[gcc r11-9826] c++: repeated friend template [PR101894]

[gcc r11-9826] c++: repeated friend template [PR101894]

[Jason Merrill]

https://gcc.gnu.org/g:ad4b23729b2e57676efb3d8313f4fc5300b94339

commit r11-9826-gad4b23729b2e57676efb3d8313f4fc5300b94339
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Apr 1 16:18:31 2022 -0400

    c++: repeated friend template [PR101894]
    
    Since olddecl isn't a definition, it doesn't get DECL_FRIEND_CONTEXT, so we
    need to copy it from newdecl when we merge the declarations.
    
            PR c++/101894
    
    gcc/cp/ChangeLog:
    
            * decl.c (duplicate_decls): Copy DECL_FRIEND_CONTEXT.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/lookup/friend22.C: New test.

Diff:
---
 gcc/cp/decl.c                          | 5 +++++
 gcc/testsuite/g++.dg/lookup/friend22.C | 7 +++++++
 2 files changed, 12 insertions(+)

diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 491a03cd94f..8d7d71d0590 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -2273,6 +2273,9 @@ duplicate_decls (tree newdecl, tree olddecl, bool hiding, bool was_hidden)
 	      for (parm = DECL_ARGUMENTS (old_result); parm;
 		   parm = DECL_CHAIN (parm))
 		DECL_CONTEXT (parm) = old_result;
+
+	      if (tree fc = DECL_FRIEND_CONTEXT (new_result))
+		SET_DECL_FRIEND_CONTEXT (old_result, fc);
 	    }
 	}
 
@@ -2592,6 +2595,8 @@ duplicate_decls (tree newdecl, tree olddecl, bool hiding, bool was_hidden)
 	     otherwise it is a DECL_FRIEND_CONTEXT.  */
 	  if (DECL_VIRTUAL_P (newdecl))
 	    SET_DECL_THUNKS (newdecl, DECL_THUNKS (olddecl));
+	  else if (tree fc = DECL_FRIEND_CONTEXT (newdecl))
+	    SET_DECL_FRIEND_CONTEXT (olddecl, fc);
 	}
       else if (VAR_P (newdecl))
 	{
diff --git a/gcc/testsuite/g++.dg/lookup/friend22.C b/gcc/testsuite/g++.dg/lookup/friend22.C
new file mode 100644
index 00000000000..f52a7d7bad5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lookup/friend22.C
@@ -0,0 +1,7 @@
+// PR c++/101894
+
+struct A
+{
+  template<int> friend void foo();
+  template<int> friend void foo() {}
+};