Tie together the two functions that ensure tail padding with
search_line_ssse3 via CPP_BUFFER_PADDING macro.

libcpp/ChangeLog:

	* internal.h (CPP_BUFFER_PADDING): New macro; use it ...
	* charset.cc (_cpp_convert_input): ...here, and ...
	* files.cc (read_file_guts): ...here, and ...
	* lex.cc (search_line_ssse3): here.

The recently introduced search_line_fast_ssse3 raised padding
requirement from 16 to 64, which was adjusted in read_file_guts,
but the corresponding ' + 16' in _cpp_convert_input was overlooked.

libcpp/ChangeLog:

	PR preprocessor/116458
	* charset.cc (_cpp_convert_input): Bump padding to 64 if
	HAVE_SSSE3.

Single argument static_assert is C++17 only.

libcpp/ChangeLog:

	* lex.cc(search_line_ssse3): fix static_assert to use 2 arguments.

The table over the years turned to be very wide, 147 columns
and any addition would add a couple of new ones.
We need a 28x23 bit matrix right now.

This patch changes the formatting, so that we need just 2 columns
per new feature and so we have some room for expansion.
In addition, the patch changes it to bitfields, which reduces
.rodata by 532 bytes (so 5.75x reduction of the variable) and
on x86_64-linux grows the cpp_set_lang function by 26 bytes (8.4%
growth).

2024-08-20  Jakub Jelinek  <jakub@redhat.com>

	* init.cc (struct lang_flags): Change all members from char
	typed fields to unsigned bit-fields.
	(lang_defaults): Change formatting of the initializer so that it
	fits to 68 columns rather than 147.

Since the characters we are searching for (CR, LF, '\', '?') all have
distinct ASCII codes mod 16, PSHUFB can help match them all at once.

Directly use the new helper if __SSSE3__ is defined. It makes the other
helpers unused, so mark them inline to prevent warnings.

Rewrite and simplify init_vectorized_lexer.

libcpp/ChangeLog:

	* config.in: Regenerate.
	* configure: Regenerate.
	* configure.ac: Check for SSSE3 instead of SSE4.2.
	* files.cc (read_file_guts): Bump padding to 64 if HAVE_SSSE3.
	* lex.cc (search_line_acc_char): Mark inline, not "unused".
	(search_line_sse2): Mark inline.
	(search_line_sse42): Replace with...
	(search_line_ssse3): ... this new function.  Adjust the use...
	(init_vectorized_lexer): ... here.  Simplify.

Host systems with only MMX and no SSE2 should be really rare now.
Let's remove the MMX code path to keep the number of custom
implementations the same.

The SSE2 code path is also somewhat dubious now (nearly everything
should have SSE4 4.2 which is >15 years old now), but the SSE2
code path is used as fallback for others and also apparently
Solaris uses it due to tool chain deficiencies.

libcpp/ChangeLog:

	* lex.cc (search_line_mmx): Remove function.
	(init_vectorized_lexer): Remove search_line_mmx.

The following patch implements the easy parts of the paper.
When @$` are added to the basic character set, it means that
R"@$`()@$`" should now be valid (here I've noticed most of the
raw string tests were tested solely with -std=c++11 or -std=gnu++11
and I've tried to change that), and on the other side even if
by extension $ is allowed in identifiers, \u0024 or \U00000024
or \u{24} should not be, similarly how \u0041 is not allowed.

The paper in 3.1 claims though that
 #include <stdio.h>

 #define STR(x) #x

int main()
{
  printf("%s", STR(\u0060)); // U+0060 is ` GRAVE ACCENT
}
should have been accepted before this paper (and rejected after it),
but g++ rejects it.

I've tried to understand it, but am confused on what is the right
behavior and why.

Consider
 #define STR(x) #x
const char *a = "\u00b7";
const char *b = STR(\u00b7);
const char *c = "\u0041";
const char *d = STR(\u0041);
const char *e = STR(a\u00b7);
const char *f = STR(a\u0041);
const char *g = STR(a \u00b7);
const char *h = STR(a \u0041);
const char *i = "\u066d";
const char *j = STR(\u066d);
const char *k = "\u0040";
const char *l = STR(\u0040);
const char *m = STR(a\u066d);
const char *n = STR(a\u0040);
const char *o = STR(a \u066d);
const char *p = STR(a \u0040);

Neither clang nor gcc emit any diagnostics on the a, c, i and k
initializers, those are certainly valid (c is invalid in C23 though).  g++
emits with -pedantic-errors errors on all the others, while clang++ on the
ones with STR involving \u0041, \u0040 and a\u0066d.  The chosen values are
\u0040 '@' as something being changed by this paper, \u0041 'A' as basic
character set char valid in identifiers before/after, \u00b7 as an example
of character which is pedantically valid in identifiers if not at the start
and \u066d s something pedantically not valid in identifiers.

Now, https://eel.is/c++draft/lex.charset#6 says that UCN used outside of a
string/character literal which corresponds to basic character set character
(or control character) is ill-formed, that would make d, f, h cases invalid
for C++ and l, n, p cases invalid for C++26.

https://eel.is/c++draft/lex.name states which characters can appear at the
start of the identifier and which can appear after the start.  And
https://eel.is/c++draft/lex.pptoken states that preprocessing-token is
either identifier, or tons of other things, or "each non-whitespace
character that cannot be one of the above"

Then https://eel.is/c++draft/lex.pptoken#1 says that this last category is
invalid if the preprocessing token is being converted into token.

And https://eel.is/c++draft/lex.pptoken#2 includes "If any character not in
the basic character set matches the last category, the program is
ill-formed."

Now, e.g.  for the C++23 STR(\u0040) case, \u0040 is there not in the basic
character set, so valid outside of the literals (not the case anymore in
C++26), but it isn't nondigit and doesn't have XID_Start property, so it
isn't IMHO an identifier and so must be the "each non-whitespace character
that cannot be one of the above" case.  Why doesn't the above mentioned
https://eel.is/c++draft/lex.pptoken#2 sentence make that invalid?  Ignoring
that, I'd say it would be then stringized and that feels like it is what
clang++ is doing.  Now, e.g.  for the STR(a\u066d) case, I wonder why that
isn't lexed as a identifier followed by \u066d "each non-whitespace
character that cannot be one of the above" token and stringified similarly,
clang++ rejects that.

What GCC libcpp seems to be doing is that if that forms_identifier_p calls
_cpp_valid_utf8 or _cpp_valid_ucn with an argument which tells it is first
or second+ in identifier, and e.g.  _cpp_valid_ucn then for UCNs valid in
string literals calls
  else if (identifier_pos)
    {
      int validity = ucn_valid_in_identifier (pfile, result, nst);

      if (validity == 0)
        cpp_error (pfile, CPP_DL_ERROR,
                   "universal character %.*s is not valid in an identifier",
                   (int) (str - base), base);
      else if (validity == 2 && identifier_pos == 1)
        cpp_error (pfile, CPP_DL_ERROR,
   "universal character %.*s is not valid at the start of an identifier",
                   (int) (str - base), base);
    }
so basically all those invalid in identifiers cases emit an error and
pretend to be valid in identifiers, rather than what e.g.  _cpp_valid_utf8
does for C but not for C++ and only for the chars completely invalid in
identifiers rather than just valid in identifiers but not at the start:
          /* In C++, this is an error for invalid character in an identifier
             because logically, the UTF-8 was converted to a UCN during
             translation phase 1 (even though we don't physically do it that
             way).  In C, this byte rather becomes grammatically a separate
             token.  */

          if (CPP_OPTION (pfile, cplusplus))
            cpp_error (pfile, CPP_DL_ERROR,
                       "extended character %.*s is not valid in an identifier",
                       (int) (*pstr - base), base);
          else
            {
              *pstr = base;
              return false;
            }
The comment doesn't really match what is done in recent C++ versions because
there UCNs are translated to characters and not the other way around.

2024-07-25  Jakub Jelinek  <jakub@redhat.com>

	PR c++/110343
libcpp/
	* lex.cc: C++26 P2558R2 - Add @, $, and ` to the basic character set.
	(lex_raw_string): For C++26 allow $@` characters in prefix.
	* charset.cc (_cpp_valid_ucn): For C++26 reject \u0024 in identifiers.
gcc/testsuite/
	* c-c++-common/raw-string-1.c: Use { c || c++11 } effective target,
	remove c++ specific dg-options.
	* c-c++-common/raw-string-2.c: Likewise.
	* c-c++-common/raw-string-4.c: Likewise.
	* c-c++-common/raw-string-5.c: Likewise.  Expect some diagnostics
	only for non-c++26, for c++26 expect different.
	* c-c++-common/raw-string-6.c: Use { c || c++11 } effective target,
	remove c++ specific dg-options.
	* c-c++-common/raw-string-11.c: Likewise.
	* c-c++-common/raw-string-13.c: Likewise.
	* c-c++-common/raw-string-14.c: Likewise.
	* c-c++-common/raw-string-15.c: Use { c || c++11 } effective target,
	change c++ specific dg-options to just -Wtrigraphs.
	* c-c++-common/raw-string-16.c: Likewise.
	* c-c++-common/raw-string-17.c: Use { c || c++11 } effective target,
	remove c++ specific dg-options.
	* c-c++-common/raw-string-18.c: Use { c || c++11 } effective target,
	remove -std=c++11 from c++ specific dg-options.
	* c-c++-common/raw-string-19.c: Likewise.
	* g++.dg/cpp26/raw-string1.C: New test.
	* g++.dg/cpp26/raw-string2.C: New test.

This patch adds support to our SARIF output for cases where
rich_loc.escape_on_output_p () is true, such as for -Wbidi-chars.

In such cases, the pertinent SARIF "location" object gains a property
bag with property "gcc/escapeNonAscii": true, and the "artifactContent"
within the location's physical location's snippet" gains a "rendered"
property (§3.3.4) that escapes non-ASCII text in the snippet, such as:

"rendered": {"text":

where "text" has a string value such as (for a "trojan source" attack):

  "9 |     /*<U+202E> } <U+2066>if (isAdmin)<U+2069> <U+2066> begin admins only */\n"
  "  |       ~~~~~~~~                                ~~~~~~~~                    ^\n"
  "  |       |                                       |                           |\n"
  "  |       |                                       |                           end of bidirectional context\n"
  "  |       U+202E (RIGHT-TO-LEFT OVERRIDE)         U+2066 (LEFT-TO-RIGHT ISOLATE)\n"

where the escaping is affected by -fdiagnostics-escape-format=; with
-fdiagnostics-escape-format=bytes, the rendered text of the above is:

  "9 |     /*<e2><80><ae> } <e2><81><a6>if (isAdmin)<e2><81><a9> <e2><81><a6> begin admins only */\n"
  "  |       ~~~~~~~~~~~~                                        ~~~~~~~~~~~~                    ^\n"
  "  |       |                                                   |                               |\n"
  "  |       U+202E (RIGHT-TO-LEFT OVERRIDE)                     U+2066 (LEFT-TO-RIGHT ISOLATE)  end of bidirectional context\n"

The patch also refactors/adds enough selftest machinery to be able to
test the snippet generation from within the selftest framework, rather
than just within DejaGnu (where the regex-based testing isn't
sophisticated enough to verify such properties as the above).

gcc/ChangeLog:
	* Makefile.in (OBJS-libcommon): Add selftest-json.o.
	* diagnostic-format-sarif.cc: Include "selftest.h",
	"selftest-diagnostic.h", "selftest-diagnostic-show-locus.h",
	"selftest-json.h", and "text-range-label.h".
	(class content_renderer): New.
	(sarif_builder::m_rules_arr): Convert to std::unique_ptr.
	(sarif_builder::make_location_object): Add class
	escape_nonascii_renderer.  If rich_loc.escape_on_output_p (),
	pass a nonnull escape_nonascii_renderer to
	maybe_make_physical_location_object as its snippet_renderer, and
	add a property bag property "gcc/escapeNonAscii" to the SARIF
	location object.  For other overloads of make_location_object,
	pass nullptr for the snippet_renderer.
	(sarif_builder::maybe_make_region_object_for_context): Add
	"snippet_renderer" param and pass it to
	maybe_make_artifact_content_object.
	(sarif_builder::make_tool_object): Drop "const".
	(sarif_builder::make_driver_tool_component_object): Likewise.
	Use typesafe unique_ptr variant of object::set for setting "rules"
	property on driver_obj.
	(sarif_builder::maybe_make_artifact_content_object): Add param "r"
	and use it to potentially set the "rendered" property (§3.3.4).
	(selftest::test_make_location_object): New.
	(selftest::diagnostic_format_sarif_cc_tests): New.
	* diagnostic-show-locus.cc: Include "text-range-label.h" and
	"selftest-diagnostic-show-locus.h".
	(selftests::diagnostic_show_locus_fixture::diagnostic_show_locus_fixture):
	New.
	(selftests::test_layout_x_offset_display_utf8): Use
	diagnostic_show_locus_fixture to simplify and consolidate setup
	code.
	(selftests::test_diagnostic_show_locus_one_liner): Likewise.
	(selftests::test_one_liner_colorized_utf8): Likewise.
	(selftests::test_diagnostic_show_locus_one_liner_utf8): Likewise.
	* gcc-rich-location.h (class text_range_label): Move to new file
	text-range-label.h.
	* selftest-diagnostic-show-locus.h: New file, based on material in
	diagnostic-show-locus.cc.
	* selftest-json.cc: New file.
	* selftest-json.h: New file.
	* selftest-run-tests.cc (selftest::run_tests): Call
	selftest::diagnostic_format_sarif_cc_tests.
	* selftest.h (selftest::diagnostic_format_sarif_cc_tests): New decl.

gcc/testsuite/ChangeLog:
	* c-c++-common/diagnostic-format-sarif-file-Wbidi-chars.c: Verify
	that we have a property bag with property "gcc/escapeNonAscii": true.
	Verify that we have a "rendered" property for a snippet.
	* gcc.dg/plugin/diagnostic_plugin_test_show_locus.c: Include
	"text-range-label.h".

gcc/ChangeLog:
	* text-range-label.h: New file, taking class text_range_label from
	gcc-rich-location.h.

libcpp/ChangeLog:
	* include/rich-location.h
	(semi_embedded_vec::semi_embedded_vec): Add copy ctor.
	(rich_location::rich_location): Remove "= delete" from decl of
	copy ctor.  Add deleted decl of move ctor.
	(rich_location::operator=): Remove "= delete" from decl of
	copy assignment.  Add deleted decl of move assignment.
	(fixit_hint::fixit_hint): Add copy ctor decl.  Add deleted decl of
	move.
	(fixit_hint::operator=): Add copy assignment decl.  Add deleted
	decl of move assignment.
	* line-map.cc (rich_location::rich_location): New copy ctor.
	(fixit_hint::fixit_hint): New copy ctor.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

Since r6-4582-g8a64515099e645 (which added class rich_location), ranges
of quoted source code have been colorized using the following rules:
- the primary range used the same color of the kind of the diagnostic
i.e. "error" vs "warning" etc (defaulting to bold red and bold magenta
respectively)
- secondary ranges alternate between "range1" and "range2" (defaulting
to green and blue respectively)

This works for cases with large numbers of highlighted ranges, but is
suboptimal for common cases.

The following patch adds a pair of color names: "highlight-a" and
"highlight-b", and uses them whenever it makes sense to highlight and
contrast two different things in the source code (e.g. a type mismatch).
These are used by diagnostic-show-locus.cc for highlighting quoted
source.  In addition the patch adds colorization to fragments within the
corresponding diagnostic messages themselves, using consistent
colorization between the message and the quoted source code for the two
different things being contrasted.

For example, consider:

demo.c: In function ‘test_bad_format_string_args’:
../../src/demo.c:25:18: warning: format ‘%i’ expects argument of
  type ‘int’, but argument 2 has type ‘const char *’ [-Wformat=]
   25 |   printf("hello %i", msg);
      |                 ~^   ~~~
      |                  |   |
      |                  int const char *
      |                 %s

Previously, the types within the message in quotes would be in bold but
not colorized, and the labelled ranges of quoted source code would use
bold magenta for the "int" and non-bold green for the "const char *".

With this patch:
- the "%i" and "int" in the message and the "int" in the quoted source
  are all colored bold green
- the "const char *" in the message and in the quoted source are both
  colored bold blue
so that the consistent use of contrasting color draws the reader's eyes
to the relationships between the diagnostic message and the source.

I've tried this with gnome-terminal with many themes, including a
variety of light versus dark backgrounds, solarized versus non-solarized
themes, etc, and it was readable in all.

My initial version of the patch used the existing %r and %R facilities
within pretty-print.cc for the messages, but this turned out to be very
uncomfortable, leading to error-prone format strings such as:

  error_at (richloc,
            "invalid operands to binary %s (have %<%r%T%R%> and %<%r%T%R%>)",
            opname,
            "highlight-a", type0,
            "highlight-b", type1);

To avoid requiring monstrosities such as the above, the patch adds a new
"%e" format code to pretty-print.cc, which expects a pp_element *, where
pp_element is a new abstract base class (actually a pp_markup::element),
along with various useful subclasses.  This lets the above be written
as:

  pp_markup::element_quoted_type element_0 (type0, highlight_colors::lhs);
  pp_markup::element_quoted_type element_1 (type1, highlight_colors::rhs);
  error_at (richloc,
            "invalid operands to binary %s (have %e and %e)",
            opname, &element_0, &element_1);

which I feel is maintainable and clear to translators; the use of %e and
pp_element * captures the type-unsafe part of the variadic call, and the
subclasses allow for type-safety (so e.g. an element_quoted_type expects
a type and a highlighting color).  This approach allows for some nice
simplifications within c-format.cc.

The patch also extends -Wformat to "teach" it about the new %e and
pp_element *.  Doing so requires c-format.cc to be able to determine
if a T * is a pp_element * (i.e. if T is a subclass).  To do so I added
a new comp_types callback for comparing types, where the C++ frontend
supplies a suitable implementation (and %e will always be wrong for C).

I've manually tested this on many diagnostics with both C and C++ and it
seems a subtle but significant improvement in readability.

I've added a new option -fno-diagnostics-show-highlight-colors in case
people prefer the old behavior.

gcc/c-family/ChangeLog:
	* c-common.cc: Include "tree-pretty-print-markup.h".
	(binary_op_error): Use pp_markup::element_quoted_type and %e.
	(check_function_arguments): Add "comp_types" param and pass it to
	check_function_format.
	* c-common.h (check_function_arguments): Add "comp_types" param.
	(check_function_format): Likewise.
	* c-format.cc: Include "tree-pretty-print-markup.h".
	(local_pp_element_ptr_node): New.
	(PP_FORMAT_CHAR_TABLE): Add entry for %e.
	(struct format_check_context): Add "m_comp_types" field.
	(check_function_format): Add "comp_types" param and pass it to
	check_format_info.
	(check_format_info): Likewise, passing it to format_ctx's ctor.
	(check_format_arg): Extract m_comp_types from format_ctx and
	pass it to check_format_info_main.
	(check_format_info_main): Add "comp_types" param and pass it to
	arg_parser's ctor.
	(class argument_parser): Add "m_comp_types" field.
	(argument_parser::check_argument_type): Pass m_comp_types to
	check_format_types.
	(handle_subclass_of_pp_element_p): New.
	(check_format_types): Add "comp_types" param, and use it to
	call handle_subclass_of_pp_element_p.
	(class element_format_substring): New.
	(class element_expected_type_with_indirection): New.
	(format_type_warning): Use element_expected_type_with_indirection
	to unify the if (wanted_type_name) branches, reducing from four
	emit_warning calls to two.  Simplify these further using %e.
	Doing so also gives suitable colorization of the text within the
	diagnostics.
	(init_dynamic_diag_info): Initialize local_pp_element_ptr_node.
	(selftest::test_type_mismatch_range_labels): Add nullptr for new
	param of gcc_rich_location label overload.
	* c-format.h (T_PP_ELEMENT_PTR): New.
	* c-type-mismatch.cc: Include "diagnostic-highlight-colors.h".
	(binary_op_rich_location::binary_op_rich_location): Use
	highlight_colors::lhs and highlight_colors::rhs for the ranges.
	* c-type-mismatch.h (class binary_op_rich_location): Add comment
	about highlight_colors.

gcc/c/ChangeLog:
	* c-objc-common.cc: Include "tree-pretty-print-markup.h".
	(print_type): Add optional "highlight_color" param and use it
	to show highlight colors in "aka" text.
	(pp_markup::element_quoted_type::print_type): New.
	* c-typeck.cc: Include "tree-pretty-print-markup.h".
	(comp_parm_types): New.
	(build_function_call_vec): Pass it to check_function_arguments.
	(inform_for_arg): Use %e and highlight colors to contrast actual
	versus expected.
	(convert_for_assignment): Use highlight_colors::actual for the
	rhs_label.
	(build_binary_op): Use highlight_colors::lhs and highlight_colors::rhs
	for the ranges.

gcc/ChangeLog:
	* common.opt (fdiagnostics-show-highlight-colors): New option.
	* common.opt.urls: Regenerate.
	* coretypes.h (pp_markup::element): New forward decl.
	(pp_element): New typedef.
	* diagnostic-color.cc (gcc_color_defaults): Add "highlight-a"
	and "highlight-b".
	* diagnostic-format-json.cc (diagnostic_output_format_init_json):
	Disable highlight colors.
	* diagnostic-format-sarif.cc (diagnostic_output_format_init_sarif):
	Likewise.
	* diagnostic-highlight-colors.h: New file.
	* diagnostic-path.cc (struct event_range): Pass nullptr for
	highlight color of m_rich_loc.
	* diagnostic-show-locus.cc (colorizer::set_range): Handle ranges
	with m_highlight_color.
	(colorizer::STATE_NAMED_COLOR): New.
	(colorizer::m_richloc): New field.
	(colorizer::colorizer): Add richloc param for initializing
	m_richloc.
	(colorizer::set_named_color): New.
	(colorizer::begin_state): Add case STATE_NAMED_COLOR.
	(layout::layout): Pass richloc to m_colorizer's ctor.
	(selftest::test_one_liner_labels): Pass nullptr for new param of
	gcc_rich_location ctor for labels.
	(selftest::test_one_liner_labels_utf8): Likewise.
	* diagnostic.h (diagnostic_context::set_show_highlight_colors):
	New.
	* doc/invoke.texi: Add option -fdiagnostics-show-highlight-colors
	and highlight-a and highlight-b color caps.
	* doc/ux.texi
	(Use color consistently when highlighting mismatches): New
	subsection.
	* gcc-rich-location.cc (gcc_rich_location::add_expr): Add
	"highlight_color" param.
	(gcc_rich_location::maybe_add_expr): Likewise.
	* gcc-rich-location.h (gcc_rich_location::gcc_rich_location):
	Split out into a pair of ctors, where if a range_label is supplied
	the caller must also supply a highlight color.
	(gcc_rich_location::add_expr): Add "highlight_color" param.
	(gcc_rich_location::maybe_add_expr): Likewise.
	* gcc.cc (driver_handle_option): Handle
	OPT_fdiagnostics_show_highlight_colors.
	* lto-wrapper.cc (merge_and_complain): Likewise.
	(append_compiler_options): Likewise.
	(append_diag_options): Likewise.
	(run_gcc): Likewise.
	* opts-common.cc (decode_cmdline_options_to_array): Add comment
	about -fno-diagnostics-show-highlight-colors.
	* opts-global.cc (init_options_once): Preserve
	pp_show_highlight_colors in case the global_dc's printer is
	recreated.
	* opts.cc (common_handle_option): Handle
	OPT_fdiagnostics_show_highlight_colors.
	(gen_command_line_string): Likewise.
	* pretty-print-markup.h: New file.
	* pretty-print.cc: Include "pretty-print-markup.h" and
	"diagnostic-highlight-colors.h".
	(pretty_printer::format): Handle %e.
	(pretty_printer::pretty_printer): Handle new field
	m_show_highlight_colors.
	(pp_string_n): New.
	(pp_markup::context::begin_quote): New.
	(pp_markup::context::end_quote): New.
	(pp_markup::context::begin_color): New.
	(pp_markup::context::end_color): New.
	(highlight_colors::expected): New.
	(highlight_colors::actual): New.
	(highlight_colors::lhs): New.
	(highlight_colors::rhs): New.
	(class selftest::test_element): New.
	(selftest::test_pp_format): Add tests of %e.
	(selftest::test_urlification): Likewise.
	* pretty-print.h (pp_markup::context): New forward decl.
	(class chunk_info): Add friend class pp_markup::context.
	(class pretty_printer): Add friend pp_show_highlight_colors.
	(pretty_printer::m_show_highlight_colors): New field.
	(pp_show_highlight_colors): New inline function.
	(pp_string_n): New decl.
	* substring-locations.cc: Include "diagnostic-highlight-colors.h".
	(format_string_diagnostic_t::highlight_color_format_string): New.
	(format_string_diagnostic_t::highlight_color_param): New.
	(format_string_diagnostic_t::emit_warning_n_va): Use highlight
	colors.
	* substring-locations.h
	(format_string_diagnostic_t::highlight_color_format_string): New.
	(format_string_diagnostic_t::highlight_color_param): New.
	* toplev.cc (general_init): Initialize global_dc's
	show_highlight_colors.
	* tree-pretty-print-markup.h: New file.

gcc/cp/ChangeLog:
	* call.cc: Include "tree-pretty-print-markup.h".
	(implicit_conversion_error): Use highlight_colors::percent_h for
	the labelled range.
	(op_error_string): Split out into...
	(concat_op_error_string): ...this.
	(binop_error_string): New.
	(op_error): Use %e, binop_error_string, highlight_colors::lhs,
	and highlight_colors::rhs.
	(maybe_inform_about_fndecl_for_bogus_argument_init): Add
	"highlight_color" param; use it for the richloc.
	(convert_like_internal): Use highlight_colors::percent_h for the
	labelled_range, and highlight_colors::percent_i for the call to
	maybe_inform_about_fndecl_for_bogus_argument_init.
	(build_over_call): Pass cp_comp_parm_types for new "comp_types"
	param of check_function_arguments.
	(complain_about_bad_argument): Use highlight_colors::percent_h for
	the labelled_range, and highlight_colors::percent_i for the call
	to maybe_inform_about_fndecl_for_bogus_argument_init.
	* cp-tree.h (maybe_inform_about_fndecl_for_bogus_argument_init):
	Add optional highlight_color param.
	(cp_comp_parm_types): New decl.
	(highlight_colors::const percent_h): New decl.
	(highlight_colors::const percent_i): New decl.
	* error.cc: Include "tree-pretty-print-markup.h".
	(highlight_colors::const percent_h): New defn.
	(highlight_colors::const percent_i): New defn.
	(type_to_string): Add param "highlight_color" and use it.
	(print_nonequal_arg): Likewise.
	(print_template_differences): Add params "highlight_color_a" and
	"highlight_color_b".
	(type_to_string_with_compare): Add params "this_highlight_color"
	and "peer_highlight_color".
	(print_template_tree_comparison): Add params "highlight_color_a"
	and "highlight_color_b".
	(cxx_format_postprocessor::handle):
	Use highlight_colors::percent_h and highlight_colors::percent_i.
	(pp_markup::element_quoted_type::print_type): New.
	(range_label_for_type_mismatch::get_text): Pass nullptr for new
	params of type_to_string_with_compare.
	* typeck.cc (cp_comp_parm_types): New.
	(cp_build_function_call_vec): Pass it to check_function_arguments.
	(convert_for_assignment): Use highlight_colors::percent_h for the
	labelled_range.

gcc/testsuite/ChangeLog:
	* g++.dg/diagnostic/bad-binary-ops-highlight-colors.C: New test.
	* g++.dg/diagnostic/bad-binary-ops-no-highlight-colors.C: New test.
	* g++.dg/plugin/plugin.exp (plugin_test_list): Add
	show-template-tree-color-no-highlight-colors.C to
	show_template_tree_color_plugin.c.
	* g++.dg/plugin/show-template-tree-color-labels.C: Update expected
	output to reflect use of highlight-a and highlight-b to contrast
	mismatches.
	* g++.dg/plugin/show-template-tree-color-no-elide-type.C:
	Likewise.
	* g++.dg/plugin/show-template-tree-color-no-highlight-colors.C:
	New test.
	* g++.dg/plugin/show-template-tree-color.C: Update expected output
	to reflect use of highlight-a and highlight-b to contrast
	mismatches.
	* g++.dg/warn/Wformat-gcc_diag-1.C: New test.
	* g++.dg/warn/Wformat-gcc_diag-2.C: New test.
	* g++.dg/warn/Wformat-gcc_diag-3.C: New test.
	* gcc.dg/bad-binary-ops-highlight-colors.c: New test.
	* gcc.dg/format/colors.c: New test.
	* gcc.dg/plugin/diagnostic_plugin_show_trees.c (show_tree): Pass
	nullptr for new param of gcc_rich_location::add_expr.

libcpp/ChangeLog:
	* include/rich-location.h (location_range::m_highlight_color): New
	field.
	(rich_location::rich_location): Add optional label_highlight_color
	param.
	(rich_location::set_highlight_color): New decl.
	(rich_location::add_range): Add optional label_highlight_color
	param.
	(rich_location::set_range): Likewise.
	* line-map.cc (rich_location::rich_location): Add
	"label_highlight_color" param and pass it to add_range.
	(rich_location::set_highlight_color): New.
	(rich_location::add_range): Add "label_highlight_color" param.
	(rich_location::set_range): Add "highlight_color" param.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

When adding validation of .sarif files against the schema
(PR testsuite/109360) I discovered various issues where we were
generating invalid .sarif files.

Specifically, in
  c-c++-common/diagnostic-format-sarif-file-bad-utf8-pr109098-1.c
the relatedLocations for the "note" diagnostics were missing column
numbers, leading to validation failure due to non-unique elements,
such as multiple:
	"message": {"text": "invalid UTF-8 character <bf>"}},
on line 25 with no column information.

Root cause is that for some diagnostics in libcpp we have a location_t
representing the line as a whole, setting a column_override on the
rich_location (since the line hasn't been fully read yet).  We were
handling this column override for plain text output, but not for .sarif
output.

Similarly, in diagnostic-format-sarif-file-pr111700.c there is a warning
emitted on "line 0" of the file, whereas SARIF requires line numbers to
be positive.

We also use column == 0 internally to mean "the line as a whole",
whereas SARIF required column numbers to be positive.

This patch fixes these various issues.

gcc/ChangeLog:
	PR testsuite/109360
	* diagnostic-format-sarif.cc
	(sarif_builder::make_location_object): Pass any column override
	from rich_loc to maybe_make_physical_location_object.
	(sarif_builder::maybe_make_physical_location_object): Add
	"column_override" param and pass it to maybe_make_region_object.
	(sarif_builder::maybe_make_region_object): Add "column_override"
	param and use it when the location has 0 for a column.  Don't
	add "startLine", "startColumn", "endLine", or "endColumn" if
	the values aren't positive.
	(sarif_builder::maybe_make_region_object_for_context): Don't
	add "startLine" or "endLine" if the values aren't positive.

libcpp/ChangeLog:
	PR testsuite/109360
	* include/rich-location.h (rich_location::get_column_override):
	New accessor.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

The first new C2Y feature, _Generic where the controlling operand is a
type name rather than an expression (as defined in N3260), was voted
into C2Y today.  (In particular, this form of _Generic allows
distinguishing qualified and unqualified versions of a type.)  This
feature also includes allowing the generic associations to specify
incomplete and function types.

Add this feature to GCC, along with the -std=c2y, -std=gnu2y and
-Wc23-c2y-compat options to control when and how it is diagnosed.  As
usual, the feature is allowed by default in older standards modes,
subject to diagnosis with -pedantic, -pedantic-errors or
-Wc23-c2y-compat.

Bootstrapped with no regressions on x86_64-pc-linux-gnu.

gcc/
	* doc/cpp.texi (__STDC_VERSION__): Document C2Y handling.
	* doc/invoke.texi (-Wc23-c2y-compat, -std=c2y, -std=gnu2y):
	Document options.
	(-std=gnu23): Update documentation.
	* doc/standards.texi (C Language): Document C2Y.  Update C23
	description.
	* config/rl78/rl78.cc (rl78_option_override): Handle "GNU C2Y"
	language name.
	* dwarf2out.cc (highest_c_language, gen_compile_unit_die):
	Likewise.

gcc/c-family/
	* c-common.cc (flag_isoc2y): New.
	(flag_isoc99, flag_isoc11, flag_isoc23): Update comments.
	* c-common.h (flag_isoc2y): New.
	(clk_c, flag_isoc23): Update comments.
	* c-opts.cc (set_std_c2y): New.
	(c_common_handle_option): Handle OPT_std_c2y and OPT_std_gnu2y.
	(set_std_c89, set_std_c99, set_std_c11, set_std_c17, set_std_c23):
	Set flag_isoc2y.
	(set_std_c23): Update comment.
	* c.opt (Wc23-c2y-compat, std=c2y, std=gnu2y): New.
	* c.opt.urls: Regenerate.

gcc/c/
	* c-errors.cc (pedwarn_c23): New.
	* c-parser.cc (disable_extension_diagnostics)
	(restore_extension_diagnostics): Save and restore
	warn_c23_c2y_compat.
	(c_parser_generic_selection): Handle type name as controlling
	operand.  Allow incomplete and function types subject to
	pedwarn_c23 calls.
	* c-tree.h (pedwarn_c23): New.

gcc/testsuite/
	* gcc.dg/c23-generic-1.c, gcc.dg/c23-generic-2.c,
	gcc.dg/c23-generic-3.c, gcc.dg/c23-generic-4.c,
	gcc.dg/c2y-generic-1.c, gcc.dg/c2y-generic-2.c,
	gcc.dg/c2y-generic-3.c, gcc.dg/gnu2y-generic-1.c: New tests.
	* gcc.dg/c23-tag-6.c: Use -pedantic-errors.

libcpp/
	* include/cpplib.h (CLK_GNUC2Y, CLK_STDC2Y): New.
	* init.cc (lang_defaults): Add GNUC2Y and STDC2Y entries.
	(cpp_init_builtins): Define __STDC_VERSION__ to 202500L for GNUC2Y
	and STDC2Y.

 Within a source file, #include is translated to import if a suitable header
 unit is available, but this wasn't working with -include.  This turned out
 to be because we suppressed the translation before the beginning of the
 main file.  After removing that, I had to tweak libcpp file handling to
 accommodate the way it moves from an -include to the main file.

gcc/ChangeLog:

	* doc/invoke.texi (C++ Modules): Mention -include.

gcc/cp/ChangeLog:

	* module.cc (maybe_translate_include): Allow before the main file.

libcpp/ChangeLog:

	* files.cc (_cpp_stack_file): LC_ENTER for -include header unit.

gcc/testsuite/ChangeLog:

	* g++.dg/modules/dashinclude-1_b.C: New test.
	* g++.dg/modules/dashinclude-1_a.H: New test.

There is a trend in the broader C++ community to use a different extension
for module interface units, even though (in GCC) they are compiled in the
same way as other source files.  Let's recognize these extensions as C++.

.ixx is the MSVC standard, while the .c*m are supported by Clang.  libc++
standard headers use .cppm, as their other source files use .cpp.
Perhaps libstdc++ might use .ccm for parallel consistency?

One issue with .c++m is that libcpp/mkdeps.cc has been using it for the
phony dependencies to express module dependencies, so I'm changing mkdeps to
something less likely to be an actual file, ".c++-module".

gcc/cp/ChangeLog:

	* lang-specs.h: Add module interface extensions.

gcc/ChangeLog:

	* doc/invoke.texi: Update module extension docs.

libcpp/ChangeLog:

	* mkdeps.cc (make_write): Change .c++m to .c++-module.

gcc/testsuite/ChangeLog:

	* g++.dg/modules/dep-1_a.C
	* g++.dg/modules/dep-1_b.C
	* g++.dg/modules/dep-2.C: Change .c++m to .c++-module.

No functional change intended.

libcpp/ChangeLog:
	* Makefile.in (TAGS_SOURCES): Add include/label-text.h.
	* include/label-text.h: New file.
	* include/rich-location.h: Include "label-text.h".
	(class label_text): Move to label-text.h.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

libcpp/ChangeLog:
	* lex.cc (do_peek_prev): Correct typo in argument to __builtin_expect()

Signed-off-by: Peter Damianov <peter0x44@disroot.org>

This patch adds some ability for links between labelled ranges when
quoting the user's source code, and uses this to add links between
events when printing diagnostic_paths, chopping them up further into
event ranges that can be printed together.
It adds links to the various "from..." - "...to" events in the
analyzer.

For example, previously we emitted this for
c-c++-common/analyzer/infinite-loop-linked-list.c's
while_loop_missing_next':

infinite-loop-linked-list.c:30:10: warning: infinite loop [CWE-835] [-Wanalyzer-infinite-loop]
   30 |   while (n)
      |          ^
  'while_loop_missing_next': events 1-5
   30 |   while (n)
      |          ^
      |          |
      |          (1) infinite loop here
      |          (2) when 'n' is non-NULL: always following 'true' branch...
      |          (5) ...to here
   31 |     {
   32 |       sum += n->val;
      |       ~~~~~~~~~~~~~
      |           |   |
      |           |   (3) ...to here
      |           (4) looping back...

whereas with the patch we now emit:

infinite-loop-linked-list.c:30:10: warning: infinite loop [CWE-835] [-Wanalyzer-infinite-loop]
   30 |   while (n)
      |          ^
  'while_loop_missing_next': events 1-3
   30 |   while (n)
      |          ^
      |          |
      |          (1) infinite loop here
      |          (2) when 'n' is non-NULL: always following 'true' branch... ->-+
      |                                                                         |
      |                                                                         |
      |+------------------------------------------------------------------------+
   31 ||    {
   32 ||      sum += n->val;
      ||             ~~~~~~
      ||              |
      |+------------->(3) ...to here
  'while_loop_missing_next': event 4
   32 |       sum += n->val;
      |       ~~~~^~~~~~~~~
      |           |
      |           (4) looping back... ->-+
      |                                  |
  'while_loop_missing_next': event 5
      |                                  |
      |+---------------------------------+
   30 ||  while (n)
      ||         ^
      ||         |
      |+-------->(5) ...to here

which I believe is easier to understand.

The patch also implements the use of unicode characters and colorization
for the lines (not shown in the above example).

There is a new option -fno-diagnostics-show-event-links for getting
back the old behavior (added to -fdiagnostics-plain-output).

gcc/analyzer/ChangeLog:
	* checker-event.h (checker_event::connect_to_next_event_p):
	Implement new diagnostic_event::connect_to_next_event_p vfunc.
	(start_cfg_edge_event::connect_to_next_event_p): Likewise.
	(start_consolidated_cfg_edges_event::connect_to_next_event_p):
	Likewise.
	* infinite-loop.cc (class looping_back_event): New subclass.
	(infinite_loop_diagnostic::add_final_event): Use it.

gcc/ChangeLog:
	* common.opt (fdiagnostics-show-event-links): New option.
	* diagnostic-label-effects.h: New file.
	* diagnostic-path.h (diagnostic_event::connect_to_next_event_p):
	New pure virtual function.
	(simple_diagnostic_event::connect_to_next_event_p): Implement it.
	(simple_diagnostic_event::connect_to_next_event): New.
	(simple_diagnostic_event::m_connected_to_next_event): New field.
	(simple_diagnostic_path::connect_to_next_event): New decl.
	* diagnostic-show-locus.cc: Include "text-art/theme.h" and
	"diagnostic-label-effects.h".
	(colorizer::set_cfg_edge): New.
	(layout::m_fallback_theme): New field.
	(layout::m_theme): New field.
	(layout::m_effect_info): New field.
	(layout::m_link_lhs_state): New enum and field.
	(layout::m_link_rhs_column): New field.
	(layout_range::has_in_edge): New.
	(layout_range::has_out_edge): New.
	(layout::layout): Add "effect_info" optional param.  Initialize
	m_theme, m_link_lhs_state, and m_link_rhs_column.
	(layout::maybe_add_location_range): Remove stray "FIXME" from
	leading comment.
	(layout::print_source_line): Replace space after margin with a
	call to print_leftmost_column.
	(layout::print_leftmost_column): New.
	(layout::start_annotation_line): Make non-const.  Gain
	responsibility for printing the leftmost column after the margin.
	(layout::print_annotation_line): Drop pp_space, as this is now
	added by start_annotation_line.
	(line_label::line_label): Add "has_in_edge" and "has_out_edge"
	params and initialize...
	(line_label::m_has_in_edge): New field.
	(line_label::m_has_out_edge): New field.
	(layout::print_any_labels): Pass edge information to line_label
	ctor.  Keep track of in-edges and out-edges, adding visualizations
	of these links between labels.
	(layout::print_leading_fixits):  Drop pp_character, as this is now
	added by start_annotation_line.
	(layout::print_trailing_fixits): Fix off-by-one errors in column
	calculation.
	(layout::move_to_column): Add comment about debugging.
	(layout::show_ruler): Make non-const.  Drop pp_space calls, as
	this is now added by start_annotation_line.
	(layout::print_line): Call print_any_right_to_left_edge_lines.
	(layout::print_any_right_to_left_edge_lines): New.
	(layout::update_any_effects): New.
	(gcc_rich_location::add_location_if_nearby): Initialize
	loc_range.m_label.
	(diagnostic_context::maybe_show_locus): Add "effects" param and
	pass it to diagnostic_context::show_locus.
	(diagnostic_context::show_locus): Add "effects" param, passing it
	to layout's ctor.  Call update_any_effects on the layout after
	printing the lines.
	(selftest::test_layout_x_offset_display_utf8): Update expected
	result for eliminated trailing newline.
	(selftest::test_layout_x_offset_display_utf8): Likewise.
	(selftest::test_layout_x_offset_display_tab): Likewise.
	* diagnostic.cc (diagnostic_context::initialize): Initialize
	m_source_printing.show_event_links_p.
	(simple_diagnostic_path::connect_to_next_event): New.
	(simple_diagnostic_event::simple_diagnostic_event): Initialize
	m_connected_to_next_event.
	* diagnostic.h (class diagnostic_source_effect_info): New forward
	decl.
	(diagnostic_source_printing_options::show_event_links_p): New
	field.
	(diagnostic_context::maybe_show_locus): Add optional "effect_info"
	param.
	(diagnostic_context::show_locus): Add "effect_info" param.
	(diagnostic_show_locus): Add optional "effect_info" param.
	* doc/invoke.texi: Add -fno-diagnostics-show-event-links.
	* lto-wrapper.cc (merge_and_complain): Add
	OPT_fdiagnostics_show_event_links to switch.
	(append_compiler_options): Likewise.
	(append_diag_options): Likewise.
	* opts-common.cc (decode_cmdline_options_to_array): Add
	"-fno-diagnostics-show-event-links" to -fdiagnostics-plain-output.
	* opts.cc (common_handle_option): Add case for
	OPT_fdiagnostics_show_event_links.
	* text-art/theme.cc (ascii_theme::get_cppchar): Handle
	cell_kind::CFG_*.
	(unicode_theme::get_cppchar): Likewise.
	* text-art/theme.h (theme::cell_kind): Add CFG_*.
	* toplev.cc (general_init): Initialize
	global_dc->m_source_printing.show_event_links_p.
	* tree-diagnostic-path.cc: Define INCLUDE_ALGORITHM,
	INCLUDE_MEMORY, and INCLUDE_STRING.  Include
	"diagnostic-label-effects.h".
	(path_label::path_label): Initialize m_effects.
	(path_label::get_effects): New.
	(class path_label::path_label_effects): New.
	(path_label::m_effects): New field.
	(class per_thread_summary): Add "friend struct event_range;".
	(per_thread_summary::per_thread_summary): Initialize m_last_event.
	(per_thread_summary::m_last_event): New field.
	(struct event_range::per_source_line_info): New.
	(event_range::event_range): Make "t" non-const.  Add
	"show_event_links" param and use it to initialize
	m_show_event_links.  Add info for initial event.
	(event_range::get_per_source_line_info): New.
	(event_range::maybe_add_event): Verify compatibility of the new
	label and existing labels with respect to the link-printing code.
	Update per-source-line info when an event is added.
	(event_range::print): Add"effect_info" param and pass to
	diagnostic_show_locus.
	(event_range::m_per_thread_summary): Make non-const.
	(event_range::m_source_line_info_map): New field.
	(event_range::m_show_event_links): New field.
	(path_summary::path_summary): Add "show_event_links" optional
	param, passing it to event_range ctor calls. Update
	pts.m_last_event.
	(thread_event_printer::print_swimlane_for_event_range): Add
	"effect_info" param and pass it to range->print.
	(print_path_summary_as_text): Keep track of the column for any
	out-edges at the end of printing each event_range and use as
	the leading in-edge for the next event_range.
	(default_tree_diagnostic_path_printer): Pass in show_event_links_p
	to path_summary ctor.
	(selftest::path_events_have_column_data_p): New.
	(class selftest::control_flow_test): New.
	(selftest::test_control_flow_1): New.
	(selftest::test_control_flow_2): New.
	(selftest::test_control_flow_3): New.
	(selftest::assert_cfg_edge_path_streq): New.
	(ASSERT_CFG_EDGE_PATH_STREQ): New macro.
	(selftest::test_control_flow_4): New.
	(selftest::test_control_flow_5): New.
	(selftest::test_control_flow_6): New.
	(selftest::control_flow_tests): New.
	(selftest::tree_diagnostic_path_cc_tests): Disable colorization on
	global_dc's printer.  Convert event_pp to a std::unique_ptr. Call
	control_flow_tests via for_each_line_table_case.
	(gen_command_line_string): Likewise.

gcc/testsuite/ChangeLog:
	* gcc.dg/analyzer/event-links-ascii.c: New test.
	* gcc.dg/analyzer/event-links-color.c: New test.
	* gcc.dg/analyzer/event-links-disabled.c: New test.
	* gcc.dg/analyzer/event-links-unicode.c: New test.

libcpp/ChangeLog:
	* include/rich-location.h (class label_effects): New forward decl.
	(range_label::get_effects): New vfunc.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

While the C23 standard isn't officially release yet,
in 2011 we've changed __STDC_VERSION__ value for C11 already
in the month in which the new __STDC_VERSION__ value has been
finalized, so we want to change this now or wait
until we implement all the C23 features?

Note, seems Clang up to 17 also used 202000L for -std=c2x but
Clang 18+ uses 202311L as specified in the latest C23 drafts.

2024-04-30  Jakub Jelinek  <jakub@redhat.com>

	* init.cc (cpp_init_builtins): Change __STDC_VERSION__
	for C23 from 202000L to 202311L.

	* doc/cpp.texi (__STDC_VERSION__): Document 202311L value
	for -std=c23/-std=gnu23.

As discussed in the PR, aclocal.m4 and configure were incorrectly
regenerated at some point.

2024-04-17  Christophe Lyon  <christophe.lyon@linaro.org>

	PR preprocessor/114748
	libcpp/
	* aclocal.m4: Regenerate.
	* configure: Regenerate.

When the file name for a #include directive is the result of stringifying a
macro argument, libcpp needs to take some care to get the whitespace
correct; in particular stringify_arg() needs to see a CPP_PADDING token
between macro tokens so that it can figure out when to output space between
tokens. The CPP_PADDING tokens are not normally generated when handling a
preprocessor directive, but for #include-like directives, libcpp sets the
state variable pfile->state.directive_wants_padding to TRUE so that the
CPP_PADDING tokens will be output, and then everything works fine for
computed includes.

As the PR points out, things do not work fine for __has_include. Fix that by
setting the state variable the same as is done for #include.

libcpp/ChangeLog:

	PR preprocessor/110558
	* macro.cc (builtin_has_include): Set
	pfile->state.directive_wants_padding prior to lexing the
	file name, in case it comes from macro expansion.

gcc/testsuite/ChangeLog:

	PR preprocessor/110558
	* c-c++-common/cpp/has-include-2.c: New test.
	* c-c++-common/cpp/has-include-2.h: New test.

In libcpp/files.cc, the function _cpp_has_header(), which implements
__has_include and __has_include_next, does not check for a NULL return value
from search_path_head(), leading to an ICE tripping an assert when
_cpp_find_file() tries to use it. Fix it by checking for that case and
silently returning false instead.

As suggested by the PR author, it is easiest to make a testcase by using
the -idirafter option. To enable that, also modify the dg-additional-options
testsuite procedure to make the global $srcdir available, since -idirafter
requires the full path.

libcpp/ChangeLog:

	PR preprocessor/80755
	* files.cc (search_path_head): Add SUPPRESS_DIAGNOSTIC argument
	defaulting to false.
	(_cpp_has_header): Silently return false if the search path has been
	exhausted, rather than issuing a diagnostic and then hitting an
	assert.

gcc/testsuite/ChangeLog:

	* lib/gcc-defs.exp (dg-additional-options): Make $srcdir usable in a
	dg-additional-options directive.
	* c-c++-common/cpp/has-include-next-2-dir/has-include-next-2.h: New test.
	* c-c++-common/cpp/has-include-next-2.c: New test.

c: Handle scoped attributes in __has*attribute and scoped attribute parsing changes in -std=c11 etc. modes [PR114007]

We aren't able to parse __has_attribute (vendor::attr) (and __has_c_attribute
and __has_cpp_attribute) in strict C < C23 modes.  While in -std=gnu* modes
or in -std=c23 there is CPP_SCOPE token, in -std=c* (except for -std=c23)
there are is just a pair of CPP_COLON tokens.
The c-lex.cc hunk adds support for that.

That leads to a question if we should return 1 or 0 from
__has_attribute (gnu::unused) or not, because while
[[gnu::unused]] is parsed fine in -std=gnu*/-std=c23 modes (sure, with
pedwarn for < C23), we do not parse it at all in -std=c* (except for
-std=c23), we only parse [[__extension__ gnu::unused]] there.  While
the __extension__ in there helps to avoid the pedwarn, I think it is
better to be consistent between GNU and strict C < C23 modes and
parse [[gnu::unused]] too; on the other side, I think parsing
[[__extension__ gnu : : unused]] is too weird and undesirable.

So, the following patch adds a flag during preprocessing at the point
where we normally create CPP_SCOPE tokens out of 2 consecutive colons
on the first CPP_COLON to mark the consecutive case (as we are tight
on the bits, I've reused the PURE_ZERO flag, which is used just by the
C++ FE and only ever set (both C and C++) on CPP_NUMBER tokens, this
new flag has the same value and is only ever used on CPP_COLON tokens)
and instead of checking loose_scope_p argument (i.e. whether it is
[[__extension__ ...]] or not), it just parses CPP_SCOPE or CPP_COLON
with CLONE_SCOPE flag followed by another CPP_COLON the same.
The latter will never appear in >= C23 or -std=gnu* modes, though
guarding its use say with flag_iso && !flag_isoc23 && doesn't really
work because the __extension__ case temporarily clears flag_iso flag.

This makes the -std=c11 etc. behavior more similar to -std=gnu11 or
-std=c23, the only difference I'm aware of are the
 #define JOIN2(A, B) A##B
 [[vendor JOIN2(:,:) attr]]
 [[__extension__ vendor JOIN2(:,:) attr]]
cases, which are accepted in the latter modes, but results in error
in -std=c11; but the error is during preprocessing that :: doesn't
form a valid preprocessing token, which is true, so just don't do that if
you try to have __STRICT_ANSI__ && __STDC_VERSION__ <= 201710L
compatibility.

2024-02-22  Jakub Jelinek  <jakub@redhat.com>

	PR c/114007
gcc/
	* doc/extend.texi: (__extension__): Remove comments about scope
	tokens vs. two colons.
gcc/c-family/
	* c-lex.cc (c_common_has_attribute): Parse 2 CPP_COLONs with
	the first one with COLON_SCOPE flag the same as CPP_SCOPE.
gcc/c/
	* c-parser.cc (c_parser_std_attribute): Remove loose_scope_p argument.
	Instead of checking it, parse 2 CPP_COLONs with the first one with
	COLON_SCOPE flag the same as CPP_SCOPE.
	(c_parser_std_attribute_list): Remove loose_scope_p argument, don't
	pass it to c_parser_std_attribute.
	(c_parser_std_attribute_specifier): Adjust c_parser_std_attribute_list
	caller.
gcc/testsuite/
	* gcc.dg/c23-attr-syntax-6.c: Adjust testcase for :: being valid
	even in -std=c11 even without __extension__ and : : etc. not being
	valid anymore even with __extension__.
	* gcc.dg/c23-attr-syntax-7.c: Likewise.
	* gcc.dg/c23-attr-syntax-8.c: New test.
libcpp/
	* include/cpplib.h (COLON_SCOPE): Define to PURE_ZERO.
	* lex.cc (_cpp_lex_direct): When lexing CPP_COLON with another
	colon after it, if !CPP_OPTION (pfile, scope) set COLON_SCOPE
	flag on the first CPP_COLON token.