undefined reference to `tcc_backtrace' when linking against v generated .so file on Linux

[plicease]

Describe the bug

When creating a dynamic library on Linux I get a .so file referring to tcc symbols. Trying to link a C program with the system compiler (gcc) will fail as these symbols are missing. Using the same procedure it worked on macOS.

Aside: I know I can put C files into my V project and build a program that way, what I really want to be able to do is call into the v .so using FFI from Perl.

Reproduction Steps

✅ plicease-clean% v up
Updating V...
> git_command: git pull https://github.com/vlang/v master
V is already updated.
Current V version: V 0.4.8 afc07f4, timestamp: 2024-12-18 00:49:07 +0200
✅ plicease-clean% v new --lib libfoo
Input your project description: foo
Input your project version: (0.0.0)
Input your project license: (MIT)
Initialising ...
Created library project `libfoo`
✅ plicease-clean% cd libfoo
✅ plicease-clean% v -shared .
✅ plicease-clean% cat > foo.c
#include <stdio.h>

int libfoo__square(int);

int main() {
  printf("%d\n", libfoo__square(2));
}
✅ plicease-clean% gcc foo.c -L. -lfoo
/usr/bin/ld: ./libfoo.so: undefined reference to `tcc_backtrace'
/usr/bin/ld: ./libfoo.so: undefined reference to `__bt_exit'
/usr/bin/ld: ./libfoo.so: undefined reference to `__bt_init'
collect2: error: ld returned 1 exit status

Expected Behavior

I would expect a binary to be built and it should print out 4 when run.

Current Behavior

/usr/bin/ld: ./libfoo.so: undefined reference to `tcc_backtrace'
/usr/bin/ld: ./libfoo.so: undefined reference to `__bt_exit'
/usr/bin/ld: ./libfoo.so: undefined reference to `__bt_init'
collect2: error: ld returned 1 exit status

Possible Solution

I looked at the C source generated by I noticed that references to Tiny C were wrapped in #ifdefs for __TINYC__, so some knob to turn that define off or not including whatever that does define might do it. Trying to build generated by V with gcc gave me this error:

libfoo.c:749:2: error: #error VERROR_MESSAGE Header file <gc.h>, needed for module `builtin` was not found. Please install the corresponding development headers.
  749 | #error VERROR_MESSAGE Header file <gc.h>, needed for module `builtin` was not found. Please install the corresponding development headers.
      |  ^~~~~

Additional Information/Context

I tried this with both the 2024.50 and 2024.51 pre-built binaries and by building from git, and always got the same error. Using the pre-built 2024.51 on macOS worked fine though.

V version

Current V version: V 0.4.8 afc07f4, timestamp: 2024-12-18 00:49:07 +0200

Environment details (OS name and version, etc.)

V full version: V 0.4.8 afc07f4
OS: linux, Ubuntu 24.04.1 LTS (VM)
Processor: 32 cpus, 64bit, little endian, AMD EPYC 7702P 64-Core Processor

getwd: /home/ollisg/test/v/libfoo
vexe: /home/ollisg/opt/v/git/v
vexe mtime: 2024-12-18 03:47:43

vroot: OK, value: /home/ollisg/opt/v/git
VMODULES: OK, value: /home/ollisg/.vmodules
VTMP: OK, value: /tmp/v_2855

Git version: git version 2.43.0
Git vroot status: afc07f46
.git/config present: true

CC version: cc (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0
emcc version: N/A
thirdparty/tcc status: thirdparty-linux-amd64 0134e9b9

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_{Huly®: V_0.6-21635}

[plicease]

Okay building generating the C and then building that with -lgc and -ltcc seems to have worked:

✅ plicease-clean% gcc -fPIC -I/home/ollisg/opt/v/git/thirdparty/libgc/include  -shared -L/home/ollisg/opt/v/git/thirdparty/tcc/lib/ libfoo.c -L/home/ollisg/opt/v/git/thirdparty/tcc/lib/ -o libfoo.so -lgc -ltcc
✅ plicease-clean% perl -MFFI::Platypus -E '$ffi = FFI::Platypus->new( api => 2, lib => "./libfoo.so"); say $ffi->function(libfoo__square => ["int"] => "int")->call(2)'
4

so I am guessing something went wrong in the link step.

[spytheman]

You can pass -d no_backtrace too, when compiling with tcc,
or you can pass -cc gcc, and compile your .so that way, i.e. v -shared -cc gcc . .

[spytheman]

Turning off the GC can be done with -gc none .

[spytheman]

[spytheman]

After running cpan i FFI::Platypus:

#0 16:51:44 ^ /v/oo/libfoo>perl -MFFI::Platypus -E '$ffi = FFI::Platypus->new( api => 2, lib => "./libfoo.so"); say $ffi->function(libfoo__square => ["int"] => "int")->call(2)'
4

[plicease]

@spytheman Thanks that is super helpful! I think it should work without having to know how to use those flags but will leave it up to other folks to decide if this needs addressing further.