Add pragma to perform module import and use it in -E output.

Many of our supported configurations support modules but do not have any
first-class syntax to perform a module import. This leaves us with a problem:
there is no way to represent the expansion of a #include that imports a module
in the -E output for such languages. (We don't want to just leave it as a
#include because that requires the consumer of the preprocessed source to have
the same file system layout and include paths as the creator.)

This patch adds a new pragma:

  #pragma clang module import MODULE.NAME.HERE

that imports a module, and changes -E and -frewrite-includes to use it when
rewriting a #include that maps to a module import. We don't make any attempt
to use a native language syntax import if one exists, to get more consistent
output. (If in the future, @import and #include have different semantics in
some way, the pragma will track the #include semantics.)

llvm-svn: 301725

1 files changed, 35 insertions, 0 deletions

diff --git a/clang/test/Modules/import-syntax.c b/clang/test/Modules/import-syntax.c
new file mode 100644
index 00000000000..a29e07aa1c2
--- /dev/null
+++ b/clang/test/Modules/import-syntax.c
@@ -0,0 +1,35 @@
+// RUN: rm -rf %t
+//
+// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t -fimplicit-module-maps -I%S/Inputs -verify -x c -DINCLUDE %s
+// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t -fimplicit-module-maps -I%S/Inputs -verify -x objective-c -DINCLUDE %s
+// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t -fimplicit-module-maps -I%S/Inputs -verify -x c++ -DINCLUDE %s
+//
+// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t -fimplicit-module-maps -I%S/Inputs -verify -x objective-c -DAT_IMPORT=1 %s
+// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t -fimplicit-module-maps -I%S/Inputs -verify -x objective-c++ -DAT_IMPORT=1 %s
+//
+// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t -fimplicit-module-maps -I%S/Inputs -verify -x c++ -fmodules-ts -DIMPORT=1 %s
+// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t -fimplicit-module-maps -I%S/Inputs -verify -x objective-c++ -fmodules-ts -DIMPORT=1 %s
+//
+// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t -fimplicit-module-maps -I%S/Inputs -verify -x c -DPRAGMA %s
+// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t -fimplicit-module-maps -I%S/Inputs -verify -x objective-c -DPRAGMA %s
+// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t -fimplicit-module-maps -I%S/Inputs -verify -x c++ -DPRAGMA %s
+
+// expected-no-diagnostics
+
+// All forms of module import should make both declarations and macros visible.
+
+#if INCLUDE
+#include "dummy.h"
+#elif AT_IMPORT
+@import dummy;
+#elif IMPORT
+import dummy;
+#elif PRAGMA
+#pragma clang module import dummy
+#endif
+
+#ifndef DUMMY_H
+#error "macros not visible"
+#endif
+
+void *p = &dummy1;