[Buildroot] [PATCH 1/1] package/cpp-httplib: depends on BR2_TOOLCHAIN_HAS_SYNC_1

[Buildroot] [PATCH 1/1] package/cpp-httplib: depends on BR2_TOOLCHAIN_HAS_SYNC_1

[Bernd Kuhls]

Buildroot commit 8dad17ea06260ef0bd23eebc47c95a8510310bf5 bumped the
package from 0.27.0 to 0.37.2. This bump includes upstream commit
https://github.com/yhirose/cpp-httplib/commit/464867a9cedef2b6185e25e3e912d3f796fe58fd
which added WebSocket support to version 0.33.0 and causes a build error
detected by the Gitlab pipelines for bootlin-sparc-uclibc:

/builds/bkuhls/buildroot/br-test-pkg/bootlin-sparc-uclibc/host/opt/ext-toolchain/bin/../lib/gcc/sparc-buildroot-linux-uclibc/14.3.0/../../../../sparc-buildroot-linux-uclibc/bin/ld:
 /tmp/cciyXsAR.ltrans6.ltrans.o: in function
 `httplib::ws::WebSocket::close(httplib::ws::CloseStatus,
 std::__cxx11::basic_string<char, std::char_traits<char>,
 std::allocator<char> > const&)':
<artificial>:(.text+0x6408): undefined reference to `__atomic_exchange_1'

Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
---
Gitlab pipelines passed:
https://gitlab.com/bkuhls/buildroot/-/commits/1f16e14c1131a99a61f16200285b71d0cfe47020

 package/cpp-httplib/Config.in | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/package/cpp-httplib/Config.in b/package/cpp-httplib/Config.in
index 9bd93ee0af..7d1244c2ac 100644
--- a/package/cpp-httplib/Config.in
+++ b/package/cpp-httplib/Config.in
@@ -1,10 +1,12 @@
 comment "cpp-httplib needs a toolchain w/ C++, wchar, threads"
+	depends on BR2_TOOLCHAIN_HAS_SYNC_1
 	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_USE_WCHAR || !BR2_TOOLCHAIN_HAS_THREADS
 
 config BR2_PACKAGE_CPP_HTTPLIB
 	bool "cpp-httplib"
 	depends on BR2_INSTALL_LIBSTDCPP
 	depends on BR2_TOOLCHAIN_HAS_THREADS
+	depends on BR2_TOOLCHAIN_HAS_SYNC_1
 	depends on BR2_USE_WCHAR
 	help
 	  A C++ header-only HTTP/HTTPS server and client library.
-- 
2.47.3

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Re: [Buildroot] [PATCH 1/1] package/cpp-httplib: depends on BR2_TOOLCHAIN_HAS_SYNC_1

[Thomas Petazzoni via buildroot]

On Sat, Jun 20, 2026 at 09:03:43AM +0200, Bernd Kuhls wrote:
> Buildroot commit 8dad17ea06260ef0bd23eebc47c95a8510310bf5 bumped the
> package from 0.27.0 to 0.37.2. This bump includes upstream commit
> https://github.com/yhirose/cpp-httplib/commit/464867a9cedef2b6185e25e3e912d3f796fe58fd
> which added WebSocket support to version 0.33.0 and causes a build error
> detected by the Gitlab pipelines for bootlin-sparc-uclibc:
> 
> /builds/bkuhls/buildroot/br-test-pkg/bootlin-sparc-uclibc/host/opt/ext-toolchain/bin/../lib/gcc/sparc-buildroot-linux-uclibc/14.3.0/../../../../sparc-buildroot-linux-uclibc/bin/ld:
>  /tmp/cciyXsAR.ltrans6.ltrans.o: in function
>  `httplib::ws::WebSocket::close(httplib::ws::CloseStatus,
>  std::__cxx11::basic_string<char, std::char_traits<char>,
>  std::allocator<char> > const&)':
> <artificial>:(.text+0x6408): undefined reference to `__atomic_exchange_1'

Thanks for the patch. However, I believe you're making a confusion
between __sync builtins
(https://gcc.gnu.org/onlinedocs/gcc/_005f_005fsync-Builtins.html) and
__atomic builtins
(https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html).

__sync builtins are in Buildroot covered by the
BR2_TOOLCHAIN_HAS_SYNC_xyz options.

On the other hand, __atomic built-ins are covered by
BR2_TOOLCHAIN_HAS_ATOMIC and BR2_TOOLCHAIN_HAS_LIBATOMIC.

So what you want to do here is:

1. Add depends on BR2_TOOLCHAIN_HAS_ATOMIC in Config.in

2. Ensure that the code is linked against libatomic if
   BR2_TOOLCHAIN_HAS_LIBATOMIC

Could you have a look into this?

Thanks a lot!

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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