symbol lookup error: /usr/lib/libSDL2_gfx-1.0.so.0: undefined symbol: sincos

[rnestler]

I tried to test the gfx-demo using cargo run --features=gfx --example=gfx-demo . It compiles successfully, but running crashes with a symbol lookup error:

target/debug/examples/gfx-demo: symbol lookup error: /usr/lib/libSDL2_gfx-1.0.so.0: undefined symbol: sincos
cargo run --features=gfx --example=gfx-demo  86.95s user 9.44s system 536% cpu 17.965 total

I'm running ArchLinux and have the following package versions installed:

Name            : sdl2-compat
Version         : 2.32.60-1
Name            : sdl2_gfx
Version         : 1:1.0.4-4

[antonilol]

For me it does work, I also run ArchLinux and have the same versions as you for sdl2-compat and sdl2_gfx. sincos is from glibc if I am correct (https://man7.org/linux/man-pages/man3/sincos.3.html#HISTORY).
What version of glibc do you have? (pacman -Q glibc)
What does ldd target/debug/examples/gfx-demo show?

[rnestler]

% pacman -Q glibc
glibc 2.42+r33+gde1fe81f4714-1

% ldd target/debug/examples/gfx-demo
	linux-vdso.so.1 (0x00007f9ac8c73000)
	libSDL2-2.0.so.0 => /usr/lib/libSDL2-2.0.so.0 (0x00007f9ac8b54000)
	libSDL2_gfx-1.0.so.0 => /usr/lib/libSDL2_gfx-1.0.so.0 (0x00007f9ac8b41000)
	libgcc_s.so.1 => /usr/lib/libgcc_s.so.1 (0x00007f9ac8b14000)
	libc.so.6 => /usr/lib/libc.so.6 (0x00007f9ac8800000)
	/lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2 (0x00007f9ac8c75000)

According to your link (and also other stuff I found online), sincos is defined in libm, not the glibc?

If I LD_PRELOAD that library I get a seg fault:

% LD_PRELOAD="/usr/lib/libm.so.6" target/debug/examples/gfx-demo
target/debug/examples/gfx-demo: Relink `/usr/lib/libSDL2_gfx-1.0.so.0' with `/usr/lib/libm.so.6' for IFUNC symbol `sincos'
[1]    395634 segmentation fault (core dumped)  LD_PRELOAD="/usr/lib/libm.so.6" target/debug/examples/gfx-demo

Looking into it I noticed that /usr/lib/libm.so isn't a symlink to the shared library, but an ld script:

% cat /usr/lib/libm.so
/* GNU ld script
*/
OUTPUT_FORMAT(elf64-x86-64)
GROUP ( /usr/lib/libm.so.6  AS_NEEDED ( /usr/lib/libmvec.so.1 ) )

If I LD_PRELOAD that it works:

% LD_PRELOAD="/usr/lib/libmvec.so.1" target/debug/examples/gfx-demo
mouse btn down at (204,176)
mouse btn down at (382,248)
mouse btn down at (483,129)
mouse btn down at (299,455)
mouse btn down at (62,403)
mouse btn down at (295,251)
mouse btn down at (646,434)
LD_PRELOAD="/usr/lib/libmvec.so.1" target/debug/examples/gfx-demo  3.49s user 3.39s system 98% cpu 6.988 total

libSDL2_gfx dosn't seem to link to libm:

% ldd  /usr/lib/libSDL2_gfx-1.0.so.0
	linux-vdso.so.1 (0x00007ff1cdeab000)
	libSDL2-2.0.so.0 => /usr/lib/libSDL2-2.0.so.0 (0x00007ff1cddec000)
	libc.so.6 => /usr/lib/libc.so.6 (0x00007ff1cda00000)
	/usr/lib64/ld-linux-x86-64.so.2 (0x00007ff1cdead000)

Maybe an ArchLinux packaging bug?

[antonilol]

Versions look expected.

sincos is defined in libm, not the glibc?

libm is part of glibc, but yeah defined in libm.

Looking into it I noticed that /usr/lib/libm.so isn't a symlink to the shared library, but an ld script:

/usr/lib/libm.so.6 and /usr/lib/libmvec.so.1 are the library I think, that script looks like some smarter version of a symlink to those.

If I LD_PRELOAD that it works:

% LD_PRELOAD="/usr/lib/libmvec.so.1" target/debug/examples/gfx-demo
...

This works for me too, but just target/debug/examples/gfx-demo does not work I just found out.
What I originally tried is cargo run --features=gfx --example=gfx-demo, that works without LD_PRELOAD.

Maybe an ArchLinux packaging bug?

Could be, I do think it is more likely that there is something wrong with the build process, given that it does work when cargo runs it but running it directly does not work.