Hi!
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.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2024-02-21 Jakub Jelinek <ja...@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.
--- gcc/doc/extend.texi.jj 2024-02-21 10:46:55.746515061 +0100
+++ gcc/doc/extend.texi 2024-02-21 17:03:22.137717754 +0100
@@ -12626,10 +12626,7 @@ In C, writing:
@end smallexample
suppresses warnings about using @samp{[[]]} attributes in C versions
-that predate C23@. Since the scope token @samp{::} is not a single
-lexing token in earlier versions of C, this construct also allows two colons
-to be used in place of @code{::}. GCC does not check whether the two
-colons are immediately adjacent.
+that predate C23@.
@end itemize
@code{__extension__} has no effect aside from this.
--- gcc/c-family/c-lex.cc.jj 2024-01-03 12:07:02.171734141 +0100
+++ gcc/c-family/c-lex.cc 2024-02-21 18:07:37.615640395 +0100
@@ -357,7 +357,24 @@ c_common_has_attribute (cpp_reader *pfil
do
nxt_token = cpp_peek_token (pfile, idx++);
while (nxt_token->type == CPP_PADDING);
- if (nxt_token->type == CPP_SCOPE)
+ if (!c_dialect_cxx ()
+ && nxt_token->type == CPP_COLON
+ && (nxt_token->flags & COLON_SCOPE) != 0)
+ {
+ do
+ nxt_token = cpp_peek_token (pfile, idx++);
+ while (nxt_token->type == CPP_PADDING);
+ if (nxt_token->type == CPP_COLON)
+ {
+ /* __has_attribute (vendor::attr) in -std=c17 etc. modes.
+ :: isn't CPP_SCOPE but 2 CPP_COLON tokens, where the
+ first one should have COLON_SCOPE flag to distinguish
+ it from : :. */
+ have_scope = true;
+ get_token_no_padding (pfile); // Eat first colon.
+ }
+ }
+ if (nxt_token->type == CPP_SCOPE || have_scope)
{
have_scope = true;
get_token_no_padding (pfile); // Eat scope.
--- gcc/c/c-parser.cc.jj 2024-02-14 14:26:19.599812963 +0100
+++ gcc/c/c-parser.cc 2024-02-21 18:07:20.583874512 +0100
@@ -5705,8 +5705,7 @@ c_parser_omp_sequence_args (c_parser *pa
indicates whether this relaxation is in effect. */
static tree
-c_parser_std_attribute (c_parser *parser, bool for_tm,
- bool loose_scope_p = false)
+c_parser_std_attribute (c_parser *parser, bool for_tm)
{
c_token *token = c_parser_peek_token (parser);
tree ns, name, attribute;
@@ -5720,8 +5719,8 @@ c_parser_std_attribute (c_parser *parser
name = canonicalize_attr_name (token->value);
c_parser_consume_token (parser);
if (c_parser_next_token_is (parser, CPP_SCOPE)
- || (loose_scope_p
- && c_parser_next_token_is (parser, CPP_COLON)
+ || (c_parser_next_token_is (parser, CPP_COLON)
+ && (c_parser_peek_token (parser)->flags & COLON_SCOPE) != 0
&& c_parser_peek_2nd_token (parser)->type == CPP_COLON))
{
ns = name;
@@ -5841,8 +5840,7 @@ c_parser_std_attribute (c_parser *parser
}
static tree
-c_parser_std_attribute_list (c_parser *parser, bool for_tm,
- bool loose_scope_p = false)
+c_parser_std_attribute_list (c_parser *parser, bool for_tm)
{
tree attributes = NULL_TREE;
while (true)
@@ -5855,7 +5853,7 @@ c_parser_std_attribute_list (c_parser *p
c_parser_consume_token (parser);
continue;
}
- tree attribute = c_parser_std_attribute (parser, for_tm, loose_scope_p);
+ tree attribute = c_parser_std_attribute (parser, for_tm);
if (attribute != error_mark_node)
{
TREE_CHAIN (attribute) = attributes;
@@ -5883,7 +5881,7 @@ c_parser_std_attribute_specifier (c_pars
{
auto ext = disable_extension_diagnostics ();
c_parser_consume_token (parser);
- attributes = c_parser_std_attribute_list (parser, for_tm, true);
+ attributes = c_parser_std_attribute_list (parser, for_tm);
restore_extension_diagnostics (ext);
}
else
--- gcc/testsuite/gcc.dg/c23-attr-syntax-6.c.jj 2023-11-09 09:04:19.499530894
+0100
+++ gcc/testsuite/gcc.dg/c23-attr-syntax-6.c 2024-02-21 19:16:48.904662570
+0100
@@ -9,19 +9,14 @@
typedef int [[__extension__ gnu::vector_size (4)]] g1;
typedef int [[__extension__ gnu :: vector_size (4)]] g2;
-typedef int [[__extension__ gnu : : vector_size (4)]] g3;
-typedef int [[__extension__ gnu: :vector_size (4)]] g4;
-typedef int [[__extension__ gnu FOO vector_size (4)]] g5;
-typedef int [[__extension__ gnu BAR BAR vector_size (4)]] g6;
-typedef int [[__extension__ gnu :/**/: vector_size (4)]] g7;
-typedef int [[__extension__ gnu JOIN(:,:) vector_size (4)]] g8;
-typedef int [[__extension__ gnu :: vector_size (sizeof (void (*)(...)))]] g10;
-typedef int [[__extension__]] g11;
-typedef int [[__extension__,]] g12;
-typedef int [[__extension__, ,,,, ,, ,]] g13;
-[[__extension__ deprecated]] int g14 ();
-[[__extension__ nodiscard]] int g15 ();
-[[__extension__ noreturn]] void g16 ();
+typedef int [[__extension__ gnu FOO vector_size (4)]] g3;
+typedef int [[__extension__ gnu :: vector_size (sizeof (void (*)(...)))]] g4;
+typedef int [[__extension__]] g5;
+typedef int [[__extension__,]] g6;
+typedef int [[__extension__, ,,,, ,, ,]] g7;
+[[__extension__ deprecated]] int g8 ();
+[[__extension__ nodiscard]] int g9 ();
+[[__extension__ noreturn]] void g10 ();
int
cases (int x)
@@ -51,12 +46,42 @@ typedef int [[__extension__ unknown_attr
typedef int [[__extension__ gnu:vector_size(4)]] b4; /* { dg-error {expected
'\]' before ':'} } */
/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
typedef int [[__extension__ gnu JOIN2(:,:) vector_size (4)]] b5; /* { dg-error
{pasting ":" and ":" does not give a valid preprocessing token} } */
-typedef int [[gnu::vector_size(4)]] b6; /* { dg-error {expected '\]' before
':'} } */
+/* { dg-error {expected '\]' before ':'} "" { target *-*-* } .-1 } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-2 } */
+typedef int [[__extension__ gnu : : vector_size (4)]] b6; /* { dg-error
{expected '\]' before ':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+typedef int [[__extension__ gnu: :vector_size (4)]] b7; /* { dg-error
{expected '\]' before ':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+typedef int [[__extension__ gnu BAR BAR vector_size (4)]] b8; /* { dg-error
{expected '\]' before ':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+typedef int [[__extension__ gnu :/**/: vector_size (4)]] b9; /* { dg-error
{expected '\]' before ':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+typedef int [[__extension__ gnu JOIN(:,:) vector_size (4)]] b10; /* { dg-error
{expected '\]' before ':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+typedef int [[gnu::vector_size(4)]] b11; /* { dg-error {attributes before C23}
} */
+typedef int [[gnu : : vector_size(4)]] b12; /* { dg-error {expected '\]'
before ':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+/* { dg-error {attributes before C23} "" { target *-*-* } .-2 } */
+typedef int [[gnu : vector_size(4)]] b13; /* { dg-error {expected '\]' before
':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+/* { dg-error {attributes before C23} "" { target *-*-* } .-2 } */
+typedef int [[gnu: :vector_size (4)]] b14; /* { dg-error {expected '\]' before
':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+/* { dg-error {attributes before C23} "" { target *-*-* } .-2 } */
+typedef int [[gnu BAR BAR vector_size (4)]] b15; /* { dg-error {expected '\]'
before ':'} } */
/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
/* { dg-error {attributes before C23} "" { target *-*-* } .-2 } */
-typedef int [[gnu : : vector_size(4)]] b7; /* { dg-error {expected '\]' before
':'} } */
+typedef int [[gnu :/**/: vector_size (4)]] b16; /* { dg-error {expected '\]'
before ':'} } */
/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
/* { dg-error {attributes before C23} "" { target *-*-* } .-2 } */
-typedef int [[gnu : vector_size(4)]] b8; /* { dg-error {expected '\]' before
':'} } */
+typedef int [[gnu JOIN(:,:) vector_size (4)]] b17; /* { dg-error {expected
'\]' before ':'} } */
/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
/* { dg-error {attributes before C23} "" { target *-*-* } .-2 } */
+typedef int [[gnu :: vector_size (4)]] b18; /* { dg-error {attributes before
C23} } */
+typedef int [[gnu FOO vector_size (4)]] b19; /* { dg-error {attributes before
C23} } */
+typedef int [[gnu :: vector_size (sizeof (void (*)(...)))]] b20; /* { dg-error
{attributes before C23} } */
+/* { dg-error {requires a named argument before} "" { target *-*-* } .-1 } */
+typedef int [[gnu JOIN2(:,:) vector_size (4)]] b21; /* { dg-error {pasting ":"
and ":" does not give a valid preprocessing token} } */
+/* { dg-error {expected '\]' before ':'} "" { target *-*-* } .-1 } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-2 } */
+/* { dg-error {attributes before C23} "" { target *-*-* } .-3 } */
--- gcc/testsuite/gcc.dg/c23-attr-syntax-7.c.jj 2023-11-09 09:04:19.499530894
+0100
+++ gcc/testsuite/gcc.dg/c23-attr-syntax-7.c 2024-02-21 19:17:19.193247405
+0100
@@ -9,19 +9,14 @@
typedef int [[__extension__ gnu::vector_size (4)]] g1;
typedef int [[__extension__ gnu :: vector_size (4)]] g2;
-typedef int [[__extension__ gnu : : vector_size (4)]] g3;
-typedef int [[__extension__ gnu: :vector_size (4)]] g4;
-typedef int [[__extension__ gnu FOO vector_size (4)]] g5;
-typedef int [[__extension__ gnu BAR BAR vector_size (4)]] g6;
-typedef int [[__extension__ gnu :/**/: vector_size (4)]] g7;
-typedef int [[__extension__ gnu JOIN(:,:) vector_size (4)]] g8;
-typedef int [[__extension__ gnu :: vector_size (sizeof (void (*)(...)))]] g10;
-typedef int [[__extension__]] g11;
-typedef int [[__extension__,]] g12;
-typedef int [[__extension__, ,,,, ,, ,]] g13;
-[[__extension__ deprecated]] int g14 ();
-[[__extension__ nodiscard]] int g15 ();
-[[__extension__ noreturn]] void g16 ();
+typedef int [[__extension__ gnu FOO vector_size (4)]] g3;
+typedef int [[__extension__ gnu :: vector_size (sizeof (void (*)(...)))]] g4;
+typedef int [[__extension__]] g5;
+typedef int [[__extension__,]] g6;
+typedef int [[__extension__, ,,,, ,, ,]] g7;
+[[__extension__ deprecated]] int g8 ();
+[[__extension__ nodiscard]] int g9 ();
+[[__extension__ noreturn]] void g10 ();
int
cases (int x)
@@ -51,10 +46,37 @@ typedef int [[__extension__ unknown_attr
typedef int [[__extension__ gnu:vector_size(4)]] b4; /* { dg-error {expected
'\]' before ':'} } */
/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
typedef int [[__extension__ gnu JOIN2(:,:) vector_size (4)]] b5;
-typedef int [[gnu::vector_size(4)]] b6; /* { dg-warning {attributes before
C23} } */
-typedef int [[gnu : : vector_size(4)]] b7; /* { dg-error {expected '\]' before
':'} } */
+typedef int [[__extension__ gnu : : vector_size (4)]] b6; /* { dg-error
{expected '\]' before ':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+typedef int [[__extension__ gnu: :vector_size (4)]] b7; /* { dg-error
{expected '\]' before ':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+typedef int [[__extension__ gnu BAR BAR vector_size (4)]] b8; /* { dg-error
{expected '\]' before ':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+typedef int [[__extension__ gnu :/**/: vector_size (4)]] b9; /* { dg-error
{expected '\]' before ':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+typedef int [[__extension__ gnu JOIN(:,:) vector_size (4)]] b10; /* { dg-error
{expected '\]' before ':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+typedef int [[gnu::vector_size(4)]] b11; /* { dg-warning {attributes before
C23} } */
+typedef int [[gnu : : vector_size(4)]] b12; /* { dg-error {expected '\]'
before ':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+/* { dg-warning {attributes before C23} "" { target *-*-* } .-2 } */
+typedef int [[gnu : vector_size(4)]] b13; /* { dg-error {expected '\]' before
':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+/* { dg-warning {attributes before C23} "" { target *-*-* } .-2 } */
+typedef int [[gnu: :vector_size (4)]] b14; /* { dg-error {expected '\]' before
':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+/* { dg-warning {attributes before C23} "" { target *-*-* } .-2 } */
+typedef int [[gnu BAR BAR vector_size (4)]] b15; /* { dg-error {expected '\]'
before ':'} } */
+/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
+/* { dg-warning {attributes before C23} "" { target *-*-* } .-2 } */
+typedef int [[gnu :/**/: vector_size (4)]] b16; /* { dg-error {expected '\]'
before ':'} } */
/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
/* { dg-warning {attributes before C23} "" { target *-*-* } .-2 } */
-typedef int [[gnu : vector_size(4)]] b8; /* { dg-error {expected '\]' before
':'} } */
+typedef int [[gnu JOIN(:,:) vector_size (4)]] b17; /* { dg-error {expected
'\]' before ':'} } */
/* { dg-error {'gnu' attribute ignored} "" { target *-*-* } .-1 } */
/* { dg-warning {attributes before C23} "" { target *-*-* } .-2 } */
+typedef int [[gnu :: vector_size (4)]] b18; /* { dg-warning {attributes before
C23} } */
+typedef int [[gnu FOO vector_size (4)]] b19; /* { dg-warning {attributes
before C23} } */
+typedef int [[gnu :: vector_size (sizeof (void (*)(...)))]] b20; /* {
dg-warning {attributes before C23} } */
+/* { dg-warning {requires a named argument before} "" { target *-*-* } .-1 } */
+typedef int [[gnu JOIN2(:,:) vector_size (4)]] b21; /* { dg-warning
{attributes before C23} } */
--- gcc/testsuite/gcc.dg/c23-attr-syntax-8.c.jj 2024-02-21 17:12:06.949467337
+0100
+++ gcc/testsuite/gcc.dg/c23-attr-syntax-8.c 2024-02-21 17:07:37.412189117
+0100
@@ -0,0 +1,12 @@
+/* PR c/114007 */
+/* { dg-do compile } */
+/* { dg-options "-std=c11" } */
+
+#if __has_c_attribute (gnu::unused)
+[[gnu::unused]]
+#endif
+int i;
+#if __has_cpp_attribute (gnu::unused)
+[[gnu::unused]]
+#endif
+int j;
--- libcpp/include/cpplib.h.jj 2024-01-05 08:35:13.720827001 +0100
+++ libcpp/include/cpplib.h 2024-02-21 16:45:17.134709568 +0100
@@ -200,6 +200,7 @@ struct GTY(()) cpp_string {
#define DECIMAL_INT (1 << 6) /* Decimal integer, set in c-lex.cc. */
#define PURE_ZERO (1 << 7) /* Single 0 digit, used by the C++ frontend,
set in c-lex.cc. */
+#define COLON_SCOPE PURE_ZERO /* Adjacent colons in C < 23. */
#define SP_DIGRAPH (1 << 8) /* # or ## token was a digraph. */
#define SP_PREV_WHITE (1 << 9) /* If whitespace before a ##
operator, or before this token
--- libcpp/lex.cc.jj 2024-01-03 12:07:27.589378046 +0100
+++ libcpp/lex.cc 2024-02-21 16:38:38.719164770 +0100
@@ -4235,8 +4235,13 @@ _cpp_lex_direct (cpp_reader *pfile)
case ':':
result->type = CPP_COLON;
- if (*buffer->cur == ':' && CPP_OPTION (pfile, scope))
- buffer->cur++, result->type = CPP_SCOPE;
+ if (*buffer->cur == ':')
+ {
+ if (CPP_OPTION (pfile, scope))
+ buffer->cur++, result->type = CPP_SCOPE;
+ else
+ result->flags |= COLON_SCOPE;
+ }
else if (*buffer->cur == '>' && CPP_OPTION (pfile, digraphs))
{
buffer->cur++;
Jakub
