|
|
There are two different ways of declaring a class in an hs-boot file:
- a full declaration, where everything is written as it is
in the .hs file,
- an abstract declaration, where class methods and superclasses
are left out.
However, a declaration with no methods and a trivial superclass,
such as:
class () => C a
was erroneously considered to be an abstract declaration, because
the superclass is trivial.
This is remedied by a one line fix in GHC.Tc.TyCl.tcClassDecl1.
This patch also further clarifies the documentation around
class declarations in hs-boot files.
Fixes #20661, #20588.
|
