Compiler internal error on iterator it(T: typedesc[Base]) called with it(Child), where Child = object of Base

[nanoant]

Following IMHO valid code crashes latest Nim compiler 0.11.2 with internal error.

Since using 1st arg of typedesc[ClassName] is proper way to define class methods (not instance methods) making this work is pretty important.

import typetraits

type
  Base = object of RootObj
  Child = object of Base

proc pr(T: typedesc[Base]) = echo "call from " & T.name

iterator it(T: typedesc[Base]) = yield "yield from " & T.name

Base.pr
Child.pr

for s in Base.it: echo s
for s in Child.it: echo s # <- internal error: getUniqueType

Commenting out last line makes everything work well, so the bug applies only to iterators.

Full error stack:

Error: internal error: getUniqueType
Traceback (most recent call last)
nim.nim(94)              nim
nim.nim(56)              handleCmdLine
main.nim(252)            mainCommand
main.nim(63)             commandCompileToC
modules.nim(203)         compileProject
modules.nim(151)         compileModule
passes.nim(197)          processModule
passes.nim(137)          processTopLevelStmt
cgen.nim(1210)           myProcess
ccgstmts.nim(1111)       genStmts
ccgexprs.nim(2075)       expr
ccgstmts.nim(1111)       genStmts
ccgexprs.nim(2072)       expr
ccgstmts.nim(502)        genBlock
ccgexprs.nim(2075)       expr
ccgstmts.nim(1111)       genStmts
ccgexprs.nim(2075)       expr
ccgstmts.nim(1111)       genStmts
ccgexprs.nim(2094)       expr
ccgstmts.nim(259)        genVarStmt
ccgstmts.nim(237)        genSingleVar
cgen.nim(404)            assignLocalVar
cgen.nim(389)            localVarDecl
ccgtypes.nim(693)        getTypeDesc
ccgtypes.nim(528)        getTypeDescAux
ccgutils.nim(102)        getUniqueType
msgs.nim(849)            internalError
msgs.nim(771)            rawMessage
msgs.nim(768)            rawMessage
msgs.nim(715)            handleError