3 files changed, 23 insertions, 0 deletions
diff --git a/clang/test/Frontend/Inputs/SystemHeaderPrefix/line.h b/clang/test/Frontend/Inputs/SystemHeaderPrefix/line.h
new file mode 100644
index 00000000000..c4c15e58e4d
--- /dev/null
+++ b/clang/test/Frontend/Inputs/SystemHeaderPrefix/line.h
@@ -0,0 +1,2 @@
+#line 1 "foo.h"
+foo();
diff --git a/clang/test/Frontend/Inputs/SystemHeaderPrefix/noline.h b/clang/test/Frontend/Inputs/SystemHeaderPrefix/noline.h
new file mode 100644
index 00000000000..a280f9a5cce
--- /dev/null
+++ b/clang/test/Frontend/Inputs/SystemHeaderPrefix/noline.h
@@ -0,0 +1 @@
+foo();
diff --git a/clang/test/Frontend/system-header-line-directive.c b/clang/test/Frontend/system-header-line-directive.c
new file mode 100644
index 00000000000..16dde643a5b
--- /dev/null
+++ b/clang/test/Frontend/system-header-line-directive.c
@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -Wall %s -isystem %S/Inputs/SystemHeaderPrefix -verify
+// RUN: %clang_cc1 %s -E -o - -isystem %S/Inputs/SystemHeaderPrefix | FileCheck %s
+#include <noline.h>
+#include <line.h>
+
+// This tests that "#line" directives in system headers preserve system
+// header-ness just like GNU line markers that don't have filenames.  This was
+// PR30752.
+
+// expected-no-diagnostics
+
+// CHECK: # {{[0-9]+}} "{{.*}}system-header-line-directive.c" 2
+// CHECK: # 1 "{{.*}}noline.h" 1 3
+// CHECK: foo();
+// CHECK: # 4 "{{.*}}system-header-line-directive.c" 2
+// CHECK: # 1 "{{.*}}line.h" 1 3
+//      The "3" below indicates that "foo.h" is considered a system header.
+// CHECK: # 1 "foo.h" 3
+// CHECK: foo();
+// CHECK: # {{[0-9]+}} "{{.*}}system-header-line-directive.c" 2