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discard """
errormsg: "cannot cast to a non concrete type: 'ptr SomeNumber'"
line: 36
"""
# https://github.com/nim-lang/Nim/issues/5428
type
MemFile = object
mem: pointer
proc memfileopen(filename: string, newFileSize: int): MemFile =
# just a memfile mock
return
type
MyData = object
member1: seq[int]
member2: int
type
MyReadWrite = object
memfile: MemFile
offset: int
# Here, SomeNumber is bound to a concrete type, and that's OK
proc write(rw: var MyReadWrite; value: SomeNumber): void =
(cast[ptr SomeNumber](cast[uint](rw.memfile.mem) + rw.offset.uint))[] = value
rw.offset += sizeof(SomeNumber)
# Here, we try to use SomeNumber without binding it to a type. This should
# produce an error message for now. It's also possible to relax the rules
# and allow for type-class based type inference in such situations.
proc write[T](rw: var MyReadWrite; value: seq[T]): void =
rw.write value.len
let dst = cast[ptr SomeNumber](cast[uint](rw.memfile.mem) + uint(rw.offset))
let src = cast[pointer](value[0].unsafeAddr)
let size = sizeof(T) * value.len
copyMem(dst, src, size)
rw.offset += size
proc saveBinFile(arg: var MyData, filename: string): void =
var rw: MyReadWrite
rw.memfile = memfileOpen(filename, newFileSize = rw.offset)
rw.offset = 0
rw.write arg.member1
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