Hi Joseph,
here is the revised patch. I remove the 'fallthrough'
code as suggested, so everything becomes even simpler.
Some tests had to be changed then, but it seems Ok to
me.
Best,
Martin
diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog
index ca844ca775a..c656b5f4cc5 100644
--- a/gcc/c/ChangeLog
+++ b/gcc/c/ChangeLog
@@ -1,3 +1,8 @@
+2020-11-06 Martin Uecker <muec...@gwdg.de>
+
+ * c-parser.c (c_parser_label): Implement mixing of labels and code.
+ (c_parser_all_labels): Likewise.
+
2020-10-29 Asher Gordon <asd...@posteo.net>
* c-typeck.c (free_all_tagged_tu_seen_up_to): Replace free
diff --git a/gcc/c/c-parser.c b/gcc/c/c-parser.c
index fc97aa3f95f..53179f10985 100644
--- a/gcc/c/c-parser.c
+++ b/gcc/c/c-parser.c
@@ -1521,7 +1521,7 @@ static void c_parser_initval (c_parser *, struct c_expr *,
struct obstack *);
static tree c_parser_compound_statement (c_parser *, location_t * = NULL);
static location_t c_parser_compound_statement_nostart (c_parser *);
-static void c_parser_label (c_parser *);
+static void c_parser_label (c_parser *, tree);
static void c_parser_statement (c_parser *, bool *, location_t * = NULL);
static void c_parser_statement_after_labels (c_parser *, bool *,
vec<tree> * = NULL);
@@ -5523,7 +5523,7 @@ c_parser_initval (c_parser *parser, struct c_expr *after,
}
/* Parse a compound statement (possibly a function body) (C90 6.6.2,
- C99 6.8.2, C11 6.8.2).
+ C99 6.8.2, C11 6.8.2, C2X 6.8.2).
compound-statement:
{ block-item-list[opt] }
@@ -5534,6 +5534,7 @@ c_parser_initval (c_parser *parser, struct c_expr *after,
block-item-list block-item
block-item:
+ label
nested-declaration
statement
@@ -5674,7 +5675,7 @@ c_parser_compound_statement_nostart (c_parser *parser)
{
location_t loc = c_parser_peek_token (parser)->location;
loc = expansion_point_location_if_in_system_header (loc);
- /* Standard attributes may start a statement or a declaration. */
+ /* Standard attributes may start a label, statement or declaration. */
bool have_std_attrs
= c_parser_nth_token_starts_std_attributes (parser, 1);
tree std_attrs = NULL_TREE;
@@ -5685,7 +5686,6 @@ c_parser_compound_statement_nostart (c_parser *parser)
|| (c_parser_next_token_is (parser, CPP_NAME)
&& c_parser_peek_2nd_token (parser)->type == CPP_COLON))
{
- c_warn_unused_attributes (std_attrs);
if (c_parser_next_token_is_keyword (parser, RID_CASE))
label_loc = c_parser_peek_2nd_token (parser)->location;
else
@@ -5693,27 +5693,31 @@ c_parser_compound_statement_nostart (c_parser *parser)
last_label = true;
last_stmt = false;
mark_valid_location_for_stdc_pragma (false);
- c_parser_label (parser);
+ c_parser_label (parser, std_attrs);
}
- else if (!last_label
- && (c_parser_next_tokens_start_declaration (parser)
- || (have_std_attrs
- && c_parser_next_token_is (parser, CPP_SEMICOLON))))
+ else if (c_parser_next_tokens_start_declaration (parser)
+ || (have_std_attrs
+ && c_parser_next_token_is (parser, CPP_SEMICOLON)))
{
- last_label = false;
+ if (last_label)
+ pedwarn_c11 (c_parser_peek_token (parser)->location, OPT_Wpedantic,
+ "a label can only be part of a statement and "
+ "a declaration is not a statement");
+
mark_valid_location_for_stdc_pragma (false);
bool fallthru_attr_p = false;
c_parser_declaration_or_fndef (parser, true, !have_std_attrs,
true, true, true, NULL,
vNULL, have_std_attrs, std_attrs,
NULL, &fallthru_attr_p);
+
if (last_stmt && !fallthru_attr_p)
pedwarn_c90 (loc, OPT_Wdeclaration_after_statement,
"ISO C90 forbids mixed declarations and code");
last_stmt = fallthru_attr_p;
+ last_label = false;
}
- else if (!last_label
- && c_parser_next_token_is_keyword (parser, RID_EXTENSION))
+ else if (c_parser_next_token_is_keyword (parser, RID_EXTENSION))
{
/* __extension__ can start a declaration, but is also an
unary operator that can start an expression. Consume all
@@ -5796,7 +5800,7 @@ c_parser_compound_statement_nostart (c_parser *parser)
parser->error = false;
}
if (last_label)
- error_at (label_loc, "label at end of compound statement");
+ pedwarn_c11 (label_loc, OPT_Wpedantic, "label at end of compound
statement");
location_t endloc = c_parser_peek_token (parser)->location;
c_parser_consume_token (parser);
/* Restore the value we started with. */
@@ -5812,19 +5816,29 @@ c_parser_compound_statement_nostart (c_parser *parser)
static void
c_parser_all_labels (c_parser *parser)
{
+ tree std_attrs = NULL;
if (c_parser_nth_token_starts_std_attributes (parser, 1))
{
- tree std_attrs = c_parser_std_attribute_specifier_sequence (parser);
+ std_attrs = c_parser_std_attribute_specifier_sequence (parser);
if (c_parser_next_token_is (parser, CPP_SEMICOLON))
c_parser_error (parser, "expected statement");
- else
- c_warn_unused_attributes (std_attrs);
}
while (c_parser_next_token_is_keyword (parser, RID_CASE)
|| c_parser_next_token_is_keyword (parser, RID_DEFAULT)
|| (c_parser_next_token_is (parser, CPP_NAME)
&& c_parser_peek_2nd_token (parser)->type == CPP_COLON))
- c_parser_label (parser);
+ {
+ c_parser_label (parser, std_attrs);
+ std_attrs = NULL;
+ if (c_parser_nth_token_starts_std_attributes (parser, 1))
+ {
+ std_attrs = c_parser_std_attribute_specifier_sequence (parser);
+ if (c_parser_next_token_is (parser, CPP_SEMICOLON))
+ c_parser_error (parser, "expected statement");
+ }
+ }
+ if (std_attrs)
+ c_warn_unused_attributes (std_attrs);
}
/* Parse a label (C90 6.6.1, C99 6.8.1, C11 6.8.1).
@@ -5846,9 +5860,8 @@ c_parser_all_labels (c_parser *parser)
in the caller, to distinguish statements from declarations. Any
attribute-specifier-sequence after the label is parsed in this
function. */
-
static void
-c_parser_label (c_parser *parser)
+c_parser_label (c_parser *parser, tree std_attrs)
{
location_t loc1 = c_parser_peek_token (parser)->location;
tree label = NULL_TREE;
@@ -5898,8 +5911,13 @@ c_parser_label (c_parser *parser)
if (tlab)
{
decl_attributes (&tlab, attrs, 0);
+ decl_attributes (&tlab, std_attrs, 0);
label = add_stmt (build_stmt (loc1, LABEL_EXPR, tlab));
}
+ if (attrs
+ && c_parser_next_tokens_start_declaration (parser))
+ warning_at (loc2, OPT_Wattributes, "GNU-style attribute between"
+ " label and declaration appertains to the label");
}
if (label)
{
@@ -5907,55 +5925,6 @@ c_parser_label (c_parser *parser)
FALLTHROUGH_LABEL_P (LABEL_EXPR_LABEL (label)) = fallthrough_p;
else
FALLTHROUGH_LABEL_P (CASE_LABEL (label)) = fallthrough_p;
-
- /* Standard attributes are only allowed here if they start a
- statement, not a declaration (including the case of an
- attribute-declaration with only attributes). */
- bool have_std_attrs
- = c_parser_nth_token_starts_std_attributes (parser, 1);
- tree std_attrs = NULL_TREE;
- if (have_std_attrs)
- std_attrs = c_parser_std_attribute_specifier_sequence (parser);
-
- /* Allow '__attribute__((fallthrough));'. */
- if (!have_std_attrs
- && c_parser_next_token_is_keyword (parser, RID_ATTRIBUTE))
- {
- location_t loc = c_parser_peek_token (parser)->location;
- tree attrs = c_parser_gnu_attributes (parser);
- if (attribute_fallthrough_p (attrs))
- {
- if (c_parser_next_token_is (parser, CPP_SEMICOLON))
- {
- tree fn = build_call_expr_internal_loc (loc,
- IFN_FALLTHROUGH,
- void_type_node, 0);
- add_stmt (fn);
- }
- else
- warning_at (loc, OPT_Wattributes, "%<fallthrough%> attribute "
- "not followed by %<;%>");
- }
- else if (attrs != NULL_TREE)
- warning_at (loc, OPT_Wattributes, "only attribute %<fallthrough%>"
- " can be applied to a null statement");
- }
- if (c_parser_next_tokens_start_declaration (parser)
- || (have_std_attrs
- && c_parser_next_token_is (parser, CPP_SEMICOLON)))
- {
- error_at (c_parser_peek_token (parser)->location,
- "a label can only be part of a statement and "
- "a declaration is not a statement");
- c_parser_declaration_or_fndef (parser, /*fndef_ok*/ false,
- /*static_assert_ok*/ true,
- /*empty_ok*/ true, /*nested*/ true,
- /*start_attr_ok*/ true, NULL,
- vNULL, have_std_attrs, std_attrs);
- }
- else if (std_attrs)
- /* Nonempty attributes on the following statement are ignored. */
- c_warn_unused_attributes (std_attrs);
}
}
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 7a6ecce6a84..89179e243c6 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -55,7 +55,7 @@ extensions, accepted by GCC in C90 mode and in C++.
* Designated Inits:: Labeling elements of initializers.
* Case Ranges:: `case 1 ... 9' and such.
* Cast to Union:: Casting to union type from any member of the union.
-* Mixed Declarations:: Mixing declarations and code.
+* Mixed Labels and Declarations:: Mixing declarations, labels and code.
* Function Attributes:: Declaring that functions have no side effects,
or that they can never return.
* Variable Attributes:: Specifying attributes of variables.
@@ -2353,15 +2353,17 @@ void hack (union foo);
hack ((union foo) x);
@end smallexample
-@node Mixed Declarations
-@section Mixed Declarations and Code
+@node Mixed Labels and Declarations
+@section Mixed Declarations, Labels and Code
@cindex mixed declarations and code
@cindex declarations, mixed with code
@cindex code, mixed with declarations
ISO C99 and ISO C++ allow declarations and code to be freely mixed
-within compound statements. As an extension, GNU C also allows this in
-C90 mode. For example, you could do:
+within compound statements. ISO C2X allows labels to be
+placed before declarations and at the end of a compound statement.
+As an extension, GNU C also allows all this in C90 mode. For example,
+you could do:
@smallexample
int i;
@@ -8630,7 +8632,8 @@ details of the exact syntax for using attributes. Other
attributes are
available for functions (@pxref{Function Attributes}), variables
(@pxref{Variable Attributes}), enumerators (@pxref{Enumerator Attributes}),
statements (@pxref{Statement Attributes}), and for types
-(@pxref{Type Attributes}).
+(@pxref{Type Attributes}). A label attribute followed
+by a declaration appertains to the label and not the declaration.
This example uses the @code{cold} label attribute to indicate the
@code{ErrorHandling} branch is unlikely to be taken and that the
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 5320e6c1e1e..eeb54fb46d9 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -7592,7 +7592,7 @@ except when the same as the default promotion.
@opindex Wno-declaration-after-statement
Warn when a declaration is found after a statement in a block. This
construct, known from C++, was introduced with ISO C99 and is by default
-allowed in GCC@. It is not supported by ISO C90. @xref{Mixed Declarations}.
+allowed in GCC@. It is not supported by ISO C90. @xref{Mixed Labels and
Declarations}.
@item -Wshadow
@opindex Wshadow
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 40200222446..2a8233c04e4 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,22 @@
+2020-11-06 Martin Uecker <muec...@gwdg.de>
+
+ * gcc.dg/20031223-1.c: Update compiler flags and adapt test.
+ * gcc.dg/c11-labels-1.c: New test.
+ * gcc.dg/c11-labels-2.c: New test.
+ * gcc.dg/c11-labels-3.c: New test.
+ * gcc.dg/c2x-attr-syntax-3.c: Adapt test.
+ * gcc.dg/c2x-labels-1.c: New test.
+ * gcc.dg/c2x-labels-2.c: New test.
+ * gcc.dg/c2x-labels-3.c: New test.
+ * gcc.dg/decl-9.c: Update compiler flags and add error.
+ * gcc.dg/c-c++-common/attr-fallthrough-2.c: Update compiler flags.
+ * gcc.dg/c-c++-common/Wimplicit-fallthrough-20.c: Adapt test.
+ * gcc.dg/gomp/barrier-2.c: Update compiler flags and add warning.
+ * gcc.dg/gomp/declare-simd-5.c: Update compiler flags and adapt test.
+ * gcc.dg/gomp/declare-variant-2.c: Update compiler flags and add error.
+ * gcc.dg/label-compound-stmt-1.c: Update compiler flags.
+ * gcc.dg/parse-decl-after-label.c: Update compiler flags.
+
2020-11-03 Jan Hubicka <j...@suse.cz>
* gcc.c-torture/execute/pr97695.c: New test.
diff --git a/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-20.c
b/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-20.c
index d37a840a0d9..810c331b19a 100644
--- a/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-20.c
+++ b/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-20.c
@@ -27,13 +27,13 @@ g (int i)
switch (i)
{
case -1:
- __attribute__((used)); /* { dg-warning "ignored|only attribute" } */
+ __attribute__((used)); /* { dg-warning "empty declaration" } */
default:
- __attribute__((used)); /* { dg-warning "ignored|only attribute" } */
+ __attribute__((used)); /* { dg-warning "empty declaration" } */
case 1:
return 6;
case 2 ... 4:
- __attribute__((used)); /* { dg-warning "ignored|only attribute" } */
+ __attribute__((used)); /* { dg-warning "empty declaration" } */
case 5:
return 7;
}
diff --git a/gcc/testsuite/c-c++-common/attr-fallthrough-2.c
b/gcc/testsuite/c-c++-common/attr-fallthrough-2.c
index e8659e572ca..be61d5e6666 100644
--- a/gcc/testsuite/c-c++-common/attr-fallthrough-2.c
+++ b/gcc/testsuite/c-c++-common/attr-fallthrough-2.c
@@ -1,6 +1,6 @@
/* PR c/7652 */
/* { dg-do compile } */
-/* { dg-options "-Wall -Wextra -Wpedantic -Wno-unused
-Wno-implicit-fallthrough" } */
+/* { dg-options "-Wall -Wextra -Wno-unused -Wno-implicit-fallthrough" } */
extern void bar (int);
void
diff --git a/gcc/testsuite/gcc.dg/20031223-1.c
b/gcc/testsuite/gcc.dg/20031223-1.c
index 68aa74ffe50..c529739e7ec 100644
--- a/gcc/testsuite/gcc.dg/20031223-1.c
+++ b/gcc/testsuite/gcc.dg/20031223-1.c
@@ -3,11 +3,10 @@
because GCC was trying to expand the trees to rtl. */
/* { dg-do compile } */
-/* { dg-options "" } */
+/* { dg-options "-std=c17 -pedantic-errors" } */
void f ()
{
l: int; /* { dg-error "a label can only be part of a statement and a
declaration is not a statement" "not stmt" } */
- /* { dg-warning "useless type name in empty declaration" "type name" { target
*-*-* } .-1 } */
- /* { dg-error "label at end of compound statement" "label" { target *-*-* }
.-2 } */
+ /* { dg-error "useless type name in empty declaration" "type name" { target
*-*-* } .-1 } */
}
diff --git a/gcc/testsuite/gcc.dg/c2x-attr-syntax-3.c
b/gcc/testsuite/gcc.dg/c2x-attr-syntax-3.c
index 1f883d825e0..2f0d9f60cc0 100644
--- a/gcc/testsuite/gcc.dg/c2x-attr-syntax-3.c
+++ b/gcc/testsuite/gcc.dg/c2x-attr-syntax-3.c
@@ -25,13 +25,14 @@ f2 (void)
}
/* Declarations, including attribute declarations, cannot appear after
- labels. */
+ labels when a statement is expected. */
void
f3 (void)
{
- x: [[]];; /* { dg-error "can only be part of a statement" } */
-}
+ if (1)
+ x: [[]]; /* { dg-error "expected" } */
+}
/* Prefix attributes cannot appear on type names. */
diff --git a/gcc/testsuite/gcc.dg/decl-9.c b/gcc/testsuite/gcc.dg/decl-9.c
index eeca8e05e14..9bb15609d83 100644
--- a/gcc/testsuite/gcc.dg/decl-9.c
+++ b/gcc/testsuite/gcc.dg/decl-9.c
@@ -1,5 +1,5 @@
/* { dg-do compile } */
-/* { dg-options "-std=gnu89" } */
+/* { dg-options "-std=gnu89 -pedantic-errors" } */
w *x; /* { dg-error "unknown type name 'w'" } */
@@ -12,6 +12,7 @@ int f1()
int d, e;
d * e; /* { dg-bogus "unknown type name 'd'" } */
g * h; /* { dg-error "unknown type name 'g'" } */
+ /* { dg-error "mixed declarations" "" { target *-*-* } .-1 } */
g i; /* { dg-error "unknown type name 'g'" } */
}
diff --git a/gcc/testsuite/gcc.dg/gomp/barrier-2.c
b/gcc/testsuite/gcc.dg/gomp/barrier-2.c
index 5a7091946c4..c0d62f572bb 100644
--- a/gcc/testsuite/gcc.dg/gomp/barrier-2.c
+++ b/gcc/testsuite/gcc.dg/gomp/barrier-2.c
@@ -1,4 +1,5 @@
/* { dg-do compile } */
+/* { dg-options "-Wall -std=c17 -fopenmp -pedantic-errors" } */
void f1(void)
{
@@ -16,6 +17,7 @@ void f1(void)
void f2(void)
{
label: /* { dg-error "label at end of compound statement" } */
+ /* { dg-warning "defined but not used" "" { target *-*-* } .-1 } */
#pragma omp barrier /* { dg-error "may only be used in
compound statements" } */
}
diff --git a/gcc/testsuite/gcc.dg/gomp/declare-simd-5.c
b/gcc/testsuite/gcc.dg/gomp/declare-simd-5.c
index fe236525d62..b9a4161c0c9 100644
--- a/gcc/testsuite/gcc.dg/gomp/declare-simd-5.c
+++ b/gcc/testsuite/gcc.dg/gomp/declare-simd-5.c
@@ -1,5 +1,6 @@
/* Test parsing of #pragma omp declare simd */
/* { dg-do compile } */
+/* { dg-options "-std=c17 -fopenmp -pedantic-errors" } */
int
f1 (int x)
@@ -14,7 +15,7 @@ f1 (int x)
lab:
#pragma omp declare simd simdlen (8) aligned (b : 8 * sizeof (int))
extern int f5 (int a, int *b, int c); /* { dg-error "must be followed
by function declaration or definition" } */
- x++; /* { dg-error "expected
expression before" "" { target *-*-* } .-1 } */
+ x++; /* { dg-error "a label can only
be part of a statement and a declaration is not a statement" "" { target *-*-*
} .-1 } */
}
return x;
}
diff --git a/gcc/testsuite/gcc.dg/gomp/declare-variant-2.c
b/gcc/testsuite/gcc.dg/gomp/declare-variant-2.c
index 701d83b0ec3..39c2c1d40ee 100644
--- a/gcc/testsuite/gcc.dg/gomp/declare-variant-2.c
+++ b/gcc/testsuite/gcc.dg/gomp/declare-variant-2.c
@@ -1,5 +1,6 @@
/* Test parsing of #pragma omp declare variant */
/* { dg-do compile } */
+/* { dg-options "-std=c17 -fopenmp -pedantic-errors" } */
int f0 (int, int *, int);
@@ -16,7 +17,7 @@ f1 (int x)
lab:
#pragma omp declare variant (fn0) match (user={condition(0)})
extern int f5 (int a, int *b, int c); /* { dg-error "must be followed
by function declaration or definition" } */
- x++; /* { dg-error "expected
expression before" "" { target *-*-* } .-1 } */
+ x++; /* { dg-error "a label can only
be part of a statement and a declaration is not a statement" "" { target *-*-*
} .-1 } */
}
return x;
}
diff --git a/gcc/testsuite/gcc.dg/label-compound-stmt-1.c
b/gcc/testsuite/gcc.dg/label-compound-stmt-1.c
index 2f8fa4e65c2..2ae2b82ef1c 100644
--- a/gcc/testsuite/gcc.dg/label-compound-stmt-1.c
+++ b/gcc/testsuite/gcc.dg/label-compound-stmt-1.c
@@ -1,7 +1,7 @@
/* Test that labels at ends of compound statements are hard errors. */
/* Origin: Joseph Myers <j...@polyomino.org.uk> */
/* { dg-do compile } */
-/* { dg-options "" } */
+/* { dg-options "-std=c17 -pedantic-errors" } */
void f(void) { g: } /* { dg-bogus "warning" "warning in place of error" } */
/* { dg-error "label|parse|syntax" "label at end of compound statement" {
target *-*-* } .-1 } */
diff --git a/gcc/testsuite/gcc.dg/parse-decl-after-label.c
b/gcc/testsuite/gcc.dg/parse-decl-after-label.c
index 9c9886a108f..6e2a047eb2e 100644
--- a/gcc/testsuite/gcc.dg/parse-decl-after-label.c
+++ b/gcc/testsuite/gcc.dg/parse-decl-after-label.c
@@ -1,6 +1,6 @@
/* PR 29062
{ dg-do compile }
-{ dg-options "-fsyntax-only" }
+{ dg-options "-std=c17 -pedantic-errors -fsyntax-only" }
*/
int f(int x)
