[PATCH 1/6] limits-h: add BOOL_MAX, BOOL_WIDTH

[Paul Eggert]

* doc/posix-headers/limits.texi (limits.h): Document them.
* lib/limits.in.h: Also define CHAR_WIDTH etc. if C2x.
(BOOL_MAX, BOOL_WIDTH): New macros, from C2x.
* m4/limits-h.m4 (gl_LIMITS_H): Also check BOOL_WIDTH.
---
 ChangeLog                     |  8 ++++++++
 doc/posix-headers/limits.texi |  4 ++++
 lib/limits.in.h               | 16 +++++++++++++---
 m4/limits-h.m4                |  3 ++-
 4 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index d8a9bb1b8..dbf648571 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2021-07-30  Paul Eggert  <eggert@cs.ucla.edu>
+
+       limits-h: add BOOL_MAX, BOOL_WIDTH
+       * doc/posix-headers/limits.texi (limits.h): Document them.
+       * lib/limits.in.h: Also define CHAR_WIDTH etc. if C2x.
+       (BOOL_MAX, BOOL_WIDTH): New macros, from C2x.
+       * m4/limits-h.m4 (gl_LIMITS_H): Also check BOOL_WIDTH.
+
 2021-07-28  Simon Josefsson  <simon@josefsson.org>
 
        maintainer-makefile: Respect cfg.mk setting announcement_Cc_,
diff --git a/doc/posix-headers/limits.texi b/doc/posix-headers/limits.texi
index edfc71619..22dc4239f 100644
--- a/doc/posix-headers/limits.texi
+++ b/doc/posix-headers/limits.texi
@@ -17,6 +17,10 @@ glibc 2.11 without @code{-D_GNU_SOURCE}, Cygwin, mingw, MSVC 
14.
 @item
 Macros like @code{CHAR_WIDTH} are not defined on some platforms:
 glibc 2.24, NetBSD 9.0, many others.
+@item
+The macros @code{BOOL_MAX} and @code{BOOL_WIDTH} are not defined on
+some platforms:
+glibc 2.32, many others.
 @end itemize
 
 Portability problems fixed by Gnulib module @code{gethostname}:
diff --git a/lib/limits.in.h b/lib/limits.in.h
index 65ea12dbc..2ecafebb0 100644
--- a/lib/limits.in.h
+++ b/lib/limits.in.h
@@ -99,10 +99,11 @@
 # endif
 #endif
 
-/* Macros specified by ISO/IEC TS 18661-1:2014.  */
+/* Macros specified by C2x and by ISO/IEC TS 18661-1:2014.  */
 
 #if (! defined ULLONG_WIDTH                                             \
-     && (defined _GNU_SOURCE || defined __STDC_WANT_IEC_60559_BFP_EXT__))
+     && (defined _GNU_SOURCE || defined __STDC_WANT_IEC_60559_BFP_EXT__ \
+         || (defined __STDC_VERSION__ && 201710 < __STDC_VERSION__)))
 # define CHAR_WIDTH _GL_INTEGER_WIDTH (CHAR_MIN, CHAR_MAX)
 # define SCHAR_WIDTH _GL_INTEGER_WIDTH (SCHAR_MIN, SCHAR_MAX)
 # define UCHAR_WIDTH _GL_INTEGER_WIDTH (0, UCHAR_MAX)
@@ -114,7 +115,16 @@
 # define ULONG_WIDTH _GL_INTEGER_WIDTH (0, ULONG_MAX)
 # define LLONG_WIDTH _GL_INTEGER_WIDTH (LLONG_MIN, LLONG_MAX)
 # define ULLONG_WIDTH _GL_INTEGER_WIDTH (0, ULLONG_MAX)
-#endif /* !ULLONG_WIDTH && (_GNU_SOURCE || __STDC_WANT_IEC_60559_BFP_EXT__) */
+#endif
+
+/* Macros specified by C2x.  */
+
+#if (! defined BOOL_WIDTH \
+     && (defined _GNU_SOURCE \
+         || (defined __STDC_VERSION__ && 201710 < __STDC_VERSION__)))
+# define BOOL_MAX 1
+# define BOOL_WIDTH 1
+#endif
 
 #endif /* _@GUARD_PREFIX@_LIMITS_H */
 #endif /* _@GUARD_PREFIX@_LIMITS_H */
diff --git a/m4/limits-h.m4 b/m4/limits-h.m4
index 70dbb7dcf..00c9fe9e5 100644
--- a/m4/limits-h.m4
+++ b/m4/limits-h.m4
@@ -11,7 +11,7 @@ AC_DEFUN_ONCE([gl_LIMITS_H],
 [
   gl_CHECK_NEXT_HEADERS([limits.h])
 
-  AC_CACHE_CHECK([whether limits.h has LLONG_MAX, WORD_BIT, ULLONG_WIDTH etc.],
+  AC_CACHE_CHECK([whether limits.h has WORD_BIT, BOOL_WIDTH etc.],
     [gl_cv_header_limits_width],
     [AC_COMPILE_IFELSE(
        [AC_LANG_PROGRAM(
@@ -22,6 +22,7 @@ AC_DEFUN_ONCE([gl_LIMITS_H],
             long long llm = LLONG_MAX;
             int wb = WORD_BIT;
             int ullw = ULLONG_WIDTH;
+            int bw = BOOL_WIDTH;
           ]])],
        [gl_cv_header_limits_width=yes],
        [gl_cv_header_limits_width=no])])
-- 
2.31.1