Re: [Buildroot] [PATCH] package/atop: fix musl build

[Julien Olivain via buildroot <buildroot@buildroot.org>]

Hi,

On 10/10/2026 12:01, Thomas Perale via buildroot wrote:
> Hi,
> 
> Tested by modifying `support/testing/tests/package/test_atop.py` to use 
> musl
> library.
> 
> I would just add the reference to the buildroot commit that made the 
> bump: 2110131cab2a613567c99491ba540bb33440e46c

I applied this patch after adding the reference to the commit, as 
suggested.

> Tested-By: Thomas Perale <thomas.perale@mind.be>
> 
> In reply of:
>> Since the bump to version 2.13.0, atop fails to build with musl:
>> 
>> drawbar.c:2336:33: error: implicit declaration of function 'waddwstr'; 
>> did you mean 'waddstr'? [-Wimplicit-function-declaration]
>> 
>> (Before 2.13.0, the same configurations already failed earlier on
>> uClibc because _POSIX_C_SOURCE was defined without a value. Upstream
>> fixed that in 2.13.0 by giving it an explicit value, but the same
>> pattern remains for _XOPEN_SOURCE.)
>> 
>> ncurses only declares its wide-character API, including waddwstr(),
>> when NCURSES_WIDECHAR is set. If the application does not set it,
>> curses.h derives it from the feature test macros:
>> 
>>   #if defined(_XOPEN_SOURCE_EXTENDED) || \
>>       (defined(_XOPEN_SOURCE) && (_XOPEN_SOURCE - 0 >= 500))
>> 
>> drawbar.c defines _XOPEN_SOURCE with an empty value, which makes the
>> check evaluate as 0 >= 500 and fail.
>> 
>> This only breaks with musl because of the C library's <features.h>,
>> which curses.h pulls in through <stdio.h> before doing the check.
>> glibc and uClibc both redefine _XOPEN_SOURCE to 700 and define
>> _XOPEN_SOURCE_EXTENDED whenever _GNU_SOURCE is set, which drawbar.c
>> does, so the empty definition gets fixed up. musl never modifies the
>> application's feature test macros, so the empty value reaches
>> curses.h and the wide-character prototypes are left out.
>> 
>> Add a patch that defines _XOPEN_SOURCE as 700, matching the
>> _POSIX_C_SOURCE value of 200809L that is already used.
>> 
>> Fixes:
>>  - 
>> https://autobuild.buildroot.org/results/914c1d8fa0fc8bbef64e4a64d58e5941d0077a3e
>>  - 
>> https://autobuild.buildroot.org/results/b91/b91ea0722202de0d1fdeeaeea167fd1b21b6d5d6
>> 
>> Assisted-by: Claude:claude-opus-5-5
>> Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
> 
>> ---
>>  ...xplicit-value-for-_XOPEN_SOURCE-macr.patch | 48 
>> +++++++++++++++++++
>>  1 file changed, 48 insertions(+)
>>  create mode 100644 
>> package/atop/0001-drawbar-define-explicit-value-for-_XOPEN_SOURCE-macr.patch
>> 
>> diff --git 
>> a/package/atop/0001-drawbar-define-explicit-value-for-_XOPEN_SOURCE-macr.patch 
>> b/package/atop/0001-drawbar-define-explicit-value-for-_XOPEN_SOURCE-macr.patch
>> new file mode 100644
>> index 0000000000..d526d58433
>> --- /dev/null
>> +++ 
>> b/package/atop/0001-drawbar-define-explicit-value-for-_XOPEN_SOURCE-macr.patch
>> @@ -0,0 +1,48 @@
>> +From 54799216beac63a195cd6d34b22476fc15a80295 Mon Sep 17 00:00:00 
>> 2001
>> +From: Yegor Yefremov <yegorslists@googlemail.com>
>> +Date: Wed, 30 Sep 2026 10:59:49 +0200
>> +Subject: [PATCH] drawbar: define explicit value for _XOPEN_SOURCE 
>> macro
>> +
>> +drawbar.c uses the wide-character curses function waddwstr(). ncurses
>> +only declares its wide-character API when NCURSES_WIDECHAR is set,
>> +which curses.h derives from the feature test macros:
>> +
>> +  #if defined(_XOPEN_SOURCE_EXTENDED) || \
>> +      (defined(_XOPEN_SOURCE) && (_XOPEN_SOURCE - 0 >= 500))
>> +
>> +drawbar.c defines _XOPEN_SOURCE without a value, so _XOPEN_SOURCE - 0
>> +evaluates to 0 and the check fails.
>> +
>> +With glibc and uClibc this goes unnoticed, because their <features.h>
>> +redefines _XOPEN_SOURCE to 700 (and defines _XOPEN_SOURCE_EXTENDED)
>> +whenever _GNU_SOURCE is set. musl does not touch the application's
>> +feature test macros, so the empty definition reaches curses.h
>> +unchanged and the build fails:
>> +
>> +drawbar.c:2336:33: error: implicit declaration of function 
>> 'waddwstr'; did you mean 'waddstr'? [-Wimplicit-function-declaration]
>> +
>> +Define _XOPEN_SOURCE as 700, which matches the already explicit
>> +_POSIX_C_SOURCE value of 200809L (both refer to POSIX.1-2008).
>> +
>> +Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
>> +Upstream: https://github.com/Atoptool/atop/pull/415
>> +---
>> + drawbar.c | 2 +-
>> + 1 file changed, 1 insertion(+), 1 deletion(-)
>> +
>> +diff --git a/drawbar.c b/drawbar.c
>> +index 651a81e..e4db0d6 100644
>> +--- a/drawbar.c
>> ++++ b/drawbar.c
>> +@@ -104,7 +104,7 @@
>> + // the other.
>> + 
>> /////////////////////////////////////////////////////////////////////////////
>> + #define _POSIX_C_SOURCE	200809L
>> +-#define _XOPEN_SOURCE
>> ++#define _XOPEN_SOURCE	700
>> + #define _GNU_SOURCE
>> + #define _DEFAULT_SOURCE
>> +
>> +--
>> +2.34.1
>> +
>> --
>> 2.34.1

Best regards,

Julien.
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