
d6c1e77c | 342 | * local static variables in extern inline functions will be shared between |
343 | translation units. | |
344 | ||
9031d10b | 345 | * -fvtable-thunks is supported for all targets, and is the default for |
5d89bd6f | 346 | GNU/Linux with glibc 2.x (also called libc 6.x). |
d6c1e77c | 347 | |
1423c9c0 | 348 | * bool is now always the same size as another built-in type. Previously, |
349 | a 64-bit RISC target using a 32-bit ABI would have 32-bit pointers and a | |
350 | 64-bit bool. This should only affect Irix 6, which was not supported in | |
351 | 2.7.2. | |
352 | ||
353 | * new (nothrow) is now supported. | |
354 | ||
1423c9c0 | 355 | * Synthesized destructors are no longer made virtual just because the class |
356 | already has virtual functions, only if they override a virtual destructor | |
357 | in a base class. The compiler will warn if this affects your code. | |
358 | ||
747ffee6 | 359 | * The g++ driver now only links against libstdc++, not libg++; it is |
1423c9c0 | 360 | functionally identical to the c++ driver. |
361 | ||
362 | * (void *)0 is no longer considered a null pointer constant; NULL in | |
363 | <stddef.h> is now defined as __null, a magic constant of type (void *) | |
364 | normally, or (size_t) with -ansi. | |
365 | ||
1423c9c0 | 366 | * The name of a class is now implicitly declared in its own scope; A::A |
367 | refers to A. | |
368 | ||
1146f179 | 369 | * Local classes are now supported. |
1423c9c0 | 370 | |
1423c9c0 | 371 | * __attribute__ can now be attached to types as well as declarations. |
372 | ||
1423c9c0 | 373 | * The compiler no longer emits a warning if an ellipsis is used as a |
374 | function's argument list. | |
375 | ||
1423c9c0 | 376 | * Definition of nested types outside of their containing class is now |
172b2e47 | 377 | supported. For instance: |
1423c9c0 | 378 | |
379 | struct A { | |
653e5405 | 380 | struct B; |
381 | B* bp; | |
1423c9c0 | 382 | }; |
383 | ||
384 | struct A::B { | |
653e5405 | 385 | int member; |
1423c9c0 | 386 | }; |
387 | ||
1423c9c0 | 388 | * On the HPPA, some classes that do not define a copy constructor |
389 | will be passed and returned in memory again so that functions | |
390 | returning those types can be inlined. | |
b1cfe2be | 391 | |
392 | *** The g++ team thanks everyone that contributed to this release, | |
393 | but especially: | |
394 | ||
395 | * Joe Buck <jbuck@synopsys.com>, the maintainer of the g++ FAQ. | |
396 | * Brendan Kehoe <brendan@cygnus.com>, who coordinates testing of g++. | |
397 | * Jason Merrill <jason@cygnus.com>, the g++ maintainer. | |
9031d10b | 398 | * Mark Mitchell <mmitchell@usa.net>, who implemented member function |
b1cfe2be | 399 | templates and explicit qualification of function templates. |
400 | * Mike Stump <mrs@wrs.com>, the previous g++ maintainer, who did most of | |
401 | the exception handling work. | |
7dfbd804 | 402 | |
403 | \f | |
fbd26352 | 404 | Copyright (C) 1997-2019 Free Software Foundation, Inc. |
7dfbd804 | 405 | |
406 | Copying and distribution of this file, with or without modification, | |
407 | are permitted in any medium without royalty provided the copyright | |
408 | notice and this notice are preserved. |