This PR is a request to add a way how to suppress the warning about
ignored attributes. We concluded that -Wattributes isn't the right
warning for this case, so I went ahead with Richi's suggestion to
add -Wignored-attributes.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2016-03-23 Marek Polacek <pola...@redhat.com>
PR c++/69884
* c.opt (Wignored-attributes): New option.
* pt.c (canonicalize_type_argument): Use OPT_Wignored_attributes.
* doc/invoke.texi: Document -Wignored-attributes.
* g++.dg/warn/Wignored-attributes-1.C: New test.
* g++.dg/warn/Wignored-attributes-2.C: New test.
diff --git gcc/c-family/c.opt gcc/c-family/c.opt
index 7c5f6c7..4f86876 100644
--- gcc/c-family/c.opt
+++ gcc/c-family/c.opt
@@ -482,6 +482,10 @@ Wignored-qualifiers
C C++ Var(warn_ignored_qualifiers) Warning EnabledBy(Wextra)
Warn whenever type qualifiers are ignored.
+Wignored-attributes
+C C++ Var(warn_ignored_attributes) Init(1) Warning
+Warn whenever attributes are ignored.
+
Wincompatible-pointer-types
C ObjC Var(warn_incompatible_pointer_types) Init(1) Warning
Warn when there is a conversion between pointers that have incompatible types.
diff --git gcc/cp/pt.c gcc/cp/pt.c
index 45cd1ea..6837438 100644
--- gcc/cp/pt.c
+++ gcc/cp/pt.c
@@ -6950,7 +6950,8 @@ canonicalize_type_argument (tree arg, tsubst_flags_t
complain)
tree canon = strip_typedefs (arg, &removed_attributes);
if (removed_attributes
&& (complain & tf_warning))
- warning (0, "ignoring attributes on template argument %qT", arg);
+ warning (OPT_Wignored_attributes,
+ "ignoring attributes on template argument %qT", arg);
return canon;
}
diff --git gcc/doc/invoke.texi gcc/doc/invoke.texi
index 99ac11b..9e54bb7 100644
--- gcc/doc/invoke.texi
+++ gcc/doc/invoke.texi
@@ -267,7 +267,7 @@ Objective-C and Objective-C++ Dialects}.
-Wno-format-contains-nul -Wno-format-extra-args -Wformat-nonliteral @gol
-Wformat-security -Wformat-signedness -Wformat-y2k -Wframe-address @gol
-Wframe-larger-than=@var{len} -Wno-free-nonheap-object -Wjump-misses-init @gol
--Wignored-qualifiers -Wincompatible-pointer-types @gol
+-Wignored-qualifiers -Wignored-attributes -Wincompatible-pointer-types @gol
-Wimplicit -Wimplicit-function-declaration -Wimplicit-int @gol
-Winit-self -Winline -Wno-int-conversion @gol
-Wno-int-to-pointer-cast -Winvalid-memory-model -Wno-invalid-offsetof @gol
@@ -3886,6 +3886,14 @@ even without this option.
This warning is also enabled by @option{-Wextra}.
+@item -Wignored-attributes @r{(C and C++ only)}
+@opindex Wignored-attributes
+@opindex Wno-ignored-attributes
+Warn when an attribute is ignored. This is different from the
+@option{-Wattributes} option in that it warns whenever the compiler decides
+to drop an attribute, not that the attribute is either unknown, used in a
+wrong place, etc. This warning is enabled by default.
+
@item -Wmain
@opindex Wmain
@opindex Wno-main
diff --git gcc/testsuite/g++.dg/warn/Wignored-attributes-1.C
gcc/testsuite/g++.dg/warn/Wignored-attributes-1.C
index e69de29..46ccc4a 100644
--- gcc/testsuite/g++.dg/warn/Wignored-attributes-1.C
+++ gcc/testsuite/g++.dg/warn/Wignored-attributes-1.C
@@ -0,0 +1,6 @@
+// PR c++/69884
+// { dg-do compile }
+
+typedef float __m128 __attribute__((__vector_size__(16), __may_alias__));
+template <typename> struct A;
+template <> struct A<__m128>; // { dg-warning "ignoring attributes on template
argument" }
diff --git gcc/testsuite/g++.dg/warn/Wignored-attributes-2.C
gcc/testsuite/g++.dg/warn/Wignored-attributes-2.C
index e69de29..6431607 100644
--- gcc/testsuite/g++.dg/warn/Wignored-attributes-2.C
+++ gcc/testsuite/g++.dg/warn/Wignored-attributes-2.C
@@ -0,0 +1,7 @@
+// PR c++/69884
+// { dg-do compile }
+// { dg-options "-Wno-ignored-attributes" }
+
+typedef float __m128 __attribute__((__vector_size__(16), __may_alias__));
+template <typename> struct A;
+template <> struct A<__m128>;
Marek
