Fix non-exhaustive pattern match in dhall lint
#780
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`dhall lint` would fail on the following expression:
```
let replicate = https://prelude.dhall-lang.org/List/replicate
in let Config = { name : Text, age : Natural }
in let Configs = List Config
in replicate 10 Text "!"
```
... because the code (incorrectly) assumed that simplifying an inner
`let` binding would preserve at least one `let` binding. However, when the
outer `let` (beginning with `let replicate`) is simplified the inner `let`
(beginning with `let Config`) simplifies down to just `replicate 10 Text "!"`
which has no `let` binding at all, leading to a pattern match failure.
This change fixes that by extending the code to correctly handle that case
with an exhaustive pattern match.
|
Looks good, but how did this make it into |
|
@ocharles: It is being built with |
... as suggested by @ocharles to prevent this from recurring I added an exception to the `Dhall` module since fixing those non-exhaustive pattern matches requires more invasive changes
…l into gabriel/fix_lint
This is supposed to be only turned on for specific CI builds
|
I almost opened an issue to report this bug, but stumbled onto it by accident. In case it helps future searches of this bug, the error is: |
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dhall lintwould fail on the following expression:... because the code (incorrectly) assumed that simplifying an inner
letbinding would preserve at least oneletbinding. However, when theouter
let(beginning withlet replicate) is simplified the innerlet(beginning with
let Config) simplifies down to justreplicate 10 Text "!"which has no
letbinding at all, leading to a pattern match failure.This change fixes that by extending the code to correctly handle that case
with an exhaustive pattern match.