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chr() of a variant returns the wrong character — the slot is read as an ordinal

xs = [97, 98]
print(chr(xs[0]))     # CPython: a     pxx: X

out = ""
for o in [97, 98]:
    out = out + chr(o)
print(out)            # CPython: ab    pxx: (empty)

ord() is fine; only chr() is affected.

Measured

expression CPython pxx
chr(97) (literal) a a ✓
o = 97; chr(o) (int var) a a ✓
chr(int(xs[0])) (explicit unbox) a a ✓
chr(xs[0]) (list element) a X
chr(o) where o is a loop variable a empty
chr(o) where o is an unannotated param a empty
chr(xs[0] + 1) b x
ord(xs[0]), ord(<param>), ord(<loop var>) correct correct ✓

The explicit chr(int(v)) working is the tell: the value is fine, the unboxing is missing.

Cause

parser.inc, the shared Ord/Chr soft-keyword intrinsic. Ord has a special case that routes a non-ordinal operand to pylib:

        { Python has no char type: `ord("a")` takes a 1-length STR, which the
          ordinal intrinsic would read as the string's pointer. Route a string
          operand to pylib instead ... }
        if (op = Ord(tkOrd)) and PyExprMode and
           ((IntToTypeKind(ASTTk[CurASTNode]) = tyString) or
            (IntToTypeKind(ASTTk[CurASTNode]) = tyAnsiString)) then

Chr has no equivalent arm, so a tyVariant argument falls through to the -tkChr intrinsic, which reads the 16-byte variant slot as an ordinal — hence a character derived from the tag/handle rather than from the payload.

Same "the sibling grew a case and this one did not" shape as [[bug-nilpy-indexing-an-unannotated-str-parameter-segfaults]].

Fix

Give Chr the mirror arm: when PyExprMode and the argument is tyVariant, wrap it in pyvar_to_int before the intrinsic (that helper already applies Python's numeric rules and raises TypeError for a non-number). Keep the literal and int-typed paths untouched so ordinary chr(65) stays a single instruction.

Gate

make test-nilpy + self-host byte-identical, plus a .npy of the table above against CPython's own output, and a caesar-cipher round trip (chr(((ord(c) - 97 + k) % 26) + 97) over a loop variable) as the end-to-end case — that is the program this was found in.

Log