fixup! [libc][math][c23] Add fabsf16 C23 math function

Fix llvm-libc-types/float16.h including internal header and exposing internal C++ using float16 stmt.

Author: overmighty

libc/include/llvm-libc-types/float16.h

@@ -1,4 +1,4 @@
-//===-- Definition of float16 type ----------------------------------------===//
+//===-- Detection of _Float16 compiler builtin type -----------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -9,12 +9,9 @@
 #ifndef LLVM_LIBC_TYPES_FLOAT16_H
 #define LLVM_LIBC_TYPES_FLOAT16_H
 
-#include "src/__support/macros/properties/compiler.h"
-
 #if defined(__FLT16_MANT_DIG__) &&                                             \
-    (!defined(LIBC_COMPILER_IS_GCC) || LIBC_COMPILER_GCC_VER >= 1301)
+    (!defined(__GNUC__) || __GNUC__ >= 13 || defined(__clang__))
 #define LIBC_TYPES_HAS_FLOAT16
-using float16 = _Float16;
 #endif
 
 #endif // LLVM_LIBC_TYPES_FLOAT16_H

libc/src/__support/macros/properties/types.h

@@ -12,7 +12,7 @@
 
 #include "hdr/float_macros.h"                      // LDBL_MANT_DIG
 #include "include/llvm-libc-types/float128.h"      // float128
-#include "include/llvm-libc-types/float16.h"       // float16
+#include "include/llvm-libc-types/float16.h"       // LIBC_TYPES_HAS_FLOAT16
 #include "src/__support/macros/properties/architectures.h"
 #include "src/__support/macros/properties/compiler.h"
 #include "src/__support/macros/properties/cpu_features.h"
@@ -40,8 +40,11 @@
 #endif // defined(__SIZEOF_INT128__)
 
 // -- float16 support ---------------------------------------------------------
-// LIBC_TYPES_HAS_FLOAT16 and 'float16' type are provided by
-// "include/llvm-libc-types/float16.h"
+// LIBC_TYPES_HAS_FLOAT16 is provided by "include/llvm-libc-types/float16.h"
+#ifdef LIBC_TYPES_HAS_FLOAT16
+// Type alias for internal use.
+using float16 = _Float16;
+#endif // LIBC_TYPES_HAS_FLOAT16
 
 // -- float128 support --------------------------------------------------------
 // LIBC_TYPES_HAS_FLOAT128 and 'float128' type are provided by

libc/src/math/fabsf16.h

@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_SRC_MATH_FABSF16_H
 #define LLVM_LIBC_SRC_MATH_FABSF16_H
 
-#include "include/llvm-libc-types/float16.h"
+#include "src/__support/macros/properties/types.h"
 
 namespace LIBC_NAMESPACE {