\case should trigger auto-multiline mode in ghci (#10453) · Issues · Glasgow Haskell Compiler / GHC

\case should trigger auto-multiline mode in ghci

In ghci, most block heralds trigger the multiline mode when :set +m is on. However, \case does not (and should). Compare:

Prelude> ($True) (\case
Prelude|  x -> x
Prelude| )
True
Prelude> ($True) $ \case

<interactive>:11:11:
    Empty list of alternatives in case expression
      Use EmptyCase to allow this

Trac metadata

Trac field	Value
Version	7.10.1
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

In ghci, most block heralds trigger the multiline mode when :set +m is on. However, \\case does not (and should). Compare:

```
Prelude> ($True) (\case
Prelude|  x -> x
Prelude| )
True
Prelude> ($True) $ \case

<interactive>:11:11:
    Empty list of alternatives in case expression
      Use EmptyCase to allow this
```

<details><summary>Trac metadata</summary>

| Trac field             | Value          |
| ---------------------- | -------------- |
| Version                | 7.10.1         |
| Type                   | FeatureRequest |
| TypeOfFailure          | OtherFailure   |
| Priority               | normal         |
| Resolution             | Unresolved     |
| Component              | Compiler       |
| Test case              |                |
| Differential revisions |                |
| BlockedBy              |                |
| Related                |                |
| Blocking               |                |
| CC                     |                |
| Operating system       |                |
| Architecture           |                |

</details>