[gcc r10-10737] c++: template conversion op [PR101698]

[Jason Merrill <jason@gcc.gnu.org>]

https://gcc.gnu.org/g:f06e1ff97cb383118afed4c87dfa104e7c4b141d

commit r10-10737-gf06e1ff97cb383118afed4c87dfa104e7c4b141d
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Apr 13 14:49:04 2022 -0400

    c++: template conversion op [PR101698]
    
    Asking for conversion to a dependent type also makes a BASELINK dependent.
    
            PR c++/101698
    
    gcc/cp/ChangeLog:
    
            * pt.c (tsubst_baselink): Also check dependent optype.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/template/conv19.C: New test.

Diff:
---
 gcc/cp/pt.c                            |  3 ++-
 gcc/testsuite/g++.dg/template/conv19.C | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index a29e8fb7ad7..c326a80183f 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -16139,7 +16139,8 @@ tsubst_baselink (tree baselink, tree object_type,
 
   tree binfo_type = BINFO_TYPE (BASELINK_BINFO (baselink));
   binfo_type = tsubst (binfo_type, args, complain, in_decl);
-  bool dependent_p = binfo_type != BINFO_TYPE (BASELINK_BINFO (baselink));
+  bool dependent_p = (binfo_type != BINFO_TYPE (BASELINK_BINFO (baselink))
+		      || optype != BASELINK_OPTYPE (baselink));
 
   if (dependent_p)
     {
diff --git a/gcc/testsuite/g++.dg/template/conv19.C b/gcc/testsuite/g++.dg/template/conv19.C
new file mode 100644
index 00000000000..7a3da939c1f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/conv19.C
@@ -0,0 +1,34 @@
+// PR c++/101698
+// { dg-do compile { target c++11 } }
+
+class Base {
+ public:
+  template <class T>
+  operator const T&() const = delete;
+
+  virtual operator const int&() const {
+    static int res;
+    return res;
+  }
+};
+
+template <class T>
+class Derive : public Base {
+ public:
+  operator const T&() const override {
+    using Y = int;
+    //static_assert(__is_same_as(T,Y), "");
+
+    static int res;
+
+    res = Base::operator const Y&(); // OK
+    res = Base::operator const T&(); // { dg-bogus "deleted" }
+    return res;
+  }
+};
+
+int main() {
+  Derive<int> a;
+  const int& b = a;
+  (void)b;
+}