On 4/18/20 10:49 AM, Marek Polacek wrote:
This is an ICE on invalid, because we're specializing S::foo in the
wrong namespace. cp_parser_class_specifier_1 parses S::foo in M
and then it tries to push the nested-name-specifier of foo, which is
S. By that, we're breaking the assumption of push_inner_scope that
the pushed scope must be a scope nested inside current scope: current
scope is M, but the namespace context of S is N, and N is not nested
in M, so we fell into an infinite loop in push_inner_scope_r.
(cp_parser_class_head called check_specialization_namespace which already
gave a permerror.)
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
This doesn't seem to be a regresssion, so OK for stage 1.
PR c++/94255
* parser.c (cp_parser_class_specifier_1): Check that the scope is
nested inside current scope before pushing it.
* g++.dg/template/spec41.C: New test.
---
gcc/cp/parser.c | 7 ++++++-
gcc/testsuite/g++.dg/template/spec41.C | 17 +++++++++++++++++
2 files changed, 23 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/template/spec41.C
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index d2f3f853cb4..d4482ef5a90 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -23858,7 +23858,12 @@ cp_parser_class_specifier_1 (cp_parser* parser)
if (nested_name_specifier_p)
{
scope = CP_DECL_CONTEXT (TYPE_MAIN_DECL (type));
- old_scope = push_inner_scope (scope);
+ /* SCOPE must be a scope nested inside current scope. */
+ if (is_nested_namespace (current_namespace,
+ decl_namespace_context (scope)))
+ old_scope = push_inner_scope (scope); > + else
+ nested_name_specifier_p = false;
}
type = begin_class_definition (type);
diff --git a/gcc/testsuite/g++.dg/template/spec41.C b/gcc/testsuite/g++.dg/template/spec41.C
new file mode 100644
index 00000000000..249fde74c3a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/spec41.C
@@ -0,0 +1,17 @@
+// PR c++/94255 - crash with template spec in different namespace.
+// { dg-do compile { target c++11 } }
+
+namespace N {
+ class S {
+ template <typename> struct foo;
+ };
+ namespace M {
+ using S = ::N::S;
+ }
+}
+
+namespace N {
+ namespace M {
+ template <> struct S::foo<int> {}; // { dg-error "specialization of" }
+ }
+}
base-commit: b57e1621eb76ba80c949ad098829aa8171a8c4ab
