[gcc r12-7830] c++: ICE when building builtin operator->* set [PR103455]

[gcc r12-7830] c++: ICE when building builtin operator->* set [PR103455]

[Patrick Palka]

https://gcc.gnu.org/g:04f19580e8dbdbc7366d0f5fd068aa0cecafdc9d

commit r12-7830-g04f19580e8dbdbc7366d0f5fd068aa0cecafdc9d
Author: Patrick Palka <ppalka@redhat.com>
Date:   Sat Mar 26 10:20:16 2022 -0400

    c++: ICE when building builtin operator->* set [PR103455]
    
    Here when constructing the builtin operator->* candidate set according
    to the available conversion functions for the operand types, we end up
    considering a candidate with C1=T (through B's dependent conversion
    function) and C2=F, during which we crash from DERIVED_FROM_P because
    dependent_type_p sees a TEMPLATE_TYPE_PARM outside of a template
    context.
    
    Sidestepping the question of whether we should be considering such a
    dependent conversion function here in the first place, it seems futile
    to test DERIVED_FROM_P for anything other than an actual class type, so
    this patch fixes this ICE by simply guarding the DERIVED_FROM_P test
    with CLASS_TYPE_P instead of MAYBE_CLASS_TYPE_P.
    
            PR c++/103455
    
    gcc/cp/ChangeLog:
    
            * call.cc (add_builtin_candidate) <case MEMBER_REF>: Test
            CLASS_TYPE_P instead of MAYBE_CLASS_TYPE_P.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/overload/builtin6.C: New test.

Diff:
---
 gcc/cp/call.cc                           |  2 +-
 gcc/testsuite/g++.dg/overload/builtin6.C | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
index ec6c5d5baa2..dfe370d685d 100644
--- a/gcc/cp/call.cc
+++ b/gcc/cp/call.cc
@@ -2821,7 +2821,7 @@ add_builtin_candidate (struct z_candidate **candidates, enum tree_code code,
 	  tree c1 = TREE_TYPE (type1);
 	  tree c2 = TYPE_PTRMEM_CLASS_TYPE (type2);
 
-	  if (MAYBE_CLASS_TYPE_P (c1) && DERIVED_FROM_P (c2, c1)
+	  if (CLASS_TYPE_P (c1) && DERIVED_FROM_P (c2, c1)
 	      && (TYPE_PTRMEMFUNC_P (type2)
 		  || is_complete (TYPE_PTRMEM_POINTED_TO_TYPE (type2))))
 	    break;
diff --git a/gcc/testsuite/g++.dg/overload/builtin6.C b/gcc/testsuite/g++.dg/overload/builtin6.C
new file mode 100644
index 00000000000..de192be67ec
--- /dev/null
+++ b/gcc/testsuite/g++.dg/overload/builtin6.C
@@ -0,0 +1,14 @@
+// PR c++/103455
+
+struct A { };
+
+struct B {
+  operator A*() const;
+  template<class T> operator T*() const;
+};
+
+typedef void (A::*F)();
+
+void f(B b, F pmf) {
+  (b->*pmf)();
+}