[WIP] Meson build system

[mia-0]

Since CMake has too many problems to list and Autotools doesn’t really integrate with anything, I decided to port most of the Autotools build system to Meson. This includes maintainer mode. I did not touch any existing files other than for the commit that removes CMake, so this is not as clean and simple as it could be.

The genfft part deviates a bit from Autotools by using (requiring) Dune, which will download and compile known-working versions of the OCaml toolchain and any required packages as necessary.

See README-meson.md in the top-level directory for more information.

Tested

On openSUSE Tumbleweed:

Targets

GCC 15 with glibc except as noted. Cross-compiled builds were tested by running the bench program through a few cases using QEMU binfmt wrappers or WINE and making sure it also picked a few SIMD code paths.

• x86_64 native
• aarch64 cross (Android NDK r28c, Clang)
• loongarch64 cross
• ppc64le cross
• riscv64 cross
• s390x cross
• MinGW-w64 x86_64 cross

Environments

• plain
• KDevelop
• VSCode with Meson extension

Other

• Creating dist tarballs
• Including FFTW as subproject of another project via Meson’s Wrap system

On Windows 11:

MSVC cl 19.50 / link 14.50. Other than MSVS 2026, only Meson and Ninja were installed using the MSI package from Meson’s Release page. No WSL or other external dependencies.

Static library build only because we’re not explicitly exporting some internal symbols that are needed to dynamically link threads/omp/mpi libs and tools to the main library. But yes, it basically works with MSVC-style toolchains as well. Was easier than I thought, too.

Targets

• x86 native
• x86_64 native

Environments

• plain (developer console)
• Visual Studio 2026 (Meson vs2022 backend)
• Visual Studio 2026 (vslite project setup)

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I also wanted to test some BSDs but didn’t get around to it yet. As for macOS and other Apple targets, Meson does have an Xcode backend, but I was unable to test it because I do not have a Mac and my aging travel laptop took more than half an hour just to boot a macOS VM (it really is not meant to run on anything but Apple hardware). Help is appreciated.

To Do

These are required to reach feature parity with Autotools:

• Fortran wrappers (needs replacements for Autoconf-provided macros)
• ARM v7a/v8 performance counters
• Commercialized tarballs

Bonus features:

• Build multiple precisions at once
• Replace Perl wrapper with proper Meson test and benchmark suites
• Generate more complete set of CMake support files (please somebody else do this)