Ts1261 Filename Casing

TS1261 (filename casing)

Problem

Diagnostic 1261 in typescript (Already_included_file_name_0_differs_from_file_name_1_only_in_casing): one path comes from an import, another from include / program — same file on a case-insensitive disk, different casing in the string.

Typical cause: git tracks fooBar.ts but imports ./FooBar; or a case-only rename left the index with old casing.

Fix

Canonical name = what imports use (and consistent Pascal/camel across repo).

Case-insensitive FS (macOS default, Windows): case-only renames need a temporary middle name so git and the filesystem both update.

cd path/to/dir
git mv WrongCaseName.ts _tmp_rename.ts
git mv _tmp_rename.ts RightCaseName.ts

Then npm run compile.

Why not a single git mv?

git mv a.ts A.ts often no-ops or fails when a and A resolve to the same path — the two-step move is the reliable fix.

git rm / index

Goal is an index entry whose path string matches imports. git rm --cached <wrong-cased-path> removes that index entry; you still must put content on disk under the right cased name (again: use intermediate mv on case-insensitive FS). Two-step git mv updates index + working tree in one workflow without a detached delete step.

Verify

• npm run compile
• git ls-files path/to/dir | grep -i <basename> shows one line, casing matches imports

Checklist

• Read TS1261 lines: identify both casing spellings
• Choose spelling that matches existing imports
• Two-step git mv if case-only change on case-insensitive FS
• Re-run compile