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.

3 files changed, 27 insertions, 0 deletions

diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 4fbe522..321d416 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 0000000..d5f89d0
--- /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 0000000..48ac751
--- /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();
+}