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

[tobiasdiez]

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.

Yes, I think so (not sure what exactly happens on Windows...)

[dimpase]

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

I'm going to post on pari-dev, but first one needs to figure out how to add that functionality to their perl-based
build system...

Anyway, we need to support the current pari versions, too.

[dimpase]

and it's a comedy of errors/bugs:

$ python -m build --wheel .  -Csetup-args="-Dc_link_args=\"-Wl,-rpath=$PPREF/lib -L$PPREF/lib\"" -Csetup-args="--debug" -Csetup-args="-Dpari-prefix=$PPREF"
* Creating isolated environment: venv+pip...
* Installing packages in isolated environment:
  - cysignals>=1.11.3
  - cython>=3.0
  - meson-python>=0.18.0
* Getting build dependencies for wheel...
* Building wheel...
+ meson setup /home/dima/software/cypari2 /home/dima/software/cypari2/.mesonpy-b1zcsuwc -Dbuildtype=release -Db_ndebug=if-release -Db_vscrt=md -Dc_link_args="-Wl,-rpath=/home/dima/software/pari/lib -L/home/dima/software/pari/lib" --debug -Dpari-prefix=/home/dima/software/pari --native-file=/home/dima/software/cypari2/.mesonpy-b1zcsuwc/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-b1zcsuwc
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 3.2.3)
Host machine cpu family: x86_64
Host machine cpu: x86_64
Program python found: YES (/tmp/build-env-v95r7enx/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

../meson.build:98:18: ERROR: Could not run pari version

A full log can be found at /home/dima/software/cypari2/.mesonpy-b1zcsuwc/meson-logs/meson-log.txt

ERROR Backend subprocess exited when trying to invoke build_wheel

however if I take the meson setup line from the log, remove --native-file part, and run it separately, it works. Thus, build writes some stuff into native-file which breaks things.

With pip it's even worse, it's unable to chain -Csetup-args=, despite it being version 25, and despite
meson manual claiming that it's been fixed in pip 23.1. It seems to be broken again.

[tobiasdiez]

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

I'm going to post on pari-dev, but first one needs to figure out how to add that functionality to their perl-based build system...

A few months ago, I already expressed the wish for a pkg-config file on their mailing list (along with a couple of other things that would support building on Windows). No reaction so far, so it would be good if you could reinforce that wish.

Anyway, we need to support the current pari versions, too.

It's working, but only if Pari is installed in a standard location... As the only semi-urgent use case for a non-standard location is sage-the-distro, I would say that supporting non-standard locations only for new Pari versions with pkg-config would be an acceptable trade-off (of course given that Pari would add pkg-config files relatively soon).

[dimpase]

It's working, but only if Pari is installed in a standard location...

in this case, does libpari still get bundled into binary wheels? Anyhow, there is no really standard location on macOS to speak about.

[tobiasdiez]

It's working, but only if Pari is installed in a standard location...

in this case, does libpari still get bundled into binary wheels?

Yes, that should still work.