On Cygwin, I see:
In file included from test-tsearch.c:22:
test-tsearch.c:25:18: warning: initialization of 'void * (*)(const void *,
void * const*, int (*)(const void *, const void *))' from incompatible pointer
type 'void * (*)(const void *, void **, int (*)(const void *, const void *))'
[-Wincompatible-pointer-types]
25 | SIGNATURE_CHECK (tfind, void *, (void const *, void * const *,
| ^~~~~
signature.h:46:57: note: in definition of macro 'SIGNATURE_CHECK2'
46 | _GL_UNUSED static ret (*signature_check ## id) args = fn
| ^~
signature.h:39:3: note: in expansion of macro 'SIGNATURE_CHECK1'
39 | SIGNATURE_CHECK1 (fn, ret, args, __LINE__)
| ^~~~~~~~~~~~~~~~
test-tsearch.c:25:1: note: in expansion of macro 'SIGNATURE_CHECK'
25 | SIGNATURE_CHECK (tfind, void *, (void const *, void * const *,
| ^~~~~~~~~~~~~~~
This is because Cygwin's tfind function is missing a 'const'
qualifier. I have written to the Cygwin list in hopes they fix this
since it will cause annoying -Wdiscarded-qualifiers warnings in
applications that expect the POSIX prototype [1].
Pushed the attached patch to disable the signature check and document
the differing prototype.
Collin
[1] https://cygwin.com/pipermail/cygwin/2025-April/258032.html
>From 30c887298af4a59915c98524f7a1909e4d6e874c Mon Sep 17 00:00:00 2001
From: Collin Funk <collin.fu...@gmail.com>
Date: Wed, 23 Apr 2025 20:29:25 -0700
Subject: [PATCH] tsearch tests: Disable tfind signature check on Cygwin.
* tests/test-tsearch.c [__CYGWIN__]: Skip the tfind signature check.
* doc/posix-functions/tfind.texi: Mention the Cygwin signature.
---
ChangeLog | 6 ++++++
doc/posix-functions/tfind.texi | 5 +++++
tests/test-tsearch.c | 2 ++
3 files changed, 13 insertions(+)
diff --git a/ChangeLog b/ChangeLog
index 3ee1063908..26d9817c59 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2025-04-23 Collin Funk <collin.fu...@gmail.com>
+
+ tsearch tests: Disable tfind signature check on Cygwin.
+ * tests/test-tsearch.c [__CYGWIN__]: Skip the tfind signature check.
+ * doc/posix-functions/tfind.texi: Mention the Cygwin signature.
+
2025-04-22 Collin Funk <collin.fu...@gmail.com>
random_r tests: Disable signature check on Haiku.
diff --git a/doc/posix-functions/tfind.texi b/doc/posix-functions/tfind.texi
index 60f76605ea..225b51f02b 100644
--- a/doc/posix-functions/tfind.texi
+++ b/doc/posix-functions/tfind.texi
@@ -16,4 +16,9 @@ @node tfind
Portability problems not fixed by Gnulib:
@itemize
+@item
+This function uses @code{void **} instead of @code{void *const *} for
+the second parameter on some platforms:
+@c https://cygwin.com/pipermail/cygwin/2025-April/258032.html
+Cygwin.
@end itemize
diff --git a/tests/test-tsearch.c b/tests/test-tsearch.c
index 292ff0d3ad..ea41505dd6 100644
--- a/tests/test-tsearch.c
+++ b/tests/test-tsearch.c
@@ -22,8 +22,10 @@
#include "signature.h"
SIGNATURE_CHECK (tdelete, void *, (void const *, void **,
int (*) (void const *, void const *)));
+#if !defined __CYGWIN__
SIGNATURE_CHECK (tfind, void *, (void const *, void * const *,
int (*) (void const *, void const *)));
+#endif
SIGNATURE_CHECK (tsearch, void *, (void const *, void **,
int (*) (void const *, void const *)));
SIGNATURE_CHECK (twalk, void, (void const *,
--
2.49.0
