Add Meson build system as alternative to CMake by munechika-koyo · Pull Request #10 · iterorganization/IMAS-Core

munechika-koyo · 2025-12-05T18:57:10Z

Summary

This pull request introduces Meson as an alternative build system for IMAS-Core, complementing the existing CMake build system. This addition provides developers with a modern, fast, and user-friendly build option while maintaining full backward compatibility with the current CMake workflow.

Motivation

Build System Diversity: Offers developers choice between CMake and Meson based on their preferences and requirements
Modern Build Experience: Meson provides faster configuration, better dependency management, and more intuitive syntax
Cross-Platform Support: Enhanced support for various platforms with Meson's robust cross-compilation features
Future-Proofing: Prepares the project for potential future migration while maintaining current stability

Key Features

🔧 Complete Build System Implementation

Core Library: Full support for building al-core with all backends (HDF5, UDA, MDSplus)
Python Bindings: Native Meson integration with Cython for imas-core Python package
Testing: Integration with test executables and test runners
Configuration Options: Comprehensive build options matching CMake functionality

📦 Backend Support

✅ HDF5 Backend (enabled by default)
✅ UDA Backend (enabled by default)
🔄 MDSplus Backend (planned for future implementation)
🔄 MDSplus Models (planned for future implementation)

🐍 Python Integration

Version detection via setuptools-scm
Cython binding compilation with proper dependency management

Files Added/Modified

New Meson Files

meson.build - Main build configuration
meson_options.txt - Build options and feature toggles
src/meson.build - Core library build configuration
include/meson.build - Public Header installation configuration
python/meson.build - Python bindings build configuration

Build Options

# Configure with Meson (examples)
meson setup builddir
meson setup builddir -Dal_backend_hdf5=true -Dal_backend_uda=false
meson setup builddir -Dal_core=false -Dpython_bindings=true

# Build
meson compile -C builddir

# Test
meson setup builddir -Dal_dummy_exe=true
meson test -C builddir

Compatibility

No Migration Required: CMake remains the primary build system
Parallel Support: Both build systems can coexist without conflicts
Feature Parity: All CMake options have equivalent Meson counterparts
Same Dependencies: Uses identical external dependencies (HDF5, UDA, MDSplus, etc.)

Testing

Builds on macOS
Builds on Linux
Builds on Windows
All backends compile correctly (except for MDSplus)
Python bindings generate properly
Test dummy executable build and run
Test al-core executables build and run
Test Python bindings imas-core

Development Environment

We used pixi to manage the development environment for testing the Meson build system.
The pixi.toml file has been updated to include Meson and Ninja as build tools, ensuring a consistent and reproducible environment for developers.
Here is the configuration I used:

pixi.toml

[workspace]
channels = ["conda-forge"]
name = "imas-core"
platforms = ["osx-arm64", "osx-64", "linux-64", "win-64"]

[tasks]
setup = { cmd = [
    "meson",
    "setup",
    "builddir",
], description = "Setup the build directory" }

build = { cmd = [
    "meson",
    "compile",
    "-C",
    "builddir",
], description = "Build the project" }

install = { cmd = [
    "meson",
    "install",
    "-C",
    "builddir",
    "--destdir",
    "{{ destdir }}",
], args = [
    { arg = "destdir", default = "build-install" },
], description = "Install the project" }

test = { cmd = [
    "meson",
    "test",
    "-C",
    "builddir",
    "--verbose",
], description = "Run the tests", depends-on = [
    { task = "setup", args = [
        "-Dal_dummy_exe=true",
    ] },
] }


[target.unix.activation.env]
BOOST_INCLUDEDIR = "$CONDA_PREFIX/include"
BOOST_LIBRARYDIR = "$CONDA_PREFIX/lib"

[target.win-64.activation.env]
BOOST_INCLUDEDIR = "%CONDA_PREFIX%/Library/include"
BOOST_LIBRARYDIR = "%CONDA_PREFIX%/Library/lib"

[dependencies]
# Compiler
cxx-compiler = ">=1.11.0,<2"

# Build tools
meson = ">=1.9.1,<2"
ninja = ">=1.13.2,<2"
pkg-config = ">=0.29.2,<0.30"
setuptools-scm = ">=9.2.2,<10"

# Link Libraries
libboost-devel = ">=1.88.0,<2"
hdf5 = ">=1.14.6,<2"
uda-cpp = ">=2.9.3,<3"
libxml2-devel = ">=2.15.1,<3"
zlib = ">=1.3.1,<2"

# Link and Tools for the python wrapper
python = ">=3.14.1,<3.15"
numpy = ">=2.3.5,<3"
cython = ">=3.2.2,<4"

[target.win-64.dependencies]
# Build tools
cmake = ">=4.2.1,<5"

# Link Libraries
dlfcn-win32 = ">=1.4.2,<2"
winpthreads-devel = ">=12.0.0.r4.gg4f2fc60ca,<13"

meson command can be used through pixi run meson ....

Note: This is a non-breaking change that purely adds functionality. All existing CMake-based workflows continue to work unchanged.

- Introduced meson.build files for project setup and library configuration. - Added options for building internal core library and dummy executable. - Included source files for HDF5 and UDA backends. - Configured public headers and installation paths.

…son.build

…on and add option for building tests

…pendencies

…on.py

add test cases for lowlevel executables and modify dummy executable option

…'python -m setuptools_scm'

…uration

…2 dependency method in Meson build configuration

…rce handling for UDA and HDF5 backends

…endencies Format code

… adjust project languages

…pport

to make consist between .dll and .lib file name

prasad-sawantdesai · 2026-02-09T14:08:17Z

@munechika-koyo Could you please check this PR? This fixes numpy issue on SDCC. munechika-koyo#1

prasad-sawantdesai

Thanks for adding this build system @munechika-koyo
It seems faster than normal cmake workflow.

time meson setup --reconfigure builddir --prefix="$HOME/.local"
real    0m20.597s
user    0m3.148s
sys     0m6.954s

time meson compile -C builddir
real    1m19.796s
user    2m2.108s
sys     0m20.637s

prasad-sawantdesai · 2026-02-09T14:17:42Z

src/meson.build

+# =============================================================================
+# Add Optional Backends
+# =============================================================================
+if get_option('al_backend_hdf5')


is it possible to use capital case here or are there any limitations? -DAL_BACKEND_UDA=OFF -DAL_BACKEND_UDAFAT=OFF -DAL_BACKEND_MDSPLUS=OFF

We should not use capital names in the meson build to follow the style guide.
Additionally, many built-in options are already defined in lowercase, so we should follow that convention to avoid confusion.

prasad-sawantdesai · 2026-02-09T14:24:31Z

meson.build

+# =============================================================================
+# Summary
+# =============================================================================
+if get_option('al_core')


Should we add github workflow for testing meson build?

prasad-sawantdesai · 2026-02-09T14:26:40Z

meson.build

Is it possible to add small list of steps in the sphinx documentation? https://github.com/iterorganization/IMAS-Core/blob/develop/docs/source/user_guide/installation.rst somewhere here?

munechika-koyo · 2026-02-09T14:57:58Z

Thanks for adding this build system @munechika-koyo It seems faster than normal cmake workflow.
time meson setup --reconfigure builddir --prefix="$HOME/.local"
real    0m20.597s
user    0m3.148s
sys     0m6.954s

time meson compile -C builddir
real    1m19.796s
user    2m2.108s
sys     0m20.637s

Thank you for measuring the compilation time!
Could you add the cmake-case time for the comparison?

prasad-sawantdesai · 2026-02-09T15:36:23Z

Thanks for adding this build system @munechika-koyo It seems faster than normal cmake workflow.
time meson setup --reconfigure builddir --prefix="$HOME/.local"
real    0m20.597s
user    0m3.148s
sys     0m6.954s

time meson compile -C builddir
real    1m19.796s
user    2m2.108s
sys     0m20.637s
Thank you for measuring the compilation time! Could you add the cmake-case time for the comparison?

Yes, it is slower..

time  cmake -Bbuild -S . 

real    0m44.060s
user    0m14.387s
sys     0m6.725s

time cmake --build build 
real    7m28.771s
user    4m35.985s
sys     1m53.904s

munechika-koyo and others added 22 commits December 5, 2025 01:08

Update Meson version requirement and improve section formatting in me…

a83d76a

…son.build

Refactor Meson build configuration to use external al-core installati…

fb947cb

…on and add option for building tests

Add Meson build configuration for Python extension module

c7de00b

Add Meson build configuration for test executables

58407e0

Fix version comparison syntax in Meson build configuration for UDA de…

cf45462

…pendencies

Add versioning support in Meson build configuration and create _versi…

662586d

…on.py

Update Meson build configuration

06b1922

add test cases for lowlevel executables and modify dummy executable option

Format comment bars

e5fe0e2

Update version retrieval command in Meson build configuration to use …

fbc8419

…'python -m setuptools_scm'

Fix variable name for UDA fat client dependency in Meson build config…

5e9b832

…uration

Replace Windows thread dependency with pthreads and update dlfcn-win3…

0b4a380

…2 dependency method in Meson build configuration

Add conditional compiler flags for HDF5 on Windows

cf9a7ea

Format

ee653f5

Refactor Meson build configuration for al_defs.h and public headers

2c641fe

Add include directories section to Meson build configuration

06edbaf

Enhance Meson build configuration with warning flags and refactor sou…

613bf1a

…rce handling for UDA and HDF5 backends

Add MDSplus backend support in Meson build configuration

ab5bee6

Add additional warning flags for Darwin in Meson build configuration

aeff008

Refactor Meson build configuration to remove 'required' flag from dep…

b3c08f6

…endencies Format code

Remove '-Wno-switch' from warning flags in Meson build configuration

8e5ceb4

Merge branch 'iterorganization:develop' into feature/meson

829a2b7

munechika-koyo marked this pull request as ready for review January 22, 2026 15:46

munechika-koyo added 3 commits February 6, 2026 14:01

Refactor Meson build configuration to use C++ for HDF5 dependency and…

b4170b6

… adjust project languages

Update Meson build configuration to conditionally add C++ language su…

f5debf6

…pport

Use find_program() func for python and git

c3894e0

SimonPinches assigned SimonPinches and olivhoenen Feb 6, 2026

munechika-koyo added 2 commits February 9, 2026 08:47

Revert c/c++ std config

0599eed

Remove default warning flags from Meson build configuration

5edba1e

olivhoenen requested review from olivhoenen and prasad-sawantdesai February 9, 2026 12:48

munechika-koyo and others added 3 commits February 9, 2026 13:50

Remove version specification from al_core library definition

d949a4f

to make consist between .dll and .lib file name

Add 'fix_include_windows.h' to the list of installed public headers

73a337b

fixed search numpy on SDCC

12344ba

prasad-sawantdesai reviewed Feb 9, 2026

View reviewed changes

Refactor numpy dependency handling in meson.build

e7c37f0

munechika-koyo and others added 4 commits February 9, 2026 18:16

Migrate to cpp compile for cython transpile

072346e

Refactor Python dependency handling in Meson build configuration

8456945

Merge branch 'feature/meson' into pr-10

a71d1d4

Merge pull request #1 from prasad-sawantdesai/pr-10

8cd89a1

Provide feedback

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Add Meson build system as alternative to CMake#10

Add Meson build system as alternative to CMake#10
munechika-koyo wants to merge 35 commits intoiterorganization:developfrom
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Summary

Motivation

Key Features

🔧 Complete Build System Implementation

📦 Backend Support

🐍 Python Integration

Files Added/Modified

New Meson Files

Build Options

Compatibility

Testing

Development Environment

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munechika-koyo commented Dec 5, 2025 •

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