Re: [PATCH v19 02/40] c-family, c++: Look up built-in traits through gperf

[Ken Matsui <kmatsui@cs.washington.edu>]

On Sun, Oct 15, 2023 at 2:50 PM Patrick Palka <ppalka@redhat.com> wrote:
>
> On Sun, 15 Oct 2023, Ken Matsui wrote:
>
> > On Sun, Oct 15, 2023 at 1:43 PM Patrick Palka <ppalka@redhat.com> wrote:
> > >
> > > On Fri, 13 Oct 2023, Ken Matsui wrote:
> > >
> > > > Since RID_MAX soon reaches 255 and all built-in traits are used approximately
> > > > once in a C++ translation unit, this patch removes all RID values for built-in
> > > > traits and uses gperf to look up the specific trait.  Rather than holding
> > > > traits as keywords, we set all trait identifiers as cik_trait, which is a new
> > > > cp_identifier_kind.  As cik_reserved_for_udlit was unused and
> > > > cp_identifier_kind is 3 bits, we replaced the unused field with the new
> > > > cik_trait.  Also, the later patch handles a subsequent token to the built-in
> > > > identifier so that we accept the use of non-function-like built-in trait
> > > > identifiers.
> > >
> > > Awesome!  It's great we won't have to rename any existing identifiers in
> > > libstdc++ with this approach.
> > >
> > > I think this patch looks perfect, assuming we want to stick with the gperf
> > > approach, but I just noticed that IDENTIFIER nodes have an IDENTIFIER_CP_INDEX
> > > field which is currently only used for operator name identifiers to
> > > optimize looking up operator information.  Could we reuse this field for
> > > IDENTIFIER_TRAIT_P identifiers as well in order to store their
> > > corresponding cp_trait_kind?  If so then I think we wouldn't need to use
> > > gperf for the built-in traits at all, since the mapping from identifier
> > > to cp_trait_kind would be implicit in each IDENTIFIER node, which would
> > > perhaps be a nice simplification (and just as fast if not faster than gperf)?
> > >
> >
> > Thank you! I think this way decreases the size of the compiler even if
> > we do not see speed improvements. Since IDENTIFIER_CP_INDEX
> > (base.u.bits.address_space) is an unsigned char (addr_space_t), we can
> > have only up to 255 traits. Is this acceptable?
>
> Good points.  Given there's so far around 150 standard library traits, a
> limit of 255 should last us quite a while so IMHO it's acceptable :)
>

Sounds great! I will update the patch in this way. Thank you!

> >
> > > >
> > > > gcc/c-family/ChangeLog:
> > > >
> > > >       * c-common.cc (c_common_reswords): Remove all mappings of
> > > >       built-in traits.
> > > >       * c-common.h (enum rid): Remove all RID values for built-in traits.
> > > >
> > > > gcc/cp/ChangeLog:
> > > >
> > > >       * Make-lang.in: Add targets to generate cp-trait.gperf and
> > > >       cp-trait.h.
> > > >       * cp-objcp-common.cc (names_builtin_p): Remove all RID value
> > > >       cases for built-in traits.  Check for built-in traits via
> > > >       the new cik_trait identifier.
> > > >       * cp-tree.h (cik_reserved_for_udlit): Rename to ...
> > > >       (cik_trait): ... this.
> > > >       (IDENTIFIER_ANY_OP_P): Exclude cik_trait.
> > > >       (IDENTIFIER_TRAIT_P): New macro to detect cik_trait.
> > > >       * lex.cc (init_cp_traits): New function to set cik_trait for all
> > > >       built-in trait identifiers.
> > > >       (cxx_init): Call init_cp_traits function.
> > > >       * parser.cc (cp_lexer_lookup_trait): New function to look up a
> > > >       built-in trait from a token by gperf.
> > > >       (cp_lexer_lookup_trait_expr): Likewise, look up an
> > > >       expression-yielding built-in trait.
> > > >       (cp_lexer_lookup_trait_type): Likewise, look up a type-yielding
> > > >       built-in trait.
> > > >       (cp_keyword_starts_decl_specifier_p): Remove all RID value cases
> > > >       for built-in traits.
> > > >       (cp_lexer_next_token_is_decl_specifier_keyword): Handle
> > > >       type-yielding built-in traits.
> > > >       (cp_parser_primary_expression): Remove all RID value cases for
> > > >       built-in traits.  Handle expression-yielding built-in traits.
> > > >       (cp_parser_trait): Handle cp_trait instead of enum rid.
> > > >       (cp_parser_simple_type_specifier): Remove all RID value cases
> > > >       for built-in traits.  Handle type-yielding built-in traits.
> > > >       * cp-trait-head.in: New file.
> > > >       * cp-trait.gperf: New file.
> > > >       * cp-trait.h: New file.
> > > >
> > > > Co-authored-by: Patrick Palka <ppalka@redhat.com>
> > > > Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> > > > ---
> > > >  gcc/c-family/c-common.cc  |   7 --
> > > >  gcc/c-family/c-common.h   |   5 -
> > > >  gcc/cp/Make-lang.in       |  26 ++++
> > > >  gcc/cp/cp-objcp-common.cc |   8 +-
> > > >  gcc/cp/cp-trait-head.in   |  30 +++++
> > > >  gcc/cp/cp-trait.gperf     |  74 ++++++++++++
> > > >  gcc/cp/cp-trait.h         | 247 ++++++++++++++++++++++++++++++++++++++
> > > >  gcc/cp/cp-tree.h          |  14 ++-
> > > >  gcc/cp/lex.cc             |  19 +++
> > > >  gcc/cp/parser.cc          | 132 ++++++++++++--------
> > > >  10 files changed, 492 insertions(+), 70 deletions(-)
> > > >  create mode 100644 gcc/cp/cp-trait-head.in
> > > >  create mode 100644 gcc/cp/cp-trait.gperf
> > > >  create mode 100644 gcc/cp/cp-trait.h
> > > >
> > > > diff --git a/gcc/c-family/c-common.cc b/gcc/c-family/c-common.cc
> > > > index f044db5b797..21fd333ef57 100644
> > > > --- a/gcc/c-family/c-common.cc
> > > > +++ b/gcc/c-family/c-common.cc
> > > > @@ -508,13 +508,6 @@ const struct c_common_resword c_common_reswords[] =
> > > >    { "wchar_t",               RID_WCHAR,      D_CXXONLY },
> > > >    { "while",         RID_WHILE,      0 },
> > > >
> > > > -#define DEFTRAIT(TCC, CODE, NAME, ARITY) \
> > > > -  { NAME,            RID_##CODE,     D_CXXONLY },
> > > > -#include "cp/cp-trait.def"
> > > > -#undef DEFTRAIT
> > > > -  /* An alias for __is_same.  */
> > > > -  { "__is_same_as",  RID_IS_SAME,    D_CXXONLY },
> > > > -
> > > >    /* C++ transactional memory.  */
> > > >    { "synchronized",  RID_SYNCHRONIZED, D_CXX_OBJC | D_TRANSMEM },
> > > >    { "atomic_noexcept",       RID_ATOMIC_NOEXCEPT, D_CXXONLY | D_TRANSMEM },
> > > > diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
> > > > index 1fdba7ef3ea..051a442e0f4 100644
> > > > --- a/gcc/c-family/c-common.h
> > > > +++ b/gcc/c-family/c-common.h
> > > > @@ -168,11 +168,6 @@ enum rid
> > > >    RID_BUILTIN_LAUNDER,
> > > >    RID_BUILTIN_BIT_CAST,
> > > >
> > > > -#define DEFTRAIT(TCC, CODE, NAME, ARITY) \
> > > > -  RID_##CODE,
> > > > -#include "cp/cp-trait.def"
> > > > -#undef DEFTRAIT
> > > > -
> > > >    /* C++11 */
> > > >    RID_CONSTEXPR, RID_DECLTYPE, RID_NOEXCEPT, RID_NULLPTR, RID_STATIC_ASSERT,
> > > >
> > > > diff --git a/gcc/cp/Make-lang.in b/gcc/cp/Make-lang.in
> > > > index 2727fb7f8cc..a67d1c3e9f3 100644
> > > > --- a/gcc/cp/Make-lang.in
> > > > +++ b/gcc/cp/Make-lang.in
> > > > @@ -34,6 +34,8 @@
> > > >  # - the compiler proper (eg: cc1plus)
> > > >  # - define the names for selecting the language in LANGUAGES.
> > > >
> > > > +AWK = @AWK@
> > > > +
> > > >  # Actual names to use when installing a native compiler.
> > > >  CXX_INSTALL_NAME := $(shell echo c++|sed '$(program_transform_name)')
> > > >  GXX_INSTALL_NAME := $(shell echo g++|sed '$(program_transform_name)')
> > > > @@ -186,6 +188,30 @@ endif
> > > >  # This is the file that depends on the generated header file.
> > > >  cp/name-lookup.o: $(srcdir)/cp/std-name-hint.h
> > > >
> > > > +# We always need the dependency on the .gperf file
> > > > +# because it itself is generated.
> > > > +ifeq ($(ENABLE_MAINTAINER_RULES), true)
> > > > +$(srcdir)/cp/cp-trait.h: $(srcdir)/cp/cp-trait.gperf
> > > > +else
> > > > +$(srcdir)/cp/cp-trait.h: | $(srcdir)/cp/cp-trait.gperf
> > > > +endif
> > > > +     gperf -o -C -E -k '8' -D -N 'find' -L C++ \
> > > > +             $(srcdir)/cp/cp-trait.gperf --output-file $(srcdir)/cp/cp-trait.h
> > > > +
> > > > +# The cp-trait.gperf file itself is generated from
> > > > +# cp-trait-head.in and cp-trait.def files.
> > > > +$(srcdir)/cp/cp-trait.gperf: $(srcdir)/cp/cp-trait-head.in $(srcdir)/cp/cp-trait.def
> > > > +     cat $< > $@
> > > > +     $(AWK) -F', *' '/^DEFTRAIT_/ { \
> > > > +             type = (index($$1, "DEFTRAIT_TYPE") != 0 ? "true" : "false"); \
> > > > +             gsub(/DEFTRAIT_(EXPR|TYPE) \(/, "", $$1); \
> > > > +             gsub(/\)/, "", $$3); \
> > > > +             print $$2", CPTK_" $$1", "$$3", "type; \
> > > > +     }' $(srcdir)/cp/cp-trait.def >> $@
> > > > +
> > > > +# This is the file that depends on the generated header file.
> > > > +cp/parser.o: $(srcdir)/cp/cp-trait.h
> > > > +
> > > >  components_in_prev = "bfd opcodes binutils fixincludes gas gcc gmp mpfr mpc isl gold intl ld libbacktrace libcpp libcody libdecnumber libiberty libiberty-linker-plugin libiconv zlib lto-plugin libctf libsframe"
> > > >  components_in_prev_target = "libstdc++-v3 libsanitizer libvtv libgcc libbacktrace libphobos zlib libgomp libatomic"
> > > >
> > > > diff --git a/gcc/cp/cp-objcp-common.cc b/gcc/cp/cp-objcp-common.cc
> > > > index 93b027b80ce..b1adacfec07 100644
> > > > --- a/gcc/cp/cp-objcp-common.cc
> > > > +++ b/gcc/cp/cp-objcp-common.cc
> > > > @@ -421,6 +421,10 @@ names_builtin_p (const char *name)
> > > >       }
> > > >      }
> > > >
> > > > +  /* Check for built-in traits.  */
> > > > +  if (IDENTIFIER_TRAIT_P (id))
> > > > +    return true;
> > > > +
> > > >    /* Also detect common reserved C++ words that aren't strictly built-in
> > > >       functions.  */
> > > >    switch (C_RID_CODE (id))
> > > > @@ -434,10 +438,6 @@ names_builtin_p (const char *name)
> > > >      case RID_BUILTIN_ASSOC_BARRIER:
> > > >      case RID_BUILTIN_BIT_CAST:
> > > >      case RID_OFFSETOF:
> > > > -#define DEFTRAIT(TCC, CODE, NAME, ARITY) \
> > > > -    case RID_##CODE:
> > > > -#include "cp-trait.def"
> > > > -#undef DEFTRAIT
> > > >        return true;
> > > >      default:
> > > >        break;
> > > > diff --git a/gcc/cp/cp-trait-head.in b/gcc/cp/cp-trait-head.in
> > > > new file mode 100644
> > > > index 00000000000..9357eea1238
> > > > --- /dev/null
> > > > +++ b/gcc/cp/cp-trait-head.in
> > > > @@ -0,0 +1,30 @@
> > > > +%language=C++
> > > > +%define class-name cp_trait_lookup
> > > > +%struct-type
> > > > +%{
> > > > +/* Copyright (C) 2023 Free Software Foundation, Inc.
> > > > +
> > > > +This file is part of GCC.
> > > > +
> > > > +GCC is free software; you can redistribute it and/or modify it under
> > > > +the terms of the GNU General Public License as published by the Free
> > > > +Software Foundation; either version 3, or (at your option) any later
> > > > +version.
> > > > +
> > > > +GCC is distributed in the hope that it will be useful, but WITHOUT ANY
> > > > +WARRANTY; without even the implied warranty of MERCHANTABILITY or
> > > > +FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
> > > > +for more details.
> > > > +
> > > > +You should have received a copy of the GNU General Public License
> > > > +along with GCC; see the file COPYING3.  If not see
> > > > +<http://www.gnu.org/licenses/>.  */
> > > > +%}
> > > > +struct cp_trait {
> > > > +  const char *name;
> > > > +  enum cp_trait_kind kind;
> > > > +  short arity;
> > > > +  bool type;
> > > > +};
> > > > +%%
> > > > +"__is_same_as", CPTK_IS_SAME, 2, false
> > > > diff --git a/gcc/cp/cp-trait.gperf b/gcc/cp/cp-trait.gperf
> > > > new file mode 100644
> > > > index 00000000000..47e3c1af499
> > > > --- /dev/null
> > > > +++ b/gcc/cp/cp-trait.gperf
> > > > @@ -0,0 +1,74 @@
> > > > +%language=C++
> > > > +%define class-name cp_trait_lookup
> > > > +%struct-type
> > > > +%{
> > > > +/* Copyright (C) 2023 Free Software Foundation, Inc.
> > > > +
> > > > +This file is part of GCC.
> > > > +
> > > > +GCC is free software; you can redistribute it and/or modify it under
> > > > +the terms of the GNU General Public License as published by the Free
> > > > +Software Foundation; either version 3, or (at your option) any later
> > > > +version.
> > > > +
> > > > +GCC is distributed in the hope that it will be useful, but WITHOUT ANY
> > > > +WARRANTY; without even the implied warranty of MERCHANTABILITY or
> > > > +FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
> > > > +for more details.
> > > > +
> > > > +You should have received a copy of the GNU General Public License
> > > > +along with GCC; see the file COPYING3.  If not see
> > > > +<http://www.gnu.org/licenses/>.  */
> > > > +%}
> > > > +struct cp_trait {
> > > > +  const char *name;
> > > > +  enum cp_trait_kind kind;
> > > > +  short arity;
> > > > +  bool type;
> > > > +};
> > > > +%%
> > > > +"__is_same_as", CPTK_IS_SAME, 2, false
> > > > +"__has_nothrow_assign", CPTK_HAS_NOTHROW_ASSIGN, 1, false
> > > > +"__has_nothrow_constructor", CPTK_HAS_NOTHROW_CONSTRUCTOR, 1, false
> > > > +"__has_nothrow_copy", CPTK_HAS_NOTHROW_COPY, 1, false
> > > > +"__has_trivial_assign", CPTK_HAS_TRIVIAL_ASSIGN, 1, false
> > > > +"__has_trivial_constructor", CPTK_HAS_TRIVIAL_CONSTRUCTOR, 1, false
> > > > +"__has_trivial_copy", CPTK_HAS_TRIVIAL_COPY, 1, false
> > > > +"__has_trivial_destructor", CPTK_HAS_TRIVIAL_DESTRUCTOR, 1, false
> > > > +"__has_unique_object_representations", CPTK_HAS_UNIQUE_OBJ_REPRESENTATIONS, 1, false
> > > > +"__has_virtual_destructor", CPTK_HAS_VIRTUAL_DESTRUCTOR, 1, false
> > > > +"__is_abstract", CPTK_IS_ABSTRACT, 1, false
> > > > +"__is_aggregate", CPTK_IS_AGGREGATE, 1, false
> > > > +"__is_assignable", CPTK_IS_ASSIGNABLE, 2, false
> > > > +"__is_base_of", CPTK_IS_BASE_OF, 2, false
> > > > +"__is_class", CPTK_IS_CLASS, 1, false
> > > > +"__is_constructible", CPTK_IS_CONSTRUCTIBLE, -1, false
> > > > +"__is_convertible", CPTK_IS_CONVERTIBLE, 2, false
> > > > +"__is_empty", CPTK_IS_EMPTY, 1, false
> > > > +"__is_enum", CPTK_IS_ENUM, 1, false
> > > > +"__is_final", CPTK_IS_FINAL, 1, false
> > > > +"__is_layout_compatible", CPTK_IS_LAYOUT_COMPATIBLE, 2, false
> > > > +"__is_literal_type", CPTK_IS_LITERAL_TYPE, 1, false
> > > > +"__is_nothrow_assignable", CPTK_IS_NOTHROW_ASSIGNABLE, 2, false
> > > > +"__is_nothrow_constructible", CPTK_IS_NOTHROW_CONSTRUCTIBLE, -1, false
> > > > +"__is_nothrow_convertible", CPTK_IS_NOTHROW_CONVERTIBLE, 2, false
> > > > +"__is_pointer_interconvertible_base_of", CPTK_IS_POINTER_INTERCONVERTIBLE_BASE_OF, 2, false
> > > > +"__is_pod", CPTK_IS_POD, 1, false
> > > > +"__is_polymorphic", CPTK_IS_POLYMORPHIC, 1, false
> > > > +"__is_same", CPTK_IS_SAME, 2, false
> > > > +"__is_standard_layout", CPTK_IS_STD_LAYOUT, 1, false
> > > > +"__is_trivial", CPTK_IS_TRIVIAL, 1, false
> > > > +"__is_trivially_assignable", CPTK_IS_TRIVIALLY_ASSIGNABLE, 2, false
> > > > +"__is_trivially_constructible", CPTK_IS_TRIVIALLY_CONSTRUCTIBLE, -1, false
> > > > +"__is_trivially_copyable", CPTK_IS_TRIVIALLY_COPYABLE, 1, false
> > > > +"__is_union", CPTK_IS_UNION, 1, false
> > > > +"__reference_constructs_from_temporary", CPTK_REF_CONSTRUCTS_FROM_TEMPORARY, 2, false
> > > > +"__reference_converts_from_temporary", CPTK_REF_CONVERTS_FROM_TEMPORARY, 2, false
> > > > +"__remove_cv", CPTK_REMOVE_CV, 1, true
> > > > +"__remove_cvref", CPTK_REMOVE_CVREF, 1, true
> > > > +"__remove_reference", CPTK_REMOVE_REFERENCE, 1, true
> > > > +"__type_pack_element", CPTK_TYPE_PACK_ELEMENT, -1, true
> > > > +"__underlying_type", CPTK_UNDERLYING_TYPE, 1, true
> > > > +"__is_deducible ", CPTK_IS_DEDUCIBLE, 2, false
> > > > +"__bases", CPTK_BASES, 1, true
> > > > +"__direct_bases", CPTK_DIRECT_BASES, 1, true
> > > > diff --git a/gcc/cp/cp-trait.h b/gcc/cp/cp-trait.h
> > > > new file mode 100644
> > > > index 00000000000..97ba8492d15
> > > > --- /dev/null
> > > > +++ b/gcc/cp/cp-trait.h
> > > > @@ -0,0 +1,247 @@
> > > > +/* C++ code produced by gperf version 3.1 */
> > > > +/* Command-line: gperf -o -C -E -k 8 -D -N find -L C++ --output-file ../../gcc/cp/cp-trait.h ../../gcc/cp/cp-trait.gperf  */
> > > > +
> > > > +#if !((' ' == 32) && ('!' == 33) && ('"' == 34) && ('#' == 35) \
> > > > +      && ('%' == 37) && ('&' == 38) && ('\'' == 39) && ('(' == 40) \
> > > > +      && (')' == 41) && ('*' == 42) && ('+' == 43) && (',' == 44) \
> > > > +      && ('-' == 45) && ('.' == 46) && ('/' == 47) && ('0' == 48) \
> > > > +      && ('1' == 49) && ('2' == 50) && ('3' == 51) && ('4' == 52) \
> > > > +      && ('5' == 53) && ('6' == 54) && ('7' == 55) && ('8' == 56) \
> > > > +      && ('9' == 57) && (':' == 58) && (';' == 59) && ('<' == 60) \
> > > > +      && ('=' == 61) && ('>' == 62) && ('?' == 63) && ('A' == 65) \
> > > > +      && ('B' == 66) && ('C' == 67) && ('D' == 68) && ('E' == 69) \
> > > > +      && ('F' == 70) && ('G' == 71) && ('H' == 72) && ('I' == 73) \
> > > > +      && ('J' == 74) && ('K' == 75) && ('L' == 76) && ('M' == 77) \
> > > > +      && ('N' == 78) && ('O' == 79) && ('P' == 80) && ('Q' == 81) \
> > > > +      && ('R' == 82) && ('S' == 83) && ('T' == 84) && ('U' == 85) \
> > > > +      && ('V' == 86) && ('W' == 87) && ('X' == 88) && ('Y' == 89) \
> > > > +      && ('Z' == 90) && ('[' == 91) && ('\\' == 92) && (']' == 93) \
> > > > +      && ('^' == 94) && ('_' == 95) && ('a' == 97) && ('b' == 98) \
> > > > +      && ('c' == 99) && ('d' == 100) && ('e' == 101) && ('f' == 102) \
> > > > +      && ('g' == 103) && ('h' == 104) && ('i' == 105) && ('j' == 106) \
> > > > +      && ('k' == 107) && ('l' == 108) && ('m' == 109) && ('n' == 110) \
> > > > +      && ('o' == 111) && ('p' == 112) && ('q' == 113) && ('r' == 114) \
> > > > +      && ('s' == 115) && ('t' == 116) && ('u' == 117) && ('v' == 118) \
> > > > +      && ('w' == 119) && ('x' == 120) && ('y' == 121) && ('z' == 122) \
> > > > +      && ('{' == 123) && ('|' == 124) && ('}' == 125) && ('~' == 126))
> > > > +/* The character set is not based on ISO-646.  */
> > > > +#error "gperf generated tables don't work with this execution character set. Please report a bug to <bug-gperf@gnu.org>."
> > > > +#endif
> > > > +
> > > > +#line 4 "../../gcc/cp/cp-trait.gperf"
> > > > +
> > > > +/* Copyright (C) 2023 Free Software Foundation, Inc.
> > > > +
> > > > +This file is part of GCC.
> > > > +
> > > > +GCC is free software; you can redistribute it and/or modify it under
> > > > +the terms of the GNU General Public License as published by the Free
> > > > +Software Foundation; either version 3, or (at your option) any later
> > > > +version.
> > > > +
> > > > +GCC is distributed in the hope that it will be useful, but WITHOUT ANY
> > > > +WARRANTY; without even the implied warranty of MERCHANTABILITY or
> > > > +FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
> > > > +for more details.
> > > > +
> > > > +You should have received a copy of the GNU General Public License
> > > > +along with GCC; see the file COPYING3.  If not see
> > > > +<http://www.gnu.org/licenses/>.  */
> > > > +#line 23 "../../gcc/cp/cp-trait.gperf"
> > > > +struct cp_trait {
> > > > +  const char *name;
> > > > +  enum cp_trait_kind kind;
> > > > +  short arity;
> > > > +  bool type;
> > > > +};
> > > > +/* maximum key range = 79, duplicates = 0 */
> > > > +
> > > > +class cp_trait_lookup
> > > > +{
> > > > +private:
> > > > +  static inline unsigned int hash (const char *str, size_t len);
> > > > +public:
> > > > +  static const struct cp_trait *find (const char *str, size_t len);
> > > > +};
> > > > +
> > > > +inline unsigned int
> > > > +cp_trait_lookup::hash (const char *str, size_t len)
> > > > +{
> > > > +  static const unsigned char asso_values[] =
> > > > +    {
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86,  1, 86, 86,
> > > > +       0, 35, 86,  0, 86,  0, 86, 86, 10, 10,
> > > > +      50, 15, 55, 86, 30,  5, 15,  0, 86, 86,
> > > > +      86, 20, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
> > > > +      86, 86, 86, 86, 86, 86
> > > > +    };
> > > > +  unsigned int hval = len;
> > > > +
> > > > +  switch (hval)
> > > > +    {
> > > > +      default:
> > > > +        hval += asso_values[static_cast<unsigned char>(str[7])];
> > > > +      /*FALLTHROUGH*/
> > > > +      case 7:
> > > > +        break;
> > > > +    }
> > > > +  return hval;
> > > > +}
> > > > +
> > > > +const struct cp_trait *
> > > > +cp_trait_lookup::find (const char *str, size_t len)
> > > > +{
> > > > +  enum
> > > > +    {
> > > > +      TOTAL_KEYWORDS = 45,
> > > > +      MIN_WORD_LENGTH = 7,
> > > > +      MAX_WORD_LENGTH = 37,
> > > > +      MIN_HASH_VALUE = 7,
> > > > +      MAX_HASH_VALUE = 85
> > > > +    };
> > > > +
> > > > +  static const struct cp_trait wordlist[] =
> > > > +    {
> > > > +#line 73 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__bases", CPTK_BASES, 1, true},
> > > > +#line 56 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_pod", CPTK_IS_POD, 1, false},
> > > > +#line 48 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_enum", CPTK_IS_ENUM, 1, false},
> > > > +#line 64 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_union", CPTK_IS_UNION, 1, false},
> > > > +#line 44 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_class", CPTK_IS_CLASS, 1, false},
> > > > +#line 60 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_trivial", CPTK_IS_TRIVIAL, 1, false},
> > > > +#line 41 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_aggregate", CPTK_IS_AGGREGATE, 1, false},
> > > > +#line 72 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_deducible ", CPTK_IS_DEDUCIBLE, 2, false},
> > > > +#line 43 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_base_of", CPTK_IS_BASE_OF, 2, false},
> > > > +#line 40 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_abstract", CPTK_IS_ABSTRACT, 1, false},
> > > > +#line 58 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_same", CPTK_IS_SAME, 2, false},
> > > > +#line 42 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_assignable", CPTK_IS_ASSIGNABLE, 2, false},
> > > > +#line 59 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_standard_layout", CPTK_IS_STD_LAYOUT, 1, false},
> > > > +#line 30 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_same_as", CPTK_IS_SAME, 2, false},
> > > > +#line 63 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_trivially_copyable", CPTK_IS_TRIVIALLY_COPYABLE, 1, false},
> > > > +#line 39 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__has_virtual_destructor", CPTK_HAS_VIRTUAL_DESTRUCTOR, 1, false},
> > > > +#line 61 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_trivially_assignable", CPTK_IS_TRIVIALLY_ASSIGNABLE, 2, false},
> > > > +#line 57 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_polymorphic", CPTK_IS_POLYMORPHIC, 1, false},
> > > > +#line 71 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__underlying_type", CPTK_UNDERLYING_TYPE, 1, true},
> > > > +#line 62 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_trivially_constructible", CPTK_IS_TRIVIALLY_CONSTRUCTIBLE, -1, false},
> > > > +#line 74 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__direct_bases", CPTK_DIRECT_BASES, 1, true},
> > > > +#line 51 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_literal_type", CPTK_IS_LITERAL_TYPE, 1, false},
> > > > +#line 33 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__has_nothrow_copy", CPTK_HAS_NOTHROW_COPY, 1, false},
> > > > +#line 31 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__has_nothrow_assign", CPTK_HAS_NOTHROW_ASSIGN, 1, false},
> > > > +#line 55 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_pointer_interconvertible_base_of", CPTK_IS_POINTER_INTERCONVERTIBLE_BASE_OF, 2, false},
> > > > +#line 52 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_nothrow_assignable", CPTK_IS_NOTHROW_ASSIGNABLE, 2, false},
> > > > +#line 54 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_nothrow_convertible", CPTK_IS_NOTHROW_CONVERTIBLE, 2, false},
> > > > +#line 32 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__has_nothrow_constructor", CPTK_HAS_NOTHROW_CONSTRUCTOR, 1, false},
> > > > +#line 53 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_nothrow_constructible", CPTK_IS_NOTHROW_CONSTRUCTIBLE, -1, false},
> > > > +#line 50 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_layout_compatible", CPTK_IS_LAYOUT_COMPATIBLE, 2, false},
> > > > +#line 67 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__remove_cv", CPTK_REMOVE_CV, 1, true},
> > > > +#line 36 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__has_trivial_copy", CPTK_HAS_TRIVIAL_COPY, 1, false},
> > > > +#line 68 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__remove_cvref", CPTK_REMOVE_CVREF, 1, true},
> > > > +#line 34 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__has_trivial_assign", CPTK_HAS_TRIVIAL_ASSIGN, 1, false},
> > > > +#line 69 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__remove_reference", CPTK_REMOVE_REFERENCE, 1, true},
> > > > +#line 37 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__has_trivial_destructor", CPTK_HAS_TRIVIAL_DESTRUCTOR, 1, false},
> > > > +#line 35 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__has_trivial_constructor", CPTK_HAS_TRIVIAL_CONSTRUCTOR, 1, false},
> > > > +#line 49 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_final", CPTK_IS_FINAL, 1, false},
> > > > +#line 47 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_empty", CPTK_IS_EMPTY, 1, false},
> > > > +#line 46 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_convertible", CPTK_IS_CONVERTIBLE, 2, false},
> > > > +#line 45 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__is_constructible", CPTK_IS_CONSTRUCTIBLE, -1, false},
> > > > +#line 66 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__reference_converts_from_temporary", CPTK_REF_CONVERTS_FROM_TEMPORARY, 2, false},
> > > > +#line 65 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__reference_constructs_from_temporary", CPTK_REF_CONSTRUCTS_FROM_TEMPORARY, 2, false},
> > > > +#line 70 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__type_pack_element", CPTK_TYPE_PACK_ELEMENT, -1, true},
> > > > +#line 38 "../../gcc/cp/cp-trait.gperf"
> > > > +      {"__has_unique_object_representations", CPTK_HAS_UNIQUE_OBJ_REPRESENTATIONS, 1, false}
> > > > +    };
> > > > +
> > > > +  static const signed char lookup[] =
> > > > +    {
> > > > +      -1, -1, -1, -1, -1, -1, -1,  0,  1,  2,  3,  4,  5, -1,
> > > > +       6,  7, -1,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
> > > > +      19, 20, -1, -1, 21, 22, -1, 23, -1, 24, 25, 26, 27, 28,
> > > > +      29, -1, -1, -1, 30, -1, 31, 32, 33, -1, -1, 34, 35, 36,
> > > > +      -1, -1, -1, -1, 37, -1, -1, -1, -1, 38, 39, -1, 40, -1,
> > > > +      41, -1, 42, -1, 43, -1, -1, -1, -1, -1, -1, -1, -1, -1,
> > > > +      -1, 44
> > > > +    };
> > > > +
> > > > +  if (len <= MAX_WORD_LENGTH && len >= MIN_WORD_LENGTH)
> > > > +    {
> > > > +      unsigned int key = hash (str, len);
> > > > +
> > > > +      if (key <= MAX_HASH_VALUE)
> > > > +        {
> > > > +          int index = lookup[key];
> > > > +
> > > > +          if (index >= 0)
> > > > +            {
> > > > +              const char *s = wordlist[index].name;
> > > > +
> > > > +              if (*str == *s && !strcmp (str + 1, s + 1))
> > > > +                return &wordlist[index];
> > > > +            }
> > > > +        }
> > > > +    }
> > > > +  return 0;
> > > > +}
> > > > diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
> > > > index 6e34952da99..62e134886fb 100644
> > > > --- a/gcc/cp/cp-tree.h
> > > > +++ b/gcc/cp/cp-tree.h
> > > > @@ -1226,7 +1226,7 @@ enum cp_identifier_kind {
> > > >    cik_simple_op = 4, /* Non-assignment operator name.  */
> > > >    cik_assign_op = 5, /* An assignment operator name.  */
> > > >    cik_conv_op = 6,   /* Conversion operator name.  */
> > > > -  cik_reserved_for_udlit = 7,        /* Not yet in use  */
> > > > +  cik_trait = 7,     /* Built-in trait name.  */
> > > >    cik_max
> > > >  };
> > > >
> > > > @@ -1271,9 +1271,9 @@ enum cp_identifier_kind {
> > > >      & IDENTIFIER_KIND_BIT_0 (NODE))
> > > >
> > > >  /* True if this identifier is for any operator name (including
> > > > -   conversions).  Value 4, 5, 6 or 7.  */
> > > > +   conversions).  Value 4, 5, or 6.  */
> > > >  #define IDENTIFIER_ANY_OP_P(NODE)            \
> > > > -  (IDENTIFIER_KIND_BIT_2 (NODE))
> > > > +  (IDENTIFIER_KIND_BIT_2 (NODE) && !IDENTIFIER_TRAIT_P (NODE))
> > > >
> > > >  /* True if this identifier is for an overloaded operator. Values 4, 5.  */
> > > >  #define IDENTIFIER_OVL_OP_P(NODE)            \
> > > > @@ -1286,12 +1286,18 @@ enum cp_identifier_kind {
> > > >     & IDENTIFIER_KIND_BIT_0 (NODE))
> > > >
> > > >  /* True if this identifier is the name of a type-conversion
> > > > -   operator.  Value 7.  */
> > > > +   operator.  Value 6.  */
> > > >  #define IDENTIFIER_CONV_OP_P(NODE)           \
> > > >    (IDENTIFIER_ANY_OP_P (NODE)                        \
> > > >     & IDENTIFIER_KIND_BIT_1 (NODE)            \
> > > >     & (!IDENTIFIER_KIND_BIT_0 (NODE)))
> > > >
> > > > +/* True if this identifier is the name of a built-in trait.  */
> > > > +#define IDENTIFIER_TRAIT_P(NODE)             \
> > > > +  (IDENTIFIER_KIND_BIT_0 (NODE)                      \
> > > > +   && IDENTIFIER_KIND_BIT_1 (NODE)           \
> > > > +   && IDENTIFIER_KIND_BIT_2 (NODE))
> > > > +
> > > >  /* True if this identifier is a new or delete operator.  */
> > > >  #define IDENTIFIER_NEWDEL_OP_P(NODE)         \
> > > >    (IDENTIFIER_OVL_OP_P (NODE)                        \
> > > > diff --git a/gcc/cp/lex.cc b/gcc/cp/lex.cc
> > > > index 64bcfb18196..f6e1f6a4075 100644
> > > > --- a/gcc/cp/lex.cc
> > > > +++ b/gcc/cp/lex.cc
> > > > @@ -35,6 +35,7 @@ along with GCC; see the file COPYING3.  If not see
> > > >  #include "langhooks.h"
> > > >
> > > >  static int interface_strcmp (const char *);
> > > > +static void init_cp_traits (void);
> > > >  static void init_cp_pragma (void);
> > > >
> > > >  static tree parse_strconst_pragma (const char *, int);
> > > > @@ -283,6 +284,23 @@ init_reswords (void)
> > > >      }
> > > >  }
> > > >
> > > > +/* Initialize the C++ traits.  */
> > > > +static void
> > > > +init_cp_traits (void)
> > > > +{
> > > > +  tree id;
> > > > +
> > > > +#define DEFTRAIT(TCC, CODE, NAME, ARITY) \
> > > > +  id = get_identifier (NAME); \
> > > > +  set_identifier_kind (id, cik_trait);
> > > > +#include "cp/cp-trait.def"
> > > > +#undef DEFTRAIT
> > > > +
> > > > +  /* An alias for __is_same.  */
> > > > +  id = get_identifier ("__is_same_as");
> > > > +  set_identifier_kind (id, cik_trait);
> > > > +}
> > > > +
> > > >  static void
> > > >  init_cp_pragma (void)
> > > >  {
> > > > @@ -324,6 +342,7 @@ cxx_init (void)
> > > >    input_location = BUILTINS_LOCATION;
> > > >
> > > >    init_reswords ();
> > > > +  init_cp_traits ();
> > > >    init_tree ();
> > > >    init_cp_semantics ();
> > > >    init_operators ();
> > > > diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
> > > > index f3abae716fe..39952893ffa 100644
> > > > --- a/gcc/cp/parser.cc
> > > > +++ b/gcc/cp/parser.cc
> > > > @@ -49,6 +49,7 @@ along with GCC; see the file COPYING3.  If not see
> > > >  #include "contracts.h"
> > > >  #include "bitmap.h"
> > > >  #include "builtins.h"
> > > > +#include "cp-trait.h"
> > > >
> > > >
> > > >  /* The lexer.  */
> > > > @@ -246,6 +247,12 @@ static void cp_lexer_start_debugging
> > > >    (cp_lexer *) ATTRIBUTE_UNUSED;
> > > >  static void cp_lexer_stop_debugging
> > > >    (cp_lexer *) ATTRIBUTE_UNUSED;
> > > > +static const cp_trait *cp_lexer_lookup_trait
> > > > +  (const cp_token *);
> > > > +static const cp_trait *cp_lexer_lookup_trait_expr
> > > > +  (const cp_token *);
> > > > +static const cp_trait *cp_lexer_lookup_trait_type
> > > > +  (const cp_token *);
> > > >
> > > >  static cp_token_cache *cp_token_cache_new
> > > >    (cp_token *, cp_token *);
> > > > @@ -1167,12 +1174,6 @@ cp_keyword_starts_decl_specifier_p (enum rid keyword)
> > > >      case RID_CONSTEVAL:
> > > >        return true;
> > > >
> > > > -#define DEFTRAIT_TYPE(CODE, NAME, ARITY) \
> > > > -    case RID_##CODE:
> > > > -#include "cp-trait.def"
> > > > -#undef DEFTRAIT_TYPE
> > > > -      return true;
> > > > -
> > > >      default:
> > > >        if (keyword >= RID_FIRST_INT_N
> > > >         && keyword < RID_FIRST_INT_N + NUM_INT_N_ENTS
> > > > @@ -1182,6 +1183,51 @@ cp_keyword_starts_decl_specifier_p (enum rid keyword)
> > > >      }
> > > >  }
> > > >
> > > > +/* Look ups the corresponding built-in trait if a given token is
> > > > +   a built-in trait.  Otherwise, returns nullptr.  */
> > > > +
> > > > +static const cp_trait *
> > > > +cp_lexer_lookup_trait (const cp_token *token)
> > > > +{
> > > > +  tree id = token->u.value;
> > > > +
> > > > +  if (token->type == CPP_NAME
> > > > +      && TREE_CODE (id) == IDENTIFIER_NODE
> > > > +      && IDENTIFIER_TRAIT_P (id))
> > > > +    {
> > > > +      const char *id_str = IDENTIFIER_POINTER (id);
> > > > +      const int id_len = IDENTIFIER_LENGTH (id);
> > > > +      return cp_trait_lookup::find (id_str, id_len);
> > > > +    }
> > > > +  return nullptr;
> > > > +}
> > > > +
> > > > +/* Similarly, but only if the token is an expression-yielding
> > > > +   built-in trait.  */
> > > > +
> > > > +static const cp_trait *
> > > > +cp_lexer_lookup_trait_expr (const cp_token *token)
> > > > +{
> > > > +  const cp_trait *trait = cp_lexer_lookup_trait (token);
> > > > +  if (trait && !trait->type)
> > > > +    return trait;
> > > > +
> > > > +  return nullptr;
> > > > +}
> > > > +
> > > > +/* Similarly, but only if the token is a type-yielding
> > > > +   built-in trait.  */
> > > > +
> > > > +static const cp_trait *
> > > > +cp_lexer_lookup_trait_type (const cp_token *token)
> > > > +{
> > > > +  const cp_trait *trait = cp_lexer_lookup_trait (token);
> > > > +  if (trait && trait->type)
> > > > +    return trait;
> > > > +
> > > > +  return nullptr;
> > > > +}
> > > > +
> > > >  /* Return true if the next token is a keyword for a decl-specifier.  */
> > > >
> > > >  static bool
> > > > @@ -1190,6 +1236,8 @@ cp_lexer_next_token_is_decl_specifier_keyword (cp_lexer *lexer)
> > > >    cp_token *token;
> > > >
> > > >    token = cp_lexer_peek_token (lexer);
> > > > +  if (cp_lexer_lookup_trait_type (token))
> > > > +    return true;
> > > >    return cp_keyword_starts_decl_specifier_p (token->keyword);
> > > >  }
> > > >
> > > > @@ -2854,7 +2902,7 @@ static void cp_parser_late_parsing_default_args
> > > >  static tree cp_parser_sizeof_operand
> > > >    (cp_parser *, enum rid);
> > > >  static cp_expr cp_parser_trait
> > > > -  (cp_parser *, enum rid);
> > > > +  (cp_parser *, const cp_trait *);
> > > >  static bool cp_parser_declares_only_class_p
> > > >    (cp_parser *);
> > > >  static void cp_parser_set_storage_class
> > > > @@ -6021,12 +6069,6 @@ cp_parser_primary_expression (cp_parser *parser,
> > > >       case RID_OFFSETOF:
> > > >         return cp_parser_builtin_offsetof (parser);
> > > >
> > > > -#define DEFTRAIT_EXPR(CODE, NAME, ARITY) \
> > > > -     case RID_##CODE:
> > > > -#include "cp-trait.def"
> > > > -#undef DEFTRAIT_EXPR
> > > > -       return cp_parser_trait (parser, token->keyword);
> > > > -
> > > >       // C++ concepts
> > > >       case RID_REQUIRES:
> > > >         return cp_parser_requires_expression (parser);
> > > > @@ -6065,6 +6107,12 @@ cp_parser_primary_expression (cp_parser *parser,
> > > >        `::' as the beginning of a qualified-id, or the "operator"
> > > >        keyword.  */
> > > >      case CPP_NAME:
> > > > +      {
> > > > +     const cp_trait* trait = cp_lexer_lookup_trait_expr (token);
> > > > +     if (trait)
> > > > +       return cp_parser_trait (parser, trait);
> > > > +      }
> > > > +      /* FALLTHRU */
> > > >      case CPP_SCOPE:
> > > >      case CPP_TEMPLATE_ID:
> > > >      case CPP_NESTED_NAME_SPECIFIER:
> > > > @@ -11033,28 +11081,11 @@ cp_parser_builtin_offsetof (cp_parser *parser)
> > > >  /* Parse a builtin trait expression or type.  */
> > > >
> > > >  static cp_expr
> > > > -cp_parser_trait (cp_parser* parser, enum rid keyword)
> > > > +cp_parser_trait (cp_parser* parser, const cp_trait* trait)
> > > >  {
> > > > -  cp_trait_kind kind;
> > > >    tree type1, type2 = NULL_TREE;
> > > > -  bool binary = false;
> > > > -  bool variadic = false;
> > > > -  bool type = false;
> > > > -
> > > > -  switch (keyword)
> > > > -    {
> > > > -#define DEFTRAIT(TCC, CODE, NAME, ARITY) \
> > > > -    case RID_##CODE:                  \
> > > > -      kind = CPTK_##CODE;             \
> > > > -      binary = (ARITY == 2);          \
> > > > -      variadic = (ARITY == -1);               \
> > > > -      type = (TCC == tcc_type);               \
> > > > -      break;
> > > > -#include "cp-trait.def"
> > > > -#undef DEFTRAIT
> > > > -    default:
> > > > -      gcc_unreachable ();
> > > > -    }
> > > > +  const bool binary = (trait->arity == 2);
> > > > +  const bool variadic = (trait->arity == -1);
> > > >
> > > >    /* Get location of initial token.  */
> > > >    location_t start_loc = cp_lexer_peek_token (parser->lexer)->location;
> > > > @@ -11063,12 +11094,12 @@ cp_parser_trait (cp_parser* parser, enum rid keyword)
> > > >    cp_lexer_consume_token (parser->lexer);
> > > >
> > > >    matching_parens parens;
> > > > -  if (kind == CPTK_TYPE_PACK_ELEMENT)
> > > > +  if (trait->kind == CPTK_TYPE_PACK_ELEMENT)
> > > >      cp_parser_require (parser, CPP_LESS, RT_LESS);
> > > >    else
> > > >      parens.require_open (parser);
> > > >
> > > > -  if (kind == CPTK_IS_DEDUCIBLE)
> > > > +  if (trait->kind == CPTK_IS_DEDUCIBLE)
> > > >      {
> > > >        const cp_token* token = cp_lexer_peek_token (parser->lexer);
> > > >        type1 = cp_parser_id_expression (parser,
> > > > @@ -11079,7 +11110,7 @@ cp_parser_trait (cp_parser* parser, enum rid keyword)
> > > >                                      /*optional_p=*/false);
> > > >        type1 = cp_parser_lookup_name_simple (parser, type1, token->location);
> > > >      }
> > > > -  else if (kind == CPTK_TYPE_PACK_ELEMENT)
> > > > +  else if (trait->kind == CPTK_TYPE_PACK_ELEMENT)
> > > >      /* __type_pack_element takes an expression as its first argument and uses
> > > >         template-id syntax instead of function call syntax (for consistency
> > > >         with Clang).  We special case these properties of __type_pack_element
> > > > @@ -11094,7 +11125,7 @@ cp_parser_trait (cp_parser* parser, enum rid keyword)
> > > >    if (type1 == error_mark_node)
> > > >      return error_mark_node;
> > > >
> > > > -  if (kind == CPTK_TYPE_PACK_ELEMENT)
> > > > +  if (trait->kind == CPTK_TYPE_PACK_ELEMENT)
> > > >      {
> > > >        cp_parser_require (parser, CPP_COMMA, RT_COMMA);
> > > >        tree trailing = cp_parser_enclosed_template_argument_list (parser);
> > > > @@ -11144,7 +11175,7 @@ cp_parser_trait (cp_parser* parser, enum rid keyword)
> > > >      }
> > > >
> > > >    location_t finish_loc = cp_lexer_peek_token (parser->lexer)->location;
> > > > -  if (kind == CPTK_TYPE_PACK_ELEMENT)
> > > > +  if (trait->kind == CPTK_TYPE_PACK_ELEMENT)
> > > >      /* cp_parser_enclosed_template_argument_list above already took care
> > > >         of parsing the closing '>'.  */;
> > > >    else
> > > > @@ -11158,17 +11189,17 @@ cp_parser_trait (cp_parser* parser, enum rid keyword)
> > > >
> > > >    /* Complete the trait expression, which may mean either processing
> > > >       the trait expr now or saving it for template instantiation.  */
> > > > -  switch (kind)
> > > > +  switch (trait->kind)
> > > >      {
> > > >      case CPTK_BASES:
> > > >        return cp_expr (finish_bases (type1, false), trait_loc);
> > > >      case CPTK_DIRECT_BASES:
> > > >        return cp_expr (finish_bases (type1, true), trait_loc);
> > > >      default:
> > > > -      if (type)
> > > > -     return finish_trait_type (kind, type1, type2, tf_warning_or_error);
> > > > +      if (trait->type)
> > > > +     return finish_trait_type (trait->kind, type1, type2, tf_warning_or_error);
> > > >        else
> > > > -     return finish_trait_expr (trait_loc, kind, type1, type2);
> > > > +     return finish_trait_expr (trait_loc, trait->kind, type1, type2);
> > > >      }
> > > >  }
> > > >
> > > > @@ -20081,20 +20112,21 @@ cp_parser_simple_type_specifier (cp_parser* parser,
> > > >
> > > >        return type;
> > > >
> > > > -#define DEFTRAIT_TYPE(CODE, NAME, ARITY) \
> > > > -    case RID_##CODE:
> > > > -#include "cp-trait.def"
> > > > -#undef DEFTRAIT_TYPE
> > > > -      type = cp_parser_trait (parser, token->keyword);
> > > > +    default:
> > > > +      break;
> > > > +    }
> > > > +
> > > > +  /* If token is a type-yielding built-in traits, parse it.  */
> > > > +  const cp_trait* trait = cp_lexer_lookup_trait_type (token);
> > > > +  if (trait)
> > > > +    {
> > > > +      type = cp_parser_trait (parser, trait);
> > > >        if (decl_specs)
> > > >       cp_parser_set_decl_spec_type (decl_specs, type,
> > > >                                     token,
> > > >                                     /*type_definition_p=*/false);
> > > >
> > > >        return type;
> > > > -
> > > > -    default:
> > > > -      break;
> > > >      }
> > > >
> > > >    /* If token is an already-parsed decltype not followed by ::,
> > > > --
> > > > 2.42.0
> > > >
> > > >
> > >
> >
> >