add an meson option to pass pari location

[dimpase]

fixes #194

[dimpase]

This doesn't quite work, as custom prefix pari clashes with a system-wide one

[dimpase]

$ uv pip install . --config-settings=setup-args="-Dpari-prefix=/home/dima/software/pari"
  × Failed to build `cypari2 @ file:///home/dima/software/cypari2`
  ├─▶ The build backend returned an error
  ╰─▶ Call to `mesonpy.build_wheel` failed (exit status: 1)

      [stdout]
      + meson setup /home/dima/software/cypari2 /home/dima/software/cypari2/.mesonpy-smpp0m2z -Dbuildtype=release -Db_ndebug=if-release -Db_vscrt=md -Dpari-prefix=/home/dima/software/pari
      --native-file=/home/dima/software/cypari2/.mesonpy-smpp0m2z/meson-python-native-file.ini
      The Meson build system
      Version: 1.10.0
      Source dir: /home/dima/software/cypari2
      Build dir: /home/dima/software/cypari2/.mesonpy-smpp0m2z
      Build type: native build
      Project name: cypari2
      Project version: 2.2.4
      C compiler for the host machine: /usr/bin/ccache cc (gcc 15.2.1 "cc (Gentoo 15.2.1_p20251122 p3) 15.2.1 20251122")
      C linker for the host machine: cc ld.bfd 2.45.1
      Cython compiler for the host machine: cython (cython 3.2.2)
      Host machine cpu family: x86_64
      Host machine cpu: x86_64
      Program python found: YES (/home/dima/.cache/uv/builds-v0/.tmpQEchNn/bin/python)
      Found pkg-config: YES (/usr/bin/pkg-config) 2.5.1
      Run-time dependency gmp found: YES 6.3.0
      Has header "pari/pari.h" : YES
      Has header "pari/pari.h" : YES
      Library pari found: YES
      Checking if "pari version" with dependencies -lpari, gmp runs: YES
      Message: PARI Version: [2, 17, 2]
      Checking if "pari datadir" with dependencies -lpari, gmp runs: YES
      Message: PARI Datadir: /usr/share/pari
      Found pkg-config: YES (/usr/bin/pkg-config) 2.5.1
      Run-time dependency python found: YES 3.13
      Configuring cypari2.pc using configuration
      Build targets in project: 9

      cypari2 2.2.4

        User defined options
          Native files: /home/dima/software/cypari2/.mesonpy-smpp0m2z/meson-python-native-file.ini
          b_ndebug    : if-release
          b_vscrt     : md
          buildtype   : release
          pari-prefix : /home/dima/software/pari

      Found ninja-1.13.2 at /usr/bin/ninja
      + /usr/bin/ninja
      [1/27] Compiling Cython source /home/dima/software/cypari2/cypari2/string_utils.pyx
      [2/27] Compiling Cython source /home/dima/software/cypari2/cypari2/custom_block.pyx
      [3/27] Compiling Cython source /home/dima/software/cypari2/cypari2/handle_error.pyx
      [4/27] Compiling C object cypari2/string_utils.cpython-313-x86_64-linux-gnu.so.p/meson-generated_cypari2_string_utils.pyx.c.o
      [5/27] Linking target cypari2/string_utils.cpython-313-x86_64-linux-gnu.so
      [6/27] Compiling C object cypari2/custom_block.cpython-313-x86_64-linux-gnu.so.p/meson-generated_cypari2_custom_block.pyx.c.o
      [7/27] Linking target cypari2/custom_block.cpython-313-x86_64-linux-gnu.so
      FAILED: [code=1] cypari2/custom_block.cpython-313-x86_64-linux-gnu.so
      cc  -o cypari2/custom_block.cpython-313-x86_64-linux-gnu.so cypari2/custom_block.cpython-313-x86_64-linux-gnu.so.p/meson-generated_cypari2_custom_block.pyx.c.o -Wl,--as-needed
      -Wl,--allow-shlib-undefined -Wl,-O1 -shared -fPIC -Wl,--start-group /usr/lib64/libpari.so /usr/lib64/libgmp.so -Wl,--end-group
      /usr/lib/gcc/x86_64-pc-linux-gnu/15/../../../../x86_64-pc-linux-gnu/bin/ld: PARI_SIGINT_pending: TLS definition in /usr/lib64/libpari.so section .tbss mismatches non-TLS reference in
      cypari2/custom_block.cpython-313-x86_64-linux-gnu.so.p/meson-generated_cypari2_custom_block.pyx.c.o
      /usr/lib/gcc/x86_64-pc-linux-gnu/15/../../../../x86_64-pc-linux-gnu/bin/ld: /usr/lib64/libpari.so: error adding symbols: bad value
      collect2: error: ld returned 1 exit status
      [8/27] Compiling Cython source /home/dima/software/cypari2/tests/test.pyx
      [9/27] Compiling Cython source /home/dima/software/cypari2/cypari2/closure.pyx
      [10/27] Compiling Cython source /home/dima/software/cypari2/cypari2/stack.pyx
      [11/27] Compiling Cython source /home/dima/software/cypari2/cypari2/convert.pyx
      [12/27] Compiling C object cypari2/handle_error.cpython-313-x86_64-linux-gnu.so.p/meson-generated_cypari2_handle_error.pyx.c.o
      [13/27] Compiling Cython source /home/dima/software/cypari2/cypari2/gen.pyx
      warning: /home/dima/software/cypari2/cypari2/gen.pyx:2030:4: __nonzero__ was removed in Python 3; use __bool__ instead
      [14/27] Compiling Cython source /home/dima/software/cypari2/cypari2/pari_instance.pyx
      warning: /home/dima/software/cypari2/cypari2/pari_instance.pyx:588:8: The 'IF' statement is deprecated and will be removed in a future Cython version. Consider using runtime
      conditions or C macros instead. See https://github.com/cython/cython/issues/4310
      warning: /home/dima/software/cypari2/cypari2/pari_instance.pyx:1420:0: The 'IF' statement is deprecated and will be removed in a future Cython version. Consider using runtime
      conditions or C macros instead. See https://github.com/cython/cython/issues/4310
      ninja: build stopped: subcommand failed.

      hint: This usually indicates a problem with the package or the build environment.

this what I get if I install pari 2.17.3 to /home/dima/software/pari, pass it to pip, and try building. How does one tell meson not to use system-wide pari?
@tobiasdiez

[tobiasdiez]

The simplest solution would be to convince the pari people to add a pkg-config file...

[dimpase]

I pushed a solution involving setting LDFLAGS (CI needs adjusting accordingly, I guess), no idea why args setting in compiler.run, as suggested on mesonbuild tracker, doesn't work.

cf the commit message:

this allows an external pari library, with LDFLAGS set
with PPREF set to point at pari install prefix,
do

 export LDFLAGS="-Wl,-rpath=$PPREF/lib -L$PPREF/lib -lpari"
 pip install . --config-settings=setup-args="-Dpari-prefix=$PPREF"

works

[dimpase]

The simplest solution would be to convince the pari people to add a pkg-config file...

Does meson use rpath in this case? That's what's needed for building wheels.

[dimpase]

cf. mesonbuild/meson#13811 (reply in thread)

[dimpase]

is setting LDFLAGS equivalent to passing an argument to meson?

[dimpase]

is setting LDFLAGS equivalent to passing an argument to meson?

OK, turns out I can use -Dc_link_args to pass what should be in LDFLAGS, that is,

meson setup build/ --debug -Dpari-prefix=$PPREF -Dc_link_args="-Wl,-rpath=$PPREF/lib -L$PPREF/lib -lpari"

now I need to figure out how to pass all this to pip