[Headers] Reapply: Add #include_next for tgmath.h on Darwin
Reapply r289181 but rename the include guard to avoid
conflict with the one from Darwin.
Allow darwin to provide additional definitions and implementation
specifc values for tgmath.h on Apple platforms.
rdar://problem/19019845
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@298013 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 4d6eb59efd5dfda74bf2ddd78da9497055bb339f)
diff --git a/lib/Headers/tgmath.h b/lib/Headers/tgmath.h
index 318e118..34e26dc 100644
--- a/lib/Headers/tgmath.h
+++ b/lib/Headers/tgmath.h
@@ -22,12 +22,21 @@
*
\*===----------------------------------------------------------------------===*/
-#ifndef __TGMATH_H
-#define __TGMATH_H
+#ifndef __CLANG_TGMATH_H
+#define __CLANG_TGMATH_H
/* C99 7.22 Type-generic math <tgmath.h>. */
#include <math.h>
+/*
+ * Allow additional definitions and implementation-defined values on Apple
+ * platforms. This is done after #include <math.h> to avoid depcycle conflicts
+ * between libcxx and darwin in C++ modules builds.
+ */
+#if defined(__APPLE__) && __STDC_HOSTED__ && __has_include_next(<tgmath.h>)
+# include_next <tgmath.h>
+#else
+
/* C++ handles type genericity with overloading in math.h. */
#ifndef __cplusplus
#include <complex.h>
@@ -1371,4 +1380,5 @@
#undef _TG_ATTRS
#endif /* __cplusplus */
-#endif /* __TGMATH_H */
+#endif /* __has_include_next */
+#endif /* __CLANG_TGMATH_H */
diff --git a/test/Headers/Inputs/usr/include/math.h b/test/Headers/Inputs/usr/include/math.h
new file mode 100644
index 0000000..4171d4f
--- /dev/null
+++ b/test/Headers/Inputs/usr/include/math.h
@@ -0,0 +1 @@
+// math.h
diff --git a/test/Headers/Inputs/usr/include/tgmath.h b/test/Headers/Inputs/usr/include/tgmath.h
new file mode 100644
index 0000000..897962d
--- /dev/null
+++ b/test/Headers/Inputs/usr/include/tgmath.h
@@ -0,0 +1,4 @@
+#ifndef SYS_TGMATH_H
+#define SYS_TGMATH_H
+
+#endif /* SYS_TGMATH_H */
diff --git a/test/Headers/tgmath-darwin.c b/test/Headers/tgmath-darwin.c
new file mode 100644
index 0000000..916605a
--- /dev/null
+++ b/test/Headers/tgmath-darwin.c
@@ -0,0 +1,12 @@
+// REQUIRES: system-darwin
+// RUN: %clang -target x86_64-apple-darwin10 -fsyntax-only -std=c11 -isysroot %S/Inputs %s
+#include <tgmath.h>
+
+// Test the #include_next of tgmath.h works on Darwin.
+#ifndef SYS_TGMATH_H
+ #error "SYS_TGMATH_H not defined"
+#endif
+
+#ifndef __CLANG_TGMATH_H
+ #error "__CLANG_TGMATH_H not defined"
+#endif
