[Modules] Add 'no_undeclared_includes' module map attribute

The 'no_undeclared_includes' attribute should be used in a module to
tell that only non-modular headers and headers from used modules are
accepted.

The main motivation behind this is to prevent dep cycles between system
libraries (such as darwin) and libc++.

Patch by Richard Smith!

llvm-svn: 284797

3 files changed, 7 insertions, 0 deletions

diff --git a/clang/test/Modules/Inputs/libc-libcxx/include/c++/math.h b/clang/test/Modules/Inputs/libc-libcxx/include/c++/math.h
new file mode 100644
index 00000000000..890db371de6
--- /dev/null
+++ b/clang/test/Modules/Inputs/libc-libcxx/include/c++/math.h
@@ -0,0 +1,2 @@
+#include_next <math.h>
+template<typename T> T abs(T t) { return (t < 0) ? -t : t; }
diff --git a/clang/test/Modules/Inputs/libc-libcxx/include/c++/module.modulemap b/clang/test/Modules/Inputs/libc-libcxx/include/c++/module.modulemap
new file mode 100644
index 00000000000..fd15779e934
--- /dev/null
+++ b/clang/test/Modules/Inputs/libc-libcxx/include/c++/module.modulemap
@@ -0,0 +1,4 @@
+module "libc++" {
+  module math { header "math.h" export * }
+  module stdlib { header "stdlib.h" export * }
+}
diff --git a/clang/test/Modules/Inputs/libc-libcxx/include/c++/stdlib.h b/clang/test/Modules/Inputs/libc-libcxx/include/c++/stdlib.h
new file mode 100644
index 00000000000..6e736cbbaa0
--- /dev/null
+++ b/clang/test/Modules/Inputs/libc-libcxx/include/c++/stdlib.h
@@ -0,0 +1 @@
+#include_next "stdlib.h"