Add -fuse-line-directive flag to control usage of #line with -E

Currently -fms-extensions controls this behavior, which doesn't make
much sense. It means we can't identify what is and isn't a system header
when compiling our own preprocessed output, because #line doesn't
represent this information.

If someone is feeding Clang's preprocessed output to another compiler,
they can use this flag.

Fixes PR20553.

Reviewers: rsmith

Differential Revision: http://reviews.llvm.org/D5217

llvm-svn: 230587

1 files changed, 22 insertions, 0 deletions

diff --git a/clang/test/Frontend/rewrite-includes-line-markers.c b/clang/test/Frontend/rewrite-includes-line-markers.c
new file mode 100644
index 00000000000..14692a19e9b
--- /dev/null
+++ b/clang/test/Frontend/rewrite-includes-line-markers.c
@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 -E -frewrite-includes -I %S/Inputs %s | FileCheck %s --check-prefix=GNU
+// RUN: %clang_cc1 -E -frewrite-includes -fuse-line-directives -I %S/Inputs %s | FileCheck %s --check-prefix=LINE
+#include "test.h"
+int f() { return x; }
+
+// GNU: {{^}}# 1 "{{.*}}rewrite-includes-line-markers.c"
+// GNU: {{^}}#include "test.h"
+// GNU: {{^}}# 1 "{{.*}}test.h"
+// GNU: {{^}}#include "test2.h"
+// GNU: {{^}}# 1 "{{.*}}test2.h"
+// GNU: {{^}}int x;
+// GNU: {{^}}# 4 "{{.*}}rewrite-includes-line-markers.c" 2
+// GNU: {{^}}int f() { return x; }
+
+// LINE: {{^}}#line 1 "{{.*}}rewrite-includes-line-markers.c"
+// LINE: {{^}}#include "test.h"
+// LINE: {{^}}#line 1 "{{.*}}test.h"
+// LINE: {{^}}#include "test2.h"
+// LINE: {{^}}#line 1 "{{.*}}test2.h"
+// LINE: {{^}}int x;
+// LINE: {{^}}#line 4 "{{.*}}rewrite-includes-line-markers.c"
+// LINE: {{^}}int f() { return x; }