[AIX][clang] include_next through clang provided float.h

[daltenty]

Summary

AIX provides additional definitions in the system libc float.h that we
would like to be available to users, so we need to include_next through,
similar to what is done on some other platforms.

We also adjust the guards for some definitions which are restricted
based on language level to also be provide with the _ALL_SOURCE feature
test macro on AIX, similar to what is done by the platform float.h
header, so we don't run into cases where we don't provide the compiler
macro but still have a different definition from the system.

[hubert.reinterpretcast]

Refresh with full context

[hubert.reinterpretcast]

More comments may follow, but didn't want to delay the first one.

clang/lib/Headers/float.h

22–23

Fix the binding of the && and remove the preexisting excess parentheses.

[hubert.reinterpretcast]

clang/lib/Headers/float.h

41–44

Do not remove scoping indentation; see below where reformatting actively causes confusion.

70–73

Change in indentation makes it look like (an casual reading) that the corresponding #endif is the one on line 80.

95–98

I understand why _ALL_SOURCE matters when __STDC_HOSTED__ does not evaluate to 0, but the general logic of the file is that platform extensions are not present for freestanding. The interfaces injected via _ALL_SOURCE are platform extensions.

133–136

Same comment as above. Applies also to similar changes in the rest of the file.

clang/test/Headers/float.c

7 ↗

(On Diff #402156)

The changes to the test are for functionality that I do not believe should be present (see earlier comments).

[daltenty]

Address review comments

[hubert.reinterpretcast]

LGTM with minor comment.

clang/test/Headers/Inputs/include/float.h

3

Minor nit: Suggest to use more explicit name.

clang/test/Headers/float-aix.c

7

[daltenty]

Use more unique macro name

clang/lib/Headers/float.h

 /*===---- float.h - Characteristics of floating point types ----------------===
  *
  * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  * See https://llvm.org/LICENSE.txt for license information.
  * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  *
  *===-----------------------------------------------------------------------===
  */
 
 #ifndef __CLANG_FLOAT_H
 #define __CLANG_FLOAT_H
 
 /* If we're on MinGW, fall back to the system's float.h, which might have
  * additional definitions provided for Windows.
  * For more details see http://msdn.microsoft.com/en-us/library/y0ybw9fy.aspx
  *
- * Also fall back on Darwin to allow additional definitions and
+ * Also fall back on Darwin and AIX to allow additional definitions and
  * implementation-defined values.
  */
-#if (defined(__APPLE__) || (defined(__MINGW32__) || defined(_MSC_VER))) && \
+#if (defined(__APPLE__) || defined(__MINGW32__) || defined(_MSC_VER) ||        \
+     defined(_AIX)) &&                                                         \
     __STDC_HOSTED__ && __has_include_next(<float.h>)
 
 /* Prior to Apple's 10.7 SDK, float.h SDK header used to apply an extra level
  * of #include_next<float.h> to keep Metrowerks compilers happy. Avoid this
  * extra indirection.
  */
 #ifdef __APPLE__
 #define _FLOAT_H_
 #endif
 
 #  include_next <float.h>
 
 /* Undefine anything that we'll be redefining below. */
 #  undef FLT_EVAL_METHOD
 #  undef FLT_ROUNDS
 #  undef FLT_RADIX
 #  undef FLT_MANT_DIG
 #  undef DBL_MANT_DIG
 #  undef LDBL_MANT_DIG
-#  if __STDC_VERSION__ >= 199901L || !defined(__STRICT_ANSI__) || __cplusplus >= 201103L
+#  if __STDC_VERSION__ >= 199901L || !defined(__STRICT_ANSI__) ||              \
+      __cplusplus >= 201103L ||                                                \
+      (__STDC_HOSTED__ && defined(_AIX) && defined(_ALL_SOURCE))
 #    undef DECIMAL_DIG
 #  endif
 #  undef FLT_DIG
 #  undef DBL_DIG
 #  undef LDBL_DIG
 #  undef FLT_MIN_EXP
 #  undef DBL_MIN_EXP
 #  undef LDBL_MIN_EXP
 #  undef FLT_MIN_10_EXP

 #  undef DBL_MAX
 #  undef LDBL_MAX
 #  undef FLT_EPSILON
 #  undef DBL_EPSILON
 #  undef LDBL_EPSILON
 #  undef FLT_MIN
 #  undef DBL_MIN
 #  undef LDBL_MIN
-#  if __STDC_VERSION__ >= 201112L || !defined(__STRICT_ANSI__) || __cplusplus >= 201703L
+#  if __STDC_VERSION__ >= 201112L || !defined(__STRICT_ANSI__) ||              \
+      __cplusplus >= 201703L ||                                                \
+      (__STDC_HOSTED__ && defined(_AIX) && defined(_ALL_SOURCE))
 #    undef FLT_TRUE_MIN
 #    undef DBL_TRUE_MIN
 #    undef LDBL_TRUE_MIN
 #    undef FLT_DECIMAL_DIG
 #    undef DBL_DECIMAL_DIG
 #    undef LDBL_DECIMAL_DIG
 #    undef FLT_HAS_SUBNORM
 #    undef DBL_HAS_SUBNORM
 #    undef LDBL_HAS_SUBNORM
 #  endif
 #endif
 
 /* Characteristics of floating point types, C99 5.2.4.2.2 */
 
 #define FLT_EVAL_METHOD __FLT_EVAL_METHOD__
 #define FLT_ROUNDS (__builtin_flt_rounds())
 #define FLT_RADIX __FLT_RADIX__
 
 #define FLT_MANT_DIG __FLT_MANT_DIG__
 #define DBL_MANT_DIG __DBL_MANT_DIG__
 #define LDBL_MANT_DIG __LDBL_MANT_DIG__
 
-#if __STDC_VERSION__ >= 199901L || !defined(__STRICT_ANSI__) || __cplusplus >= 201103L
+#if __STDC_VERSION__ >= 199901L || !defined(__STRICT_ANSI__) ||                \
+    __cplusplus >= 201103L ||                                                  \
+    (__STDC_HOSTED__ && defined(_AIX) && defined(_ALL_SOURCE))
 #  define DECIMAL_DIG __DECIMAL_DIG__
 #endif
 
 #define FLT_DIG __FLT_DIG__
 #define DBL_DIG __DBL_DIG__
 #define LDBL_DIG __LDBL_DIG__
 
 #define FLT_MIN_EXP __FLT_MIN_EXP__
 #define DBL_MIN_EXP __DBL_MIN_EXP__

 #define FLT_EPSILON __FLT_EPSILON__
 #define DBL_EPSILON __DBL_EPSILON__
 #define LDBL_EPSILON __LDBL_EPSILON__
 
 #define FLT_MIN __FLT_MIN__
 #define DBL_MIN __DBL_MIN__
 #define LDBL_MIN __LDBL_MIN__
 
-#if __STDC_VERSION__ >= 201112L || !defined(__STRICT_ANSI__) || __cplusplus >= 201703L
+#if __STDC_VERSION__ >= 201112L || !defined(__STRICT_ANSI__) ||                \
+    __cplusplus >= 201703L ||                                                  \
+    (__STDC_HOSTED__ && defined(_AIX) && defined(_ALL_SOURCE))
 #  define FLT_TRUE_MIN __FLT_DENORM_MIN__
 #  define DBL_TRUE_MIN __DBL_DENORM_MIN__
 #  define LDBL_TRUE_MIN __LDBL_DENORM_MIN__
 #  define FLT_DECIMAL_DIG __FLT_DECIMAL_DIG__
 #  define DBL_DECIMAL_DIG __DBL_DECIMAL_DIG__
 #  define LDBL_DECIMAL_DIG __LDBL_DECIMAL_DIG__
 #  define FLT_HAS_SUBNORM __FLT_HAS_DENORM__
 #  define DBL_HAS_SUBNORM __DBL_HAS_DENORM__
 #  define LDBL_HAS_SUBNORM __LDBL_HAS_DENORM__

clang/test/Headers/Inputs/include/float.h

+#pragma once
+#define FLOAT_LOCAL_DEF 1

clang/test/Headers/float-aix.c

+// RUN: %clang_cc1 -triple powerpc-ibm-aix -fsyntax-only -verify -internal-isystem %S/Inputs/include %s
+// expected-no-diagnostics
+
+#include <float.h>
+
+_Static_assert(FLOAT_LOCAL_DEF, "");