Hi!
The following patch uses the new lookup_attribute overload and extra
tests to avoid emitting weird warnings on foreign namespace attributes
which we should just ignore (perhaps with a warning), but shouldn't
imply any meaning to them just because they have a name matching some
standard or gnu attribute name.
Lightly tested so far, ok for trunk if full bootstrap/regtest succeeds?
2022-10-05 Jakub Jelinek <ja...@redhat.com>
gcc/c-family/
* c-common.cc (attribute_fallthrough_p): Lookup fallthrough attribute
only in gnu namespace or as standard attribute, treat fallthrough
attributes in other namespaces like any other unknown attribute.
gcc/cp/
* parser.cc (cp_parser_check_std_attribute): Only do checks if
attribute is a standard attribute or in gnu namespace and only
lookup other attributes in those namespaces.
* cp-gimplify.cc (lookup_hotness_attribute): Adjust function comment.
Only return true for standard attribute or gnu namespace attribute.
(remove_hotness_attribute): Only remove hotness attributes when
they are standard or in gnu namespace, implement it in a single
loop rather than former 4 now 8 remove_attribute calls.
gcc/testsuite/
* g++.dg/cpp1z/fallthrough2.C: New test.
* g++.dg/cpp2a/attr-likely7.C: New test.
--- gcc/c-family/c-common.cc.jj 2022-10-03 18:00:58.548661062 +0200
+++ gcc/c-family/c-common.cc 2022-10-05 12:58:08.396043609 +0200
@@ -6007,12 +6007,15 @@ attribute_fallthrough_p (tree attr)
{
if (attr == error_mark_node)
return false;
- tree t = lookup_attribute ("fallthrough", attr);
+ tree t = lookup_attribute (NULL, "fallthrough", attr);
+ if (t == NULL_TREE)
+ t = lookup_attribute ("gnu", "fallthrough", attr);
if (t == NULL_TREE)
return false;
/* It is no longer true that "this attribute shall appear at most once in
each attribute-list", but we still give a warning. */
- if (lookup_attribute ("fallthrough", TREE_CHAIN (t)))
+ if (lookup_attribute (NULL, "fallthrough", TREE_CHAIN (t))
+ || lookup_attribute ("gnu", "fallthrough", TREE_CHAIN (t)))
warning (OPT_Wattributes, "attribute %<fallthrough%> specified multiple "
"times");
/* No attribute-argument-clause shall be present. */
@@ -6023,9 +6026,11 @@ attribute_fallthrough_p (tree attr)
for (t = attr; t != NULL_TREE; t = TREE_CHAIN (t))
{
tree name = get_attribute_name (t);
- if (!is_attribute_p ("fallthrough", name))
+ tree ns = get_attribute_namespace (t);
+ if (!is_attribute_p ("fallthrough", name)
+ || (ns && !is_attribute_p ("gnu", ns)))
{
- if (!c_dialect_cxx () && get_attribute_namespace (t) == NULL_TREE)
+ if (!c_dialect_cxx () && ns == NULL_TREE)
/* The specifications of standard attributes in C mean
this is a constraint violation. */
pedwarn (input_location, OPT_Wattributes, "%qE attribute ignored",
--- gcc/cp/parser.cc.jj 2022-10-05 11:28:28.292141301 +0200
+++ gcc/cp/parser.cc 2022-10-05 13:29:38.203433190 +0200
@@ -29265,7 +29265,10 @@ cp_parser_check_std_attribute (location_
if (attributes)
for (const auto &a : alist)
if (is_attribute_p (a, get_attribute_name (attribute))
- && lookup_attribute (a, attributes))
+ && (get_attribute_namespace (attribute) == NULL_TREE
+ || get_attribute_namespace (attribute) == gnu_identifier)
+ && (lookup_attribute (NULL, a, attributes)
+ || lookup_attribute ("gnu", a, attributes)))
{
if (!from_macro_expansion_at (loc))
warning_at (loc, OPT_Wattributes, "attribute %qs specified "
--- gcc/cp/cp-gimplify.cc.jj 2022-10-05 11:19:19.160573401 +0200
+++ gcc/cp/cp-gimplify.cc 2022-10-05 12:53:08.367115180 +0200
@@ -3027,7 +3027,7 @@ cp_fold (tree x)
return x;
}
-/* Look up either "hot" or "cold" in attribute list LIST. */
+/* Look up "hot", "cold", "likely" or "unlikely" in attribute list LIST. */
tree
lookup_hotness_attribute (tree list)
@@ -3039,20 +3039,38 @@ lookup_hotness_attribute (tree list)
|| is_attribute_p ("cold", name)
|| is_attribute_p ("likely", name)
|| is_attribute_p ("unlikely", name))
- break;
+ {
+ tree ns = get_attribute_namespace (list);
+ if (ns == NULL_TREE || ns == gnu_identifier)
+ break;
+ }
}
return list;
}
-/* Remove both "hot" and "cold" attributes from LIST. */
+/* Remove "hot", "cold", "likely" and "unlikely" attributes from LIST. */
static tree
remove_hotness_attribute (tree list)
{
- list = remove_attribute ("hot", list);
- list = remove_attribute ("cold", list);
- list = remove_attribute ("likely", list);
- list = remove_attribute ("unlikely", list);
+ for (tree *p = &list; *p; )
+ {
+ tree l = *p;
+ tree name = get_attribute_name (l);
+ if (is_attribute_p ("hot", name)
+ || is_attribute_p ("cold", name)
+ || is_attribute_p ("likely", name)
+ || is_attribute_p ("unlikely", name))
+ {
+ tree ns = get_attribute_namespace (list);
+ if (ns == NULL_TREE || ns == gnu_identifier)
+ {
+ *p = TREE_CHAIN (l);
+ continue;
+ }
+ }
+ p = &TREE_CHAIN (l);
+ }
return list;
}
--- gcc/testsuite/g++.dg/cpp1z/fallthrough2.C.jj 2022-10-05
13:11:31.622152911 +0200
+++ gcc/testsuite/g++.dg/cpp1z/fallthrough2.C 2022-10-05 13:31:48.175672763
+0200
@@ -0,0 +1,24 @@
+// { dg-do compile { target c++17 } }
+// { dg-options "-Wextra -Wall -Wpedantic" }
+
+int
+foo (int i)
+{
+ switch (i)
+ {
+ case 2:
+ ++i;
+ [[fallthrough, whatever::fallthrough]]; // { dg-bogus
"attribute 'fallthrough' specified multiple times" }
+ case 3: // { dg-warning
"'fallthrough' attribute ignored" "" { target *-*-* } .-1 }
+ ++i;
+ [[fallthrough, whatever2::fallthrough(1, 2, 3)]]; // { dg-bogus
"attribute 'fallthrough' specified multiple times" }
+ case 4: // { dg-warning
"'fallthrough' attribute ignored" "" { target *-*-* } .-1 }
+ [[whatever3::fallthrough("abcd")]]; // { dg-warning
"attributes at the beginning of statement are ignored" }
+ case 5:
+ [[whatever4::fallthrough]]; // { dg-bogus
"attribute 'fallthrough' not preceding a case label or default label" }
+ ++i; // { dg-warning
"attributes at the beginning of statement are ignored" "" { target *-*-* } .-1 }
+ default:
+ break;
+ }
+ return i;
+}
--- gcc/testsuite/g++.dg/cpp2a/attr-likely7.C.jj 2022-10-05
13:12:21.910471659 +0200
+++ gcc/testsuite/g++.dg/cpp2a/attr-likely7.C 2022-10-05 13:35:01.318056722
+0200
@@ -0,0 +1,38 @@
+// { dg-do compile { target c++20 } }
+// { dg-additional-options -fdump-tree-gimple }
+// { dg-final { scan-tree-dump-times "hot label" 5 "gimple" } }
+// { dg-final { scan-tree-dump-times "cold label" 3 "gimple" } }
+
+bool b;
+
+template <class T> int f()
+{
+ if (b)
+ [[likely, whatever::unlikely ("abcd")]] return 0; // { dg-bogus
"ignoring attribute 'unlikely' after earlier 'likely'" }
+ else // { dg-warning
"attributes at the beginning of statement are ignored" "" { target *-*-* } .-1 }
+ [[unlikely, whatever2::hot]] flabel: return 1; // { dg-warning
"'whatever2::hot' scoped attribute directive ignored" }
+ switch (b)
+ {
+ [[likely, whatever3::cold (1, 2, 3)]] case true: break; // { dg-warning
"'whatever3::cold' scoped attribute directive ignored" }
+ };
+ return 1;
+}
+
+int main()
+{
+ if (b)
+ [[whatever4::unlikely (1), likely]] return 0; // { dg-bogus
"ignoring attribute 'likely' after earlier 'unlikely'" }
+ else if (b) // { dg-warning
"attributes at the beginning of statement are ignored" "" { target *-*-* } .-1 }
+ [[whatever5::hot, unlikely]] elabel: // { dg-warning
"'whatever5::hot' scoped attribute directive ignored" }
+ return 1;
+ else
+ [[whatever6::cold, likely]] b = false; // { dg-bogus
"ignoring attribute 'likely' after earlier 'cold'" }
+ // { dg-warning
"attributes at the beginning of statement are ignored" "" { target *-*-* } .-1 }
+ f<int>();
+
+ switch (b)
+ {
+ [[whatever7::unlikely (1), likely]] case true: break; // { dg-warning
"'whatever7::unlikely' scoped attribute directive ignored" }
+ [[whatever8::unlikely, unlikely]] case false: break; // { dg-bogus
"attribute 'unlikely' specified multiple times" }
+ }; // { dg-warning
"'whatever8::unlikely' scoped attribute directive ignored" "" { target *-*-* }
.-1 }
+}
Jakub
