Re: [PATCH] Test -flto on both compiler and linker

[Ludovic Courtès]

Hi Sergei,

Sergei Trofimovich <slyich@gmail.com> skribis:

> Before the change ./configure incorrectly enabled -flto on toolchains
> that support -flto on compiler side but don't support -flto on linker
> side. This caused incorrect type size detection on nixpkgs' Darwin:
>
>  configure:54594: checking size of size_t
>  configure:54600: clang -std=gnu11 -o conftest -g -O2 -flto   conftest.c  >&5
>  ld: warning: ignoring file 
> /private/tmp/nix-build-guile-3.0.8.drv-0/conftest-00e93d.o,
>    building for macOS-x86_64 but attempting to link with file built
>    for unknown-unsupported file format ( 0xDE 0xC0 0x17 0x0B 0x00 0x00 0x00 
> 0x00 0x14 0x00 0x00 0x00 0x80 0x1A 0x00 0x00 )
>  Undefined symbols for architecture x86_64:
>    "_main", referenced from:
>       implicit entry/start for main executable
>  ld: symbol(s) not found for architecture x86_64
>  clang-11: error: linker command failed with exit code 1 (use -v to see 
> invocation)
>
> Taken from 
> https://github.com/NixOS/nixpkgs/pull/160051#issuecomment-1046105041
>
> The change makes sure -flto support tests basic support of just for
> object file generation but for linker as well.
>
> * configure.ac: use AC_LINK_IFELSE instead of AC_COMPILE_IFELSE.

Applied, thanks!

Ludo’.