On 04/08/2016 08:54 PM, Martin Sebor wrote:
>> The name for new option "-Wduplicate-decl-specifier" and wording was
>> chosen to match the same option in Clang.
>
> My version of Clang also warns in C++ mode but if I'm reading
> the patch right, GCC would warn only C mode. I would find it
> surprising if GCC provided the same option as Clang but didn't
> make it available in the same languages. Do you have some
> reason for leaving it out that I'm not thinking of?
It is an error in C++ mode. Do we want to change this behavior?
>
> Also, in C11 mode, Clang issues the warning for duplicated
> _Atomic qualifiers but it doesn't look like GCC would with
> the patch. Here again, unless there's some reason not to,
> I would expect GCC to issue the same warning as Clang for
> the same code.
>
Fixed.
--
Regards,
Mikhail Maltsev
gcc/c/ChangeLog:
2016-04-08 Mikhail Maltsev <malts...@gmail.com>
PR c/43651
* c-decl.c (declspecs_add_qual): Warn when -Wduplicate-decl-specifier
is enabled.
* c-errors.c (pedwarn_c90): Return true if warned.
* c-tree.h (pedwarn_c90): Change return type to bool.
(enum c_declspec_word): Add new enumerator cdw_atomic.
gcc/ChangeLog:
2016-04-08 Mikhail Maltsev <malts...@gmail.com>
PR c/43651
* doc/invoke.texi (Wduplicate-decl-specifier): Document new option.
gcc/testsuite/ChangeLog:
2016-04-08 Mikhail Maltsev <malts...@gmail.com>
PR c/43651
* gcc.dg/Wduplicate-decl-specifier-c11.c: New test.
* gcc.dg/Wduplicate-decl-specifier.c: Likewise.
gcc/c-family/ChangeLog:
2016-04-08 Mikhail Maltsev <malts...@gmail.com>
PR c/43651
* c.opt (Wduplicate-decl-specifier): New option.
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 4f86876..f7f844d 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -1000,6 +1000,10 @@ Wsubobject-linkage
C++ ObjC++ Var(warn_subobject_linkage) Warning Init(1)
Warn if a class type has a base or a field whose type uses the anonymous namespace or depends on a type with no linkage.
+Wduplicate-decl-specifier
+C ObjC Var(warn_duplicate_decl_specifier) Warning LangEnabledBy(C ObjC,Wall)
+Warn when a declaration has duplicate const, volatile, restrict or _Atomic specifier.
+
ansi
C ObjC C++ ObjC++
A synonym for -std=c89 (for C) or -std=c++98 (for C++).
diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c
index 0dd2121..bc3af02 100644
--- a/gcc/c/c-decl.c
+++ b/gcc/c/c-decl.c
@@ -9539,32 +9539,48 @@ declspecs_add_qual (source_location loc,
gcc_assert (TREE_CODE (qual) == IDENTIFIER_NODE
&& C_IS_RESERVED_WORD (qual));
i = C_RID_CODE (qual);
+ location_t prev_loc = 0;
switch (i)
{
case RID_CONST:
dupe = specs->const_p;
specs->const_p = true;
+ prev_loc = specs->locations[cdw_const];
specs->locations[cdw_const] = loc;
break;
case RID_VOLATILE:
dupe = specs->volatile_p;
specs->volatile_p = true;
+ prev_loc = specs->locations[cdw_volatile];
specs->locations[cdw_volatile] = loc;
break;
case RID_RESTRICT:
dupe = specs->restrict_p;
specs->restrict_p = true;
+ prev_loc = specs->locations[cdw_restrict];
specs->locations[cdw_restrict] = loc;
break;
case RID_ATOMIC:
dupe = specs->atomic_p;
specs->atomic_p = true;
+ prev_loc = specs->locations[cdw_atomic];
+ specs->locations[cdw_atomic] = loc;
break;
default:
gcc_unreachable ();
}
if (dupe)
- pedwarn_c90 (loc, OPT_Wpedantic, "duplicate %qE", qual);
+ {
+ bool warned = pedwarn_c90 (loc, OPT_Wpedantic,
+ "duplicate %qE declaration specifier", qual);
+ if (!warned
+ && warn_duplicate_decl_specifier
+ && prev_loc >= RESERVED_LOCATION_COUNT
+ && !from_macro_expansion_at (prev_loc)
+ && !from_macro_expansion_at (loc))
+ warning_at (loc, OPT_Wduplicate_decl_specifier,
+ "duplicate %qE declaration specifier", qual);
+ }
return specs;
}
diff --git a/gcc/c/c-errors.c b/gcc/c/c-errors.c
index d5e78b8..af157c0 100644
--- a/gcc/c/c-errors.c
+++ b/gcc/c/c-errors.c
@@ -71,11 +71,12 @@ pedwarn_c99 (location_t location, int opt, const char *gmsgid, ...)
ISO C99 but not supported in ISO C90, thus we explicitly don't pedwarn
when C99 is specified. (There is no flag_c90.) */
-void
+bool
pedwarn_c90 (location_t location, int opt, const char *gmsgid, ...)
{
diagnostic_info diagnostic;
va_list ap;
+ bool warned = false;
rich_location richloc (line_table, location);
va_start (ap, gmsgid);
@@ -92,6 +93,7 @@ pedwarn_c90 (location_t location, int opt, const char *gmsgid, ...)
? DK_PEDWARN : DK_WARNING);
diagnostic.option_index = opt;
report_diagnostic (&diagnostic);
+ warned = true;
goto out;
}
}
@@ -114,7 +116,9 @@ pedwarn_c90 (location_t location, int opt, const char *gmsgid, ...)
diagnostic_set_info (&diagnostic, gmsgid, &ap, &richloc, DK_PEDWARN);
diagnostic.option_index = opt;
report_diagnostic (&diagnostic);
+ warned = true;
}
out:
va_end (ap);
+ return warned;
}
diff --git a/gcc/c/c-tree.h b/gcc/c/c-tree.h
index 96ab049..a3fad13 100644
--- a/gcc/c/c-tree.h
+++ b/gcc/c/c-tree.h
@@ -253,6 +253,7 @@ enum c_declspec_word {
cdw_const,
cdw_volatile,
cdw_restrict,
+ cdw_atomic,
cdw_saturating,
cdw_alignas,
cdw_address_space,
@@ -716,7 +717,7 @@ extern void c_bind (location_t, tree, bool);
extern bool tag_exists_p (enum tree_code, tree);
/* In c-errors.c */
-extern void pedwarn_c90 (location_t, int opt, const char *, ...)
+extern bool pedwarn_c90 (location_t, int opt, const char *, ...)
ATTRIBUTE_GCC_DIAG(3,4);
extern bool pedwarn_c99 (location_t, int opt, const char *, ...)
ATTRIBUTE_GCC_DIAG(3,4);
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index e9763d4..63f21e9 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -3538,6 +3538,7 @@ Options} and @ref{Objective-C and Objective-C++ Dialect Options}.
-Wc++11-compat -Wc++14-compat@gol
-Wchar-subscripts @gol
-Wcomment @gol
+-Wduplicate-decl-specifier @r{(C and Objective-C only)} @gol
-Wenum-compare @r{(in C/ObjC; this is on by default in C++)} @gol
-Wformat @gol
-Wimplicit @r{(C and Objective-C only)} @gol
@@ -3694,6 +3695,13 @@ float area(float radius)
the compiler performs the entire computation with @code{double}
because the floating-point literal is a @code{double}.
+@item -Wduplicate-decl-specifier @r{(C and Objective-C only)}
+@opindex Wduplicate-decl-specifier
+@opindex Wno-duplicate-decl-specifier
+Warn if a declaration has duplicate @code{const}, @code{volatile},
+@code{restrict} or @code{_Atomic} specifier. This warning is enabled by
+@option{-Wall}.
+
@item -Wformat
@itemx -Wformat=@var{n}
@opindex Wformat
diff --git a/gcc/testsuite/gcc.dg/Wduplicate-decl-specifier-c11.c b/gcc/testsuite/gcc.dg/Wduplicate-decl-specifier-c11.c
new file mode 100644
index 0000000..c2db525
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wduplicate-decl-specifier-c11.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-std=c11 -Wduplicate-decl-specifier" } */
+
+typedef _Atomic int AT1;
+#define AT2 _Atomic int
+
+void
+foo (void)
+{
+ _Atomic AT1 x1;
+ _Atomic AT2 x2;
+ AT1 _Atomic x3;
+ AT2 _Atomic x4;
+ _Atomic int _Atomic x5; /* { dg-warning "duplicate ._Atomic." } */
+}
+
+void a1(_Atomic AT1 t) { }
+void a2(_Atomic AT2 t) { }
+void a3(AT1 _Atomic t) { }
+void a4(AT2 _Atomic t) { }
+void a5(_Atomic int _Atomic t) { } /* { dg-warning "duplicate ._Atomic." } */
+
+typedef _Atomic AT1 AAT1;
+typedef _Atomic AT2 AAT2;
+typedef AT1 _Atomic AT1A;
+typedef AT2 _Atomic AT2A;
+typedef _Atomic int _Atomic AIA; /* { dg-warning "duplicate ._Atomic." } */
diff --git a/gcc/testsuite/gcc.dg/Wduplicate-decl-specifier.c b/gcc/testsuite/gcc.dg/Wduplicate-decl-specifier.c
new file mode 100644
index 0000000..d7a3919
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wduplicate-decl-specifier.c
@@ -0,0 +1,63 @@
+/* PR43651 */
+/* { dg-do compile } */
+/* { dg-options "-Wduplicate-decl-specifier" } */
+
+typedef const int CT1;
+#define CT2 const int
+typedef volatile int VT1;
+#define VT2 volatile int
+typedef char *restrict RT1;
+#define RT2 char *restrict
+
+void
+foo (void)
+{
+ const CT1 x1;
+ const CT2 x2;
+ CT1 const x3;
+ CT2 const x4;
+ const int const x5; /* { dg-warning "duplicate .const." } */
+ const int *const x6;
+ volatile VT1 y1;
+ volatile VT2 y2;
+ VT1 volatile y3;
+ VT2 volatile y4;
+ volatile int volatile y5; /* { dg-warning "duplicate .volatile." } */
+ volatile int *volatile y6;
+ RT1 restrict r1;
+ RT2 restrict r2;
+ restrict RT1 r3;
+ /* "restrict RT2" is invalid */
+ char *restrict restrict r4; /* { dg-warning "duplicate .restrict." } */
+ char *restrict *restrict r5;
+}
+
+void c1(const CT1 t) { }
+void c2(const CT2 t) { }
+void c3(CT1 const t) { }
+void c4(CT2 const t) { }
+void c5(const int const t) { } /* { dg-warning "duplicate .const." } */
+void v1(volatile VT1 t) { }
+void v2(volatile VT2 t) { }
+void v3(VT1 volatile t) { }
+void v4(VT2 volatile t) { }
+void v5(volatile int volatile t) { } /* { dg-warning "duplicate .volatile." } */
+void r1(restrict RT1 t) { }
+void r2(RT1 restrict t) { }
+void r3(RT2 restrict t) { }
+void r4(char *restrict restrict t) { } /* { dg-warning "duplicate .restrict." } */
+
+typedef const CT1 CCT1;
+typedef const CT2 CCT2;
+typedef CT1 const CT1C;
+typedef CT2 const CT2C;
+typedef const int const CIC; /* { dg-warning "duplicate .const." } */
+typedef volatile VT1 VVT1;
+typedef volatile VT2 VVT2;
+typedef VT1 volatile VT1V;
+typedef VT2 volatile VT2V;
+typedef volatile int volatile VIV; /* { dg-warning "duplicate .volatile." } */
+typedef RT1 restrict RT1R;
+typedef RT2 restrict RT2R;
+typedef restrict RT1 RRT1;
+typedef int *restrict restrict IRR; /* { dg-warning "duplicate .restrict." } */
