Re: [PATCH] c++: ICE when building builtin operator->* set [PR103455]

[Jason Merrill via Gcc-patches]

On 3/25/22 14:09, Patrick Palka wrote:

When constructing the builtin operator->* candidate set according to
the available conversion functions for each operand type, we end up
considering a candidate with C1=T (a TEMPLATE_TYPE_PARM) and C2=F,
during which we crash from lookup_base because dependent_type_p sees
a TEMPLATE_TYPE_PARM when processing_template_decl is cleared.

Sidestepping the question of whether we should be considering a
dependent conversion function here in the first place (which I'm not
sure about), it seems futile to check DERIVED_FROM_P for anything other
than an actual class type, so this patch fixes this ICE by guarding
the DERIVED_FROM_P test with CLASS_TYPE_P instead of MAYBE_CLASS_TYPE_P.

Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk and perhaps the release branches?

OK for trunk and branches.

        PR c++/103455

gcc/cp/ChangeLog:

        * call.cc (add_builtin_candidate) <case MEMBER_REF>: Check
        CLASS_TYPE_P instead of MAYBE_CLASS_TYPE_P.

gcc/testsuite/ChangeLog:

        * g++.dg/overload/builtin6.C: New test.
---
  gcc/cp/call.cc                           |  2 +-
  gcc/testsuite/g++.dg/overload/builtin6.C | 14 ++++++++++++++
  2 files changed, 15 insertions(+), 1 deletion(-)
  create mode 100644 gcc/testsuite/g++.dg/overload/builtin6.C

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..25e45040094
--- /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 foo(B b, F f) {
+  (b->*f)();
+}