From: Bruno Haible <bruno@clisp.org>
Date: Wed, 23 Jul 2025 07:12:55 +0000 (+0200)
Subject: thrd: Avoid conversion between different function pointer types.
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=49a35c02d2a0132bdb7a1b49fa3effa678be7831;p=thirdparty%2Fgnulib.git

thrd: Avoid conversion between different function pointer types.

Reported by Collin Funk in
<https://lists.gnu.org/archive/html/bug-gnulib/2025-07/msg00170.html>.

* m4/thrd.m4 (gl_FUNC_THRD_JOIN): Define BROKEN_THRD_START_T or
BROKEN_THRD_JOIN. Don't define BROKEN_THRD_START_T_OR_JOIN.
* lib/thrd.c (thrd_main_func): Define with the right return type,
depending on BROKEN_THRD_START_T.
---

diff --git a/ChangeLog b/ChangeLog
index 15c7c1a941..8a226b449a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2025-07-23  Bruno Haible  <bruno@clisp.org>
+
+	thrd: Avoid conversion between different function pointer types.
+	Reported by Collin Funk in
+	<https://lists.gnu.org/archive/html/bug-gnulib/2025-07/msg00170.html>.
+	* m4/thrd.m4 (gl_FUNC_THRD_JOIN): Define BROKEN_THRD_START_T or
+	BROKEN_THRD_JOIN. Don't define BROKEN_THRD_START_T_OR_JOIN.
+	* lib/thrd.c (thrd_main_func): Define with the right return type,
+	depending on BROKEN_THRD_START_T.
+
 2025-07-22  Collin Funk  <collin.funk1@gmail.com>
 	    Paul Eggert  <eggert@cs.ucla.edu>
 
diff --git a/lib/thrd.c b/lib/thrd.c
index ea7f0f5397..b8ddb3fd52 100644
--- a/lib/thrd.c
+++ b/lib/thrd.c
@@ -26,7 +26,7 @@
 #if HAVE_THREADS_H
 /* Provide workarounds.  */
 
-# if BROKEN_THRD_START_T_OR_JOIN
+# if BROKEN_THRD_START_T || BROKEN_THRD_JOIN
 
 #  undef thrd_t
 
@@ -70,7 +70,12 @@ typedef union
         }
         main_arg_t;
 
-static void *
+static
+#  if BROKEN_THRD_START_T
+void *
+#  else /* BROKEN_THRD_JOIN */
+int
+#  endif
 thrd_main_func (void *pmarg)
 {
   /* Unpack the object that combines mainfunc and arg.  */
@@ -91,7 +96,11 @@ thrd_main_func (void *pmarg)
         /* Clean up the thread, like thrd_join would do.  */
         free (&main_arg->t);
       }
+#  if BROKEN_THRD_START_T
     return NULL;
+#  else /* BROKEN_THRD_JOIN */
+    return 0;
+#  endif
   }
 }
 
diff --git a/m4/thrd.m4 b/m4/thrd.m4
index 18298dadb7..a79e186ed2 100644
--- a/m4/thrd.m4
+++ b/m4/thrd.m4
@@ -1,5 +1,5 @@
 # thrd.m4
-# serial 6
+# serial 7
 dnl Copyright (C) 2019-2025 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -39,8 +39,13 @@ AC_DEFUN([gl_FUNC_THRD_JOIN],
       REPLACE_THRD_EQUAL=1
       REPLACE_THRD_EXIT=1
       REPLACE_THRD_JOIN=1
-      AC_DEFINE([BROKEN_THRD_START_T_OR_JOIN], [1],
-        [Define if the thrd_start_t type is not as described in ISO C 11 or if thrd_join discards the thread's exit code.])
+      if test $BROKEN_THRD_START_T = 1; then
+        AC_DEFINE([BROKEN_THRD_START_T], [1],
+          [Define if the thrd_start_t type is not as described in ISO C 11.])
+      else
+        AC_DEFINE([BROKEN_THRD_JOIN], [1],
+          [Define if thrd_start_t is OK but thrd_join discards the thread's exit code.])
+      fi
       dnl The thrd_exit replacement relies on pthread_exit, which on AIX is in
       dnl libpthread.
       LIBSTDTHREAD="$LIBSTDTHREAD $LIBPTHREAD"