On 6/16/19 10:10 AM, Marek Polacek wrote:
On Sat, Jun 15, 2019 at 10:39:13AM -0400, Marek Polacek wrote:
On Sat, Jun 15, 2019 at 04:33:26PM +0200, Jakub Jelinek wrote:
On Sat, Jun 15, 2019 at 10:29:17AM -0400, Marek Polacek wrote:
[dcl.attr.noreturn] says "The first declaration of a function shall specify the
noreturn attribute if any declaration of that function specifies the noreturn
attribute" meaning that we should diagnose
void func ();
void func [[noreturn]] ();
but we do not. I'd been meaning to issue a hard error for [[noreturn]] and
only a warning for __attribute__((noreturn)) but then I found out that we
treat [[noreturn]] exactly as the GNU attribute, and so cxx11_attribute_p
returns false for it, so I decided to make it a pedwarn for all the cases.
A pedwarn counts as a diagnostic, so we'd be conforming still.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
IMHO we should treat __attribute__((noreturn)) as before without any
warnings, just [[noreturn]] that way. There is nothing wrong on declaring
it just on second or following declaration, it is an optimization attribute.
That's a complication then; currently [[noreturn]], [[gnu::noreturn]], and
__attribute__((noreturn)) are not distinguishable. :(
Guess I will really have to make the changes to treat [[noreturn]] similarly
to e.g. [[nodiscard]], so that cxx11_attribute_p works.
Thus. Changes I've made:
* don't treat [[noreturn]] as an equivalent to __attribute__((noreturn));
* for that I had to adjust decl_attributes, it wasn't preserving the
C++11 form (a list in another list); fix shadowing while at it;
* the above turned up two spots that were wrongly accessing TREE_PURPOSE
directly instead of using get_attribute_name;
* give error only for [[noreturn]] but not for __attribute__((noreturn))
or [[gnu::noreturn]].
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2019-06-16 Marek Polacek <pola...@redhat.com>
PR c++/60364 - noreturn after first decl not diagnosed.
* attribs.c (get_attribute_namespace): No longer static.
(decl_attributes): Avoid shadowing. Preserve the C++11 form for C++11
attributes.
* attribs.h (get_attribute_namespace): Declare.
* tree-inline.c (function_attribute_inlinable_p): Use
get_attribute_name.
* c-attribs.c (handle_noreturn_attribute): No longer static.
* c-common.h (handle_noreturn_attribute): Declare.
* c-format.c (check_function_format): Use get_attribute_name.
* decl.c (duplicate_decls): Give an error when a function is
declared [[noreturn]] after its first declaration.
* parser.c (cp_parser_std_attribute): Don't treat C++11 noreturn
attribute as equivalent to GNU's.
* tree.c (std_attribute_table): Add noreturn.
* g++.dg/warn/noreturn-8.C: New test.
...
diff --git gcc/cp/tree.c gcc/cp/tree.c
index cd021b7f594..bb695e14e73 100644
--- gcc/cp/tree.c
+++ gcc/cp/tree.c
@@ -4453,6 +4453,8 @@ const struct attribute_spec std_attribute_table[] =
handle_likeliness_attribute, attr_cold_hot_exclusions },
{ "unlikely", 0, 0, false, false, false, false,
handle_likeliness_attribute, attr_cold_hot_exclusions },
+ { "noreturn", 0, 0, true, false, false, false,
+ handle_noreturn_attribute, NULL },
^^^^
The GNU attribute is made mutually exclusive with a bunch of other
attributes (e.g., malloc or warn_unused_result) by setting the last
member to the array of exclusive attribute. Does the change preserve
this relationship some other way?
Martin
