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Re: Interference between two installations of gnulib


From: Bruno Haible
Subject: Re: Interference between two installations of gnulib
Date: Sun, 18 Apr 2021 13:16:12 +0200
User-agent: KMail/5.1.3 (Linux/4.4.0-206-generic; KDE/5.18.0; x86_64; ; )

I wrote:
> The problem is that the macro gl_STDIO_H_REQUIRE_DEFAULTS must only be 
> invoked,
> never AC_REQUIREd. Hence all gl_STDIO_MODULE_INDICATOR invocations must also
> only be invoked, never AC_REQUIREd.

This deserves to be documented.


2021-04-18  Bruno Haible  <bruno@clisp.org>

        Add comments after 2021-04-11 change.
        * m4/*_h.m4: Add comments regarding *_REQUIRE_DEFAULTS and
        *_MODULE_INDICATOR macros.

diff --git a/m4/arpa_inet_h.m4 b/m4/arpa_inet_h.m4
index 868ebdf..a3ba256 100644
--- a/m4/arpa_inet_h.m4
+++ b/m4/arpa_inet_h.m4
@@ -1,4 +1,4 @@
-# arpa_inet_h.m4 serial 16
+# arpa_inet_h.m4 serial 17
 dnl Copyright (C) 2006, 2008-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -40,6 +40,10 @@ AC_DEFUN_ONCE([gl_ARPA_INET_H],
     ]], [inet_ntop inet_pton])
 ])
 
+# gl_ARPA_INET_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_ARPA_INET_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -47,6 +51,9 @@ AC_DEFUN([gl_ARPA_INET_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_SET_VARIABLE([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_ARPA_INET_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_ARPA_INET_H_MODULE_INDICATOR_DEFAULTS], 
[
diff --git a/m4/ctype.m4 b/m4/ctype.m4
index d48847a..efdae45 100644
--- a/m4/ctype.m4
+++ b/m4/ctype.m4
@@ -1,4 +1,4 @@
-# ctype_h.m4 serial 8
+# ctype_h.m4 serial 9
 dnl Copyright (C) 2009-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -17,6 +17,10 @@ AC_DEFUN_ONCE([gl_CTYPE_H],
     ]], [isblank])
 ])
 
+# gl_CTYPE_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_CTYPE_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -24,6 +28,9 @@ AC_DEFUN([gl_CTYPE_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_SET_VARIABLE([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_CTYPE_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_CTYPE_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/dirent_h.m4 b/m4/dirent_h.m4
index 3bcf34b..17e2a20 100644
--- a/m4/dirent_h.m4
+++ b/m4/dirent_h.m4
@@ -1,4 +1,4 @@
-# dirent_h.m4 serial 18
+# dirent_h.m4 serial 19
 dnl Copyright (C) 2008-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -27,6 +27,10 @@ AC_DEFUN_ONCE([gl_DIRENT_H],
     ]], [alphasort closedir dirfd fdopendir opendir readdir rewinddir scandir])
 ])
 
+# gl_DIRENT_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_DIRENT_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -36,6 +40,9 @@ AC_DEFUN([gl_DIRENT_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_DIRENT_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_DIRENT_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/fcntl_h.m4 b/m4/fcntl_h.m4
index 822bf02..aba4473 100644
--- a/m4/fcntl_h.m4
+++ b/m4/fcntl_h.m4
@@ -1,4 +1,4 @@
-# serial 19
+# serial 20
 # Configure fcntl.h.
 dnl Copyright (C) 2006-2007, 2009-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
@@ -26,6 +26,10 @@ AC_DEFUN_ONCE([gl_FCNTL_H],
     ]], [fcntl openat])
 ])
 
+# gl_FCNTL_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_FCNTL_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -35,6 +39,9 @@ AC_DEFUN([gl_FCNTL_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_FCNTL_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_FCNTL_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/fnmatch_h.m4 b/m4/fnmatch_h.m4
index d12c698..e9bcb66 100644
--- a/m4/fnmatch_h.m4
+++ b/m4/fnmatch_h.m4
@@ -1,4 +1,4 @@
-# fnmatch_h.m4 serial 6
+# fnmatch_h.m4 serial 7
 dnl Copyright (C) 2009-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -57,6 +57,10 @@ AC_DEFUN([gl_REPLACE_FNMATCH_H],
   AM_CONDITIONAL([GL_GENERATE_FNMATCH_H], [test -n "$FNMATCH_H"])
 ])
 
+# gl_FNMATCH_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_FNMATCH_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -66,6 +70,9 @@ AC_DEFUN([gl_FNMATCH_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_FNMATCH_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_FNMATCH_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/glob_h.m4 b/m4/glob_h.m4
index 68e7b4d..5332c81 100644
--- a/m4/glob_h.m4
+++ b/m4/glob_h.m4
@@ -1,4 +1,4 @@
-# glob_h.m4 serial 7
+# glob_h.m4 serial 8
 dnl Copyright (C) 2018-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -52,6 +52,10 @@ AC_DEFUN([gl_REPLACE_GLOB_H],
   AM_CONDITIONAL([GL_GENERATE_GLOB_H], [test -n "$GLOB_H"])
 ])
 
+# gl_GLOB_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_GLOB_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -61,6 +65,9 @@ AC_DEFUN([gl_GLOB_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_GLOB_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_GLOB_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/iconv_h.m4 b/m4/iconv_h.m4
index e4fccc0..2940988 100644
--- a/m4/iconv_h.m4
+++ b/m4/iconv_h.m4
@@ -1,4 +1,4 @@
-# iconv_h.m4 serial 14
+# iconv_h.m4 serial 15
 dnl Copyright (C) 2007-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -29,6 +29,10 @@ AC_DEFUN([gl_REPLACE_ICONV_H],
   AM_CONDITIONAL([GL_GENERATE_ICONV_H], [test -n "$ICONV_H"])
 ])
 
+# gl_ICONV_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_ICONV_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -36,6 +40,9 @@ AC_DEFUN([gl_ICONV_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_SET_VARIABLE([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_ICONV_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_ICONV_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/inttypes.m4 b/m4/inttypes.m4
index 4e81446..64b1de5 100644
--- a/m4/inttypes.m4
+++ b/m4/inttypes.m4
@@ -1,4 +1,4 @@
-# inttypes.m4 serial 34
+# inttypes.m4 serial 35
 dnl Copyright (C) 2006-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -136,6 +136,10 @@ AC_DEFUN([gl_INTTYPES_CHECK_LONG_LONG_INT_CONDITION],
   AC_SUBST([$1])
 ])
 
+# gl_INTTYPES_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_INTTYPES_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -143,6 +147,9 @@ AC_DEFUN([gl_INTTYPES_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_SET_VARIABLE([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_INTTYPES_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_INTTYPES_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/langinfo_h.m4 b/m4/langinfo_h.m4
index 8e199db..87959f7 100644
--- a/m4/langinfo_h.m4
+++ b/m4/langinfo_h.m4
@@ -1,4 +1,4 @@
-# langinfo_h.m4 serial 11
+# langinfo_h.m4 serial 12
 dnl Copyright (C) 2009-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -104,6 +104,10 @@ int a = YESEXPR;
     ]], [nl_langinfo])
 ])
 
+# gl_LANGINFO_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_LANGINFO_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -113,6 +117,9 @@ AC_DEFUN([gl_LANGINFO_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_LANGINFO_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_LANGINFO_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/locale_h.m4 b/m4/locale_h.m4
index 44f0b49..444a381 100644
--- a/m4/locale_h.m4
+++ b/m4/locale_h.m4
@@ -1,4 +1,4 @@
-# locale_h.m4 serial 27
+# locale_h.m4 serial 28
 dnl Copyright (C) 2007, 2009-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -129,6 +129,10 @@ AC_DEFUN([gl_LOCALE_T],
   AC_SUBST([HAVE_XLOCALE_H])
 ])
 
+# gl_LOCALE_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_LOCALE_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -138,6 +142,9 @@ AC_DEFUN([gl_LOCALE_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_LOCALE_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_LOCALE_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/malloc_h.m4 b/m4/malloc_h.m4
index 6144ce5..fe7ca09 100644
--- a/m4/malloc_h.m4
+++ b/m4/malloc_h.m4
@@ -1,4 +1,4 @@
-# malloc_h.m4 serial 3
+# malloc_h.m4 serial 4
 dnl Copyright (C) 2020-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -29,6 +29,10 @@ AC_DEFUN_ONCE([gl_MALLOC_H],
     ]], [memalign])
 ])
 
+# gl_MALLOC_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_MALLOC_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -38,6 +42,9 @@ AC_DEFUN([gl_MALLOC_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_MALLOC_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_MALLOC_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/math_h.m4 b/m4/math_h.m4
index 384aa9c..b3a10c3 100644
--- a/m4/math_h.m4
+++ b/m4/math_h.m4
@@ -1,4 +1,4 @@
-# math_h.m4 serial 124
+# math_h.m4 serial 125
 dnl Copyright (C) 2007-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -53,6 +53,10 @@ AC_DEFUN_ONCE([gl_MATH_H],
      tanf tanl tanhf trunc truncf truncl])
 ])
 
+# gl_MATH_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_MATH_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -62,6 +66,9 @@ AC_DEFUN([gl_MATH_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_MATH_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_MATH_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/monetary_h.m4 b/m4/monetary_h.m4
index dc56c1b..8ffa2af 100644
--- a/m4/monetary_h.m4
+++ b/m4/monetary_h.m4
@@ -1,4 +1,4 @@
-# monetary_h.m4 serial 7
+# monetary_h.m4 serial 8
 dnl Copyright (C) 2017-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -47,6 +47,10 @@ AC_DEFUN_ONCE([gl_MONETARY_H],
   AM_CONDITIONAL([GL_GENERATE_MONETARY_H], [test -n "$MONETARY_H"])
 ])
 
+# gl_MONETARY_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_MONETARY_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -54,6 +58,9 @@ AC_DEFUN([gl_MONETARY_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_SET_VARIABLE([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_MONETARY_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_MONETARY_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/netdb_h.m4 b/m4/netdb_h.m4
index 69f7b78..eb7c3b8 100644
--- a/m4/netdb_h.m4
+++ b/m4/netdb_h.m4
@@ -1,4 +1,4 @@
-# netdb_h.m4 serial 14
+# netdb_h.m4 serial 15
 dnl Copyright (C) 2008-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -21,6 +21,10 @@ AC_DEFUN_ONCE([gl_NETDB_H],
     [getaddrinfo freeaddrinfo gai_strerror getnameinfo])
 ])
 
+# gl_NETDB_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_NETDB_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -30,6 +34,9 @@ AC_DEFUN([gl_NETDB_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_NETDB_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_NETDB_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/poll_h.m4 b/m4/poll_h.m4
index 3037676..1f0d796 100644
--- a/m4/poll_h.m4
+++ b/m4/poll_h.m4
@@ -1,4 +1,4 @@
-# poll_h.m4 serial 5
+# poll_h.m4 serial 6
 dnl Copyright (C) 2010-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -31,6 +31,10 @@ AC_DEFUN_ONCE([gl_POLL_H],
     [poll])
 ])
 
+# gl_POLL_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_POLL_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -40,6 +44,9 @@ AC_DEFUN([gl_POLL_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_POLL_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_POLL_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/pthread_h.m4 b/m4/pthread_h.m4
index d07d85d..62a6ca8 100644
--- a/m4/pthread_h.m4
+++ b/m4/pthread_h.m4
@@ -1,4 +1,4 @@
-# pthread_h.m4 serial 7
+# pthread_h.m4 serial 8
 dnl Copyright (C) 2009-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -137,6 +137,10 @@ AC_DEFUN_ONCE([gl_PTHREAD_H],
   AC_SUBST([LIB_PTHREAD])
 ])
 
+# gl_PTHREAD_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_PTHREAD_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -146,6 +150,9 @@ AC_DEFUN([gl_PTHREAD_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_PTHREAD_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_PTHREAD_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/pty_h.m4 b/m4/pty_h.m4
index 8fe5465..172e6d6 100644
--- a/m4/pty_h.m4
+++ b/m4/pty_h.m4
@@ -1,4 +1,4 @@
-# pty_h.m4 serial 13
+# pty_h.m4 serial 14
 dnl Copyright (C) 2009-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -50,6 +50,10 @@ AC_DEFUN_ONCE([gl_PTY_H],
     ]], [forkpty openpty])
 ])
 
+# gl_PTY_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_PTY_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -59,6 +63,9 @@ AC_DEFUN([gl_PTY_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_PTY_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_PTY_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/sched_h.m4 b/m4/sched_h.m4
index 03377aa..a840e3d 100644
--- a/m4/sched_h.m4
+++ b/m4/sched_h.m4
@@ -1,4 +1,4 @@
-# sched_h.m4 serial 14
+# sched_h.m4 serial 15
 dnl Copyright (C) 2008-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -73,6 +73,10 @@ AC_DEFUN_ONCE([gl_SCHED_H],
     ]], [sched_yield])
 ])
 
+# gl_SCHED_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SCHED_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -82,6 +86,9 @@ AC_DEFUN([gl_SCHED_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SCHED_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_SCHED_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/search_h.m4 b/m4/search_h.m4
index 6cdcfdf..1d1e8bf 100644
--- a/m4/search_h.m4
+++ b/m4/search_h.m4
@@ -1,4 +1,4 @@
-# search_h.m4 serial 14
+# search_h.m4 serial 15
 dnl Copyright (C) 2007-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -44,6 +44,10 @@ AC_DEFUN_ONCE([gl_SEARCH_H],
   AC_REQUIRE([AC_C_RESTRICT])
 ])
 
+# gl_SEARCH_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SEARCH_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -53,6 +57,9 @@ AC_DEFUN([gl_SEARCH_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SEARCH_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_SEARCH_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/signal_h.m4 b/m4/signal_h.m4
index f68e890..8b93880 100644
--- a/m4/signal_h.m4
+++ b/m4/signal_h.m4
@@ -1,4 +1,4 @@
-# signal_h.m4 serial 21
+# signal_h.m4 serial 22
 dnl Copyright (C) 2007-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -52,6 +52,10 @@ AC_DEFUN([gl_CHECK_TYPE_SIGSET_T],
   fi
 ])
 
+# gl_SIGNAL_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SIGNAL_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -61,6 +65,9 @@ AC_DEFUN([gl_SIGNAL_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SIGNAL_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_SIGNAL_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/spawn_h.m4 b/m4/spawn_h.m4
index 7dc515f..134b7b9 100644
--- a/m4/spawn_h.m4
+++ b/m4/spawn_h.m4
@@ -1,4 +1,4 @@
-# spawn_h.m4 serial 20
+# spawn_h.m4 serial 21
 dnl Copyright (C) 2008-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -79,6 +79,10 @@ AC_DEFUN([gl_HAVE_POSIX_SPAWN],
   fi
 ])
 
+# gl_SPAWN_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SPAWN_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -88,6 +92,9 @@ AC_DEFUN([gl_SPAWN_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SPAWN_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_SPAWN_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/stddef_h.m4 b/m4/stddef_h.m4
index 53a69dd..1303d2e 100644
--- a/m4/stddef_h.m4
+++ b/m4/stddef_h.m4
@@ -1,4 +1,4 @@
-# stddef_h.m4 serial 10
+# stddef_h.m4 serial 11
 dnl Copyright (C) 2009-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -68,6 +68,10 @@ AC_DEFUN_ONCE([gl_STDDEF_H],
   fi
 ])
 
+# gl_STDDEF_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_STDDEF_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -75,6 +79,9 @@ AC_DEFUN([gl_STDDEF_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_SET_VARIABLE([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_STDDEF_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_STDDEF_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/stdio_h.m4 b/m4/stdio_h.m4
index d9820e4..e704383 100644
--- a/m4/stdio_h.m4
+++ b/m4/stdio_h.m4
@@ -1,4 +1,4 @@
-# stdio_h.m4 serial 55
+# stdio_h.m4 serial 56
 dnl Copyright (C) 2007-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -93,6 +93,10 @@ AC_DEFUN_ONCE([gl_STDIO_H],
   fi
 ])
 
+# gl_STDIO_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_STDIO_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -102,6 +106,9 @@ AC_DEFUN([gl_STDIO_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_STDIO_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_STDIO_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/stdlib_h.m4 b/m4/stdlib_h.m4
index e938b5a..2de57f7 100644
--- a/m4/stdlib_h.m4
+++ b/m4/stdlib_h.m4
@@ -1,4 +1,4 @@
-# stdlib_h.m4 serial 61
+# stdlib_h.m4 serial 62
 dnl Copyright (C) 2007-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -46,6 +46,10 @@ AC_DEFUN_ONCE([gl_STDLIB_H],
   fi
 ])
 
+# gl_STDLIB_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_STDLIB_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -55,6 +59,9 @@ AC_DEFUN([gl_STDLIB_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_STDLIB_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_STDLIB_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/string_h.m4 b/m4/string_h.m4
index e44461f..80d1e58 100644
--- a/m4/string_h.m4
+++ b/m4/string_h.m4
@@ -5,7 +5,7 @@
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
 
-# serial 31
+# serial 32
 
 # Written by Paul Eggert.
 
@@ -28,6 +28,10 @@ AC_DEFUN_ONCE([gl_STRING_H],
   AC_REQUIRE([AC_C_RESTRICT])
 ])
 
+# gl_STRING_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_STRING_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -37,6 +41,9 @@ AC_DEFUN([gl_STRING_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_STRING_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_STRING_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/strings_h.m4 b/m4/strings_h.m4
index da19d1b..69de32a 100644
--- a/m4/strings_h.m4
+++ b/m4/strings_h.m4
@@ -1,5 +1,5 @@
 # Configure a replacement for <strings.h>.
-# serial 8
+# serial 9
 
 # Copyright (C) 2007, 2009-2021 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@@ -30,6 +30,10 @@ AC_DEFUN_ONCE([gl_STRINGS_H],
     ]], [ffs strcasecmp strncasecmp])
 ])
 
+# gl_STRINGS_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_STRINGS_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -37,6 +41,9 @@ AC_DEFUN([gl_STRINGS_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_SET_VARIABLE([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_STRINGS_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_STRINGS_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/sys_file_h.m4 b/m4/sys_file_h.m4
index 4515c73..bcde4d7 100644
--- a/m4/sys_file_h.m4
+++ b/m4/sys_file_h.m4
@@ -1,5 +1,5 @@
 # Configure a replacement for <sys/file.h>.
-# serial 8
+# serial 9
 
 # Copyright (C) 2008-2021 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@@ -28,12 +28,19 @@ AC_DEFUN_ONCE([gl_SYS_FILE_H],
     ]], [flock])
 ])
 
+# gl_SYS_FILE_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_FILE_MODULE_INDICATOR],
 [
   gl_SYS_FILE_H_REQUIRE_DEFAULTS
   gl_MODULE_INDICATOR_SET_VARIABLE([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SYS_FILE_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_FILE_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/sys_ioctl_h.m4 b/m4/sys_ioctl_h.m4
index 9f36509..cd00410 100644
--- a/m4/sys_ioctl_h.m4
+++ b/m4/sys_ioctl_h.m4
@@ -1,4 +1,4 @@
-# sys_ioctl_h.m4 serial 14
+# sys_ioctl_h.m4 serial 15
 dnl Copyright (C) 2008-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -44,6 +44,10 @@ AC_DEFUN_ONCE([gl_SYS_IOCTL_H],
     ]], [ioctl])
 ])
 
+# gl_SYS_IOCTL_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_IOCTL_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -53,6 +57,9 @@ AC_DEFUN([gl_SYS_IOCTL_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SYS_IOCTL_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_IOCTL_H_MODULE_INDICATOR_DEFAULTS], 
[
diff --git a/m4/sys_random_h.m4 b/m4/sys_random_h.m4
index 621601f..37bc316 100644
--- a/m4/sys_random_h.m4
+++ b/m4/sys_random_h.m4
@@ -1,4 +1,4 @@
-# sys_random_h.m4 serial 7
+# sys_random_h.m4 serial 8
 dnl Copyright (C) 2020-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -35,6 +35,10 @@ AC_DEFUN_ONCE([gl_SYS_RANDOM_H],
     [getrandom])
 ])
 
+# gl_SYS_RANDOM_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_RANDOM_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -44,6 +48,9 @@ AC_DEFUN([gl_SYS_RANDOM_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SYS_RANDOM_H_REQUIRE_DEFAULTS],
 [
   
m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_RANDOM_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/sys_resource_h.m4 b/m4/sys_resource_h.m4
index 4570a01..0b85e7b 100644
--- a/m4/sys_resource_h.m4
+++ b/m4/sys_resource_h.m4
@@ -1,4 +1,4 @@
-# sys_resource_h.m4 serial 4
+# sys_resource_h.m4 serial 5
 dnl Copyright (C) 2012-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -30,6 +30,10 @@ AC_DEFUN_ONCE([gl_SYS_RESOURCE_H],
     [getrusage])
 ])
 
+# gl_SYS_RESOURCE_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_RESOURCE_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -39,6 +43,9 @@ AC_DEFUN([gl_SYS_RESOURCE_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SYS_RESOURCE_H_REQUIRE_DEFAULTS],
 [
   
m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_RESOURCE_H_MODULE_INDICATOR_DEFAULTS], 
[
diff --git a/m4/sys_select_h.m4 b/m4/sys_select_h.m4
index 198bb05..2e7d140 100644
--- a/m4/sys_select_h.m4
+++ b/m4/sys_select_h.m4
@@ -1,4 +1,4 @@
-# sys_select_h.m4 serial 22
+# sys_select_h.m4 serial 23
 dnl Copyright (C) 2006-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -75,6 +75,10 @@ AC_DEFUN_ONCE([gl_SYS_SELECT_H],
     ]], [pselect select])
 ])
 
+# gl_SYS_SELECT_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_SELECT_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -84,6 +88,9 @@ AC_DEFUN([gl_SYS_SELECT_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SYS_SELECT_H_REQUIRE_DEFAULTS],
 [
   
m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_SELECT_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/sys_socket_h.m4 b/m4/sys_socket_h.m4
index 8a8075c..5676a0d 100644
--- a/m4/sys_socket_h.m4
+++ b/m4/sys_socket_h.m4
@@ -1,4 +1,4 @@
-# sys_socket_h.m4 serial 27
+# sys_socket_h.m4 serial 28
 dnl Copyright (C) 2005-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -156,6 +156,10 @@ AC_DEFUN([gl_PREREQ_SYS_H_WS2TCPIP],
   AC_SUBST([HAVE_WS2TCPIP_H])
 ])
 
+# gl_SYS_SOCKET_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_SOCKET_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -165,6 +169,9 @@ AC_DEFUN([gl_SYS_SOCKET_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SYS_SOCKET_H_REQUIRE_DEFAULTS],
 [
   
m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_SOCKET_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/sys_stat_h.m4 b/m4/sys_stat_h.m4
index 02a621c..ac91d42 100644
--- a/m4/sys_stat_h.m4
+++ b/m4/sys_stat_h.m4
@@ -1,4 +1,4 @@
-# sys_stat_h.m4 serial 40   -*- Autoconf -*-
+# sys_stat_h.m4 serial 41   -*- Autoconf -*-
 dnl Copyright (C) 2006-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -52,6 +52,10 @@ AC_DEFUN_ONCE([gl_SYS_STAT_H],
   AC_REQUIRE([AC_C_RESTRICT])
 ])
 
+# gl_SYS_STAT_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_STAT_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -61,6 +65,9 @@ AC_DEFUN([gl_SYS_STAT_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SYS_STAT_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_STAT_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/sys_time_h.m4 b/m4/sys_time_h.m4
index 81b755d..c425a96 100644
--- a/m4/sys_time_h.m4
+++ b/m4/sys_time_h.m4
@@ -1,5 +1,5 @@
 # Configure a replacement for <sys/time.h>.
-# serial 11
+# serial 12
 
 # Copyright (C) 2007, 2009-2021 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@@ -84,6 +84,10 @@ AC_DEFUN_ONCE([gl_SYS_TIME_H],
     ]], [gettimeofday])
 ])
 
+# gl_SYS_TIME_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_TIME_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -93,6 +97,9 @@ AC_DEFUN([gl_SYS_TIME_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SYS_TIME_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_TIME_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/sys_times_h.m4 b/m4/sys_times_h.m4
index c83a9d6..577ead6 100644
--- a/m4/sys_times_h.m4
+++ b/m4/sys_times_h.m4
@@ -1,5 +1,5 @@
 # Configure a replacement for <sys/times.h>.
-# serial 10
+# serial 11
 
 # Copyright (C) 2008-2021 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@@ -36,6 +36,10 @@ AC_DEFUN_ONCE([gl_SYS_TIMES_H],
     ]], [times])
 ])
 
+# gl_SYS_TIMES_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_TIMES_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -43,6 +47,9 @@ AC_DEFUN([gl_SYS_TIMES_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_SET_VARIABLE([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SYS_TIMES_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_TIMES_H_MODULE_INDICATOR_DEFAULTS], 
[
diff --git a/m4/sys_types_h.m4 b/m4/sys_types_h.m4
index 53f2c09..6dd6fee 100644
--- a/m4/sys_types_h.m4
+++ b/m4/sys_types_h.m4
@@ -1,4 +1,4 @@
-# sys_types_h.m4 serial 12
+# sys_types_h.m4 serial 13
 dnl Copyright (C) 2011-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -31,6 +31,9 @@ AC_DEFUN_ONCE([gl_SYS_TYPES_H],
   AC_SUBST([WINDOWS_STAT_INODES])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SYS_TYPES_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_TYPE_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/sys_uio_h.m4 b/m4/sys_uio_h.m4
index baea88a..fa176e0 100644
--- a/m4/sys_uio_h.m4
+++ b/m4/sys_uio_h.m4
@@ -1,4 +1,4 @@
-# sys_uio_h.m4 serial 2
+# sys_uio_h.m4 serial 3
 dnl Copyright (C) 2011-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -17,6 +17,10 @@ AC_DEFUN_ONCE([gl_SYS_UIO_H],
   AC_SUBST([HAVE_SYS_UIO_H])
 ])
 
+# gl_SYS_UIO_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_UIO_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -26,6 +30,9 @@ AC_DEFUN([gl_SYS_UIO_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SYS_UIO_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_UIO_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/sys_utsname_h.m4 b/m4/sys_utsname_h.m4
index cc1d849..9a0f0e3 100644
--- a/m4/sys_utsname_h.m4
+++ b/m4/sys_utsname_h.m4
@@ -1,4 +1,4 @@
-# sys_utsname_h.m4 serial 10
+# sys_utsname_h.m4 serial 11
 dnl Copyright (C) 2009-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -38,6 +38,10 @@ AC_DEFUN_ONCE([gl_SYS_UTSNAME_H],
     ]], [uname])
 ])
 
+# gl_SYS_UTSNAME_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_UTSNAME_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -45,6 +49,9 @@ AC_DEFUN([gl_SYS_UTSNAME_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_SET_VARIABLE([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SYS_UTSNAME_H_REQUIRE_DEFAULTS],
 [
   
m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_UTSNAME_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/sys_wait_h.m4 b/m4/sys_wait_h.m4
index 294ab52..d7c412a 100644
--- a/m4/sys_wait_h.m4
+++ b/m4/sys_wait_h.m4
@@ -1,4 +1,4 @@
-# sys_wait_h.m4 serial 8
+# sys_wait_h.m4 serial 9
 dnl Copyright (C) 2008-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -20,6 +20,10 @@ AC_DEFUN_ONCE([gl_SYS_WAIT_H],
     [waitpid])
 ])
 
+# gl_SYS_WAIT_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_SYS_WAIT_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -29,6 +33,9 @@ AC_DEFUN([gl_SYS_WAIT_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_SYS_WAIT_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_WAIT_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/termios_h.m4 b/m4/termios_h.m4
index c7d57fc..861b232 100644
--- a/m4/termios_h.m4
+++ b/m4/termios_h.m4
@@ -1,4 +1,4 @@
-# termios_h.m4 serial 6
+# termios_h.m4 serial 7
 dnl Copyright (C) 2010-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -25,6 +25,10 @@ AC_DEFUN_ONCE([gl_TERMIOS_H],
     [tcgetsid])
 ])
 
+# gl_TERMIOS_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_TERMIOS_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -34,6 +38,9 @@ AC_DEFUN([gl_TERMIOS_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_TERMIOS_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_TERMIOS_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/threads.m4 b/m4/threads.m4
index 2a2bfea..53ec6d5 100644
--- a/m4/threads.m4
+++ b/m4/threads.m4
@@ -1,4 +1,4 @@
-# threads.m4 serial 9
+# threads.m4 serial 10
 dnl Copyright (C) 2019-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -137,6 +137,10 @@ AC_DEFUN([gl_THREAD_LOCAL_DEFINITION],
 #endif
 ]])
 
+# gl_THREADS_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_THREADS_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -146,6 +150,9 @@ AC_DEFUN([gl_THREADS_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_THREADS_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_THREADS_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/time_h.m4 b/m4/time_h.m4
index 8c8648e..b57474b 100644
--- a/m4/time_h.m4
+++ b/m4/time_h.m4
@@ -2,7 +2,7 @@
 
 # Copyright (C) 2000-2001, 2003-2007, 2009-2021 Free Software Foundation, Inc.
 
-# serial 17
+# serial 18
 
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -106,6 +106,10 @@ AC_DEFUN([gl_CHECK_TYPE_STRUCT_TIMESPEC],
   AC_SUBST([UNISTD_H_DEFINES_STRUCT_TIMESPEC])
 ])
 
+# gl_TIME_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_TIME_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -115,6 +119,9 @@ AC_DEFUN([gl_TIME_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_TIME_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_TIME_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/uchar.m4 b/m4/uchar.m4
index 6ebe94d..1923f17 100644
--- a/m4/uchar.m4
+++ b/m4/uchar.m4
@@ -1,4 +1,4 @@
-# uchar.m4 serial 19
+# uchar.m4 serial 20
 dnl Copyright (C) 2019-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -120,6 +120,10 @@ AC_DEFUN_ONCE([gl_TYPE_CHAR32_T],
   AC_SUBST([GNULIBHEADERS_OVERRIDE_CHAR32_T])
 ])
 
+# gl_UCHAR_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_UCHAR_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -129,6 +133,9 @@ AC_DEFUN([gl_UCHAR_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_UCHAR_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_UCHAR_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/unistd_h.m4 b/m4/unistd_h.m4
index ada0101..a40a41b 100644
--- a/m4/unistd_h.m4
+++ b/m4/unistd_h.m4
@@ -1,4 +1,4 @@
-# unistd_h.m4 serial 87
+# unistd_h.m4 serial 88
 dnl Copyright (C) 2006-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -59,6 +59,10 @@ AC_DEFUN_ONCE([gl_UNISTD_H],
   fi
 ])
 
+# gl_UNISTD_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_UNISTD_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -68,6 +72,9 @@ AC_DEFUN([gl_UNISTD_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_UNISTD_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_UNISTD_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/utime_h.m4 b/m4/utime_h.m4
index 1daed6e..e288bb1 100644
--- a/m4/utime_h.m4
+++ b/m4/utime_h.m4
@@ -1,4 +1,4 @@
-# utime_h.m4 serial 7
+# utime_h.m4 serial 8
 dnl Copyright (C) 2017-2021 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -28,6 +28,10 @@ AC_DEFUN_ONCE([gl_UTIME_H],
     [utime])
 ])
 
+# gl_UTIME_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_UTIME_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -37,6 +41,9 @@ AC_DEFUN([gl_UTIME_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_UTIME_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_UTIME_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/wchar_h.m4 b/m4/wchar_h.m4
index 9b3e2b0..818b319 100644
--- a/m4/wchar_h.m4
+++ b/m4/wchar_h.m4
@@ -7,7 +7,7 @@ dnl with or without modifications, as long as this notice is 
preserved.
 
 dnl Written by Eric Blake.
 
-# wchar_h.m4 serial 52
+# wchar_h.m4 serial 53
 
 AC_DEFUN_ONCE([gl_WCHAR_H],
 [
@@ -125,6 +125,10 @@ Configuration aborted.])
   fi
 ])
 
+# gl_WCHAR_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_WCHAR_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -134,6 +138,9 @@ AC_DEFUN([gl_WCHAR_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_WCHAR_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_WCHAR_H_MODULE_INDICATOR_DEFAULTS], [
diff --git a/m4/wctype_h.m4 b/m4/wctype_h.m4
index b32c863..7d74212 100644
--- a/m4/wctype_h.m4
+++ b/m4/wctype_h.m4
@@ -1,4 +1,4 @@
-# wctype_h.m4 serial 29
+# wctype_h.m4 serial 30
 
 dnl A placeholder for ISO C99 <wctype.h>, for platforms that lack it.
 
@@ -157,6 +157,10 @@ AC_DEFUN_ONCE([gl_WCTYPE_H],
     ])
 ])
 
+# gl_WCTYPE_MODULE_INDICATOR([modulename])
+# sets the shell variable that indicates the presence of the given module
+# to a C preprocessor expression that will evaluate to 1.
+# This macro invocation must not occur in macros that are AC_REQUIREd.
 AC_DEFUN([gl_WCTYPE_MODULE_INDICATOR],
 [
   dnl Ensure to expand the default settings once only.
@@ -166,6 +170,9 @@ AC_DEFUN([gl_WCTYPE_MODULE_INDICATOR],
   gl_MODULE_INDICATOR_FOR_TESTS([$1])
 ])
 
+# Initializes the default values for AC_SUBSTed shell variables.
+# This macro must not be AC_REQUIREd.  It must only be invoked, and only
+# outside of macros or in macros that are not AC_REQUIREd.
 AC_DEFUN([gl_WCTYPE_H_REQUIRE_DEFAULTS],
 [
   m4_defun(GL_MODULE_INDICATOR_PREFIX[_WCTYPE_H_MODULE_INDICATOR_DEFAULTS], [




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