zig

commit b5376050092bf63c870e8518db73717d0d183eba (tree)
parent 5e1ea76798ad781f24bea3f69ca6a37259b7b69e
Author: Motiejus <motiejus@jakstys.lt>
Date:   Sat,  7 Mar 2026 09:09:35 +0000

sema: fix zirCmpEq equality check to include sign for comptime ints

The comptime equality check compared only lo/hi magnitude fields,
ignoring is_negative. This meant (-5) == 5 would return true.

Fix by also checking lhs_neg == rhs_neg. Zero is never negative
(internComptimeInt already clears neg for zero values), so this
handles the -0 == 0 edge case correctly.

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

Diffstat:
M
stage0/sema.c
 | 
5
++++-

1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/stage0/sema.c b/stage0/sema.c
@@ -1497,7 +1497,10 @@ static AirInstRef zirCmpEq(
             (void)semaCoerce(sema, block, result_ty, lhs);
             (void)semaCoerce(sema, block, result_ty, rhs);
         }
-        bool eq = (lhs_lo == rhs_lo && lhs_hi == rhs_hi);
+        // Equality: same magnitude AND same sign.
+        // Zero is never negative (internComptimeInt clears neg for 0).
+        bool eq
+            = (lhs_lo == rhs_lo) && (lhs_hi == rhs_hi) && (lhs_neg == rhs_neg);
         return AIR_REF_FROM_IP((eq == (air_tag == AIR_INST_CMP_EQ))
                 ? IP_INDEX_BOOL_TRUE
                 : IP_INDEX_BOOL_FALSE);