[llvm] [Support] Prevent leaking unique lock files (PR #130984)

[Michael Spencer via llvm-commits]

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@@ -189,6 +189,10 @@ Expected<bool> LockFileManager::tryLock() {
     return createStringError(EC, "failed to create unique file " +
                                      UniqueLockFileName);
 
+  // Clean up the unique file on signal or scope exit. This also releases the
+  // lock if it's held since the .lock symlink will point to a nonexistent file.
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Bigcheese wrote:

I know you're just moving this comment, but I think it's wrong. On Windows `create_link` makes a hard link, so removing the unique name does nothing. I also think it doesn't really matter since `readLockFile` will remove the old one if the process is dead anyway.

https://github.com/llvm/llvm-project/pull/130984