Warn about useless UNPACK pragmas
I have on several occasions seen code with useless UNPACK pragmas. Example:
data Foo a b = Foo {-# UNPACK #-} !(a -> b)or
data Enum = A Int | B Double
data Foo = {-# UNPACK #-} !EnumBy emitting a warning for those cases where the pragma has no effect we could help people understand how to use it correctly (rather than sprinkling it everywhere and hope for the best).
Trac metadata
| Trac field | Value |
|---|---|
| Version | 6.12.1 |
| Type | FeatureRequest |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
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| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |