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et: Fix custom git diff prefix handling - #191108
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`et` performs formatting by diffing the repo file against the output of the formatter for that file, which it passes to stdin (`-`). This results in `git diff` outputting the "to" path as `-`. `et` then tries to rewrite that `-` to the repo path. For users with certain git settings such as `diff.mnemonicPrefix` or `diff.noprefix` the diff path prefixes emitted in the two-line ---/+++ file pair will differ from the default `a/` and `b/`, which the existing `et format` code assumes. The end result is a (silent) failure to rewrite the "to" path, with the result that when we apply the diff, the file is rewritten to a file named `-` at the root of the repo. We now explicitly pass git diff `--src-prefix` and `--dst-prefix` flags, which override git diff settings such as `diff.mnemonicPrefix`, `diff.noprefix`, `diff.srcPrefix` and `diff.dstPrefix`. I've extracted the diff job construction into a method that we reuse where needed and added some paranoid error checking to ensure we actually rewrite the path correctly.
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Code Review
This pull request refactors the format checkers to use a centralized createDiffJob helper, ensuring consistent git diff prefixes, and adds a safeguard in applyPatch to prevent writing files to the repository root when patches target stdin. It also introduces tests to verify formatting behavior under custom git prefix configurations. The review feedback suggests updating the stdin patch target regular expression to support CRLF line endings on Windows and asserting on the exit code of the formatter process in the new tests to avoid silent failures.
| '--src-prefix=a/', | ||
| '--dst-prefix=b/', |
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No harm in using flags that were added in, check notes.... 2008. I wonder what problems that person ran in to 20 years ago.
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etperforms formatting by diffing the repo file against the output of the formatter for that file, which it passes to stdin (-). This results ingit diffoutputting the "to" path as-.etthen tries to rewrite that-to the repo path.For users with certain git settings such as
diff.mnemonicPrefixordiff.noprefixthe diff path prefixes emitted in the two-line ---/+++ file pair will differ from the defaulta/andb/, which the existinget formatcode assumes. The end result is a (silent) failure to rewrite the "to" path, with the result that when we apply the diff, the file is rewritten to a file named-at the root of the repo.We now explicitly pass git diff
--src-prefixand--dst-prefixflags, which override git diff settings such asdiff.mnemonicPrefix,diff.noprefix,diff.srcPrefixanddiff.dstPrefix.I've extracted the diff job construction into a method that we reuse where needed and added some paranoid error checking to ensure we actually rewrite the path correctly.
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