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, 16 insertions, 11 deletions

diff --git a/clang/test/Frontend/rewrite-includes-modules.c b/clang/test/Frontend/rewrite-includes-modules.c
index 613609dfce2..e70fe0dbaf0 100644
--- a/clang/test/Frontend/rewrite-includes-modules.c
+++ b/clang/test/Frontend/rewrite-includes-modules.c
@@ -1,22 +1,27 @@
 // RUN: rm -rf %t
-// RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -x objective-c %s -F %S/../Modules/Inputs -E -frewrite-includes -o - | FileCheck %s
+// RUN: mkdir %t
+// RUN: echo 'extern int dummy;' > %t/dummy.h
+// RUN: echo 'module dummy { header "dummy.h" }' > %t/module.modulemap
+// RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t %s -I%t -E -frewrite-includes -o - | FileCheck %s
+// RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -x objective-c %s -I%t -E -frewrite-includes -o - | FileCheck %s
+// RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -x c++ %s -I%t -E -frewrite-includes -o - | FileCheck %s
 
 int bar();
-#include <Module/Module.h>
+#include "dummy.h"
 int foo();
-#include <Module/Module.h>
+#include "dummy.h"
 
 // CHECK: int bar();{{$}}
 // CHECK-NEXT: #if 0 /* expanded by -frewrite-includes */{{$}}
-// CHECK-NEXT: #include <Module/Module.h>{{$}}
+// CHECK-NEXT: #include "dummy.h"{{$}}
 // CHECK-NEXT: #endif /* expanded by -frewrite-includes */{{$}}
-// CHECK-NEXT: # 5 "{{.*[/\\]}}rewrite-includes-modules.c"{{$}}
-// CHECK-NEXT: @import Module; /* clang -frewrite-includes: implicit import */{{$}}
-// CHECK-NEXT: # 6 "{{.*[/\\]}}rewrite-includes-modules.c"{{$}}
+// CHECK-NEXT: # 10 "{{.*[/\\]}}rewrite-includes-modules.c"{{$}}
+// CHECK-NEXT: #pragma clang module import dummy /* clang -frewrite-includes: implicit import */{{$}}
+// CHECK-NEXT: # 11 "{{.*[/\\]}}rewrite-includes-modules.c"{{$}}
 // CHECK-NEXT: int foo();{{$}}
 // CHECK-NEXT: #if 0 /* expanded by -frewrite-includes */{{$}}
-// CHECK-NEXT: #include <Module/Module.h>{{$}}
+// CHECK-NEXT: #include "dummy.h"{{$}}
 // CHECK-NEXT: #endif /* expanded by -frewrite-includes */{{$}}
-// CHECK-NEXT: # 7 "{{.*[/\\]}}rewrite-includes-modules.c"{{$}}
-// CHECK-NEXT: @import Module; /* clang -frewrite-includes: implicit import */{{$}}
-// CHECK-NEXT: # 8 "{{.*[/\\]}}rewrite-includes-modules.c"{{$}}
+// CHECK-NEXT: # 12 "{{.*[/\\]}}rewrite-includes-modules.c"{{$}}
+// CHECK-NEXT: #pragma clang module import dummy /* clang -frewrite-includes: implicit import */{{$}}
+// CHECK-NEXT: # 13 "{{.*[/\\]}}rewrite-includes-modules.c"{{$}}