out-of-range warnings for negative literals, without -XNegativeLiterals
By default (without NegativeLiterals) a negated literal -1 is desugared as negate (fromInteger 1). Hence the existing out-of-range literal warning doesn't trigger for -1 :: Word. But we could also recognize the pattern negate (fromInteger lit), and give a warning when -lit is out-of-range (for Word, this is whenever lit is positive).
Actually this could apply to signed integer types too: if we recognized negate (fromInteger lit) in preference to fromInteger lit, we could correctly not warn about -128 :: Int8, even when NegativeLiterals is not enabled.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 8.1 |
| Type | FeatureRequest |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
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