[gcc r15-3598] c++: Don't ICE to build private access error message [PR116323]

[Simon Martin via Gcc-cvs]

https://gcc.gnu.org/g:19831baf4904d09a74c7cf684a27b091947a610b

commit r15-3598-g19831baf4904d09a74c7cf684a27b091947a610b
Author: Simon Martin <si...@nasilyan.com>
Date:   Tue Sep 10 22:33:18 2024 +0200

    c++: Don't ICE to build private access error message [PR116323]
    
    We currently ICE upon the following code while building the "[...] is
    private within this context" error message
    
    === cut here ===
    class A { enum Enum{}; };
    template<typename E, template<typename> class Alloc>
    class B : private Alloc<E>, private A {};
    template<typename E, template<typename> class Alloc>
    int B<E, Alloc>::foo (Enum m) { return 42; }
    === cut here ===
    
    The problem is that since r11-6880, after detecting that Enum cannot be
    accessed in B, enforce_access will access the TYPE_BINFO of all the
    bases of B, which ICEs for any that is a BOUND_TEMPLATE_TEMPLATE_PARM.
    This patch simply skips such bases.
    
            PR c++/116323
    
    gcc/cp/ChangeLog:
    
            * search.cc (get_parent_with_private_access): Only call 
access_in_type
            for RECORD_OR_UNION_TYPE_P base BINFOs.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/template/access43.C: New test.

Diff:
---
 gcc/cp/search.cc                         |  8 ++++++--
 gcc/testsuite/g++.dg/template/access43.C | 11 +++++++++++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/gcc/cp/search.cc b/gcc/cp/search.cc
index 60c30ecb8818..6a21a25272b2 100644
--- a/gcc/cp/search.cc
+++ b/gcc/cp/search.cc
@@ -160,12 +160,16 @@ get_parent_with_private_access (tree decl, tree binfo)
 
   tree base_binfo = NULL_TREE;
 
-  /* Iterate through immediate parent classes.  */
+  /* Iterate through immediate parent classes.
+     Note that the base list might contain WILDCARD_TYPE_P types, that
+     should be ignored here.  */
   for (int i = 0; BINFO_BASE_ITERATE (binfo, i, base_binfo); i++)
     {
+      tree base_binfo_type = BINFO_TYPE (base_binfo);
       /* This parent had private access.  Therefore that's why BINFO can't
          access DECL.  */
-      if (access_in_type (BINFO_TYPE (base_binfo), decl) == ak_private)
+      if (RECORD_OR_UNION_TYPE_P (base_binfo_type)
+         && access_in_type (base_binfo_type, decl) == ak_private)
        return base_binfo;
     }
 
diff --git a/gcc/testsuite/g++.dg/template/access43.C 
b/gcc/testsuite/g++.dg/template/access43.C
new file mode 100644
index 000000000000..ce9e6c8fbb25
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/access43.C
@@ -0,0 +1,11 @@
+// PR c++/116323
+// { dg-do "compile" }
+// { dg-additional-options "-Wno-template-body" }
+
+class A { enum Enum{}; };
+
+template<typename E, template<typename> class Alloc>
+class B : private Alloc<E>, private A {};
+
+template<typename E, template<typename> class Alloc>
+int B<E, Alloc>::foo (Enum m) { return 42; } // { dg-error "is private" }