[C++ Patch] PR 71979

[Paolo Carlini]

Hi,

in this ICE on invalid [5/6/7] regression the gcc_assert in 
build_base_path is triggered during error recovery when lookup_base 
returns NULL_TREE (makes sense because B is looked up as base of A!). It 
seems to me that we can simply allow for this case in the assertion and 
be done with the issue (should be safe for the release branch too). 
Tested x86_64-linux.

Thanks,

Paolo.

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-------------- next part --------------
/cp
2016-09-22  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/71979
	* class.c (build_base_path): Allow for lookup_base returning
	NULL_TREE.

/testsuite
2016-09-22  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/71979
	* g++.dg/cpp0x/pr71979.C: New.
-------------- next part --------------
Index: cp/class.c
===================================================================
--- cp/class.c	(revision 240345)
+++ cp/class.c	(working copy)
@@ -296,12 +296,13 @@ build_base_path (enum tree_code code,
       /* This can happen when adjust_result_of_qualified_name_lookup can't
 	 find a unique base binfo in a call to a member function.  We
 	 couldn't give the diagnostic then since we might have been calling
-	 a static member function, so we do it now.  */
+	 a static member function, so we do it now.  In other cases, eg.
+	 during error recovery (c++/71979), we may not have a base at all.  */
       if (complain & tf_error)
 	{
 	  tree base = lookup_base (probe, BINFO_TYPE (d_binfo),
 				   ba_unique, NULL, complain);
-	  gcc_assert (base == error_mark_node);
+	  gcc_assert (base == error_mark_node || !base);
 	}
       return error_mark_node;
     }
Index: testsuite/g++.dg/cpp0x/pr71979.C
===================================================================
--- testsuite/g++.dg/cpp0x/pr71979.C	(revision 0)
+++ testsuite/g++.dg/cpp0x/pr71979.C	(working copy)
@@ -0,0 +1,15 @@
+// PR c++/71979
+// { dg-do compile { target c++11 } }
+
+struct A
+{ 
+  A & operator= (A &);
+};
+
+struct B : A {};   // { dg-error "cannot bind" }
+
+void foo ()
+{ 
+  B b;
+  b = B ();  // { dg-error "use of deleted" }
+}