c++: optimize specialization of templated member functions

This applies one of the lookup_template_class optimizations from the
previous patch to instantiate_template as well.

gcc/cp/ChangeLog:

	* pt.cc (instantiate_template): Don't substitute the context
	of the most general template if that of the partially
	instantiated template is already non-dependent.

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 079cadf..1f91fc2 100644 (file)
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -21714,8 +21714,14 @@ instantiate_template (tree tmpl, tree orig_args, tsubst_flags_t complain)
     ++processing_template_decl;
   if (DECL_CLASS_SCOPE_P (gen_tmpl))
     {
-      tree ctx = tsubst_aggr_type (DECL_CONTEXT (gen_tmpl), targ_ptr,
-                                  complain, gen_tmpl, true);
+      tree ctx;
+      if (!uses_template_parms (DECL_CONTEXT (tmpl)))
+       /* If the context of the partially instantiated template is
+          already non-dependent, then we might as well use it.  */
+       ctx = DECL_CONTEXT (tmpl);
+      else
+       ctx = tsubst_aggr_type (DECL_CONTEXT (gen_tmpl), targ_ptr,
+                               complain, gen_tmpl, true);
       push_nested_class (ctx);
     }