./hadrian/ghci compilation error that doesn't appear at build time.
Using the ./hadrian/ghci
script, I am getting this error:
/home/hecate/Contrib/GHC/ghc/compiler/GHC/Utils/Misc.hs:1214:22: error:
• Could not deduce (Foldable t0) arising from a use of ‘elem’
from the context: MonadFail m
bound by the inferred type of
readExp :: MonadFail m => [Char] -> m (Int, [Char])
at /home/hecate/Contrib/GHC/ghc/compiler/GHC/Utils/Misc.hs:(1214,6)-(1215,49)
The type variable ‘t0’ is ambiguous
These potential instances exist:
instance Foldable (Either a) -- Defined in ‘Data.Foldable’
instance Foldable Down -- Defined in ‘Data.Foldable’
instance Foldable Proxy -- Defined in ‘Data.Foldable’
...plus six others
...plus 44 instances involving out-of-scope types
(use -fprint-potential-instances to see them all)
• In the expression: e `elem` "eE"
In a stmt of a pattern guard for
an equation for ‘readExp’:
e `elem` "eE"
In an equation for ‘readExp’:
readExp (e : s) | e `elem` "eE" = readExp' s
|
1214 | readExp (e:s) | e `elem` "eE" = readExp' s
| ^^^^^^^^^^^^^
/home/hecate/Contrib/GHC/ghc/compiler/GHC/Utils/Misc.hs:1214:31: error:
• Could not deduce (IsString (t0 Char))
arising from the literal ‘"eE"’
from the context: MonadFail m
bound by the inferred type of
readExp :: MonadFail m => [Char] -> m (Int, [Char])
at /home/hecate/Contrib/GHC/ghc/compiler/GHC/Utils/Misc.hs:(1214,6)-(1215,49)
The type variable ‘t0’ is ambiguous
These potential instances exist:
instance (a ~ Char) => IsString [a] -- Defined in ‘Data.String’
...plus two instances involving out-of-scope types
(use -fprint-potential-instances to see them all)
• In the second argument of ‘elem’, namely ‘"eE"’
In the expression: e `elem` "eE"
In a stmt of a pattern guard for
an equation for ‘readExp’:
e `elem` "eE"
|
1214 | readExp (e:s) | e `elem` "eE" = readExp' s
| ^^^^
Failed, 28 modules loaded.
(13.35 secs,)
Being perfectly candid, isn't that the kind of things that are supposed to get caught in the CI?