[Buildroot] [PATCH 1/1] package/drogon: needs a toolchain with wchar support

[Buildroot] [PATCH 1/1] package/drogon: needs a toolchain with wchar support

[Dario Binacchi]

The trantor library bundled in drogon uses std::codecvt_utf8<wchar_t>
to convert strings between UTF-8 and std::wstring. Toolchains without
wide character support, such as uClibc without WCHAR, have a libstdc++
that lacks it, so any executable linked against trantor fails to link,
starting with the drogon examples.

ld: ../trantor/libtrantor.so.1.5.29: undefined reference to `std::codecvt_utf8<wchar_t, 1114111ul, (std::codecvt_mode)0>::codecvt_utf8(unsigned int)'

These conversions are part of the public API of trantor and drogon, so
they cannot be disabled. Add a dependency on BR2_USE_WCHAR, together
with the matching comment.

This issue has been present since the package was added, so it also
affects the 2026.08.x branch.

Fixes:
https://autobuild.buildroot.org/results/6b893fea68e25fd928daabff5cf034de76062ac1

Fixes: d38b4915e9437c5492836914c0a0fff12b4f1031 ("package/drogon: new package")
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---
 package/drogon/Config.in | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/package/drogon/Config.in b/package/drogon/Config.in
index ce8a8313bded..c5e20c2017f6 100644
--- a/package/drogon/Config.in
+++ b/package/drogon/Config.in
@@ -4,6 +4,7 @@ config BR2_PACKAGE_DROGON
 	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_11 # C++17/20
 	depends on BR2_TOOLCHAIN_HAS_THREADS
 	depends on BR2_USE_MMU # fork()
+	depends on BR2_USE_WCHAR # std::codecvt_utf8<wchar_t>
 	select BR2_PACKAGE_JSONCPP
 	select BR2_PACKAGE_UTIL_LINUX
 	select BR2_PACKAGE_UTIL_LINUX_LIBUUID
@@ -45,8 +46,8 @@ config BR2_PACKAGE_DROGON_YAML_CONFIG
 
 endif
 
-comment "drogon needs a toolchain w/ C++, threads, gcc >= 11"
+comment "drogon needs a toolchain w/ C++, threads, wchar, gcc >= 11"
 	depends on BR2_USE_MMU
 	depends on !BR2_INSTALL_LIBSTDCPP || \
 		!BR2_TOOLCHAIN_GCC_AT_LEAST_11 || \
-		!BR2_TOOLCHAIN_HAS_THREADS
+		!BR2_TOOLCHAIN_HAS_THREADS || !BR2_USE_WCHAR
-- 
2.43.0

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Re: [Buildroot] [PATCH 1/1] package/drogon: needs a toolchain with wchar support

[Thomas Petazzoni via buildroot]

On Tue, Oct 27, 2026 at 05:03:26PM +0100, Dario Binacchi wrote:
> The trantor library bundled in drogon uses std::codecvt_utf8<wchar_t>
> to convert strings between UTF-8 and std::wstring. Toolchains without
> wide character support, such as uClibc without WCHAR, have a libstdc++
> that lacks it, so any executable linked against trantor fails to link,
> starting with the drogon examples.
> 
> ld: ../trantor/libtrantor.so.1.5.29: undefined reference to `std::codecvt_utf8<wchar_t, 1114111ul, (std::codecvt_mode)0>::codecvt_utf8(unsigned int)'
> 
> These conversions are part of the public API of trantor and drogon, so
> they cannot be disabled. Add a dependency on BR2_USE_WCHAR, together
> with the matching comment.
> 
> This issue has been present since the package was added, so it also
> affects the 2026.08.x branch.
> 
> Fixes:
> https://autobuild.buildroot.org/results/6b893fea68e25fd928daabff5cf034de76062ac1
> 
> Fixes: d38b4915e9437c5492836914c0a0fff12b4f1031 ("package/drogon: new package")
> Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>

Applied to master, thanks!

Best regards,

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