python bindings: build/install via integrated meson support

[eli-schwartz]

The meson build system has builtin support for python packaging, and unlike hatchling it is spec-compliant. Additionally, meson is already responsible for building the shared library itself, which the python build backend can then distribute inside the wheel. This allows shipping a wheel that can find its own liblc3.so via ctypes and doesn't require passing paths to the library around, nor to install both separately and hope that this works.

[eli-schwartz]

@asoulier by the way, python packaging is another thing you can ask me about. ;)

[asoulier]

Thank Eli. That works great ;)
Can you just update the README.md with pip inistall . instead of python3 -m pip install ./python.
Thanks.

Can I also ask you for some help with building WASM with meson?
@DeltaEvo is working on a port to WASM, without relying on emscripten.
We have modified the Makefile (not committed for now) to use clang with the wasm32 target.
That works fine; I wanted to know if there is a possibility with meson to compile the wasm32 target, too (I actually only see the emscripten option).

[DeltaEvo]

We have modified the Makefile (not committed for now)

It is committed e67bb2d

[eli-schwartz]

I know little to nothing about wasm. I tried writing a simple meson cross toolchain file:

[binaries]
c = ['clang', '--target=wasm32']

[built-in options]
c_args = ['-mbulk-memory']
c_link_args = ['-nostdlib', '-Wl,--no-entry', '-Wl,--export-dynamic']
b_asneeded = false
b_lundef = false

configure log:

Build type: cross build
Project name: lc3
Project version: 1.0.4
C compiler for the host machine: clang --target=wasm32 (clang 17.0.6 "clang version 17.0.6")
C linker for the host machine: clang --target=wasm32 ld.lld 17.0.6
C compiler for the build machine: ccache cc (gcc 13.2.1 "cc (Gentoo 13.2.1_p20240113-r1 p12) 13.2.1 20240113")
C linker for the build machine: cc ld.bfd 2.41
Build machine cpu family: x86_64
Build machine cpu: x86_64
Host machine cpu family: x86_64
Host machine cpu: x86_64
Target machine cpu family: x86_64
Target machine cpu: x86_64
Library m found: NO
Found pkg-config: NO
Build targets in project: 1

lc3 1.0.4

  User defined options
    Cross files: ../cr.ini

Found ninja-1.11.1 at /usr/bin/ninja
WARNING: Cross file does not specify strip binary, result will not be stripped.
WARNING: Cross file does not specify strip binary, result will not be stripped.

compile log:

ninja: Entering directory `builddir/'
[13/13] Linking target src/liblc3.so.1
FAILED: src/liblc3.so.1 
clang --target=wasm32  -o src/liblc3.so.1 src/liblc3.so.1.p/attdet.c.o src/liblc3.so.1.p/bits.c.o src/liblc3.so.1.p/bwdet.c.o src/liblc3.so.1.p/energy.c.o src/liblc3.so.1.p/lc3.c.o src/liblc3.so.1.p/ltpf.c.o src/liblc3.so.1.p/mdct.c.o src/liblc3.so.1.p/plc.c.o src/liblc3.so.1.p/sns.c.o src/liblc3.so.1.p/spec.c.o src/liblc3.so.1.p/tables.c.o src/liblc3.so.1.p/tns.c.o -flto -shared -fPIC -Wl,--start-group -Wl,-soname,liblc3.so.1 -Wl,--end-group -nostdlib -Wl,--no-entry -Wl,--export-dynamic
wasm-ld: error: unknown argument: --start-group
wasm-ld: error: unknown argument: -soname
wasm-ld: error: unknown argument: --end-group
wasm-ld: error: cannot open liblc3.so.1: No such file or directory
clang: error: linker command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.

So close, yet so far. It seems like meson may need a small tweak or so to get this to work.

[eli-schwartz]

The start-group end-group stuff is technically used in the event that a library has multiple dependencies which liblc3 doesn't have, so my meson PR should count as a perfectly adequate workaround.

Configuring with -Ddefault_library=static tells meson to only build a wasm library for src/liblc3.a, not a shared library, which may or may not be suitable.

[eli-schwartz]

README updated. PTAL.