[modules] Track all default template arguments for a given parameter across
modules, and allow use of a default template argument if any of the parameters
providing it is visible.

llvm-svn: 239485
diff --git a/clang/test/Modules/Inputs/template-default-args/a.h b/clang/test/Modules/Inputs/template-default-args/a.h
index 1ef1ea5..3e41535 100644
--- a/clang/test/Modules/Inputs/template-default-args/a.h
+++ b/clang/test/Modules/Inputs/template-default-args/a.h
@@ -2,3 +2,4 @@
 template<typename T> struct B {};
 template<typename T> struct C;
 template<typename T> struct D;
+template<typename T> struct E;
diff --git a/clang/test/Modules/Inputs/template-default-args/c.h b/clang/test/Modules/Inputs/template-default-args/c.h
new file mode 100644
index 0000000..c204f31
--- /dev/null
+++ b/clang/test/Modules/Inputs/template-default-args/c.h
@@ -0,0 +1 @@
+template<typename T = int> struct F;
diff --git a/clang/test/Modules/Inputs/template-default-args/module.modulemap b/clang/test/Modules/Inputs/template-default-args/module.modulemap
index 6182e6b..d54dfc3 100644
--- a/clang/test/Modules/Inputs/template-default-args/module.modulemap
+++ b/clang/test/Modules/Inputs/template-default-args/module.modulemap
@@ -1 +1,5 @@
-module X { module A { header "a.h" } module B { header "b.h" } }
+module X {
+  module A { header "a.h" }
+  module B { header "b.h" }
+  module C { header "c.h" }
+}
diff --git a/clang/test/Modules/template-default-args.cpp b/clang/test/Modules/template-default-args.cpp
index 63187b8..97569f0 100644
--- a/clang/test/Modules/template-default-args.cpp
+++ b/clang/test/Modules/template-default-args.cpp
@@ -7,6 +7,7 @@
 template<typename T> struct B;
 template<typename T> struct C;
 template<typename T = int> struct D;
+template<typename T = int> struct E {};
 
 #include "b.h"
 
@@ -15,8 +16,13 @@
 template<typename T = int> struct B;
 template<typename T = int> struct C;
 template<typename T> struct D {};
+template<typename T> struct F {};
+
+#include "c.h"
 
 A<> a;
 B<> b;
 extern C<> c;
 D<> d;
+E<> e;
+F<> f;