On 1/1/26 1:00 AM, Jakub Jelinek wrote:
Hi!
is_late_template_attribute wants to return false for gnu::unused, gnu::used
and maybe_unused attributes, so that -Wunused-local-typedefs sees those
attributes applied even to typedefs to dependent types.
Before my recent r16-5937 change, for maybe_unused this happened to work
through the lookup_attribute_spec returning NULL in that case because
there is no gnu::maybe_unused attribute, but when that has been fixed,
maybe_unused needs to be listed in the exceptions next to unused and used
attributes.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
2025-12-31 Jakub Jelinek <[email protected]>
PR c++/123277
* decl2.cc (is_late_template_attribute): Return false also for
[[maybe_unused]] attribute on TYPE_DECLs to dependent types.
* g++.dg/warn/Wunused-local-typedefs-5.C: New test.
--- gcc/cp/decl2.cc.jj 2025-12-27 11:44:31.534958161 +0100
+++ gcc/cp/decl2.cc 2025-12-31 12:32:56.653139050 +0100
@@ -1480,11 +1480,14 @@ is_late_template_attribute (tree attr, t
if (is_attribute_p ("weak", name))
return true;
- /* Attributes used and unused are applied directly to typedefs for the
- benefit of maybe_warn_unused_local_typedefs. */
+ /* Attributes used and unused or std attribute maybe_unused are applied
+ directly to typedefs for the benefit of
+ maybe_warn_unused_local_typedefs. */
if (TREE_CODE (decl) == TYPE_DECL
&& (is_attribute_p ("unused", name)
- || is_attribute_p ("used", name)))
+ || is_attribute_p ("used", name)
+ || (is_attribute_p ("maybe_unused", name)
+ && get_attribute_namespace (attr) == NULL_TREE)))
return false;
/* Attribute tls_model wants to modify the symtab. */
--- gcc/testsuite/g++.dg/warn/Wunused-local-typedefs-5.C.jj 2025-12-31
12:26:55.138450671 +0100
+++ gcc/testsuite/g++.dg/warn/Wunused-local-typedefs-5.C 2025-12-31
12:26:02.483371704 +0100
@@ -0,0 +1,15 @@
+// PR c++/123277
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wunused-local-typedefs" }
+
+template <typename T>
+void
+foo (T B)
+{
+ typedef T C [[maybe_unused]];
+ typedef T D [[gnu::unused]];
+ typedef T E [[gnu::used]];
+ typedef T F;
+ typedef T G; // { dg-warning "typedef 'G' locally defined but not
used" }
+ F f;
+}
Jakub
