Crash in transf due to malformed proc passed as argument

[DiThi]

Example 1:

var x: seq[proc(i: int)]
x.add proc(e: auto) = echo i

Example 2:

proc x(f: proc(i: int)) = discard
x proc(e: auto) = echo i

The first example produces:

nim.nim                  nim
nim.nim                  handleCmdLine
main.nim                 mainCommand
main.nim                 compileToBackend
main.nim                 commandCompileToC
cbackend.nim             generateCode
cbackend.nim             generateCode
backends.nim             preprocess
transf.nim               transformBodyWithCache
transf.nim               transformBody
transf.nim               processTransf
transf.nim               transform nkError 389603 test.nim(2, 23)
idioms.nim               unreachableImpl
assertions.nim           raiseAssert
fatal.nim                sysFatal
Error: unhandled exception: transf.nim(1223, 16) unreachable: errors can't reach here [AssertionDefect]

and the second example does the same except with nkError 389709

[zerbina]

The underlying cause is the same for both examples: semInferredLambda doesn't wrap the lambda expression in a wrapper error when the body has an error, leading to the body ultimately ends up in transf.

[DiThi]

I've found another crash that seems related to this one (but it may be an issue on its own).

proc getf(f: proc(x: int): int) = discard
getf proc(x: auto): auto = foo

It's a different error unless I do something about the second auto, e.g.

proc getf(f: proc(x: int): int) = discard
getf proc(x: auto): int = foo

where it gets the same error as in the first post.

[zerbina]

The underlying cause is the same (i.e., semInferredLambda not handling nkError correctly).