1/* This file contains the definitions and documentation for the
2   additional tree codes used in the GNU C++ compiler (see tree.def
3   for the standard codes).
4   Copyright (C) 1987-2021 Free Software Foundation, Inc.
5   Hacked by Michael Tiemann (tiemann@cygnus.com)
6
7This file is part of GCC.
8
9GCC is free software; you can redistribute it and/or modify
10it under the terms of the GNU General Public License as published by
11the Free Software Foundation; either version 3, or (at your option)
12any later version.
13
14GCC is distributed in the hope that it will be useful,
15but WITHOUT ANY WARRANTY; without even the implied warranty of
16MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17GNU General Public License for more details.
18
19You should have received a copy of the GNU General Public License
20along with GCC; see the file COPYING3.  If not see
21<http://www.gnu.org/licenses/>.  */
22
23
24/* An OFFSET_REF is used in two situations:
25
26   1. An expression of the form `A::m' where `A' is a class and `m' is
27      a non-static member.  In this case, operand 0 will be a TYPE
28      (corresponding to `A') and operand 1 will be a FIELD_DECL,
29      BASELINK, or TEMPLATE_ID_EXPR (corresponding to `m').
30
31      The expression is a pointer-to-member if its address is taken,
32      but simply denotes a member of the object if its address is not
33      taken.
34
35      This form is only used during the parsing phase; once semantic
36      analysis has taken place they are eliminated.
37
38   2. An expression of the form `x.*p'.  In this case, operand 0 will
39      be an expression corresponding to `x' and operand 1 will be an
40      expression with pointer-to-member type.  */
41DEFTREECODE (OFFSET_REF, "offset_ref", tcc_reference, 2)
42
43/* A pointer-to-member constant.  For a pointer-to-member constant
44   `X::Y' The PTRMEM_CST_CLASS is the RECORD_TYPE for `X' and the
45   PTRMEM_CST_MEMBER is the _DECL for `Y'.  */
46DEFTREECODE (PTRMEM_CST, "ptrmem_cst", tcc_constant, 0)
47
48/* For NEW_EXPR, operand 0 is the placement list.
49   Operand 1 is the new-declarator.
50   Operand 2 is the number of elements in the array.
51   Operand 3 is the initializer.  */
52DEFTREECODE (NEW_EXPR, "nw_expr", tcc_expression, 4)
53DEFTREECODE (VEC_NEW_EXPR, "vec_nw_expr", tcc_expression, 3)
54
55/* For DELETE_EXPR, operand 0 is the store to be destroyed.
56   Operand 1 is the value to pass to the destroying function
57   saying whether the store should be deallocated as well.  */
58DEFTREECODE (DELETE_EXPR, "dl_expr", tcc_expression, 2)
59DEFTREECODE (VEC_DELETE_EXPR, "vec_dl_expr", tcc_expression, 2)
60
61/* Value is reference to particular overloaded class method.
62   Operand 0 is the class, operand 1 is the field
63   The COMPLEXITY field holds the class level (usually 0).  */
64DEFTREECODE (SCOPE_REF, "scope_ref", tcc_reference, 2)
65
66/* When composing an object with a member, this is the result.
67   Operand 0 is the object.  Operand 1 is the member (usually
68   a dereferenced pointer to member).  */
69DEFTREECODE (MEMBER_REF, "member_ref", tcc_reference, 2)
70
71/* Type conversion operator in C++.  TREE_TYPE is type that this
72   operator converts to.  Operand is expression to be converted.  */
73DEFTREECODE (TYPE_EXPR, "type_expr", tcc_expression, 1)
74
75/* AGGR_INIT_EXPRs have a variably-sized representation similar to
76   that of CALL_EXPRs.  Operand 0 is an INTEGER_CST node containing the
77   operand count, operand 1 is the function which performs initialization,
78   operand 2 is the slot which was allocated for this expression, and
79   the remaining operands are the arguments to the initialization function.  */
80DEFTREECODE (AGGR_INIT_EXPR, "aggr_init_expr", tcc_vl_exp, 3)
81
82/* Initialization of an array from another array, expressed at a high level
83   so that it works with TARGET_EXPR.  Operand 0 is the target, operand 1
84   is the initializer.  */
85DEFTREECODE (VEC_INIT_EXPR, "vec_init_expr", tcc_expression, 2)
86
87/* A throw expression.  operand 0 is the expression, if there was one,
88   else it is NULL_TREE.  */
89DEFTREECODE (THROW_EXPR, "throw_expr", tcc_expression, 1)
90
91/* An empty class object.  The TREE_TYPE gives the class type.  We use
92   these to avoid actually creating instances of the empty classes.  */
93DEFTREECODE (EMPTY_CLASS_EXPR, "empty_class_expr", tcc_expression, 0)
94
95/* A reference to a member function or member functions from a base
96   class.  BASELINK_FUNCTIONS gives the FUNCTION_DECL,
97   TEMPLATE_DECL, OVERLOAD, or TEMPLATE_ID_EXPR corresponding to the
98   functions.  BASELINK_BINFO gives the base from which the functions
99   come, i.e., the base to which the `this' pointer must be converted
100   before the functions are called.  BASELINK_ACCESS_BINFO gives the
101   base used to name the functions.
102
103   A BASELINK is an expression; the TREE_TYPE of the BASELINK gives
104   the type of the expression.  This type is either a FUNCTION_TYPE,
105   METHOD_TYPE, or `unknown_type_node' indicating that the function is
106   overloaded.  */
107DEFTREECODE (BASELINK, "baselink", tcc_exceptional, 0)
108
109/* Template definition.  The following fields have the specified uses,
110   although there are other macros in cp-tree.h that should be used for
111   accessing this data.
112	DECL_ARGUMENTS		template parm vector
113	DECL_TEMPLATE_INFO      template text &c
114	DECL_VINDEX		list of instantiations already produced;
115				only done for functions so far
116   For class template:
117	DECL_INITIAL		associated templates (methods &c)
118	DECL_TEMPLATE_RESULT    null
119   For non-class templates:
120	TREE_TYPE		type of object to be constructed
121	DECL_TEMPLATE_RESULT    decl for object to be created
122				(e.g., FUNCTION_DECL with tmpl parms used)
123 */
124DEFTREECODE (TEMPLATE_DECL, "template_decl", tcc_declaration, 0)
125
126/* Index into a template parameter list.  The TEMPLATE_PARM_IDX gives
127   the index (from 0) of the parameter, while the TEMPLATE_PARM_LEVEL
128   gives the level (from 1) of the parameter.
129
130   Here's an example:
131
132   template <class T> // Index 0, Level 1.
133   struct S
134   {
135      template <class U, // Index 0, Level 2.
136		class V> // Index 1, Level 2.
137      void f();
138   };
139
140   The DESCENDANTS will be a chain of TEMPLATE_PARM_INDEXs descended
141   from this one.  The first descendant will have the same IDX, but
142   its LEVEL will be one less.  The TREE_CHAIN field is used to chain
143   together the descendants.  The TEMPLATE_PARM_DECL is the
144   declaration of this parameter, either a TYPE_DECL or CONST_DECL.
145   The TEMPLATE_PARM_ORIG_LEVEL is the LEVEL of the most distant
146   parent, i.e., the LEVEL that the parameter originally had when it
147   was declared.  For example, if we instantiate S<int>, we will have:
148
149   struct S<int>
150   {
151     template <class U, // Index 0, Level 1, Orig Level 2
152	       class V> // Index 1, Level 1, Orig Level 2
153     void f();
154   };
155
156   The LEVEL is the level of the parameter when we are worrying about
157   the types of things; the ORIG_LEVEL is the level when we are
158   worrying about instantiating things.  */
159DEFTREECODE (TEMPLATE_PARM_INDEX, "template_parm_index", tcc_exceptional, 0)
160
161/* Index into a template parameter list for template template parameters.
162   This parameter must be a type.  The TYPE_FIELDS value will be a
163   TEMPLATE_PARM_INDEX.
164
165   It is used without template arguments like TT in C<TT>,
166   TYPE_NAME is a TEMPLATE_DECL.  */
167DEFTREECODE (TEMPLATE_TEMPLATE_PARM, "template_template_parm", tcc_type, 0)
168
169/* The ordering of the following codes is optimized for the checking
170   macros in tree.h.  Changing the order will degrade the speed of the
171   compiler.  TEMPLATE_TYPE_PARM, TYPENAME_TYPE, TYPEOF_TYPE,
172   BOUND_TEMPLATE_TEMPLATE_PARM.  */
173
174/* Index into a template parameter list.  This parameter must be a type.
175   The type.values field will be a TEMPLATE_PARM_INDEX.  */
176DEFTREECODE (TEMPLATE_TYPE_PARM, "template_type_parm", tcc_type, 0)
177
178/* A type designated by `typename T::t'.  TYPE_CONTEXT is `T',
179   TYPE_NAME is an IDENTIFIER_NODE for `t'.  If the type was named via
180   template-id, TYPENAME_TYPE_FULLNAME will hold the TEMPLATE_ID_EXPR.
181   TREE_TYPE is always NULL.  */
182DEFTREECODE (TYPENAME_TYPE, "typename_type", tcc_type, 0)
183
184/* A type designated by `__typeof (expr)'.  TYPEOF_TYPE_EXPR is the
185   expression in question.  */
186DEFTREECODE (TYPEOF_TYPE, "typeof_type", tcc_type, 0)
187
188/* Like TEMPLATE_TEMPLATE_PARM it is used with bound template arguments
189   like TT<int>.
190   In this case, TEMPLATE_TEMPLATE_PARM_TEMPLATE_INFO contains the
191   template name and its bound arguments.  TYPE_NAME is a TYPE_DECL.  */
192DEFTREECODE (BOUND_TEMPLATE_TEMPLATE_PARM, "bound_template_template_parm",
193	     tcc_type, 0)
194
195/* For template template argument of the form `T::template C'.
196   TYPE_CONTEXT is `T', the template parameter dependent object.
197   TYPE_NAME is a TEMPLATE_DECL, whose DECL_TEMPLATE_PARMS are any
198   template parms of the instantiation.  That decl's DECL_NAME is the
199   IDENTIFIER_NODE for `C', the member class template.  */
200DEFTREECODE (UNBOUND_CLASS_TEMPLATE, "unbound_class_template", tcc_type, 0)
201
202/* A using declaration.  USING_DECL_SCOPE contains the specified
203   scope.  In a variadic using-declaration, this is a TYPE_PACK_EXPANSION.
204   In a member using decl, unless DECL_DEPENDENT_P is true,
205   USING_DECL_DECLS contains the _DECL or OVERLOAD so named.  This is
206   not an alias, but is later expanded into multiple aliases.  */
207DEFTREECODE (USING_DECL, "using_decl", tcc_declaration, 0)
208
209/* A using directive. The operand is USING_STMT_NAMESPACE.  */
210DEFTREECODE (USING_STMT, "using_stmt", tcc_statement, 1)
211
212/* An un-parsed operand.  Holds a vector of input tokens and
213   a vector of places where the argument was instantiated before
214   parsing had occurred.  This is used for default arguments, delayed
215   NSDMIs, and noexcept-specifier parsing.  */
216DEFTREECODE (DEFERRED_PARSE, "deferred_parse", tcc_exceptional, 0)
217
218/* An uninstantiated/unevaluated noexcept-specification.  For the
219   uninstantiated case, DEFERRED_NOEXCEPT_PATTERN is the pattern from the
220   template, and DEFERRED_NOEXCEPT_ARGS are the template arguments to
221   substitute into the pattern when needed.  For the unevaluated case,
222   those slots are NULL_TREE and we use get_defaulted_eh_spec to find
223   the exception-specification.  */
224DEFTREECODE (DEFERRED_NOEXCEPT, "deferred_noexcept", tcc_exceptional, 0)
225
226/* A template-id, like foo<int>.  The first operand is the template.
227   The second is NULL if there are no explicit arguments, or a
228   TREE_VEC of arguments.  The template will be a FUNCTION_DECL,
229   TEMPLATE_DECL, or an OVERLOAD.  If the template-id refers to a
230   member template, the template may be an IDENTIFIER_NODE.  */
231DEFTREECODE (TEMPLATE_ID_EXPR, "template_id_expr", tcc_expression, 2)
232
233/* One of a set of overloaded functions.  */
234DEFTREECODE (OVERLOAD, "overload", tcc_exceptional, 0)
235
236/* A vector of binding slots.  */
237DEFTREECODE (BINDING_VECTOR, "binding_vector", tcc_exceptional, 0)
238
239/* A pseudo-destructor, of the form "OBJECT.~DESTRUCTOR" or
240   "OBJECT.SCOPE::~DESTRUCTOR.  The first operand is the OBJECT.  The
241   second operand (if non-NULL) is the SCOPE.  The third operand is
242   the TYPE node corresponding to the DESTRUCTOR.  The type of the
243   first operand will always be a scalar type.
244
245   The type of a PSEUDO_DTOR_EXPR is always "void", even though it can
246   be used as if it were a zero-argument function.  We handle the
247   function-call case specially, and giving it "void" type prevents it
248   being used in expressions in ways that are not permitted.  */
249DEFTREECODE (PSEUDO_DTOR_EXPR, "pseudo_dtor_expr", tcc_expression, 3)
250
251/* A whole bunch of tree codes for the initial, superficial parsing of
252   templates.  */
253DEFTREECODE (MODOP_EXPR, "modop_expr", tcc_expression, 3)
254DEFTREECODE (CAST_EXPR, "cast_expr", tcc_unary, 1)
255DEFTREECODE (REINTERPRET_CAST_EXPR, "reinterpret_cast_expr", tcc_unary, 1)
256DEFTREECODE (CONST_CAST_EXPR, "const_cast_expr", tcc_unary, 1)
257DEFTREECODE (STATIC_CAST_EXPR, "static_cast_expr", tcc_unary, 1)
258DEFTREECODE (DYNAMIC_CAST_EXPR, "dynamic_cast_expr", tcc_unary, 1)
259DEFTREECODE (IMPLICIT_CONV_EXPR, "implicit_conv_expr", tcc_unary, 1)
260DEFTREECODE (DOTSTAR_EXPR, "dotstar_expr", tcc_expression, 2)
261DEFTREECODE (TYPEID_EXPR, "typeid_expr", tcc_expression, 1)
262DEFTREECODE (NOEXCEPT_EXPR, "noexcept_expr", tcc_unary, 1)
263DEFTREECODE (SPACESHIP_EXPR, "spaceship_expr", tcc_expression, 2)
264
265/* A placeholder for an expression that is not type-dependent, but
266   does occur in a template.  When an expression that is not
267   type-dependent appears in a larger expression, we must compute the
268   type of that larger expression.  That computation would normally
269   modify the original expression, which would change the mangling of
270   that expression if it appeared in a template argument list.  In
271   that situation, we create a NON_DEPENDENT_EXPR to take the place of
272   the original expression.  The expression is the only operand -- it
273   is only needed for diagnostics.  */
274DEFTREECODE (NON_DEPENDENT_EXPR, "non_dependent_expr", tcc_expression, 1)
275
276/* CTOR_INITIALIZER is a placeholder in template code for a call to
277   setup_vtbl_pointer (and appears in all functions, not just ctors).  */
278DEFTREECODE (CTOR_INITIALIZER, "ctor_initializer", tcc_expression, 1)
279
280DEFTREECODE (TRY_BLOCK, "try_block", tcc_statement, 2)
281
282DEFTREECODE (EH_SPEC_BLOCK, "eh_spec_block", tcc_statement, 2)
283
284/* A HANDLER wraps a catch handler for the HANDLER_TYPE.  If this is
285   CATCH_ALL_TYPE, then the handler catches all types.  The declaration of
286   the catch variable is in HANDLER_PARMS, and the body block in
287   HANDLER_BODY.  */
288DEFTREECODE (HANDLER, "handler", tcc_statement, 2)
289
290/* A MUST_NOT_THROW_EXPR wraps an expression that may not
291   throw, and must call terminate if it does.  The second argument
292   is a condition, used in templates to express noexcept (condition).  */
293DEFTREECODE (MUST_NOT_THROW_EXPR, "must_not_throw_expr", tcc_expression, 2)
294
295/* A CLEANUP_STMT marks the point at which a declaration is fully
296   constructed.  The CLEANUP_EXPR is run on behalf of CLEANUP_DECL
297   when CLEANUP_BODY completes.  */
298DEFTREECODE (CLEANUP_STMT, "cleanup_stmt", tcc_statement, 3)
299
300/* Represents an 'if' statement. The operands are IF_COND,
301   THEN_CLAUSE, and ELSE_CLAUSE, and the current scope, respectively.  */
302/* ??? It is currently still necessary to distinguish between IF_STMT
303   and COND_EXPR for the benefit of templates.  */
304DEFTREECODE (IF_STMT, "if_stmt", tcc_statement, 4)
305
306/* Used to represent a range-based `for' statement. The operands are
307   RANGE_FOR_DECL, RANGE_FOR_EXPR, RANGE_FOR_BODY, RANGE_FOR_SCOPE,
308   RANGE_FOR_UNROLL, and RANGE_FOR_INIT_STMT, respectively.  Only used in
309   templates.  */
310DEFTREECODE (RANGE_FOR_STMT, "range_for_stmt", tcc_statement, 6)
311
312/* Used to represent an expression statement.  Use `EXPR_STMT_EXPR' to
313   obtain the expression.  */
314DEFTREECODE (EXPR_STMT, "expr_stmt", tcc_expression, 1)
315
316DEFTREECODE (TAG_DEFN, "tag_defn", tcc_expression, 0)
317
318/* Represents an 'offsetof' expression during template expansion.  */
319DEFTREECODE (OFFSETOF_EXPR, "offsetof_expr", tcc_expression, 2)
320
321/* Represents an '__builtin_addressof' expression during template
322   expansion.  This is similar to ADDR_EXPR, but it doesn't invoke
323   overloaded & operators.  */
324DEFTREECODE (ADDRESSOF_EXPR, "addressof_expr", tcc_expression, 1)
325
326/* Represents the -> operator during template expansion.  */
327DEFTREECODE (ARROW_EXPR, "arrow_expr", tcc_expression, 1)
328
329/* Represents an '__alignof__' expression during template
330   expansion.  */
331DEFTREECODE (ALIGNOF_EXPR, "alignof_expr", tcc_expression, 1)
332
333/* Represents an Objective-C++ '@encode' expression during template
334   expansion.  */
335DEFTREECODE (AT_ENCODE_EXPR, "at_encode_expr", tcc_expression, 1)
336
337/* A STMT_EXPR represents a statement-expression during template
338   expansion.  This is the GCC extension { ( ... ) }.  The
339   STMT_EXPR_STMT is the statement given by the expression.  */
340DEFTREECODE (STMT_EXPR, "stmt_expr", tcc_expression, 1)
341
342/* Unary plus. Operand 0 is the expression to which the unary plus
343   is applied.  */
344DEFTREECODE (UNARY_PLUS_EXPR, "unary_plus_expr", tcc_unary, 1)
345
346/** C++11 extensions. */
347
348/* A static assertion.  This is a C++11 extension.
349   STATIC_ASSERT_CONDITION contains the condition that is being
350   checked.  STATIC_ASSERT_MESSAGE contains the message (a string
351   literal) to be displayed if the condition fails to hold.  */
352DEFTREECODE (STATIC_ASSERT, "static_assert", tcc_exceptional, 0)
353
354/* Represents an argument pack of types (or templates). An argument
355   pack stores zero or more arguments that will be used to instantiate
356   a parameter pack.
357
358   ARGUMENT_PACK_ARGS retrieves the arguments stored in the argument
359   pack.
360
361   Example:
362     template<typename... Values>
363     class tuple { ... };
364
365     tuple<int, float, double> t;
366
367   Values is a (template) parameter pack. When tuple<int, float,
368   double> is instantiated, the Values parameter pack is instantiated
369   with the argument pack <int, float, double>. ARGUMENT_PACK_ARGS will
370   be a TREE_VEC containing int, float, and double.  */
371DEFTREECODE (TYPE_ARGUMENT_PACK, "type_argument_pack", tcc_type, 0)
372
373/* Represents an argument pack of values, which can be used either for
374   non-type template arguments or function call arguments.
375
376   NONTYPE_ARGUMENT_PACK plays precisely the same role as
377   TYPE_ARGUMENT_PACK, but will be used for packing non-type template
378   arguments (e.g., "int... Dimensions") or function arguments ("const
379   Args&... args"). */
380DEFTREECODE (NONTYPE_ARGUMENT_PACK, "nontype_argument_pack", tcc_expression, 1)
381
382/* Represents a type expression that will be expanded into a list of
383   types when instantiated with one or more argument packs.
384
385   PACK_EXPANSION_PATTERN retrieves the expansion pattern. This is
386   the type or expression that we will substitute into with each
387   argument in an argument pack.
388
389   SET_PACK_EXPANSION_PATTERN sets the expansion pattern.
390
391   PACK_EXPANSION_PARAMETER_PACKS contains a TREE_LIST of the parameter
392   packs that are used in this pack expansion.
393
394   Example:
395     template<typename... Values>
396     struct tied : tuple<Values&...> {
397       // ...
398     };
399
400   The derivation from tuple contains a TYPE_PACK_EXPANSION for the
401   template arguments. Its PACK_EXPANSION_PATTERN is "Values&" and its
402   PACK_EXPANSION_PARAMETER_PACKS will contain "Values".  */
403DEFTREECODE (TYPE_PACK_EXPANSION, "type_pack_expansion", tcc_type, 0)
404
405/* Represents an expression that will be expanded into a list of
406   expressions when instantiated with one or more argument packs.
407
408   EXPR_PACK_EXPANSION plays precisely the same role as TYPE_PACK_EXPANSION,
409   but will be used for expressions.  */
410DEFTREECODE (EXPR_PACK_EXPANSION, "expr_pack_expansion", tcc_expression, 3)
411
412/* Selects the Ith parameter out of an argument pack. This node will
413   be used when instantiating pack expansions; see
414   tsubst_pack_expansion.
415
416   ARGUMENT_PACK_SELECT_FROM_PACK contains the *_ARGUMENT_PACK node
417   from which the argument will be selected.
418
419   ARGUMENT_PACK_SELECT_INDEX contains the index into the argument
420   pack that will be returned by this ARGUMENT_PACK_SELECT node. The
421   index is a machine integer.  */
422DEFTREECODE (ARGUMENT_PACK_SELECT, "argument_pack_select", tcc_exceptional, 0)
423
424/* Fold expressions allow the expansion of a template argument pack
425   over a binary operator.
426
427   FOLD_EXPR_MOD_P is true when the fold operation is a compound assignment
428   operator.
429
430   FOLD_EXPR_OP is an INTEGER_CST storing the tree code for the folded
431   expression. Note that when FOLDEXPR_MOD_P is true, the operator is
432   a compound assignment operator for that kind of expression.
433
434   FOLD_EXPR_PACK is an expression containing an unexpanded parameter pack;
435   when expanded, each term becomes an argument of the folded expression.
436
437   In a BINARY_FOLD_EXPRESSION, FOLD_EXPR_INIT is the non-pack argument. */
438DEFTREECODE (UNARY_LEFT_FOLD_EXPR, "unary_left_fold_expr", tcc_expression, 2)
439DEFTREECODE (UNARY_RIGHT_FOLD_EXPR, "unary_right_fold_expr", tcc_expression, 2)
440DEFTREECODE (BINARY_LEFT_FOLD_EXPR, "binary_left_fold_expr", tcc_expression, 3)
441DEFTREECODE (BINARY_RIGHT_FOLD_EXPR, "binary_right_fold_expr", tcc_expression, 3)
442
443/* Represents the __builtin_bit_cast (type, expr) expression.
444   The type is in TREE_TYPE, expression in TREE_OPERAND (bitcast, 0).  */
445DEFTREECODE (BIT_CAST_EXPR, "bit_cast_expr", tcc_expression, 1)
446
447/** C++ extensions. */
448
449/* Represents a trait expression during template expansion.  */
450DEFTREECODE (TRAIT_EXPR, "trait_expr", tcc_exceptional, 0)
451
452/* A lambda expression.  This is a C++0x extension.
453   LAMBDA_EXPR_DEFAULT_CAPTURE_MODE is an enum for the default, which may be
454   none.
455   LAMBDA_EXPR_CAPTURE_LIST holds the capture-list, including `this'.
456   LAMBDA_EXPR_THIS_CAPTURE goes straight to the capture of `this', if it exists.
457   LAMBDA_EXPR_PENDING_PROXIES is a vector of capture proxies which need to
458   be pushed once scope returns to the lambda.
459   LAMBDA_EXPR_MUTABLE_P signals whether this lambda was declared mutable.  */
460DEFTREECODE (LAMBDA_EXPR, "lambda_expr", tcc_exceptional, 0)
461
462/* The declared type of an expression.  This is a C++0x extension.
463   DECLTYPE_TYPE_EXPR is the expression whose type we are computing.
464   DECLTYPE_TYPE_ID_EXPR_OR_MEMBER_ACCESS_P states whether the
465   expression was parsed as an id-expression or a member access
466   expression. When false, it was parsed as a full expression.
467   DECLTYPE_FOR_LAMBDA_CAPTURE is set if we want lambda capture semantics.
468   DECLTYPE_FOR_LAMBDA_RETURN is set if we want lambda return deduction.  */
469DEFTREECODE (DECLTYPE_TYPE, "decltype_type", tcc_type, 0)
470
471/* A type designated by `__underlying_type (type)'.
472   UNDERLYING_TYPE_TYPE is the type in question.  */
473DEFTREECODE (UNDERLYING_TYPE, "underlying_type", tcc_type, 0)
474
475/* A type designated by one of the bases type traits.
476   BASES_TYPE is the type in question.  */
477DEFTREECODE (BASES, "bases", tcc_type, 0)
478
479/* Used to represent the template information stored by template
480   specializations.
481   The accessors are:
482   TI_TEMPLATE the template declaration associated to the specialization
483   TI_ARGS the arguments of the template specialization
484   TI_TYPEDEFS_NEEDING_ACCESS_CHECKING the vector of typedefs used in
485   the pattern of the template for which access check is needed at template
486   instantiation time.  */
487DEFTREECODE (TEMPLATE_INFO, "template_info", tcc_exceptional, 0)
488
489/* OpenMP - #pragma omp depobj
490   Operand 0: OMP_DEPOBJ_DEPOBJ: Depobj expression
491   Operand 1: OMP_DEPOBJ_CLAUSES: List of clauses.  */
492DEFTREECODE (OMP_DEPOBJ, "omp_depobj", tcc_statement, 2)
493
494/* Extensions for Concepts. */
495
496/* Concept definition. This is not entirely different than a VAR_DECL
497   except that a) it must be a template, and b) doesn't have the wide
498   range of value and linkage options available to variables.  */
499DEFTREECODE (CONCEPT_DECL, "concept_decl", tcc_declaration, 0)
500
501/* Used to represent information associated with constrained declarations. */
502DEFTREECODE (CONSTRAINT_INFO, "constraint_info", tcc_exceptional, 0)
503
504/* A wildcard declaration is a placeholder for a template parameter
505   used to resolve constrained-type-names in concepts.  During
506   resolution, the matching argument is saved as the TREE_TYPE
507   of the wildcard.  */
508DEFTREECODE (WILDCARD_DECL, "wildcard_decl", tcc_declaration, 0)
509
510/* A requires-expr has three operands. The first operand is
511   its parameter list (possibly NULL). The second is a list of
512   requirements, which are denoted by the _REQ* tree codes
513   below.  The third is a TREE_VEC of template arguments to
514   be applied when substituting into the parameter list and
515   requirements, set by tsubst_requires_expr for partial instantiations.  */
516DEFTREECODE (REQUIRES_EXPR,   "requires_expr", tcc_expression, 3)
517
518/* A requirement for an expression. */
519DEFTREECODE (SIMPLE_REQ, "simple_req", tcc_expression, 1)
520
521/* A requirement for a type. */
522DEFTREECODE (TYPE_REQ, "type_req", tcc_expression, 1)
523
524/* A requirement for an expression and its properties. The
525   first operand is the expression, and the 2nd is its type.
526   The accessor COMPOUND_REQ_NOEXCEPT determines whether
527   the noexcept keyword was present. */
528DEFTREECODE (COMPOUND_REQ, "compound_req", tcc_expression, 2)
529
530/* A requires clause within a requires expression. */
531DEFTREECODE (NESTED_REQ, "nested_req", tcc_expression, 1)
532
533/* Constraints are modeled as kinds of expressions.
534   The operands of a constraint can be either types or expressions.
535   Unlike expressions, constraints do not have a type. */
536
537/* An atomic constraint evaluates an expression E. The operand of the
538   constraint is its parameter mapping. The actual expression is stored
539   in the context.
540
541   ATOMIC_CONSTR_INFO provides source info to support diagnostics.
542   ATOMIC_CONSTR_EXPR has the expression to be evaluated.
543   ATOMIC_CONSTR_PARMS is the parameter mapping for the atomic constraint
544   and is stored in the type field.  */
545DEFTREECODE (ATOMIC_CONSTR, "atomic_constr", tcc_expression, 1)
546
547/* The conjunction and disjunction of two constraints, respectively.
548   Operands are accessed using TREE_OPERAND. The third operand provides
549   source info for diagnostics.
550
551   CONJ_CONSTR_INFO and DISJ_CONSTR_INFO provide access to the source
552   information of constraints, which is stored in the TREE_TYPE.  */
553DEFTREECODE (CONJ_CONSTR, "conj_constr", tcc_expression, 2)
554DEFTREECODE (DISJ_CONSTR, "disj_constr", tcc_expression, 2)
555
556/* A check constraint represents the checking of a concept
557   C. It has two operands: the template defining the concept
558   and a sequence of template arguments.
559
560   CHECK_CONSTR_CONCEPT has the concept definition
561   CHECK_CONSTR_ARGUMENTS are the template arguments */
562DEFTREECODE (CHECK_CONSTR, "check_constr", tcc_expression, 2)
563
564/* The co_await expression is used to support coroutines.
565
566  Op 0 is the cast expresssion (potentially modified by the
567  promise "await_transform()" method).
568  Op1 is a proxy for the temp / coro frame slot 'e' value.
569  Op2 is the initialiser for Op1 (Op0, potentially modified by any
570  applicable 'co_await' operator).
571  Op3 is a vector of the [0] e.ready, [1] e.suspend and [2] e.resume calls.
572  Op4 is a mode : 0 (await) 1 (yield) 2 (initial) 3 (final) */
573DEFTREECODE (CO_AWAIT_EXPR, "co_await", tcc_expression, 5)
574
575/* The co_yield expression is used to support coroutines.
576
577   Op0 is the original expr (for use in diagnostics)
578   Op2 is the co_await derived from this. */
579DEFTREECODE (CO_YIELD_EXPR, "co_yield", tcc_expression, 2)
580
581/* The co_return expression is used to support coroutines.
582
583   Op0 is the original expr, can be void (for use in diagnostics)
584   Op1 is the promise return_xxxx call for for the expression given. */
585
586DEFTREECODE (CO_RETURN_EXPR, "co_return", tcc_statement, 2)
587
588/*
589Local variables:
590mode:c
591End:
592*/
593