gcc/cp/parser.h

   1 /* Data structures and function exported by the C++ Parser.
   2    Copyright (C) 2010-2021 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
   7    under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3, or (at your option)
   9    any later version.
  10
  11    GCC is distributed in the hope that it will be useful, but
  12    WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    General Public License 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 #ifndef GCC_CP_PARSER_H
  21 #define GCC_CP_PARSER_H
  22
  23 #include "tree.h"
  24 #include "cp/cp-tree.h"
  25 #include "c-family/c-pragma.h"
  26
  27 /* A token's value and its associated deferred access checks and
  28    qualifying scope.  */
  29
  30 struct GTY(()) tree_check {
  31   /* The value associated with the token.  */
  32   tree value;
  33   /* The checks that have been associated with value.  */
  34   vec<deferred_access_check, va_gc> *checks;
  35   /* The token's qualifying scope (used when it is a
  36      CPP_NESTED_NAME_SPECIFIER).  */
  37   tree qualifying_scope;
  38 };
  39
  40 /* A C++ token.  */
  41
  42 struct GTY (()) cp_token {
  43   /* The kind of token.  */
  44   enum cpp_ttype type : 8;
  45   /* If this token is a keyword, this value indicates which keyword.
  46      Otherwise, this value is RID_MAX.  */
  47   enum rid keyword : 8;
  48   /* Token flags.  */
  49   unsigned char flags;
  50   /* True if this token is from a context where it is implicitly extern "C" */
  51   bool implicit_extern_c : 1;
  52   /* True if an error has already been reported for this token, such as a
  53      CPP_NAME token that is not a keyword (i.e., for which KEYWORD is
  54      RID_MAX) iff this name was looked up and found to be ambiguous.  */
  55   bool error_reported : 1;
  56   /* True for a token that has been purged.  If a token is purged,
  57      it is no longer a valid token and it should be considered
  58      deleted.  */
  59   bool purged_p : 1;
  60   bool tree_check_p : 1;
  61   bool main_source_p : 1;
  62   /* 3 unused bits.  */
  63
  64   /* The location at which this token was found.  */
  65   location_t location;
  66   /* The value associated with this token, if any.  */
  67   union cp_token_value {
  68     /* Used for compound tokens such as CPP_NESTED_NAME_SPECIFIER.  */
  69     struct tree_check* GTY((tag ("true"))) tree_check_value;
  70     /* Use for all other tokens.  */
  71     tree GTY((tag ("false"))) value;
  72   } GTY((desc ("%1.tree_check_p"))) u;
  73 };
  74
  75
  76 /* We use a stack of token pointer for saving token sets.  */
  77 typedef struct cp_token *cp_token_position;
  78
  79 /* The cp_lexer structure represents the C++ lexer.  It is responsible
  80    for managing the token stream from the preprocessor and supplying
  81    it to the parser.  Tokens are never added to the cp_lexer after
  82    it is created.  */
  83
  84 struct GTY (()) cp_lexer {
  85   /* The memory allocated for the buffer.  NULL if this lexer does not
  86      own the token buffer.  */
  87   vec<cp_token, va_gc> *buffer;
  88
  89   /* A pointer just past the last available token.  The tokens
  90      in this lexer are [buffer, last_token).  */
  91   cp_token_position GTY ((skip)) last_token;
  92
  93   /* The next available token.  If NEXT_TOKEN is &eof_token, then there are
  94      no more available tokens.  */
  95   cp_token_position GTY ((skip)) next_token;
  96
  97   /* A stack indicating positions at which cp_lexer_save_tokens was
  98      called.  The top entry is the most recent position at which we
  99      began saving tokens.  If the stack is non-empty, we are saving
 100      tokens.  */
 101   vec<cp_token_position> GTY ((skip)) saved_tokens;
 102
 103   /* Saved pieces of end token we replaced with the eof token.  */
 104   enum cpp_ttype saved_type : 8;
 105   enum rid saved_keyword : 8;
 106
 107   /* The next lexer in a linked list of lexers.  */
 108   struct cp_lexer *next;
 109
 110   /* True if we should output debugging information.  */
 111   bool debugging_p;
 112
 113   /* True if we're in the context of parsing a pragma, and should not
 114      increment past the end-of-line marker.  */
 115   bool in_pragma;
 116 };
 117
 118
 119 /* cp_token_cache is a range of tokens.  There is no need to represent
 120    allocate heap memory for it, since tokens are never removed from the
 121    lexer's array.  There is also no need for the GC to walk through
 122    a cp_token_cache, since everything in here is referenced through
 123    a lexer.  */
 124
 125 struct GTY(()) cp_token_cache {
 126   /* The beginning of the token range.  */
 127   cp_token * GTY((skip)) first;
 128
 129   /* Points immediately after the last token in the range.  */
 130   cp_token * GTY ((skip)) last;
 131 };
 132
 133 typedef cp_token_cache *cp_token_cache_ptr;
 134
 135 struct cp_token_ident
 136 {
 137   unsigned int ident_len;
 138   const char *ident_str;
 139   unsigned int before_len;
 140   const char *before_str;
 141   unsigned int after_len;
 142   const char *after_str;
 143 };
 144
 145 /* An entry in a queue of function arguments that require post-processing.  */
 146
 147 struct GTY(()) cp_default_arg_entry {
 148   /* The current_class_type when we parsed this arg.  */
 149   tree class_type;
 150
 151   /* The function decl itself.  */
 152   tree decl;
 153 };
 154
 155
 156 /* An entry in a stack for member functions defined within their classes.  */
 157
 158 struct GTY(()) cp_unparsed_functions_entry {
 159   /* Functions with default arguments that require post-processing.
 160      Functions appear in this list in declaration order.  */
 161   vec<cp_default_arg_entry, va_gc> *funs_with_default_args;
 162
 163   /* Functions with defintions that require post-processing.  Functions
 164      appear in this list in declaration order.  */
 165   vec<tree, va_gc> *funs_with_definitions;
 166
 167   /* Non-static data members with initializers that require post-processing.
 168      FIELD_DECLs appear in this list in declaration order.  */
 169   vec<tree, va_gc> *nsdmis;
 170
 171   /* Functions with noexcept-specifiers that require post-processing.  */
 172   vec<tree, va_gc> *noexcepts;
 173 };
 174
 175
 176 /* The status of a tentative parse.  */
 177
 178 enum cp_parser_status_kind
 179 {
 180   /* No errors have occurred.  */
 181   CP_PARSER_STATUS_KIND_NO_ERROR,
 182   /* An error has occurred.  */
 183   CP_PARSER_STATUS_KIND_ERROR,
 184   /* We are committed to this tentative parse, whether or not an error
 185      has occurred.  */
 186   CP_PARSER_STATUS_KIND_COMMITTED
 187 };
 188
 189
 190 /* Context that is saved and restored when parsing tentatively.  */
 191 struct GTY (()) cp_parser_context {
 192   /* If this is a tentative parsing context, the status of the
 193      tentative parse.  */
 194   enum cp_parser_status_kind status;
 195   /* If non-NULL, we have just seen a `x->' or `x.' expression.  Names
 196      that are looked up in this context must be looked up both in the
 197      scope given by OBJECT_TYPE (the type of `x' or `*x') and also in
 198      the context of the containing expression.  */
 199   tree object_type;
 200
 201   /* The next parsing context in the stack.  */
 202   struct cp_parser_context *next;
 203 };
 204
 205
 206 /* Helper data structure for parsing #pragma omp declare {simd,variant}.  */
 207 struct cp_omp_declare_simd_data {
 208   bool error_seen; /* Set if error has been reported.  */
 209   bool fndecl_seen; /* Set if one fn decl/definition has been seen already.  */
 210   bool variant_p; /* Set for #pragma omp declare variant.  */
 211   vec<cp_token_cache_ptr> tokens;
 212   tree clauses;
 213 };
 214
 215 /* Helper data structure for parsing #pragma acc routine.  */
 216 struct cp_oacc_routine_data : cp_omp_declare_simd_data {
 217   location_t loc;
 218 };
 219
 220 /* The cp_parser structure represents the C++ parser.  */
 221
 222 struct GTY(()) cp_parser {
 223   /* The lexer from which we are obtaining tokens.  */
 224   cp_lexer *lexer;
 225
 226   /* The scope in which names should be looked up.  If NULL_TREE, then
 227      we look up names in the scope that is currently open in the
 228      source program.  If non-NULL, this is either a TYPE or
 229      NAMESPACE_DECL for the scope in which we should look.  It can
 230      also be ERROR_MARK, when we've parsed a bogus scope.
 231
 232      This value is not cleared automatically after a name is looked
 233      up, so we must be careful to clear it before starting a new look
 234      up sequence.  (If it is not cleared, then `X::Y' followed by `Z'
 235      will look up `Z' in the scope of `X', rather than the current
 236      scope.)  Unfortunately, it is difficult to tell when name lookup
 237      is complete, because we sometimes peek at a token, look it up,
 238      and then decide not to consume it.   */
 239   tree scope;
 240
 241   /* OBJECT_SCOPE and QUALIFYING_SCOPE give the scopes in which the
 242      last lookup took place.  OBJECT_SCOPE is used if an expression
 243      like "x->y" or "x.y" was used; it gives the type of "*x" or "x",
 244      respectively.  QUALIFYING_SCOPE is used for an expression of the
 245      form "X::Y"; it refers to X.  */
 246   tree object_scope;
 247   tree qualifying_scope;
 248
 249   /* A stack of parsing contexts.  All but the bottom entry on the
 250      stack will be tentative contexts.
 251
 252      We parse tentatively in order to determine which construct is in
 253      use in some situations.  For example, in order to determine
 254      whether a statement is an expression-statement or a
 255      declaration-statement we parse it tentatively as a
 256      declaration-statement.  If that fails, we then reparse the same
 257      token stream as an expression-statement.  */
 258   cp_parser_context *context;
 259
 260   /* True if we are parsing GNU C++.  If this flag is not set, then
 261      GNU extensions are not recognized.  */
 262   bool allow_gnu_extensions_p;
 263
 264   /* TRUE if the `>' token should be interpreted as the greater-than
 265      operator.  FALSE if it is the end of a template-id or
 266      template-parameter-list. In C++0x mode, this flag also applies to
 267      `>>' tokens, which are viewed as two consecutive `>' tokens when
 268      this flag is FALSE.  */
 269   bool greater_than_is_operator_p;
 270
 271   /* TRUE if default arguments are allowed within a parameter list
 272      that starts at this point. FALSE if only a gnu extension makes
 273      them permissible.  */
 274   bool default_arg_ok_p;
 275
 276   /* TRUE if we are parsing an integral constant-expression.  See
 277      [expr.const] for a precise definition.  */
 278   bool integral_constant_expression_p;
 279
 280   /* TRUE if we are parsing an integral constant-expression -- but a
 281      non-constant expression should be permitted as well.  This flag
 282      is used when parsing an array bound so that GNU variable-length
 283      arrays are tolerated.  */
 284   bool allow_non_integral_constant_expression_p;
 285
 286   /* TRUE if ALLOW_NON_CONSTANT_EXPRESSION_P is TRUE and something has
 287      been seen that makes the expression non-constant.  */
 288   bool non_integral_constant_expression_p;
 289
 290   /* Used to track if local variable names and/or `this' are forbidden
 291      in the current context.  */
 292 #define LOCAL_VARS_FORBIDDEN (1 << 0)
 293 #define THIS_FORBIDDEN (1 << 1)
 294 #define LOCAL_VARS_AND_THIS_FORBIDDEN (LOCAL_VARS_FORBIDDEN | THIS_FORBIDDEN)
 295   unsigned char local_variables_forbidden_p;
 296
 297   /* TRUE if the declaration we are parsing is part of a
 298      linkage-specification of the form `extern string-literal
 299      declaration'.  */
 300   bool in_unbraced_linkage_specification_p;
 301
 302   /* TRUE if we are presently parsing a declarator, after the
 303      direct-declarator.  */
 304   bool in_declarator_p;
 305
 306   /* TRUE if we are presently parsing a template-argument-list.  */
 307   bool in_template_argument_list_p;
 308
 309   /* Set to IN_ITERATION_STMT if parsing an iteration-statement,
 310      to IN_OMP_BLOCK if parsing OpenMP structured block and
 311      IN_OMP_FOR if parsing OpenMP loop.  If parsing a switch statement,
 312      this is bitwise ORed with IN_SWITCH_STMT, unless parsing an
 313      iteration-statement, OpenMP block or loop within that switch.  */
 314 #define IN_SWITCH_STMT          1
 315 #define IN_ITERATION_STMT       2
 316 #define IN_OMP_BLOCK            4
 317 #define IN_OMP_FOR              8
 318 #define IN_IF_STMT             16
 319   unsigned char in_statement;
 320
 321   /* TRUE if we are presently parsing the body of a switch statement.
 322      Note that this doesn't quite overlap with in_statement above.
 323      The difference relates to giving the right sets of error messages:
 324      "case not in switch" vs "break statement used with OpenMP...".  */
 325   bool in_switch_statement_p;
 326
 327   /* TRUE if we are parsing a type-id in an expression context.  In
 328      such a situation, both "type (expr)" and "type (type)" are valid
 329      alternatives.  */
 330   bool in_type_id_in_expr_p;
 331
 332   /* TRUE if strings in expressions should be translated to the execution
 333      character set.  */
 334   bool translate_strings_p;
 335
 336   /* TRUE if we are presently parsing the body of a function, but not
 337      a local class.  */
 338   bool in_function_body;
 339
 340   /* Nonzero if we're processing a __transaction_atomic or
 341      __transaction_relaxed statement.  */
 342   unsigned char in_transaction;
 343
 344   /* TRUE if we can auto-correct a colon to a scope operator.  */
 345   bool colon_corrects_to_scope_p;
 346
 347   /* TRUE if : doesn't start a class definition.  Should be only used
 348      together with type_definition_forbidden_message non-NULL, in
 349      contexts where new types may not be defined, and the type list
 350      is terminated by colon.  */
 351   bool colon_doesnt_start_class_def_p;
 352
 353   /* If non-NULL, then we are parsing a construct where new type
 354      definitions are not permitted.  The string stored here will be
 355      issued as an error message if a type is defined.  */
 356   const char *type_definition_forbidden_message;
 357
 358   /* Argument for type_definition_forbidden_message if needed.  */
 359   const char *type_definition_forbidden_message_arg;
 360
 361   /* A stack used for member functions of local classes.  The lists
 362      contained in an individual entry can only be processed once the
 363      outermost class being defined is complete.  */
 364   vec<cp_unparsed_functions_entry, va_gc> *unparsed_queues;
 365
 366   /* The number of classes whose definitions are currently in
 367      progress.  */
 368   unsigned num_classes_being_defined;
 369
 370   /* The number of template parameter lists that apply directly to the
 371      current declaration.  */
 372   unsigned num_template_parameter_lists;
 373
 374   /* When parsing #pragma omp declare simd, this is a pointer to a
 375      helper data structure.  */
 376   cp_omp_declare_simd_data * GTY((skip)) omp_declare_simd;
 377
 378   /* When parsing #pragma acc routine, this is a pointer to a helper data
 379      structure.  */
 380   cp_oacc_routine_data * GTY((skip)) oacc_routine;
 381
 382   /* Nonzero if parsing a parameter list where 'auto' should trigger an implicit
 383      template parameter.  */
 384   bool auto_is_implicit_function_template_parm_p;
 385
 386   /* TRUE if the function being declared was made a template due to its
 387      parameter list containing generic type specifiers (`auto' or concept
 388      identifiers) rather than an explicit template parameter list.  */
 389   bool fully_implicit_function_template_p;
 390
 391   /* Tracks the function's template parameter list when declaring a function
 392      using generic type parameters.  This is either a new chain in the case of a
 393      fully implicit function template or an extension of the function's existing
 394      template parameter list.  This is tracked to optimize calls subsequent
 395      calls to synthesize_implicit_template_parm during
 396      cp_parser_parameter_declaration.  */
 397   tree implicit_template_parms;
 398
 399   /* The scope into which an implicit template parameter list has been
 400      introduced or an existing template parameter list is being extended with
 401      implicit template parameters.  In most cases this is the sk_function_parms
 402      scope containing the use of a generic type.  In the case of an out-of-line
 403      member definition using a generic type, it is the sk_class scope.  */
 404   cp_binding_level* implicit_template_scope;
 405
 406   /* True if parsing a result type in a compound requirement. This permits
 407      constrained-type-specifiers inside what would normally be a trailing
 408      return type. */
 409   bool in_result_type_constraint_p;
 410
 411   /* True if a constrained-type-specifier is not allowed in this
 412      context e.g., because they could never be deduced.  */
 413   int prevent_constrained_type_specifiers;
 414
 415   /* Location of the string-literal token within the current linkage
 416      specification, if any, or UNKNOWN_LOCATION otherwise.  */
 417   location_t innermost_linkage_specification_location;
 418
 419 };
 420
 421 /* In parser.c  */
 422 extern void debug (cp_token &ref);
 423 extern void debug (cp_token *ptr);
 424 extern void cp_lexer_debug_tokens (vec<cp_token, va_gc> *);
 425 extern void debug (vec<cp_token, va_gc> &ref);
 426 extern void debug (vec<cp_token, va_gc> *ptr);
 427 extern void cp_debug_parser (FILE *, cp_parser *);
 428 extern void debug (cp_parser &ref);
 429 extern void debug (cp_parser *ptr);
 430 extern bool cp_keyword_starts_decl_specifier_p (enum rid keyword);
 431
 432 #endif  /* GCC_CP_PARSER_H  */