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Merge pull request #4082 from roc-lang/update-cli-platform-unreachables

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Support unification with uninhabited tag variants in more places
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Folkert de Vries 2022-09-21 12:18:38 +02:00 • committed by GitHub
commit cc202a4cf9
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4 changed files with 81 additions and 64 deletions
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12
crates/compiler/solve/src/solve.rs
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@ -1356,16 +1356,8 @@ fn solve(
);
let snapshot = subs.snapshot();
let unify_cond_and_patterns_outcome = {
// When unifying the cond type with what the branches expect, allow the
// branches to gain constructors that are uninabited; that way, we can permit
// unification of things like
// [Ok Str] ~ [Ok Str, Result []]
// which we want here, because `Result []` need not be matched - it is
// impossible to construct!
let mode = Mode::EQ_WITH_EXTENSION_BY_UNINHABITED_TYPES;
unify(&mut UEnv::new(subs), branches_var, real_var, mode)
};
let unify_cond_and_patterns_outcome =
unify(&mut UEnv::new(subs), branches_var, real_var, Mode::EQ);
let should_check_exhaustiveness;
match unify_cond_and_patterns_outcome {