posix_spawn_file_actions_*: Document musl libc bugs.

* doc/posix-functions/posix_spawn_file_actions_addclose.texi: Mention
the bug.
* doc/posix-functions/posix_spawn_file_actions_adddup2.texi: Likewise.
* doc/posix-functions/posix_spawn_file_actions_addopen.texi: Likewise.
* m4/posix_spawn.m4 (gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE): When
cross-compiling to a musl system, guess no.
(gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2): Likewise.
(gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN): Likewise.

1 files changed, 13 insertions, 10 deletions

diff --git a/m4/posix_spawn.m4 b/m4/posix_spawn.m4
index 1e2533c1f1..d50dcc9e2a 100644
--- a/m4/posix_spawn.m4
+++ b/m4/posix_spawn.m4
@@ -1,4 +1,4 @@
-# posix_spawn.m4 serial 15
+# posix_spawn.m4 serial 16
 dnl Copyright (C) 2008-2019 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -422,8 +422,8 @@ AC_DEFUN([gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE],
   if test $REPLACE_POSIX_SPAWN = 1; then
     REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE=1
   else
-    dnl On Solaris 11.0, posix_spawn_file_actions_addclose succeeds even
-    dnl if the fd argument is out of range.
+    dnl On musl libc and Solaris 11.0, posix_spawn_file_actions_addclose
+    dnl succeeds even if the fd argument is out of range.
     AC_CACHE_CHECK([whether posix_spawn_file_actions_addclose works],
       [gl_cv_func_posix_spawn_file_actions_addclose_works],
       [AC_RUN_IFELSE(
@@ -440,8 +440,9 @@ int main ()
 }]])],
          [gl_cv_func_posix_spawn_file_actions_addclose_works=yes],
          [gl_cv_func_posix_spawn_file_actions_addclose_works=no],
-         [# Guess no on Solaris, yes otherwise.
+         [# Guess no on musl libc and Solaris, yes otherwise.
           case "$host_os" in
+            *-musl*)  gl_cv_func_posix_spawn_file_actions_addclose_works="guessing no" ;;
             solaris*) gl_cv_func_posix_spawn_file_actions_addclose_works="guessing no" ;;
                       # Guess no on native Windows.
             mingw*)   gl_cv_func_posix_spawn_file_actions_addclose_works="guessing no" ;;
@@ -465,8 +466,8 @@ AC_DEFUN([gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2],
   if test $REPLACE_POSIX_SPAWN = 1; then
     REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2=1
   else
-    dnl On Solaris 11.0, posix_spawn_file_actions_adddup2 succeeds even
-    dnl if the fd argument is out of range.
+    dnl On musl libc and Solaris 11.0, posix_spawn_file_actions_adddup2
+    dnl succeeds even if the fd argument is out of range.
     AC_CACHE_CHECK([whether posix_spawn_file_actions_adddup2 works],
       [gl_cv_func_posix_spawn_file_actions_adddup2_works],
       [AC_RUN_IFELSE(
@@ -483,8 +484,9 @@ int main ()
 }]])],
          [gl_cv_func_posix_spawn_file_actions_adddup2_works=yes],
          [gl_cv_func_posix_spawn_file_actions_adddup2_works=no],
-         [# Guess no on Solaris, yes otherwise.
+         [# Guess no on musl libc and Solaris, yes otherwise.
           case "$host_os" in
+            *-musl*)  gl_cv_func_posix_spawn_file_actions_adddup2_works="guessing no";;
             solaris*) gl_cv_func_posix_spawn_file_actions_adddup2_works="guessing no";;
                       # Guess no on native Windows.
             mingw*)   gl_cv_func_posix_spawn_file_actions_adddup2_works="guessing no" ;;
@@ -508,8 +510,8 @@ AC_DEFUN([gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN],
   if test $REPLACE_POSIX_SPAWN = 1; then
     REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN=1
   else
-    dnl On Solaris 11.0, posix_spawn_file_actions_addopen succeeds even
-    dnl if the fd argument is out of range.
+    dnl On musl libc and Solaris 11.0, posix_spawn_file_actions_addopen
+    dnl succeeds even if the fd argument is out of range.
     AC_CACHE_CHECK([whether posix_spawn_file_actions_addopen works],
       [gl_cv_func_posix_spawn_file_actions_addopen_works],
       [AC_RUN_IFELSE(
@@ -528,8 +530,9 @@ int main ()
 }]])],
          [gl_cv_func_posix_spawn_file_actions_addopen_works=yes],
          [gl_cv_func_posix_spawn_file_actions_addopen_works=no],
-         [# Guess no on Solaris, yes otherwise.
+         [# Guess no on musl libc and Solaris, yes otherwise.
           case "$host_os" in
+            *-musl*)  gl_cv_func_posix_spawn_file_actions_addopen_works="guessing no";;
             solaris*) gl_cv_func_posix_spawn_file_actions_addopen_works="guessing no";;
                       # Guess no on native Windows.
             mingw*)   gl_cv_func_posix_spawn_file_actions_addopen_works="guessing no" ;;