[gcc r14-9357] c++: Fix ICE diagnosing incomplete type of overloaded function set [PR98356]

[gcc r14-9357] c++: Fix ICE diagnosing incomplete type of overloaded function set [PR98356]

[Nathaniel Shead]

https://gcc.gnu.org/g:940586a63586941a9f2b973491afc8a15a96c98b

commit r14-9357-g940586a63586941a9f2b973491afc8a15a96c98b
Author: Nathaniel Shead <nathanieloshead@gmail.com>
Date:   Tue Mar 5 01:59:41 2024 +1100

    c++: Fix ICE diagnosing incomplete type of overloaded function set [PR98356]
    
    In the linked PR the result of 'get_first_fn' is a USING_DECL against
    the template parameter, to be filled in on instantiation. But we don't
    actually need to get the first set of the member functions: it's enough
    to know that we have a (possibly overloaded) member function at all.
    
            PR c++/98356
    
    gcc/cp/ChangeLog:
    
            * typeck2.cc (cxx_incomplete_type_diagnostic): Don't assume
            'member' will be a FUNCTION_DECL (or something like it).
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/pr98356.C: New test.
    
    Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>

Diff:
---
 gcc/cp/typeck2.cc              | 11 +++++------
 gcc/testsuite/g++.dg/pr98356.C |  9 +++++++++
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/gcc/cp/typeck2.cc b/gcc/cp/typeck2.cc
index 9608bdccd8b..31198b2f9f5 100644
--- a/gcc/cp/typeck2.cc
+++ b/gcc/cp/typeck2.cc
@@ -350,16 +350,15 @@ cxx_incomplete_type_diagnostic (location_t loc, const_tree value,
     bad_member:
       {
 	tree member = TREE_OPERAND (value, 1);
-	if (is_overloaded_fn (member))
-	  member = get_first_fn (member);
-
-	if (DECL_FUNCTION_MEMBER_P (member)
-	    && ! flag_ms_extensions)
+	if (is_overloaded_fn (member) && !flag_ms_extensions)
 	  {
 	    gcc_rich_location richloc (loc);
 	    /* If "member" has no arguments (other than "this"), then
 	       add a fix-it hint.  */
-	    if (type_num_arguments (TREE_TYPE (member)) == 1)
+	    member = MAYBE_BASELINK_FUNCTIONS (member);
+	    if (TREE_CODE (member) == FUNCTION_DECL
+		&& DECL_OBJECT_MEMBER_FUNCTION_P (member)
+		&& type_num_arguments (TREE_TYPE (member)) == 1)
 	      richloc.add_fixit_insert_after ("()");
 	    complained = emit_diagnostic (diag_kind, &richloc, 0,
 			     "invalid use of member function %qD "
diff --git a/gcc/testsuite/g++.dg/pr98356.C b/gcc/testsuite/g++.dg/pr98356.C
new file mode 100644
index 00000000000..acea238593b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr98356.C
@@ -0,0 +1,9 @@
+// PR c++/98356
+// { dg-do compile { target c++11 } }
+
+template <template <typename> class T> struct S {
+  using A = T<int>;
+  using A::foo;
+  void foo ();
+  void bar () {foo.}  // { dg-error "invalid use of member function" }
+};