[2.x] fix: Only disable symlinks when truly not supported#8479
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eed3si9n merged 1 commit intosbt:developfrom Jan 11, 2026
Merged
[2.x] fix: Only disable symlinks when truly not supported#8479eed3si9n merged 1 commit intosbt:developfrom
eed3si9n merged 1 commit intosbt:developfrom
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Fix issue where symlinkSupported flag was incorrectly set to false when any FileSystemException occurred during symlink creation. Root cause: FileAlreadyExistsException (a subclass of FileSystemException) was being caught and incorrectly disabling symlinks permanently. The fix: - Only set symlinkSupported=false when the exception message indicates symlinks aren't supported (privilege/permission issues) - FileAlreadyExistsException and other transient errors now fall back to copy without permanently disabling symlinks - Add check that CAS file exists before attempting symlink creation Fixes sbt#8478 Generated-by: Cascade (AI pair programmer)
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fix: Only disable symlinks when truly not supported
What's the problem?
When you delete the disk cache while sbt is running and then recompile, symlinks stop being created. Instead, sbt copies files directly. This happens because the
symlinkSupportedflag gets permanently set tofalseduring the session.As @azdrojowa123 discovered through debugging, a
FileAlreadyExistsExceptionis thrown during step 5 of the reproduction, and this incorrectly disables symlink support.Why does this happen?
The current code catches any
FileSystemExceptionand assumes it means "symlinks aren't supported on this system." ButFileAlreadyExistsExceptionis a subclass ofFileSystemException, and it has nothing to do with symlink support - it just means the file already exists (likely a race condition).What's the fix?
Instead of disabling symlinks on any
FileSystemException, we now only disable them when the error message specifically indicates a permission or privilege issue:This way, transient errors like
FileAlreadyExistsExceptionwill fall back to copying the file, but won't permanently disable symlinks for the rest of the session.I also added a check to verify the CAS file exists before attempting to create a symlink, which helps avoid some edge cases.
Fixes #8478
Contribution by Gittensor, see my contribution statistics at https://gittensor.io/miners/details?githubId=94194147