Notes to support Visual Studio 2026

[yukawa]

While Visual Studio 2026 is now publicly available, there seem to be several blockers for us to build Mozc package with it. So I created a discussion thread keep posting your notes and findings.

[yukawa]

GitHub Actions runner

As of Nov 24, 2025, GitHub Actions runner with Visual Studio 2026 preinstalled is not yet available.

• Update/Add Visual Studio 2026 actions/runner-images#13291

This is probably a hard blocker for us to officially support Visual Studio 2026 in the Mozc project.

[yukawa]

https://github.blog/changelog/2026-02-05-github-actions-early-february-2026-updates/#windows-server-2025-with-visual-studio-2026-image-now-available-for-github-hosted-runners

A new Windows runner image with Visual Studio 2026 is now available in public preview. This dedicated image runs alongside the current windows-2025 image, providing a safe validation path ahead of the default Windows image migration. Visual Studio 2026 will be integrated into the windows-2025 image when it reaches general availability on May 4, 2026.

You can test against Visual Studio 2026 without disrupting existing pipelines, identify and fix compatibility issues on your timeline, maintain fallback options (like windows-2022) if needed, and plan migrations with full visibility into the upgrade timeline.

[yukawa]

Visual C++ redistribution files

The paths to Visual C++ redistributions files are also updated from Visual Studio 2022.

Visual Studio version	Redistribution files dir
2022	%VCToolsRedistDir%/x64/Microsoft.VC143.CRT
2026	%VCToolsRedistDir%/x64/Microsoft.VC145.CRT

There are several places where we currently hard-code Microsoft.VC143.CRT.

mozc/src/gyp/common_win.gypi

Lines 46 to 68 in ac096a5

	'conditions': [
	# https://docs.microsoft.com/en-us/cpp/preprocessor/predefined-macros
	['MSVS_VERSION=="2015"', {
	'compiler_target': 'msvs',
	'compiler_host': 'msvs',
	'vcruntime_ver': '140',
	}],
	['MSVS_VERSION=="2017"', {
	'compiler_target': 'msvs',
	'compiler_host': 'msvs',
	'vcruntime_ver': '141',
	}],
	['MSVS_VERSION=="2019"', {
	'compiler_target': 'msvs',
	'compiler_host': 'msvs',
	'vcruntime_ver': '142',
	}],
	['MSVS_VERSION=="2022"', {
	'compiler_target': 'msvs',
	'compiler_host': 'msvs',
	'vcruntime_ver': '143',
	}],
	],

mozc/src/win32/installer/build_installer.py

Line 87 in ac096a5

redist_64bit = redist_root.joinpath(arch).joinpath('Microsoft.VC143.CRT')

[yukawa]

Does GYP support Visual Studio 2026?

Probably no by default, but someone needs to look into this to confirm.

Here is the relevant code where we currently specify the Visual Studio version in the GYP build.

mozc/src/build_mozc.py

Lines 253 to 255 in ac096a5

	parser.add_option('--msvs_version', dest='msvs_version',
	default='2022',
	help='Version of the Visual Studio.')

[yukawa]

Here is a relevant pull-request in gyp-next:

• feat: add support for Visual Studio 2026 nodejs/gyp-next#319

[yukawa]

We finally removed GYP in 0e55551, so it's OK to stop worrying about Visual Studio 2026 support in GYP.

[yukawa]

This is now fully implemented with b940437.