Meson fails to parse vswhere.exe output for Visual Studio 2022 Build Tools 17.14.x (error: "Could not parse vswhere.exe output")

[vnscience]

When trying to install packages using meson-python (e.g., contourpy) on Windows with Visual Studio Build Tools 2022 version 17.14.x, Meson fails with the following error:

..\meson.build:1:0: ERROR: Could not parse vswhere.exe output

This happens during meson setup when Meson invokes vswhere.exe. However, vswhere.exe itself works correctly and returns valid JSON output.

✅ Environment:
OS: Windows 10/11 64-bit
Python: 3.13.0
pip: 25.1.1
meson: 1.8.2
meson-python: 0.18.0
Visual Studio Build Tools: 2022, version 17.14.7 (BuildTools)
vswhere.exe: Bundled with Visual Studio Installer.

✅ Steps to Reproduce:
Install Visual Studio Build Tools 2022 version 17.14.x (latest stable).

Install Meson and meson-python:

pip install --upgrade meson meson-python
Try installing a package requiring build with Meson (e.g., contourpy):

pip install contourpy
Build fails with:

ERROR: Could not parse vswhere.exe output

✅ Additional Details:
The output of vswhere.exe is valid JSON and contains required fields like installationPath, isComplete: true, productId, etc.

Here’s the actual output of:
"C:\Program Files (x86)\Microsoft Visual Studio\Installer\vswhere.exe" -products * -latest -format json

vswhere output (click to expand)

[ { "instanceId": "a4ca0acc", "installDate": "2025-07-03T07:06:21Z", "installationName": "VisualStudio/17.14.7+36221.1", "installationPath": "C:\\Program Files (x86)\\Microsoft Visual Studio\\2022\\BuildTools", "installationVersion": "17.14.36221.1", "productId": "Microsoft.VisualStudio.Product.BuildTools", "isComplete": true, "isLaunchable": true, "displayName": "Visual Studio Build Tools 2022", "channelId": "VisualStudio.17.Release" } ]

✅ Possible Cause: Meson may not correctly parse or recognize Build Tools installations without the full Visual Studio IDE, despite valid vswhere output.

This issue did not occur in older Visual Studio versions, suggesting a regression or incomplete support for newer Visual Studio Build Tools (17.14.x).

✅ Expected Behavior:
Meson should correctly detect Visual Studio Build Tools and proceed with the build process if a valid environment is available.

✅ Temporary Workarounds:
Install the full Visual Studio IDE (Community Edition) instead of just Build Tools.

Force binary-only installation using:
pip install <package> --only-binary=:all:
✅ Suggested Actions:
Review the parsing logic of vswhere.exe output in Meson (possibly in mesonbuild\environment.py).

Add compatibility for Visual Studio Build Tools ≥17.14.x.

Possibly improve error reporting to indicate where parsing failed.

✅ Additional Notes:
This issue affects many Python packages using meson-python as their build backend, especially on Windows systems with only Build Tools installed (common for headless build servers).

[rgommers]

Thanks for the report @vnscience. Could you please try to get the output of the more detailed logging in build/meson-logs/meson-log.txt? It should be available when using a fixed build dir, e.g. pip install . -Cbuild-dir=build for contourpy.

Visual Studio Build Tools version 17.14.7 is only 2 weeks old and contains a bunch of regression fixes (see https://learn.microsoft.com/en-us/visualstudio/releases/2022/release-notes?tabs=allfeatures#17.14.7) including ones that look relevant like include path quoting; it seems fairly likely this is another regression.