[gcc r15-6818] c++: modules and class attributes

[Jason Merrill via Gcc-cvs]

https://gcc.gnu.org/g:fdabd93cde4aae38d6a67fe0927eca8cea1b22b9

commit r15-6818-gfdabd93cde4aae38d6a67fe0927eca8cea1b22b9
Author: Jason Merrill <ja...@redhat.com>
Date:   Sat Nov 23 10:00:18 2024 +0100

    c++: modules and class attributes
    
    std/time/traits/is_clock.cc was getting a warning about applying the
    deprecated attribute to a variant of auto_ptr, which was wrong because it's
    on the primary type.  This turned out to be because we were ignoring the
    attributes on the definition of auto_ptr because the forward declaration in
    unique_ptr.h has no attributes.  We need to merge attributes as usual in a
    redeclaration.
    
    gcc/cp/ChangeLog:
    
            * module.cc (trees_in::decl_value): Merge attributes.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/modules/attrib-1_a.C: New test.
            * g++.dg/modules/attrib-1_b.C: New test.

Diff:
---
 gcc/cp/module.cc                          |  4 ++++
 gcc/testsuite/g++.dg/modules/attrib-1_a.C | 13 +++++++++++++
 gcc/testsuite/g++.dg/modules/attrib-1_b.C | 10 ++++++++++
 3 files changed, 27 insertions(+)

diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 4fbe522264b3..321d4164a6a7 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -8637,6 +8637,10 @@ trees_in::decl_value ()
          TYPE_STUB_DECL (type) = stub_decl ? stub_decl : inner;
          if (stub_decl)
            TREE_TYPE (stub_decl) = type;
+
+         /* Handle separate declarations with different attributes.  */
+         tree &eattr = TYPE_ATTRIBUTES (TREE_TYPE (existing));
+         eattr = merge_attributes (eattr, TYPE_ATTRIBUTES (type));
        }
 
       if (inner_tag)
diff --git a/gcc/testsuite/g++.dg/modules/attrib-1_a.C 
b/gcc/testsuite/g++.dg/modules/attrib-1_a.C
new file mode 100644
index 000000000000..d5f89d0c0688
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/attrib-1_a.C
@@ -0,0 +1,13 @@
+// { dg-additional-options "-fmodules -Wno-global-module" }
+// { dg-module-cmi M }
+
+module;
+
+template <class T> struct A {
+  void f() const { }
+} __attribute__ ((deprecated ("y tho")));
+
+export module M;
+
+export template <class T>
+A<T> a;                                // { dg-warning "deprecated" }
diff --git a/gcc/testsuite/g++.dg/modules/attrib-1_b.C 
b/gcc/testsuite/g++.dg/modules/attrib-1_b.C
new file mode 100644
index 000000000000..48ac751b03d1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/attrib-1_b.C
@@ -0,0 +1,10 @@
+// { dg-additional-options -fmodules }
+
+template <class T> struct A;
+
+import M;
+
+int main()
+{
+  a<int>.f();
+}