ci: bump AppVeyor macOS image to Sonoma

[Copilot]

• Bump AppVeyor macOS image to macos-sonoma
• Add HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK=1 prefix to brew install create-dmg to prevent cmake symlink conflicts during dependents upgrade check

Original prompt

In appveyor.yml at line 12, the macOS build worker image is set to the generic macOS, which maps to the oldest available image (Monterey 12). This is causing issues with stale pre-installed software (e.g., Homebrew cmake symlink conflicts when installing create-dmg).

Change line 12 from:

appveyor_build_worker_image: macOS

to:

appveyor_build_worker_image: macos-sonoma

This bumps the macOS CI leg to macOS 14 Sonoma, which is the newest macOS image available on AppVeyor.

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: on my https://github.com/KirillOsenkov/MSBuildStructuredLog there's an AppVeyor CI, and the mac leg fails, here's a log excerpt:

[00:33:58] Error: The brew link step did not complete successfully
[00:33:58] The formula built, but is not symlinked into /usr/local
[00:33:58] Could not symlink bin/ccmake
[00:33:58] Target /usr/local/bin/ccmake
[00:33:58] already exists. You may want to remove it:
[00:33:58] rm '/usr/local/bin/ccmake'
[00:33:58]
[00:33:58] To force the link and overwrite all conflicting files:
[00:33:58] brew link --overwrite cmake
[00:33:58]
[00:33:58] To list all files that would be deleted:
[00:33:58] brew link --overwrite cmake --dry-run
[00:33:58]
[00:33:58] Possible conflicting files are:
[00:33:58] /usr/local/bin/ccmake -> /Applications/CMake.app/Contents/bin/ccmake
[00:33:58] /usr/local/bin/cmake -> /Applications/CMake.app/Contents/bin/cmake
[00:33:58] /usr/local/bin/cpack -> /Applications/CMake.app/Contents/bin/cpack
[00:33:58] /usr/local/bin/ctest -> /Applications/CMake.app/Contents/bin/ctest
[00:34:00] ==> Summary
[00:34:00] 🍺 /usr/local/Cellar/cmake/4.3.1: 4,041 files, 73.6MB, built in 31 minutes 24 seconds

the build files should be at the root of the repo. Can you figure out what's wrong?

Assistant: The issue is not in your build scripts — it's in the appveyor.yml init step for the macOS build. Specifically, line 81:

- brew install create-dmg

When Homebrew installs create-dmg, it pulls in cmake as a dependency. The AppVeyor macOS image already has CMake pre-installed (via /Applications/CMake.app), so when Homebrew tries to symlink its own cmake binaries into /usr/local/bin/, it conflicts with the existing symlinks pointing to the app bundle version.

The error itself (brew link not completing) is technically a non-fatal warning from Homebrew — the create-dmg tool doesn't actually need cmake at runtime (it only uses hdiutil and shell scripting). However, depending on how AppVeyor treats the exit code of that brew install command, it may cause the build to fail.

Fix

You have a couple of options:

Option 1: Force-overwrite the conflicting links (simplest)

Change line 81 in appveyor.yml to:

- HOMEBREW_NO_AUTO_UPDATE=1 brew install create-dmg || true
- brew link --overwrite cmake || true

Option 2: Unlink the pre-installed CMake first

- brew unlink cmake 2>/dev/null || true
- brew install create-dmg

Option 3 (recommended): Install create-dmg without upgrading dependencies

Since create-dmg is the only tool you actually need and it has no real dependency on cmake, prevent Homebrew from trying to upgrade/link cmake at all:

- HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK=1 brew install create-dmg

This environment variable tells Homebrew to skip checking/upgrading already-installed dependencies, which avoids the cmake symlink conflict entirely.

Summary

The root cause is a symlink conflict between the pre-installed CMake.app on the AppVeyor macOS image and Homebrew's cmake formula. When brew install create-dmg pulls in cmake as a dependency, it can't overwrite the existing /usr/local/bin/cmake symlinks. The fix is to either suppress the dependency check, force-overwrite the links, or unlink the pre-installed cmake before installing.

User: is there a way to use newer macOS in AppVeyor? do I pin it to a specific version somewhere?

Assistant: Yes! In your appveyor.yml, you're currently using the generic macOS image on line 12:

appveyor_build_worker_image: macOS

The generic macOS name maps to the oldest available macOS image, which is likely Monterey (12). You can pin to a newer version by using one of these specific image names:

Image name	macOS version
macOS	Oldest available (Monterey 12)
macos-monterey	macOS 12 Monterey
macos-ventura	macOS 13 Ventura
macos-sonoma	macOS 14 Sonoma

To use the newest available image, change line 12 to:

appveyor_build_worker_image: macos-sonoma

This may also resolve (or at least reduce) the Homebrew/CMake conflict you're hitting, since newer images tend to have more up-to-date pre-installed software and fewer stale symlinks.

You can check exactly what's pre-install...

This pull request was created from Copilot chat.