[PR87770] test partial specializations for type dependence

When instantiating a partial specialization of a template member
function for a full specialization of a class template, we test
whether the context of variables local to the partial specialization,
i.e., the partial specialization itself, is dependent, and this ICEs
in type_dependent_expression_p, when checking that the function type
isn't type-dependent because it is not in a type-dependent scope.

We shouldn't have got that far: the previous block in
type_dependent_expression_p catches cases in which the function itself
takes template arguments of its own, but it only did so for primary
templates, not for partial specializations.  This patch fixes that.


for  gcc/cp/ChangeLog

	PR c++/87770
	* pt.c (instantiates_primary_template_p): New.
	(type_dependent_expression_p): Use it.

for  gcc/testsuite/ChangeLog

	PR c++/87770
	* g++.dg/pr87770.C: New.

From-SVN: r268529

gcc/cp/ChangeLog

@@ -1,3 +1,9 @@
+2019-02-05  Alexandre Oliva <aoliva@redhat.com>
+
+	PR c++/87770
+	* pt.c (instantiates_primary_template_p): New.
+	(type_dependent_expression_p): Use it.
+
 2019-02-01  Jason Merrill  <jason@redhat.com>
 
 	PR c++/88761 - ICE with reference capture of constant.

gcc/cp/pt.c

@@ -400,6 +400,36 @@ template_class_depth (tree type)
   return depth;
 }
 
+/* Return TRUE if NODE instantiates a template that has arguments of
+   its own, be it directly a primary template or indirectly through a
+   partial specializations.  */
+static bool
+instantiates_primary_template_p (tree node)
+{
+  tree tinfo = get_template_info (node);
+  if (!tinfo)
+    return false;
+
+  tree tmpl = TI_TEMPLATE (tinfo);
+  if (PRIMARY_TEMPLATE_P (tmpl))
+    return true;
+
+  if (!DECL_TEMPLATE_SPECIALIZATION (tmpl))
+    return false;
+
+  /* So now we know we have a specialization, but it could be a full
+     or a partial specialization.  To tell which, compare the depth of
+     its template arguments with those of its context.  */
+
+  tree ctxt = DECL_CONTEXT (tmpl);
+  tree ctinfo = get_template_info (ctxt);
+  if (!ctinfo)
+    return true;
+
+  return (TMPL_ARGS_DEPTH (TI_ARGS (tinfo))
+	  > TMPL_ARGS_DEPTH (TI_ARGS (ctinfo)));
+}
+
 /* Subroutine of maybe_begin_member_template_processing.
    Returns true if processing DECL needs us to push template parms.  */
 
@@ -25683,7 +25713,7 @@ type_dependent_expression_p (tree expression)
 	 that come from the template-id; the template arguments for the
 	 enclosing class do not make it type-dependent unless they are used in
 	 the type of the decl.  */
-      if (PRIMARY_TEMPLATE_P (DECL_TI_TEMPLATE (expression))
+      if (instantiates_primary_template_p (expression)
 	  && (any_dependent_template_arguments_p
 	      (INNERMOST_TEMPLATE_ARGS (DECL_TI_ARGS (expression)))))
 	return true;

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2019-02-05  Alexandre Oliva <aoliva@redhat.com>
+
+	PR c++/87770
+	* g++.dg/pr87770.C: New.
+
 2019-02-04  Harald Anlauf  <anlauf@gmx.de>
 
 	PR fortran/89077

gcc/testsuite/g++.dg/pr87770.C

@@ -0,0 +1,11 @@
+// { dg-do compile }
+
+template <typename> struct d {
+  template <typename e> d(e);
+};
+template <> template <typename e> d<int>::d(e);
+template <> template <typename e> d<int>::d(e) {
+  long g;
+  (void)g;
+}
+template d<int>::d(char);