gcc/cp/parser.h

   1 /* Data structures and function exported by the C++ Parser.
   2    Copyright (C) 2010-2017 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_BITFIELD (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_BITFIELD (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_BITFIELD 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_BITFIELD 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_BITFIELD purged_p : 1;
  60   /* 5 unused bits.  */
  61   /* The location at which this token was found.  */
  62   location_t location;
  63   /* The value associated with this token, if any.  */
  64   union cp_token_value {
  65     /* Used for compound tokens such as CPP_NESTED_NAME_SPECIFIER.  */
  66     struct tree_check* GTY((tag ("1"))) tree_check_value;
  67     /* Use for all other tokens.  */
  68     tree GTY((tag ("0"))) value;
  69   } GTY((desc ("(%1.type == CPP_TEMPLATE_ID)"
  70                "|| (%1.type == CPP_NESTED_NAME_SPECIFIER)"
  71                "|| (%1.type == CPP_DECLTYPE)"))) 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   /* The next lexer in a linked list of lexers.  */
 103   struct cp_lexer *next;
 104
 105   /* True if we should output debugging information.  */
 106   bool debugging_p;
 107
 108   /* True if we're in the context of parsing a pragma, and should not
 109      increment past the end-of-line marker.  */
 110   bool in_pragma;
 111 };
 112
 113
 114 /* cp_token_cache is a range of tokens.  There is no need to represent
 115    allocate heap memory for it, since tokens are never removed from the
 116    lexer's array.  There is also no need for the GC to walk through
 117    a cp_token_cache, since everything in here is referenced through
 118    a lexer.  */
 119
 120 struct GTY(()) cp_token_cache {
 121   /* The beginning of the token range.  */
 122   cp_token * GTY((skip)) first;
 123
 124   /* Points immediately after the last token in the range.  */
 125   cp_token * GTY ((skip)) last;
 126 };
 127
 128 typedef cp_token_cache *cp_token_cache_ptr;
 129
 130 struct cp_token_ident
 131 {
 132   unsigned int ident_len;
 133   const char *ident_str;
 134   unsigned int before_len;
 135   const char *before_str;
 136   unsigned int after_len;
 137   const char *after_str;
 138 };
 139
 140 /* An entry in a queue of function arguments that require post-processing.  */
 141
 142 struct GTY(()) cp_default_arg_entry {
 143   /* The current_class_type when we parsed this arg.  */
 144   tree class_type;
 145
 146   /* The function decl itself.  */
 147   tree decl;
 148 };
 149
 150
 151 /* An entry in a stack for member functions defined within their classes.  */
 152
 153 struct GTY(()) cp_unparsed_functions_entry {
 154   /* Functions with default arguments that require post-processing.
 155      Functions appear in this list in declaration order.  */
 156   vec<cp_default_arg_entry, va_gc> *funs_with_default_args;
 157
 158   /* Functions with defintions that require post-processing.  Functions
 159      appear in this list in declaration order.  */
 160   vec<tree, va_gc> *funs_with_definitions;
 161
 162   /* Non-static data members with initializers that require post-processing.
 163      FIELD_DECLs appear in this list in declaration order.  */
 164   vec<tree, va_gc> *nsdmis;
 165
 166   /* Nested classes go in this vector, so that we can do some final
 167      processing after parsing any NSDMIs.  */
 168   vec<tree, va_gc> *classes;
 169 };
 170
 171
 172 /* The status of a tentative parse.  */
 173
 174 enum cp_parser_status_kind
 175 {
 176   /* No errors have occurred.  */
 177   CP_PARSER_STATUS_KIND_NO_ERROR,
 178   /* An error has occurred.  */
 179   CP_PARSER_STATUS_KIND_ERROR,
 180   /* We are committed to this tentative parse, whether or not an error
 181      has occurred.  */
 182   CP_PARSER_STATUS_KIND_COMMITTED
 183 };
 184
 185
 186 /* Context that is saved and restored when parsing tentatively.  */
 187 struct GTY (()) cp_parser_context {
 188   /* If this is a tentative parsing context, the status of the
 189      tentative parse.  */
 190   enum cp_parser_status_kind status;
 191   /* If non-NULL, we have just seen a `x->' or `x.' expression.  Names
 192      that are looked up in this context must be looked up both in the
 193      scope given by OBJECT_TYPE (the type of `x' or `*x') and also in
 194      the context of the containing expression.  */
 195   tree object_type;
 196
 197   /* The next parsing context in the stack.  */
 198   struct cp_parser_context *next;
 199 };
 200
 201
 202 /* Helper data structure for parsing #pragma omp declare simd, and Cilk Plus
 203    SIMD-enabled functions' vector attribute.  */
 204 struct cp_omp_declare_simd_data {
 205   bool error_seen; /* Set if error has been reported.  */
 206   bool fndecl_seen; /* Set if one fn decl/definition has been seen already.  */
 207   vec<cp_token_cache_ptr> tokens;
 208   tree clauses;
 209 };
 210
 211 /* Helper data structure for parsing #pragma acc routine.  */
 212 struct cp_oacc_routine_data : cp_omp_declare_simd_data {
 213   location_t loc;
 214 };
 215
 216 /* The cp_parser structure represents the C++ parser.  */
 217
 218 struct GTY(()) cp_parser {
 219   /* The lexer from which we are obtaining tokens.  */
 220   cp_lexer *lexer;
 221
 222   /* The scope in which names should be looked up.  If NULL_TREE, then
 223      we look up names in the scope that is currently open in the
 224      source program.  If non-NULL, this is either a TYPE or
 225      NAMESPACE_DECL for the scope in which we should look.  It can
 226      also be ERROR_MARK, when we've parsed a bogus scope.
 227
 228      This value is not cleared automatically after a name is looked
 229      up, so we must be careful to clear it before starting a new look
 230      up sequence.  (If it is not cleared, then `X::Y' followed by `Z'
 231      will look up `Z' in the scope of `X', rather than the current
 232      scope.)  Unfortunately, it is difficult to tell when name lookup
 233      is complete, because we sometimes peek at a token, look it up,
 234      and then decide not to consume it.   */
 235   tree scope;
 236
 237   /* OBJECT_SCOPE and QUALIFYING_SCOPE give the scopes in which the
 238      last lookup took place.  OBJECT_SCOPE is used if an expression
 239      like "x->y" or "x.y" was used; it gives the type of "*x" or "x",
 240      respectively.  QUALIFYING_SCOPE is used for an expression of the
 241      form "X::Y"; it refers to X.  */
 242   tree object_scope;
 243   tree qualifying_scope;
 244
 245   /* A stack of parsing contexts.  All but the bottom entry on the
 246      stack will be tentative contexts.
 247
 248      We parse tentatively in order to determine which construct is in
 249      use in some situations.  For example, in order to determine
 250      whether a statement is an expression-statement or a
 251      declaration-statement we parse it tentatively as a
 252      declaration-statement.  If that fails, we then reparse the same
 253      token stream as an expression-statement.  */
 254   cp_parser_context *context;
 255
 256   /* True if we are parsing GNU C++.  If this flag is not set, then
 257      GNU extensions are not recognized.  */
 258   bool allow_gnu_extensions_p;
 259
 260   /* TRUE if the `>' token should be interpreted as the greater-than
 261      operator.  FALSE if it is the end of a template-id or
 262      template-parameter-list. In C++0x mode, this flag also applies to
 263      `>>' tokens, which are viewed as two consecutive `>' tokens when
 264      this flag is FALSE.  */
 265   bool greater_than_is_operator_p;
 266
 267   /* TRUE if default arguments are allowed within a parameter list
 268      that starts at this point. FALSE if only a gnu extension makes
 269      them permissible.  */
 270   bool default_arg_ok_p;
 271
 272   /* TRUE if we are parsing an integral constant-expression.  See
 273      [expr.const] for a precise definition.  */
 274   bool integral_constant_expression_p;
 275
 276   /* TRUE if we are parsing an integral constant-expression -- but a
 277      non-constant expression should be permitted as well.  This flag
 278      is used when parsing an array bound so that GNU variable-length
 279      arrays are tolerated.  */
 280   bool allow_non_integral_constant_expression_p;
 281
 282   /* TRUE if ALLOW_NON_CONSTANT_EXPRESSION_P is TRUE and something has
 283      been seen that makes the expression non-constant.  */
 284   bool non_integral_constant_expression_p;
 285
 286   /* TRUE if local variable names and `this' are forbidden in the
 287      current context.  */
 288   bool local_variables_forbidden_p;
 289
 290   /* TRUE if the declaration we are parsing is part of a
 291      linkage-specification of the form `extern string-literal
 292      declaration'.  */
 293   bool in_unbraced_linkage_specification_p;
 294
 295   /* TRUE if we are presently parsing a declarator, after the
 296      direct-declarator.  */
 297   bool in_declarator_p;
 298
 299   /* TRUE if we are presently parsing a template-argument-list.  */
 300   bool in_template_argument_list_p;
 301
 302   /* Set to IN_ITERATION_STMT if parsing an iteration-statement,
 303      to IN_OMP_BLOCK if parsing OpenMP structured block and
 304      IN_OMP_FOR if parsing OpenMP loop.  If parsing a switch statement,
 305      this is bitwise ORed with IN_SWITCH_STMT, unless parsing an
 306      iteration-statement, OpenMP block or loop within that switch.  */
 307 #define IN_SWITCH_STMT          1
 308 #define IN_ITERATION_STMT       2
 309 #define IN_OMP_BLOCK            4
 310 #define IN_OMP_FOR              8
 311 #define IN_IF_STMT             16
 312 #define IN_CILK_SIMD_FOR       32
 313 #define IN_CILK_SPAWN          64
 314   unsigned char in_statement;
 315
 316   /* TRUE if we are presently parsing the body of a switch statement.
 317      Note that this doesn't quite overlap with in_statement above.
 318      The difference relates to giving the right sets of error messages:
 319      "case not in switch" vs "break statement used with OpenMP...".  */
 320   bool in_switch_statement_p;
 321
 322   /* TRUE if we are parsing a type-id in an expression context.  In
 323      such a situation, both "type (expr)" and "type (type)" are valid
 324      alternatives.  */
 325   bool in_type_id_in_expr_p;
 326
 327   /* TRUE if we are currently in a header file where declarations are
 328      implicitly extern "C".  */
 329   bool implicit_extern_c;
 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   /* TRUE if we are parsing a C++17 discarded statement (the non-taken branch
 340      of an if constexpr).  */
 341   bool in_discarded_stmt;
 342
 343   /* Nonzero if we're processing a __transaction_atomic or
 344      __transaction_relaxed statement.  */
 345   unsigned char in_transaction;
 346
 347   /* TRUE if we can auto-correct a colon to a scope operator.  */
 348   bool colon_corrects_to_scope_p;
 349
 350   /* TRUE if : doesn't start a class definition.  Should be only used
 351      together with type_definition_forbidden_message non-NULL, in
 352      contexts where new types may not be defined, and the type list
 353      is terminated by colon.  */
 354   bool colon_doesnt_start_class_def_p;
 355
 356   /* If non-NULL, then we are parsing a construct where new type
 357      definitions are not permitted.  The string stored here will be
 358      issued as an error message if a type is defined.  */
 359   const char *type_definition_forbidden_message;
 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 Cilk Plus SIMD-enabled functions' vector attributes,
 379      this is a pointer to a helper data structure.  */
 380   cp_omp_declare_simd_data * GTY((skip)) cilk_simd_fn_info;
 381
 382   /* When parsing #pragma acc routine, this is a pointer to a helper data
 383      structure.  */
 384   cp_oacc_routine_data * GTY((skip)) oacc_routine;
 385
 386   /* Nonzero if parsing a parameter list where 'auto' should trigger an implicit
 387      template parameter.  */
 388   bool auto_is_implicit_function_template_parm_p;
 389
 390   /* TRUE if the function being declared was made a template due to its
 391      parameter list containing generic type specifiers (`auto' or concept
 392      identifiers) rather than an explicit template parameter list.  */
 393   bool fully_implicit_function_template_p;
 394
 395   /* Tracks the function's template parameter list when declaring a function
 396      using generic type parameters.  This is either a new chain in the case of a
 397      fully implicit function template or an extension of the function's existing
 398      template parameter list.  This is tracked to optimize calls subsequent
 399      calls to synthesize_implicit_template_parm during
 400      cp_parser_parameter_declaration.  */
 401   tree implicit_template_parms;
 402
 403   /* The scope into which an implicit template parameter list has been
 404      introduced or an existing template parameter list is being extended with
 405      implicit template parameters.  In most cases this is the sk_function_parms
 406      scope containing the use of a generic type.  In the case of an out-of-line
 407      member definition using a generic type, it is the sk_class scope.  */
 408   cp_binding_level* implicit_template_scope;
 409
 410   /* True if parsing a result type in a compound requirement. This permits
 411      constrained-type-specifiers inside what would normally be a trailing
 412      return type. */
 413   bool in_result_type_constraint_p;
 414
 415   /* True if a constrained-type-specifier is not allowed in this
 416      context e.g., because they could never be deduced.  */
 417   int prevent_constrained_type_specifiers;
 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  */