From: Jason Merrill <jason@redhat.com>
Date: Mon, 3 Apr 2023 22:23:58 +0000 (-0400)
Subject: c++: friend template matching [PR107484]
X-Git-Tag: basepoints/gcc-14~215
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0dfbb28a9549c2503204b0338bf550f1bff9c681;p=thirdparty%2Fgcc.git

c++: friend template matching [PR107484]

Here friend matching tries to find a matching non-template friend and fails,
so we mark the friend as a template specialization to be determined later.
Then cplus_decl_attributes tries again to find a matching function and gets
confused by DECL_TEMPLATE_INSTANTIATION without DECL_TEMPLATE_INFO.  But it
doesn't make sense for find_last_decl to be trying to match anything with
DECL_USE_TEMPLATE set; those are matched elsewhere.

	PR c++/107484

gcc/cp/ChangeLog:

	* decl2.cc (find_last_decl): Return early if DECL_USE_TEMPLATE.

gcc/testsuite/ChangeLog:

	* g++.dg/lookup/friend25.C: New test.
---

diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
index 2b195e999975..9594be4092c3 100644
--- a/gcc/cp/decl2.cc
+++ b/gcc/cp/decl2.cc
@@ -1613,6 +1613,11 @@ find_last_decl (tree decl)
 
   if (tree name = DECL_P (decl) ? DECL_NAME (decl) : NULL_TREE)
     {
+      /* Template specializations are matched elsewhere.  */
+      if (DECL_LANG_SPECIFIC (decl)
+	  && DECL_USE_TEMPLATE (decl))
+	return NULL_TREE;
+
       /* Look up the declaration in its scope.  */
       tree pushed_scope = NULL_TREE;
       if (tree ctype = DECL_CONTEXT (decl))
diff --git a/gcc/testsuite/g++.dg/lookup/friend25.C b/gcc/testsuite/g++.dg/lookup/friend25.C
new file mode 100644
index 000000000000..74cf5dc34319
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lookup/friend25.C
@@ -0,0 +1,9 @@
+// PR c++/107484
+
+namespace qualified_friend_no_match {
+  void f(int);
+  template<typename T> void f(T*);
+  struct X {
+    friend void qualified_friend_no_match::f(double); // { dg-error "does not match any template" }
+  };
+}