By: Tom Sydney Kerckhove <syd@cs-syd.eu>
Skip a build directory by its whole name, not by a prefix of it The discovery walk skipped any directory whose name started with "result", meaning to skip a nix build output. It also skipped one called "results", and every package under it went missing from discovery with nothing reported: a walk that finds no cabal file and a walk that refused to look are the same answer to a caller. The two build directories it still skips are compared as whole names now, and so is anything hidden. "result" is not named at all: it is a symlink to a build output, which the walk follows like any other directory and which holds no cabal file to find. Refusing to follow a symlink would have been the same silent loss in a different guise, because a repository that links a package in has one to find there. The predicate is top-level and exported, where the walk had it in a where clause with no signature and no test. It is pure, so the prefix case is a unit test rather than a walk over a fixture, and there is a fixture too: a package two levels under a directory called results, which is what was being dropped. The fixture needed a line in .gitignore. The global ignore file has result*, which hides a directory called results the same way this walk did.