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Add index entry for GHC-25955 #516

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Add index entry for GHC-25955 #516

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7 changes: 7 additions & 0 deletions message-index/messages/GHC-25955/illegal_explicit_forall/after/Illegal_explicit_forall.hs
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{-# LANGUAGE Haskell2010 #-}
{-# LANGUAGE ExplicitForAll #-}
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This is technically correct, although you almost never want to enable the syntax extension ExplicitForAll just for the sake of it. Most likely the very next error message from GHC will complain about missing ScopedTypeVariables or RankNTypes. This is probably something worth to discuss in index.md.

Also worth mentioning that GHC2021 / GHC2024 enable this extension by default.


module Illegal_explicit_forall where

foo :: forall a. a
foo = foo
6 changes: 6 additions & 0 deletions message-index/messages/GHC-25955/illegal_explicit_forall/before/Illegal_explicit_forall.hs
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{-# LANGUAGE Haskell2010 #-}

module Illegal_explicit_forall where

foo :: forall a. a
foo = foo
3 changes: 3 additions & 0 deletions message-index/messages/GHC-25955/illegal_explicit_forall/index.md
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---
title: ExplicitForAll without the relevant extension enabled
---
19 changes: 19 additions & 0 deletions message-index/messages/GHC-25955/index.md
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---
title: Illegal forall in type
summary: The 'forall' keyword was used in a type without the 'ExplicitForAll' extension enabled
severity: error
introduced: 9.6.1
---

## Error Message
```
Illegal symbol ‘forall’ in type
Suggested fix:
Use the ‘ExplicitForAll’ extension (implied by ‘RankNTypes’,
‘QuantifiedConstraints’, ‘ScopedTypeVariables’,
‘LiberalTypeSynonyms’ and ‘ExistentialQuantification’)
to enable syntax: forall <tvs>. <type>
|
3 | foo :: forall a. a
| ^^^^^^
```
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