tcLookup in plugins seems broken on HEAD
The operation of looking up names in a typechecker plugin seems to have been broken sometime recently. For instance:
-- MyModule
type family MyFam a b where
-- MyPlugin
tcPluginInit :: TcPluginM ()
tcPluginInit = do
myModule <- findModule myPackage myModuleName
lookupResult <- tcLookupGlobal =<< lookupOrig myModule ( mkTcOcc "MyFam" )
pprPanic "Result was:" ( ppr lookupResult )
findModule :: String -> String -> TcPluginM Module
findModule pkg modName = do
findResult <- findImportedModule ( mkModuleName modName ) ( Just $ fsLit pkg )
case findResult of
Found _ res -> pure res
FoundMultiple _ -> error $ "MyPlugin: found multiple modules named " <> modName <> "."
_ -> error $ "MyPlugin: could not find any module named " <> modName <> "."
On GHC 9.2.1 (alpha1), I get the expected result:
GHC version 9.2.0.20210331:
Result was:
Type constructor `MyFam'
On GHC HEAD, when running in ghci I get:
GHC version 9.3.20210604:
Result was:
Identifier `disableBuffering'
and when compiling normally, I get:
GHC version 9.3.20210604:
Result was:
Identifier `plugin'
I have only checked 7a05185a and 79d12d34 and they both present the same issue. Note that this is on Windows 10 x64
(10.0.19041).
See here for full reproducer:
tclookup.zip
Edited by sheaf