gcc/cp/parser.h

   1 /* Data structures and function exported by the C++ Parser.
   2    Copyright (C) 2010-2020 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   /* 4 unused bits.  */
  62
  63   /* The location at which this token was found.  */
  64   location_t location;
  65   /* The value associated with this token, if any.  */
  66   union cp_token_value {
  67     /* Used for compound tokens such as CPP_NESTED_NAME_SPECIFIER.  */
  68     struct tree_check* GTY((tag ("true"))) tree_check_value;
  69     /* Use for all other tokens.  */
  70     tree GTY((tag ("false"))) value;
  71   } GTY((desc ("%1.tree_check_p"))) u;
  72 };
  73
  74
  75 /* We use a stack of token pointer for saving token sets.  */
  76 typedef struct cp_token *cp_token_position;
  77
  78 /* The cp_lexer structure represents the C++ lexer.  It is responsible
  79    for managing the token stream from the preprocessor and supplying
  80    it to the parser.  Tokens are never added to the cp_lexer after
  81    it is created.  */
  82
  83 struct GTY (()) cp_lexer {
  84   /* The memory allocated for the buffer.  NULL if this lexer does not
  85      own the token buffer.  */
  86   vec<cp_token, va_gc> *buffer;
  87
  88   /* A pointer just past the last available token.  The tokens
  89      in this lexer are [buffer, last_token).  */
  90   cp_token_position GTY ((skip)) last_token;
  91
  92   /* The next available token.  If NEXT_TOKEN is &eof_token, then there are
  93      no more available tokens.  */
  94   cp_token_position GTY ((skip)) next_token;
  95
  96   /* A stack indicating positions at which cp_lexer_save_tokens was
  97      called.  The top entry is the most recent position at which we
  98      began saving tokens.  If the stack is non-empty, we are saving
  99      tokens.  */
 100   vec<cp_token_position> GTY ((skip)) saved_tokens;
 101
 102   /* Saved pieces of end token we replaced with the eof token.  */
 103   enum cpp_ttype saved_type : 8;
 104   enum rid saved_keyword : 8;
 105
 106   /* The next lexer in a linked list of lexers.  */
 107   struct cp_lexer *next;
 108
 109   /* True if we should output debugging information.  */
 110   bool debugging_p;
 111
 112   /* True if we're in the context of parsing a pragma, and should not
 113      increment past the end-of-line marker.  */
 114   bool in_pragma;
 115 };
 116
 117
 118 /* cp_token_cache is a range of tokens.  There is no need to represent
 119    allocate heap memory for it, since tokens are never removed from the
 120    lexer's array.  There is also no need for the GC to walk through
 121    a cp_token_cache, since everything in here is referenced through
 122    a lexer.  */
 123
 124 struct GTY(()) cp_token_cache {
 125   /* The beginning of the token range.  */
 126   cp_token * GTY((skip)) first;
 127
 128   /* Points immediately after the last token in the range.  */
 129   cp_token * GTY ((skip)) last;
 130 };
 131
 132 typedef cp_token_cache *cp_token_cache_ptr;
 133
 134 struct cp_token_ident
 135 {
 136   unsigned int ident_len;
 137   const char *ident_str;
 138   unsigned int before_len;
 139   const char *before_str;
 140   unsigned int after_len;
 141   const char *after_str;
 142 };
 143
 144 /* An entry in a queue of function arguments that require post-processing.  */
 145
 146 struct GTY(()) cp_default_arg_entry {
 147   /* The current_class_type when we parsed this arg.  */
 148   tree class_type;
 149
 150   /* The function decl itself.  */
 151   tree decl;
 152 };
 153
 154
 155 /* An entry in a stack for member functions defined within their classes.  */
 156
 157 struct GTY(()) cp_unparsed_functions_entry {
 158   /* Functions with default arguments that require post-processing.
 159      Functions appear in this list in declaration order.  */
 160   vec<cp_default_arg_entry, va_gc> *funs_with_default_args;
 161
 162   /* Functions with defintions that require post-processing.  Functions
 163      appear in this list in declaration order.  */
 164   vec<tree, va_gc> *funs_with_definitions;
 165
 166   /* Non-static data members with initializers that require post-processing.
 167      FIELD_DECLs appear in this list in declaration order.  */
 168   vec<tree, va_gc> *nsdmis;
 169
 170   /* Functions with noexcept-specifiers that require post-processing.  */
 171   vec<tree, va_gc> *noexcepts;
 172 };
 173
 174
 175 /* The status of a tentative parse.  */
 176
 177 enum cp_parser_status_kind
 178 {
 179   /* No errors have occurred.  */
 180   CP_PARSER_STATUS_KIND_NO_ERROR,
 181   /* An error has occurred.  */
 182   CP_PARSER_STATUS_KIND_ERROR,
 183   /* We are committed to this tentative parse, whether or not an error
 184      has occurred.  */
 185   CP_PARSER_STATUS_KIND_COMMITTED
 186 };
 187
 188
 189 /* Context that is saved and restored when parsing tentatively.  */
 190 struct GTY (()) cp_parser_context {
 191   /* If this is a tentative parsing context, the status of the
 192      tentative parse.  */
 193   enum cp_parser_status_kind status;
 194   /* If non-NULL, we have just seen a `x->' or `x.' expression.  Names
 195      that are looked up in this context must be looked up both in the
 196      scope given by OBJECT_TYPE (the type of `x' or `*x') and also in
 197      the context of the containing expression.  */
 198   tree object_type;
 199
 200   /* The next parsing context in the stack.  */
 201   struct cp_parser_context *next;
 202 };
 203
 204
 205 /* Helper data structure for parsing #pragma omp declare {simd,variant}.  */
 206 struct cp_omp_declare_simd_data {
 207   bool error_seen; /* Set if error has been reported.  */
 208   bool fndecl_seen; /* Set if one fn decl/definition has been seen already.  */
 209   bool variant_p; /* Set for #pragma omp declare variant.  */
 210   vec<cp_token_cache_ptr> tokens;
 211   tree clauses;
 212 };
 213
 214 /* Helper data structure for parsing #pragma acc routine.  */
 215 struct cp_oacc_routine_data : cp_omp_declare_simd_data {
 216   location_t loc;
 217 };
 218
 219 /* The cp_parser structure represents the C++ parser.  */
 220
 221 struct GTY(()) cp_parser {
 222   /* The lexer from which we are obtaining tokens.  */
 223   cp_lexer *lexer;
 224
 225   /* The scope in which names should be looked up.  If NULL_TREE, then
 226      we look up names in the scope that is currently open in the
 227      source program.  If non-NULL, this is either a TYPE or
 228      NAMESPACE_DECL for the scope in which we should look.  It can
 229      also be ERROR_MARK, when we've parsed a bogus scope.
 230
 231      This value is not cleared automatically after a name is looked
 232      up, so we must be careful to clear it before starting a new look
 233      up sequence.  (If it is not cleared, then `X::Y' followed by `Z'
 234      will look up `Z' in the scope of `X', rather than the current
 235      scope.)  Unfortunately, it is difficult to tell when name lookup
 236      is complete, because we sometimes peek at a token, look it up,
 237      and then decide not to consume it.   */
 238   tree scope;
 239
 240   /* OBJECT_SCOPE and QUALIFYING_SCOPE give the scopes in which the
 241      last lookup took place.  OBJECT_SCOPE is used if an expression
 242      like "x->y" or "x.y" was used; it gives the type of "*x" or "x",
 243      respectively.  QUALIFYING_SCOPE is used for an expression of the
 244      form "X::Y"; it refers to X.  */
 245   tree object_scope;
 246   tree qualifying_scope;
 247
 248   /* A stack of parsing contexts.  All but the bottom entry on the
 249      stack will be tentative contexts.
 250
 251      We parse tentatively in order to determine which construct is in
 252      use in some situations.  For example, in order to determine
 253      whether a statement is an expression-statement or a
 254      declaration-statement we parse it tentatively as a
 255      declaration-statement.  If that fails, we then reparse the same
 256      token stream as an expression-statement.  */
 257   cp_parser_context *context;
 258
 259   /* True if we are parsing GNU C++.  If this flag is not set, then
 260      GNU extensions are not recognized.  */
 261   bool allow_gnu_extensions_p;
 262
 263   /* TRUE if the `>' token should be interpreted as the greater-than
 264      operator.  FALSE if it is the end of a template-id or
 265      template-parameter-list. In C++0x mode, this flag also applies to
 266      `>>' tokens, which are viewed as two consecutive `>' tokens when
 267      this flag is FALSE.  */
 268   bool greater_than_is_operator_p;
 269
 270   /* TRUE if default arguments are allowed within a parameter list
 271      that starts at this point. FALSE if only a gnu extension makes
 272      them permissible.  */
 273   bool default_arg_ok_p;
 274
 275   /* TRUE if we are parsing an integral constant-expression.  See
 276      [expr.const] for a precise definition.  */
 277   bool integral_constant_expression_p;
 278
 279   /* TRUE if we are parsing an integral constant-expression -- but a
 280      non-constant expression should be permitted as well.  This flag
 281      is used when parsing an array bound so that GNU variable-length
 282      arrays are tolerated.  */
 283   bool allow_non_integral_constant_expression_p;
 284
 285   /* TRUE if ALLOW_NON_CONSTANT_EXPRESSION_P is TRUE and something has
 286      been seen that makes the expression non-constant.  */
 287   bool non_integral_constant_expression_p;
 288
 289   /* Used to track if local variable names and/or `this' are forbidden
 290      in the current context.  */
 291 #define LOCAL_VARS_FORBIDDEN (1 << 0)
 292 #define THIS_FORBIDDEN (1 << 1)
 293 #define LOCAL_VARS_AND_THIS_FORBIDDEN (LOCAL_VARS_FORBIDDEN | THIS_FORBIDDEN)
 294   unsigned char local_variables_forbidden_p;
 295
 296   /* TRUE if the declaration we are parsing is part of a
 297      linkage-specification of the form `extern string-literal
 298      declaration'.  */
 299   bool in_unbraced_linkage_specification_p;
 300
 301   /* TRUE if we are presently parsing a declarator, after the
 302      direct-declarator.  */
 303   bool in_declarator_p;
 304
 305   /* TRUE if we are presently parsing a template-argument-list.  */
 306   bool in_template_argument_list_p;
 307
 308   /* Set to IN_ITERATION_STMT if parsing an iteration-statement,
 309      to IN_OMP_BLOCK if parsing OpenMP structured block and
 310      IN_OMP_FOR if parsing OpenMP loop.  If parsing a switch statement,
 311      this is bitwise ORed with IN_SWITCH_STMT, unless parsing an
 312      iteration-statement, OpenMP block or loop within that switch.  */
 313 #define IN_SWITCH_STMT          1
 314 #define IN_ITERATION_STMT       2
 315 #define IN_OMP_BLOCK            4
 316 #define IN_OMP_FOR              8
 317 #define IN_IF_STMT             16
 318   unsigned char in_statement;
 319
 320   /* TRUE if we are presently parsing the body of a switch statement.
 321      Note that this doesn't quite overlap with in_statement above.
 322      The difference relates to giving the right sets of error messages:
 323      "case not in switch" vs "break statement used with OpenMP...".  */
 324   bool in_switch_statement_p;
 325
 326   /* TRUE if we are parsing a type-id in an expression context.  In
 327      such a situation, both "type (expr)" and "type (type)" are valid
 328      alternatives.  */
 329   bool in_type_id_in_expr_p;
 330
 331   /* TRUE if strings in expressions should be translated to the execution
 332      character set.  */
 333   bool translate_strings_p;
 334
 335   /* TRUE if we are presently parsing the body of a function, but not
 336      a local class.  */
 337   bool in_function_body;
 338
 339   /* Nonzero if we're processing a __transaction_atomic or
 340      __transaction_relaxed statement.  */
 341   unsigned char in_transaction;
 342
 343   /* TRUE if we can auto-correct a colon to a scope operator.  */
 344   bool colon_corrects_to_scope_p;
 345
 346   /* TRUE if : doesn't start a class definition.  Should be only used
 347      together with type_definition_forbidden_message non-NULL, in
 348      contexts where new types may not be defined, and the type list
 349      is terminated by colon.  */
 350   bool colon_doesnt_start_class_def_p;
 351
 352   /* If non-NULL, then we are parsing a construct where new type
 353      definitions are not permitted.  The string stored here will be
 354      issued as an error message if a type is defined.  */
 355   const char *type_definition_forbidden_message;
 356
 357   /* Argument for type_definition_forbidden_message if needed.  */
 358   const char *type_definition_forbidden_message_arg;
 359
 360   /* A stack used for member functions of local classes.  The lists
 361      contained in an individual entry can only be processed once the
 362      outermost class being defined is complete.  */
 363   vec<cp_unparsed_functions_entry, va_gc> *unparsed_queues;
 364
 365   /* The number of classes whose definitions are currently in
 366      progress.  */
 367   unsigned num_classes_being_defined;
 368
 369   /* The number of template parameter lists that apply directly to the
 370      current declaration.  */
 371   unsigned num_template_parameter_lists;
 372
 373   /* When parsing #pragma omp declare simd, this is a pointer to a
 374      helper data structure.  */
 375   cp_omp_declare_simd_data * GTY((skip)) omp_declare_simd;
 376
 377   /* When parsing #pragma acc routine, this is a pointer to a helper data
 378      structure.  */
 379   cp_oacc_routine_data * GTY((skip)) oacc_routine;
 380
 381   /* Nonzero if parsing a parameter list where 'auto' should trigger an implicit
 382      template parameter.  */
 383   bool auto_is_implicit_function_template_parm_p;
 384
 385   /* TRUE if the function being declared was made a template due to its
 386      parameter list containing generic type specifiers (`auto' or concept
 387      identifiers) rather than an explicit template parameter list.  */
 388   bool fully_implicit_function_template_p;
 389
 390   /* Tracks the function's template parameter list when declaring a function
 391      using generic type parameters.  This is either a new chain in the case of a
 392      fully implicit function template or an extension of the function's existing
 393      template parameter list.  This is tracked to optimize calls subsequent
 394      calls to synthesize_implicit_template_parm during
 395      cp_parser_parameter_declaration.  */
 396   tree implicit_template_parms;
 397
 398   /* The scope into which an implicit template parameter list has been
 399      introduced or an existing template parameter list is being extended with
 400      implicit template parameters.  In most cases this is the sk_function_parms
 401      scope containing the use of a generic type.  In the case of an out-of-line
 402      member definition using a generic type, it is the sk_class scope.  */
 403   cp_binding_level* implicit_template_scope;
 404
 405   /* True if parsing a result type in a compound requirement. This permits
 406      constrained-type-specifiers inside what would normally be a trailing
 407      return type. */
 408   bool in_result_type_constraint_p;
 409
 410   /* True if a constrained-type-specifier is not allowed in this
 411      context e.g., because they could never be deduced.  */
 412   int prevent_constrained_type_specifiers;
 413
 414   /* Location of the string-literal token within the current linkage
 415      specification, if any, or UNKNOWN_LOCATION otherwise.  */
 416   location_t innermost_linkage_specification_location;
 417
 418 };
 419
 420 /* In parser.c  */
 421 extern void debug (cp_token &ref);
 422 extern void debug (cp_token *ptr);
 423 extern void cp_lexer_debug_tokens (vec<cp_token, va_gc> *);
 424 extern void debug (vec<cp_token, va_gc> &ref);
 425 extern void debug (vec<cp_token, va_gc> *ptr);
 426 extern void cp_debug_parser (FILE *, cp_parser *);
 427 extern void debug (cp_parser &ref);
 428 extern void debug (cp_parser *ptr);
 429 extern bool cp_keyword_starts_decl_specifier_p (enum rid keyword);
 430
 431 #endif  /* GCC_CP_PARSER_H  */