gcc/cp/parser.h

   1 /* Data structures and function exported by the C++ Parser.
   2    Copyright (C) 2010-2023 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
   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   /* True if we're in the context of OpenMP directives written as C++11
 118      attributes turned into pragma.  */
 119   bool in_omp_attribute_pragma;
 120
 121   /* True for in_omp_attribute_pragma lexer that should be destroyed
 122      when it is no longer in use.  */
 123   bool orphan_p;
 124 };
 125
 126
 127 /* cp_token_cache is a range of tokens.  There is no need to represent
 128    allocate heap memory for it, since tokens are never removed from the
 129    lexer's array.  There is also no need for the GC to walk through
 130    a cp_token_cache, since everything in here is referenced through
 131    a lexer.  */
 132
 133 struct GTY(()) cp_token_cache {
 134   /* The beginning of the token range.  */
 135   cp_token * GTY((skip)) first;
 136
 137   /* Points immediately after the last token in the range.  */
 138   cp_token * GTY ((skip)) last;
 139 };
 140
 141 typedef cp_token_cache *cp_token_cache_ptr;
 142
 143 struct cp_token_ident
 144 {
 145   unsigned int ident_len;
 146   const char *ident_str;
 147   unsigned int before_len;
 148   const char *before_str;
 149   unsigned int after_len;
 150   const char *after_str;
 151 };
 152
 153 /* An entry in a queue of function arguments that require post-processing.  */
 154
 155 struct GTY(()) cp_default_arg_entry {
 156   /* The current_class_type when we parsed this arg.  */
 157   tree class_type;
 158
 159   /* The function decl itself.  */
 160   tree decl;
 161 };
 162
 163
 164 /* An entry in a stack for member functions defined within their classes.  */
 165
 166 struct GTY(()) cp_unparsed_functions_entry {
 167   /* Functions with default arguments that require post-processing.
 168      Functions appear in this list in declaration order.  */
 169   vec<cp_default_arg_entry, va_gc> *funs_with_default_args;
 170
 171   /* Functions with defintions that require post-processing.  Functions
 172      appear in this list in declaration order.  */
 173   vec<tree, va_gc> *funs_with_definitions;
 174
 175   /* Non-static data members with initializers that require post-processing.
 176      FIELD_DECLs appear in this list in declaration order.  */
 177   vec<tree, va_gc> *nsdmis;
 178
 179   /* Functions with noexcept-specifiers that require post-processing.  */
 180   vec<tree, va_gc> *noexcepts;
 181
 182   /* Functions with contract attributes that require post-processing.  */
 183   vec<tree, va_gc> *contracts;
 184 };
 185
 186
 187 /* The status of a tentative parse.  */
 188
 189 enum cp_parser_status_kind
 190 {
 191   /* No errors have occurred.  */
 192   CP_PARSER_STATUS_KIND_NO_ERROR,
 193   /* An error has occurred.  */
 194   CP_PARSER_STATUS_KIND_ERROR,
 195   /* We are committed to this tentative parse, whether or not an error
 196      has occurred.  */
 197   CP_PARSER_STATUS_KIND_COMMITTED
 198 };
 199
 200
 201 /* Context that is saved and restored when parsing tentatively.  */
 202 struct GTY (()) cp_parser_context {
 203   /* If this is a tentative parsing context, the status of the
 204      tentative parse.  */
 205   enum cp_parser_status_kind status;
 206   /* If non-NULL, we have just seen a `x->' or `x.' expression.  Names
 207      that are looked up in this context must be looked up both in the
 208      scope given by OBJECT_TYPE (the type of `x' or `*x') and also in
 209      the context of the containing expression.  */
 210   tree object_type;
 211
 212   /* The next parsing context in the stack.  */
 213   struct cp_parser_context *next;
 214 };
 215
 216
 217 /* Helper data structure for parsing #pragma omp declare {simd,variant}.  */
 218 struct cp_omp_declare_simd_data {
 219   bool error_seen; /* Set if error has been reported.  */
 220   bool fndecl_seen; /* Set if one fn decl/definition has been seen already.  */
 221   bool variant_p; /* Set for #pragma omp declare variant.  */
 222   location_t loc;
 223   vec<cp_token_cache_ptr> tokens;
 224   tree *attribs[2];
 225 };
 226
 227 /* Helper data structure for parsing #pragma acc routine.  */
 228 struct cp_oacc_routine_data : cp_omp_declare_simd_data {
 229   tree clauses;
 230 };
 231
 232 /* The cp_parser structure represents the C++ parser.  */
 233
 234 struct GTY(()) cp_parser {
 235   /* The lexer from which we are obtaining tokens.  */
 236   cp_lexer *lexer;
 237
 238   /* The scope in which names should be looked up.  If NULL_TREE, then
 239      we look up names in the scope that is currently open in the
 240      source program.  If non-NULL, this is either a TYPE or
 241      NAMESPACE_DECL for the scope in which we should look.  It can
 242      also be ERROR_MARK, when we've parsed a bogus scope.
 243
 244      This value is not cleared automatically after a name is looked
 245      up, so we must be careful to clear it before starting a new look
 246      up sequence.  (If it is not cleared, then `X::Y' followed by `Z'
 247      will look up `Z' in the scope of `X', rather than the current
 248      scope.)  Unfortunately, it is difficult to tell when name lookup
 249      is complete, because we sometimes peek at a token, look it up,
 250      and then decide not to consume it.   */
 251   tree scope;
 252
 253   /* OBJECT_SCOPE and QUALIFYING_SCOPE give the scopes in which the
 254      last lookup took place.  OBJECT_SCOPE is used if an expression
 255      like "x->y" or "x.y" was used; it gives the type of "*x" or "x",
 256      respectively.  QUALIFYING_SCOPE is used for an expression of the
 257      form "X::Y"; it refers to X.  */
 258   tree object_scope;
 259   tree qualifying_scope;
 260
 261   /* A stack of parsing contexts.  All but the bottom entry on the
 262      stack will be tentative contexts.
 263
 264      We parse tentatively in order to determine which construct is in
 265      use in some situations.  For example, in order to determine
 266      whether a statement is an expression-statement or a
 267      declaration-statement we parse it tentatively as a
 268      declaration-statement.  If that fails, we then reparse the same
 269      token stream as an expression-statement.  */
 270   cp_parser_context *context;
 271
 272   /* True if we are parsing GNU C++.  If this flag is not set, then
 273      GNU extensions are not recognized.  */
 274   bool allow_gnu_extensions_p;
 275
 276   /* TRUE if the `>' token should be interpreted as the greater-than
 277      operator.  FALSE if it is the end of a template-id or
 278      template-parameter-list. In C++0x mode, this flag also applies to
 279      `>>' tokens, which are viewed as two consecutive `>' tokens when
 280      this flag is FALSE.  */
 281   bool greater_than_is_operator_p;
 282
 283   /* TRUE if default arguments are allowed within a parameter list
 284      that starts at this point. FALSE if only a gnu extension makes
 285      them permissible.  */
 286   bool default_arg_ok_p;
 287
 288   /* TRUE if we are parsing an integral constant-expression.  See
 289      [expr.const] for a precise definition.  */
 290   bool integral_constant_expression_p;
 291
 292   /* TRUE if we are parsing an integral constant-expression -- but a
 293      non-constant expression should be permitted as well.  This flag
 294      is used when parsing an array bound so that GNU variable-length
 295      arrays are tolerated.  */
 296   bool allow_non_integral_constant_expression_p;
 297
 298   /* TRUE if ALLOW_NON_CONSTANT_EXPRESSION_P is TRUE and something has
 299      been seen that makes the expression non-constant.  */
 300   bool non_integral_constant_expression_p;
 301
 302   /* Used to track if local variable names and/or `this' are forbidden
 303      in the current context.  */
 304 #define LOCAL_VARS_FORBIDDEN (1 << 0)
 305 #define THIS_FORBIDDEN (1 << 1)
 306 #define LOCAL_VARS_AND_THIS_FORBIDDEN (LOCAL_VARS_FORBIDDEN | THIS_FORBIDDEN)
 307   unsigned char local_variables_forbidden_p;
 308
 309   /* TRUE if the declaration we are parsing is part of a
 310      linkage-specification of the form `extern string-literal
 311      declaration'.  */
 312   bool in_unbraced_linkage_specification_p;
 313
 314   /* TRUE if we are presently parsing a declarator, after the
 315      direct-declarator.  */
 316   bool in_declarator_p;
 317
 318   /* TRUE if we are presently parsing a template-argument-list.  */
 319   bool in_template_argument_list_p;
 320
 321   /* Set to IN_ITERATION_STMT if parsing an iteration-statement,
 322      to IN_OMP_BLOCK if parsing OpenMP structured block and
 323      IN_OMP_FOR if parsing OpenMP loop.  If parsing a switch statement,
 324      this is bitwise ORed with IN_SWITCH_STMT, unless parsing an
 325      iteration-statement, OpenMP block or loop within that switch.  */
 326 #define IN_SWITCH_STMT          1
 327 #define IN_ITERATION_STMT       2
 328 #define IN_OMP_BLOCK            4
 329 #define IN_OMP_FOR              8
 330 #define IN_IF_STMT             16
 331   unsigned char in_statement;
 332
 333   /* TRUE if we are presently parsing the body of a switch statement.
 334      Note that this doesn't quite overlap with in_statement above.
 335      The difference relates to giving the right sets of error messages:
 336      "case not in switch" vs "break statement used with OpenMP...".  */
 337   bool in_switch_statement_p;
 338
 339   /* TRUE if we are parsing a type-id in an expression context.  In
 340      such a situation, both "type (expr)" and "type (type)" are valid
 341      alternatives.  */
 342   bool in_type_id_in_expr_p;
 343
 344   /* TRUE if strings in expressions should be translated to the execution
 345      character set.  */
 346   bool translate_strings_p;
 347
 348   /* TRUE if we are presently parsing the body of a function, but not
 349      a local class.  */
 350   bool in_function_body;
 351
 352   /* Nonzero if we're processing a __transaction_atomic or
 353      __transaction_relaxed statement.  */
 354   unsigned char in_transaction;
 355
 356   /* TRUE if we can auto-correct a colon to a scope operator.  */
 357   bool colon_corrects_to_scope_p;
 358
 359   /* TRUE if : doesn't start a class definition.  Should be only used
 360      together with type_definition_forbidden_message non-NULL, in
 361      contexts where new types may not be defined, and the type list
 362      is terminated by colon.  */
 363   bool colon_doesnt_start_class_def_p;
 364
 365   /* TRUE if we are parsing an objective c message, and ':' is permitted
 366      to terminate an assignment-expression.  */
 367   bool objective_c_message_context_p;
 368
 369   /* If non-NULL, then we are parsing a construct where new type
 370      definitions are not permitted.  The string stored here will be
 371      issued as an error message if a type is defined.  */
 372   const char *type_definition_forbidden_message;
 373
 374   /* Argument for type_definition_forbidden_message if needed.  */
 375   const char *type_definition_forbidden_message_arg;
 376
 377   /* A stack used for member functions of local classes.  The lists
 378      contained in an individual entry can only be processed once the
 379      outermost class being defined is complete.  */
 380   vec<cp_unparsed_functions_entry, va_gc> *unparsed_queues;
 381
 382   /* The number of classes whose definitions are currently in
 383      progress.  */
 384   unsigned num_classes_being_defined;
 385
 386   /* The number of template parameter lists that apply directly to the
 387      current declaration.  */
 388   unsigned num_template_parameter_lists;
 389
 390   /* When parsing #pragma omp declare simd, this is a pointer to a
 391      helper data structure.  */
 392   cp_omp_declare_simd_data * GTY((skip)) omp_declare_simd;
 393
 394   /* When parsing #pragma acc routine, this is a pointer to a helper data
 395      structure.  */
 396   cp_oacc_routine_data * GTY((skip)) oacc_routine;
 397
 398   /* Nonzero if parsing a parameter list where 'auto' should trigger an implicit
 399      template parameter.  */
 400   bool auto_is_implicit_function_template_parm_p;
 401
 402   /* TRUE if the function being declared was made a template due to its
 403      parameter list containing generic type specifiers (`auto' or concept
 404      identifiers) rather than an explicit template parameter list.  */
 405   bool fully_implicit_function_template_p;
 406
 407   /* TRUE if omp::directive or omp::sequence attributes may not appear.  */
 408   bool omp_attrs_forbidden_p;
 409
 410   /* Tracks the function's template parameter list when declaring a function
 411      using generic type parameters.  This is either a new chain in the case of a
 412      fully implicit function template or an extension of the function's existing
 413      template parameter list.  This is tracked to optimize calls subsequent
 414      calls to synthesize_implicit_template_parm during
 415      cp_parser_parameter_declaration.  */
 416   tree implicit_template_parms;
 417
 418   /* The scope into which an implicit template parameter list has been
 419      introduced or an existing template parameter list is being extended with
 420      implicit template parameters.  In most cases this is the sk_function_parms
 421      scope containing the use of a generic type.  In the case of an out-of-line
 422      member definition using a generic type, it is the sk_class scope.  */
 423   cp_binding_level* implicit_template_scope;
 424
 425   /* True if parsing a result type in a compound requirement. This permits
 426      constrained-type-specifiers inside what would normally be a trailing
 427      return type. */
 428   bool in_result_type_constraint_p;
 429
 430   /* True if a constrained-type-specifier is not allowed in this
 431      context e.g., because they could never be deduced.  */
 432   int prevent_constrained_type_specifiers;
 433
 434   /* Location of the string-literal token within the current linkage
 435      specification, if any, or UNKNOWN_LOCATION otherwise.  */
 436   location_t innermost_linkage_specification_location;
 437
 438 };
 439
 440 /* In parser.cc  */
 441 extern void debug (cp_token &ref);
 442 extern void debug (cp_token *ptr);
 443 extern void cp_lexer_debug_tokens (vec<cp_token, va_gc> *);
 444 extern void debug (vec<cp_token, va_gc> &ref);
 445 extern void debug (vec<cp_token, va_gc> *ptr);
 446 extern void cp_debug_parser (FILE *, cp_parser *);
 447 extern void debug (cp_parser &ref);
 448 extern void debug (cp_parser *ptr);
 449 extern bool cp_keyword_starts_decl_specifier_p (enum rid keyword);
 450
 451 #endif  /* GCC_CP_PARSER_H  */