GHC Internal error when using deriving via on a data instance.
Summary
Compilation fails on provided source file with:
Bug.hs:17:53: error:
• GHC internal error: ‘m’ is not in scope during type checking, but it passed the renamer
tcl_env of environment: [at2 :-> Type variable ‘m’ = m :: *,
rrO :-> APromotionErr FamDataConPE]
• In the first argument of ‘Block’, namely ‘m’
In the first argument of ‘Header’, namely ‘(Block m)’
In the first argument of ‘AllowThunk’, namely ‘(Header (Block m))’
|
17 | deriving NoThunks via AllowThunk (Header (Block m))
| ^
Steps to reproduce
Compile the file attached to the issue.
Expected behavior
With GHC version 8.6.5 it compiles with no warnings.
Environment
- GHC version used: 8.8.3
Optional:
- Operating System: MacOS, Linux
- System Architecture: x86_64