Re: C++ PATCH for c++/83714, ICE checking return from template

[Jason Merrill]

On Wed, Jan 17, 2018 at 4:31 PM, Jason Merrill <ja...@redhat.com> wrote:
> On Wed, Jan 17, 2018 at 3:46 PM, Paolo Carlini <paolo.carl...@oracle.com> 
> wrote:
>> Hi Jason,
>>
>> On 17/01/2018 00:04, Jason Merrill wrote:
>>>
>>> Like my recent patch for 83186, we were missing a
>>> build_non_dependent_expr.
>>>
>>> Tested x86_64-pc-linux-gnu, applying to trunk.
>>
>> Lately I'm seeing (H.J. Lu too) a regression:
>>
>> FAIL: g++.dg/template/inherit4.C -std=c++11 (test for excess errors)
>> FAIL: g++.dg/template/inherit4.C -std=c++14 (test for excess errors)
>>
>> which seems related to this change of yours: if I comment out the new
>> build_non_dependent_expr call the test is accepted again. Could you please
>> have a look?
>
> Hmm, wonder why I didn't see that in my testing.  Checking a fix now.

We were failing to treat A::foo_ as an instantiation-dependent
SCOPE_REF, which it is because of the dependent base B<T>.

Tested x86_64-pc-linux-gnu, applying to trunk.

commit 1579ec4777b69f2fd55ce1b3e425d6222f1f015a
Author: Jason Merrill <ja...@redhat.com>
Date:   Wed Jan 17 16:29:45 2018 -0500

    Fix template/inherit4.C.
    
            PR c++/83714
            * search.c (any_dependent_bases_p): Handle null TREE_BINFO.
            * pt.c (instantiation_dependent_scope_ref_p): True if
            any_dependent_bases_p.

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 3d7d45864c6..0296845a31b 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -23952,6 +23952,9 @@ instantiation_dependent_scope_ref_p (tree t)
 {
   if (DECL_P (TREE_OPERAND (t, 1))
       && CLASS_TYPE_P (TREE_OPERAND (t, 0))
+      /* A dependent base could make a member inaccessible in the current
+        class.  */
+      && !any_dependent_bases_p ()
       && accessible_in_template_p (TREE_OPERAND (t, 0),
                                   TREE_OPERAND (t, 1)))
     return false;
diff --git a/gcc/cp/search.c b/gcc/cp/search.c
index 477e9aef105..920fc15468a 100644
--- a/gcc/cp/search.c
+++ b/gcc/cp/search.c
@@ -2612,6 +2612,13 @@ any_dependent_bases_p (tree type)
   if (!type || !CLASS_TYPE_P (type) || !processing_template_decl)
     return false;
 
+  /* If we haven't set TYPE_BINFO yet, we don't know anything about the bases.
+     Return false because in this situation we aren't actually looking up names
+     in the scope of the class, so it doesn't matter whether it has dependent
+     bases.  */
+  if (!TYPE_BINFO (type))
+    return false;
+
   unsigned i;
   tree base_binfo;
   FOR_EACH_VEC_SAFE_ELT (BINFO_BASE_BINFOS (TYPE_BINFO (type)), i, base_binfo)
diff --git a/gcc/testsuite/g++.dg/torture/pr83619.C 
b/gcc/testsuite/g++.dg/torture/pr83619.C
index a5ca5372f18..5afd3ce0790 100644
--- a/gcc/testsuite/g++.dg/torture/pr83619.C
+++ b/gcc/testsuite/g++.dg/torture/pr83619.C
@@ -22,7 +22,7 @@ public:
     static void
     c (e *g)
     {
-      g->c ();
+      g->c ();                 // { dg-message "incomplete" }
     }
   };
 };