[kinyoklion]

Summary

The file-based override source drops a path that is listed more than once (#477, released in 7.21.0), so that the file's entries do not collide with themselves. The comparison was exact. On Windows, where file names ignore case, a path repeated in a different case (C:\overrides\a.json and c:\Overrides\A.JSON) survived, and every key in that file then failed as its own duplicate under the default fail handling, so the reload failed and no overrides from it applied.

On Windows the comparison now ignores case. Elsewhere it stays exact, because a case-sensitive file system can hold both names as different files. The deduplication moves into uniqueFilePaths, so both behaviors are tested on every platform.

This is the gap that Bugbot found in the .NET port (launchdarkly/dotnet-core#367). The Node change is launchdarkly/js-core#2134.

Tests

• TestUniqueFilePathsIgnoresCaseOnlyWhenFileNamesIgnoreCase checks both modes directly. It fails with case folding disabled.
• TestFileSourceTreatsAPathRepeatedInDifferentCaseAsARepeatOnlyOnWindows builds a source from two paths that differ in case: one path on Windows, both elsewhere.

go test -race ./... passes and make lint reports no issues.

_{Opened from termag}

SDK-3419

---

Note

Overview
Fixes file-based override sources on Windows where listing the same path twice with different casing (e.g. C:\overrides\a.json and c:\Overrides\A.JSON) was not treated as a duplicate. That let the file load twice and triggered duplicate-key failures under default handling, so overrides could fail to apply.

Path deduplication is moved into uniqueFilePaths, which compares paths case-insensitively when ignoreCase is true (enabled on Windows via runtime.GOOS). On case-sensitive systems, comparison stays exact so two paths that differ only by case can still refer to different files.

Tests cover both modes of uniqueFilePaths and assert build-time behavior on Windows vs other platforms.

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[kinyoklion]

bugbot review

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