From: Nathan Sidwell <nathan@acm.org>
Date: Wed, 16 Dec 2020 19:49:41 +0000 (-0800)
Subject: c++: Fix template parm ICE [PR 98297]
X-Git-Tag: releases/gcc-10.3.0~508
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=27a2ffea55852d3eb73bbec8bb610dd8c5b14f76;p=thirdparty%2Fgcc.git

c++: Fix template parm ICE [PR 98297]

I think this is nonsense code, we seem to be naming an instantiation
of a template template parm.  But this fixes the ICE.  Perhaps we
should diagnose the issue earlier?

	gcc/cp/
	* parser.c (cp_parser_elaborated_type_specifier): Test
	BOUND_TEMPLATE_TEMPLATE_PARM before checking for instantiation.
	gcc/testsuite/
	* g++.dg/template/pr98297.C: New.
---

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index dada13595268..cac1133d6f43 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -18997,7 +18997,9 @@ cp_parser_elaborated_type_specifier (cp_parser* parser,
       if (TREE_CODE (type) == TYPENAME_TYPE)
 	warning (OPT_Wattributes,
 		 "attributes ignored on uninstantiated type");
-      else if (tag_type != enum_type && CLASSTYPE_TEMPLATE_INSTANTIATION (type)
+      else if (tag_type != enum_type
+	       && TREE_CODE (type) != BOUND_TEMPLATE_TEMPLATE_PARM
+	       && CLASSTYPE_TEMPLATE_INSTANTIATION (type)
 	       && ! processing_explicit_instantiation)
 	warning (OPT_Wattributes,
 		 "attributes ignored on template instantiation");
diff --git a/gcc/testsuite/g++.dg/template/pr98297.C b/gcc/testsuite/g++.dg/template/pr98297.C
new file mode 100644
index 000000000000..0dd63a57b5cc
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/pr98297.C
@@ -0,0 +1,6 @@
+// PR 98297, ICE
+// { dg-do compile { target c++11 } }
+template <template <class> class a>
+struct [[b]]
+a <int>; // { dg-error "does not declare anything" }
+// { dg-warning "ignored" "" { target *-*-* } .-1 }