-frule-check flag not recognized without parameter (#9776) · Issues · Glasgow Haskell Compiler / GHC

-frule-check flag not recognized without parameter

$ ghc Foo.hs -frule-check
ghc: on the commandline: unrecognised flag: -frule-check
Usage: For basic information, try the `--help' option.

That error message is confusing. -frule-check is a valid flag, it's just being used incorrectly. It should be followed by a parameter:

$ ghc Foo.hs -frule-check ruleFoo

Trac metadata

Trac field	Value
Version	7.9
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Driver
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

```
$ ghc Foo.hs -frule-check
ghc: on the commandline: unrecognised flag: -frule-check
Usage: For basic information, try the `--help' option.
```

That error message is confusing. `-frule-check` is a valid flag, it's just being used incorrectly. It should be followed by a parameter:

```
$ ghc Foo.hs -frule-check ruleFoo
```

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

| Trac field             | Value        |
| ---------------------- | ------------ |
| Version                | 7.9          |
| Type                   | Bug          |
| TypeOfFailure          | OtherFailure |
| Priority               | normal       |
| Resolution             | Unresolved   |
| Component              | Driver       |
| Test case              |              |
| Differential revisions |              |
| BlockedBy              |              |
| Related                |              |
| Blocking               |              |
| CC                     |              |
| Operating system       |              |
| Architecture           |              |

</details>