Modules: Search for a visible definition of the decl context when computing visibility of a default template parameter

The code is/was already correct for the case where a parameter is a
parameter of its enclosing lexical DeclContext (functions and classes).
But for other templates (alias and variable templates) they don't create
their own scope to be members of - in those cases, they parameter should
be considered visible if any definition of the lexical decl context is
visible.

[this should cleanup the failure on the libstdc++ modules buildbot]
[this doesn't actually fix the variable template case for a
secondary/compounding reason (its lexical decl context is incorrectly
considered to be the translation unit)]

Test covers all 4 kinds of templates with default args, including a
regression test for the still broken variable template case.

Reviewers: rsmith

Differential Revision: https://reviews.llvm.org/D60892

llvm-svn: 358795

1 files changed, 18 insertions, 0 deletions

diff --git a/clang/test/Modules/nested-template-default-arg-redecl.cpp b/clang/test/Modules/nested-template-default-arg-redecl.cpp
new file mode 100644
index 00000000000..3baa2022625
--- /dev/null
+++ b/clang/test/Modules/nested-template-default-arg-redecl.cpp
@@ -0,0 +1,18 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -x c++ -fmodules -fimplicit-module-maps -fmodules-cache-path=%t \
+// RUN:     -I %S/Inputs/nested-template-default-arg-redecl -std=c++14 \
+// RUN:     -fmodules-local-submodule-visibility -verify %s
+#include "alias2.h"
+#include "var2.h"
+#include "strct2.h"
+#include "func2.h"
+
+// FIXME: Variable templates lexical decl context appears to be the translation
+// unit, which is incorrect. Fixing this will hopefully address the following
+// error/bug:
+
+// expected-note@Inputs/nested-template-default-arg-redecl/var.h:4 {{default argument declared here}}
+auto var = &var_outer::var<>; // expected-error {{default argument of 'var' must be imported from module 'VAR1' before it is required}}
+auto func = &func_outer::func<>;
+strct_outer::strct<> *strct;
+alias_outer::alias<> *alias;