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