[regression] VM: Error: cannot convert -1 to uint64

[timotheecour]

VM doesn't handle properly uint64 with high bit set (except when from a literal).

Example

proc fun(): uint = cast[uint](-1)
const x0 = fun()
discard $x0 # Error: cannot convert -1 to uint64; ditto with echo x0

const x1 = cast[uint](-1)
discard $x1 # ditto

# workaround (not a real workaround since we can't get the string at CT)
let x0b = x0
discard $x0b # this works

const x2 = 18446744073709551615'u
discard $x2 # works in devel, CT error 0.20.2: Error: number out of range: '18446744073709551615'u'

Current Output

Error: cannot convert -1 to uint64

Expected Output

works

Additional Information

• It was working in version 0.20.2 (except for 3rd case x2, which works in devel but not 0.20.2)
• broken in devel 6e0c06f and since 1.0.0
• related but different (since closed and working):
  VM rejects tuples containing uint64 with high bit set #11084
  Cannot print unsigned integer constant #6838

[krux02]

This is probably related to the semchecker setting the types incorrectly since on line with the dollar, there should not be the value of -1 anymore.

certainly related even though not the same: #12700