c++: fix ptrmemfunc template instantiation [PR101219]

r12-1804 ("cp: add support for per-location warning groups.") among other
things removed warning suppression from a few places including ptrmemfuncs.

This exposed a bug in warning detection code as a reference to missing
BINFO (it's intentionally missing for ptrmemfunc types):

    crash_signal
        gcc/toplev.c:328
    perform_or_defer_access_check(tree_node*, tree_node*, tree_node*, int, access_failure_info*)
        gcc/cp/semantics.c:490
    finish_non_static_data_member(tree_node*, tree_node*, tree_node*)
        gcc/cp/semantics.c:2208
    ...

The change special cases ptrmemfuncs in templace substitution by using
build_ptrmemfunc_access_expr() instead of finish_non_static_data_member().

gcc/cp/ChangeLog:

	PR c++/101219
	* pt.c (tsubst_copy_and_build): Use build_ptrmemfunc_access_expr
	to construct ptrmemfunc expression instantiation.

gcc/testsuite/ChangeLog:

	PR c++/101219
	* g++.dg/warn/pr101219.C: New test.

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index b396ddd..42ea51c 100644 (file)
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -20530,7 +20530,13 @@ tsubst_copy_and_build (tree t,
        if (member == error_mark_node)
          RETURN (error_mark_node);
 
-       if (TREE_CODE (member) == FIELD_DECL)
+       if (object_type && TYPE_PTRMEMFUNC_P (object_type)
+           && TREE_CODE (member) == FIELD_DECL)
+         {
+           r = build_ptrmemfunc_access_expr (object, DECL_NAME (member));
+           RETURN (r);
+         }
+       else if (TREE_CODE (member) == FIELD_DECL)
          {
            r = finish_non_static_data_member (member, object, NULL_TREE);
            if (TREE_CODE (r) == COMPONENT_REF)

diff --git a/gcc/testsuite/g++.dg/warn/pr101219.C b/gcc/testsuite/g++.dg/warn/pr101219.C
new file mode 100644 (file)
index 0000000..0d23d73
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/pr101219.C
@@ -0,0 +1,11 @@
+/* PR c++/101219 - ICE on use of uninitialized memfun pointer
+   { dg-do compile }
+   { dg-options "-Wall" } */
+
+struct S { void m(); };
+
+template <int> bool f() {
+  void (S::*mp)();
+
+  return &S::m == mp; // no warning emitted here (no instantiation)
+}