[Bug]: Can't compile Mac

Bug summary

When trying to build on a Mac (15.6.1), I get:

../../subprojects/freetype-2.6.1/src/gzip/infcodes.c:71:17: error: use of undeclared identifier 'Byte'
     71 |     c->dbits = (Byte)bd;
        |                 ^

This is in a micro mamba environment, made with environment.yml.

Matplotlib seems to run in dev mode, but I need to recompile to get pytest to work.

Code for reproduction

`python -m pip install --verbose --no-build-isolation --editable ".[dev]"`

Actual outcome

  In file included from ../../subprojects/freetype-2.6.1/src/gzip/ftgzip.c:65:
  In file included from ../../subprojects/freetype-2.6.1/src/gzip/zlib.h:34:
  ../../subprojects/freetype-2.6.1/src/gzip/zconf.h:228:12: error: unknown type name 'Byte'
    228 |    typedef Byte  FAR Bytef;
        |            ^
  In file included from ../../subprojects/freetype-2.6.1/src/gzip/ftgzip.c:83:
  ../../subprojects/freetype-2.6.1/src/gzip/inftrees.h:22:7: error: unknown type name 'Byte'
     22 |       Byte Exop;        /* number of extra bits or operation */
        |       ^

...etc

Expected outcome

dev install

Additional information

No response

Operating system

MacOS 15.6.1

Matplotlib Version

main

Matplotlib Backend

No response

Python version

No response

Jupyter version

No response

Installation

conda

which compiler are you using ?

Obtaining file:///Users/jklymak/matplotlib
  Running command Checking if build backend supports build_editable
  Checking if build backend supports build_editable ... done
  Running command Preparing editable metadata (pyproject.toml)
  + meson setup /Users/jklymak/matplotlib /Users/jklymak/matplotlib/build/cp312 -Dbuildtype=release -Db_ndebug=if-release -Db_vscrt=md --native-file=/Users/jklymak/matplotlib/build/cp312/meson-python-native-file.ini
  The Meson build system
  Version: 1.9.0
  Source dir: /Users/jklymak/matplotlib
  Build dir: /Users/jklymak/matplotlib/build/cp312
  Build type: native build
  Program python found: YES 3.12.11 3.12.11
  Project name: matplotlib
  Project version: 3.11.0.dev1277+ge401f8235.d20250828
  C compiler for the host machine: arm64-apple-darwin20.0.0-clang (clang 19.1.7 "clang version 19.1.7")
  C linker for the host machine: arm64-apple-darwin20.0.0-clang ld64 954.16
  C++ compiler for the host machine: arm64-apple-darwin20.0.0-clang++ (clang 19.1.7 "clang version 19.1.7")
  C++ linker for the host machine: arm64-apple-darwin20.0.0-clang++ ld64 954.16
  Host machine cpu family: aarch64
  Host machine cpu: aarch64
  Program python found: YES (/Users/jklymak/micromamba/envs/mpl-dev/bin/python)
  Found pkg-config: YES (/Users/jklymak/micromamba/envs/mpl-dev/bin/pkg-config) 0.29.2
  Run-time dependency python found: YES 3.12
  Run-time dependency pybind11 found: YES 3.0.1

  Executing subproject freetype-2.6.1
...

Can you see if the text-overhaul branch (which has FreeType 2.13.3) works better?

@QuLogic

@QuLogic Yes, that branch installs fine.

arm64-apple-darwin20.0.0-clang

Is that the system compiler, or one that micromamba installed? If the latter, can you try removing it or vice versa?

Looks to be the micro mamba one:

$ clang++ -v
clang version 19.1.7
Target: arm64-apple-darwin24.6.0
Thread model: posix
InstalledDir: /Users/jklymak/micromamba/envs/mpl-dev/bin

I don't understand mamba well enough to know how to get the system C++. If I remove

rm /Users/jklymak/micromamba/envs/mpl-dev/bin/arm64-apple-darwin20.0.0-clang*

then I get

raise child_exception_type(errno_num, err_msg, err_filename)
  FileNotFoundError: [Errno 2] No such file or directory: 'arm64-apple-darwin20.0.0-clang++'

so the paths aren't set up properly to find the system clang.

Ah yes, after activating the environment, you can unset CC, CXX, CFLAGS, CXXFLAGS, and LDFLAGS I think, and then recreate your build directory to initialize with the system compiler.

I can unset all of those, but it still chooses arm64-apple-darwin20.0.0-clang which is the mamba clang (etc).

Sorry, I can't really tell what meson is doing to "recreate (my) build directory". This is all using the matplotlib mamba environment, so do we need to be pinning the compiler somehow? Note we ask for c-compiler and cxx-compiler. Should we not?

Sorry, I can't really tell what meson is doing to "recreate (my) build directory".

For an editable install, you would need to delete the build directory; it won't change compilers from environment variables for an existing build.

This is all using the matplotlib mamba environment, so do we need to be pinning the compiler somehow?

Possibly; I'm just unsure what changed. It seems like it was last updated a few weeks ago, but that was for the llvm21 release candidate, and you don't appear to be using that.

Note we ask for c-compiler and cxx-compiler. Should we not?

IIRC, we added these so we could have a self-contained environment on e.g., Windows or in devcontainers or indeed on macOS with Xcode.

Do you solve this problem?

Not yet, I haven't had a lot of time. I tried pinning various versions of the micro mamba c compilers but didn't have any luck with that.

Attached is my meson log. This sees to be using the Xcode compilers (versus micro mamba). I got this by doing pixi init and then pixi install.

meson-log.txt

#29247 purports to fix this, but unless I manually copy the zconf.h file into the subprojects/freetype-2.6.1/src/gzip directory, freetype will not compile. I found I also have to do

pixi add meson-python meson ninja

and then I had an editable pixi install on my Mac. If I didn't do that it was trying to pull ninja from a cache, and meson-python was not installed.

So I'm not really at all clear on what meson is or how to fix this so it's more turnkey. At least on my system, it seems that the build scripts are not fully robust.

To summarize:

If I do

cp subprojects/packagefiles/freetype-2.6.1-meson/src/gzip/zconf.h subprojects/freetype-2.6.1/src/gzip
pixi init
pixi add meson-python meson ninja

I can run matplotlib from a local pixi environment.

We no longer use FreeType 2.6.1, and given #31384 (comment), I think this is well enough fixed now.

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[Bug]: Can't compile Mac #30480

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[Bug]: Can't compile Mac #30480

Description

Bug summary

Code for reproduction

Actual outcome

Expected outcome

Additional information

Operating system

Matplotlib Version

Matplotlib Backend

Python version

Jupyter version

Installation

Activity

tacaswell commented on Aug 28, 2025

jklymak commented on Aug 28, 2025

QuLogic commented on Aug 29, 2025

jklymak commented on Aug 29, 2025

QuLogic commented on Aug 29, 2025

jklymak commented on Aug 29, 2025

QuLogic commented on Aug 30, 2025

jklymak commented on Aug 30, 2025

QuLogic commented on Aug 30, 2025

rongshaohzr-lang commented on Sep 8, 2025

jklymak commented on Sep 8, 2025

jklymak commented on Oct 17, 2025

jklymak commented on Oct 17, 2025

QuLogic commented on Jun 12, 2026

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