[Daniel Johansson (djohansson)]

This adds opt-in support for CMake's FASTBuild generator (CMake 4.2 and newer; vcpkg's own CMake is 4.4.4) to vcpkg_cmake_configure and vcpkg_cmake_build. The default generator doesn't change for any existing triplet or port.

• A portfile can pass GENERATOR FASTBuild.
• A triplet can set VCPKG_CMAKE_GENERATOR (for example set(VCPKG_CMAKE_GENERATOR FASTBuild)) to choose the generator for ports that don't pick one themselves. A portfile's own GENERATOR or WINDOWS_USE_MSBUILD still wins, so a port that must use Ninja can still say so.
• FBuild is acquired like Ninja. vcpkg_find_acquire_program(FASTBUILD) calls z_use_vcpkg_fetch(FASTBUILD), and FASTBuild 1.20 is added to scripts/vcpkg-tools.json for Windows x64, Linux x64 and macOS (a universal binary). The Linux archive carries no file modes; vcpkg fetch marks the extracted executable as executable.
• vcpkg_cmake_build passes -j${VCPKG_CONCURRENCY} to FBuild, or -j1 for DISABLE_PARALLEL, as it does for Ninja. Failure logs collect fbuild.bff, the file CMake's FASTBuild generator writes.

Why a change to a shared helper: the generator can only be chosen inside vcpkg_cmake_configure. Today using FASTBuild for every port means an overlay of vcpkg-cmake, which then has to track this port by hand. The change is inert unless a triplet or portfile asks for FASTBuild.

Motivation: I build my project and its vcpkg dependencies with FASTBuild, for its cache and distributed compilation, and I have been carrying this as an overlay of vcpkg-cmake and a fork of vcpkg.

Testing (macOS 27, arm64, vcpkg 2026-10-29 bootstrapped from this branch, binary caching off):

• An overlay triplet, the stock arm64-osx.cmake plus set(VCPKG_CMAKE_GENERATOR FASTBuild). vcpkg install zlib jsoncpp --triplet arm64-osx-fastbuild --host-triplet arm64-osx --classic succeeds. FBuild was fetched to downloads/tools/fastbuild-1.20-osx, configure got -DCMAKE_MAKE_PROGRAM=<that>/FBuild, the build trees contain fbuild.bff, and config-*-rel-fbuild.log was collected.
• The same install with the stock arm64-osx triplet still uses Ninja (build.ninja, no fbuild.bff).
• I have not run this branch on Windows or Linux. The same approach, as an overlay of vcpkg-cmake, has built my project's dependencies (70 to 90 ports per platform) with FASTBuild on Windows x64 (clang), Linux x64 and macOS arm64 since March 2026.

Documentation: MicrosoftDocs/vcpkg-docs#624 (VCPKG_CMAKE_GENERATOR on the triplet variables page, the generator order in vcpkg_cmake_configure's GENERATOR, and FASTBUILD in vcpkg_find_acquire_program's list).

• Changes comply with the maintainer guide.
• SHA512s are updated for each updated download (the new FASTBuild entries in vcpkg-tools.json).
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Exactly one version is added in each modified versions file.

🤖 Generated with Claude Code

[Copilot]

🟡 Changes recommended

The FASTBUILD acquisition script lacks the required platform- and architecture-guarded integration-test call, leaving its downloads and extracted executable paths outside existing test coverage.

1 open issue

• Add guarded FASTBUILD acquisition test coverage · New

What changed in this PR

Adds opt-in FASTBuild support to vcpkg’s CMake helpers while preserving existing default generator selection and port-level overrides.

Changes:

• Allows FASTBuild selection through port arguments or the VCPKG_CMAKE_GENERATOR triplet variable.
• Adds platform-specific tool downloads, parallel build arguments, and configure-log collection.
• Updates the vcpkg-cmake version and registry metadata.

File	Description
versions/​v-/​vcpkg-cmake.json	Records the new helper version.
versions/​baseline.json	Advances the helper’s baseline version.
scripts/​vcpkg-tools.json	Adds FASTBuild downloads for Windows, Linux, and macOS.
scripts/​cmake/​vcpkg_find_acquire_program(FASTBUILD).cmake	Delegates FASTBuild acquisition to vcpkg fetch.
ports/​vcpkg-cmake/​vcpkg.json	Bumps the helper’s version date.
ports/​vcpkg-cmake/​vcpkg_cmake_configure.cmake	Adds generator selection, tool setup, and FASTBuild log collection.
ports/​vcpkg-cmake/​vcpkg_cmake_build.cmake	Adds FASTBuild parallelism controls.

_{Review effort: Balanced}

[Daniel Johansson (djohansson)]

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[Daniel Johansson (djohansson)]

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[Copilot]

🟢 Approval recommended

No active review issues were identified for the opt-in FASTBuild integration.

No open issues 🎉

1 resolved since last review

• Add guarded FASTBUILD acquisition test coverage

_{Review effort: Balanced}

[Billy O'Neal (BillyONeal)]

The arm64-windows failure is a baseline issue: https://dev.azure.com/vcpkg/public/_build/results?buildId=140614

No change requested here.

[Billy O'Neal (BillyONeal)]

Thanks!

[Billy O'Neal (BillyONeal)]

Not included: documentation of VCPKG_CMAKE_GENERATOR for vcpkg-docs (the triplet variables page and vcpkg_cmake_configure). I can open that PR there if this direction is acceptable.

Yes please submit to https://github.com/microsoftdocs/vcpkg-docs/

[Billy O'Neal (BillyONeal)]

Hmmm please don't push random merges unless there's a specific thing you're trying to change, each time you push it resets builds, and because this change changes almost every port that's resetting >2 days of work for the build lab, so if you keep pushing we will never be able to merge this.

(We are willing to merge through some kinds of baseline issues for this kind of world rebuild situation)