Fix declareFieldLabels or declareLenses with DuplicateRecordFields #328
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arybczak
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Jul 21, 2020
| where | ||
| -- When DuplicateRecordFields is enabled, reified datatypes contain | ||
| -- "mangled" field names that look like $sel:foo:MkT where foo is the field | ||
| -- name and MkT is the first data constructor. We strip off the prefix and |
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Is MkT always the first constructor, even in cases like data T = MkT1 { name1 :: String } | MkT2 { name2 :: String } name2 will be mangled as $sel:name2:mkT1?
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Yes, it's just the first constructor in the type, regardless of whether the field occurs or not. I've tweaked the test to check this, and cleaned up the code a bit. In particular it now checks that the suffix is the expected one, which should lead to easier to understand errors if GHC's behaviour should ever change.
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arybczak
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Jul 22, 2020
| {-# LANGUAGE TypeFamilies #-} | ||
| {-# LANGUAGE TypeOperators #-} | ||
| {-# LANGUAGE UndecidableInstances #-} | ||
| {-# OPTIONS_GHC -fforce-recomp #-} |
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Oops, I left that in by mistake. For some reason changing the TH code wasn't leading to recompilation when I was testing. Fixed.
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Fixes #323.