authorgravatar for mlugg@mlugg.co.ukMatthew Lugg <mlugg@mlugg.co.uk> 2025-09-13 11:31:17+01:00
committergravatar for mlugg@mlugg.co.ukMatthew Lugg <mlugg@mlugg.co.uk> 2025-09-13 17:13:27+01:00
log32a1aabff78234b428234189ee1093fb65f85fa3
tree6a619405decf6d9334ca0b735642e9ef5fd2338d
parenta0ec4e270e680960290642468f6df3ce7e7d7664

std.math.big.int: normalize zero result for small multiplications

Resolves: #25221

2 files changed, 10 insertions(+), 4 deletions(-)

lib/std/math/big/int.zig+3-4
......@@ -786,11 +786,10 @@ pub const Mutable = struct {
786786 assert(rma.limbs.ptr != b.limbs.ptr); // illegal aliasing
787787
788788 if (a.limbs.len == 1 and b.limbs.len == 1) {
789 const ov = @mulWithOverflow(a.limbs[0], b.limbs[0]);
790 rma.limbs[0] = ov[0];
791 if (ov[1] == 0) {
789 rma.limbs[0], const overflow_bit = @mulWithOverflow(a.limbs[0], b.limbs[0]);
790 if (overflow_bit == 0) {
792791 rma.len = 1;
793 rma.positive = (a.positive == b.positive);
792 rma.positive = (a.positive == b.positive) or rma.limbs[0] == 0;
794793 return;
795794 }
796795 }
test/behavior/enum.zig+7
......@@ -1325,3 +1325,10 @@ test "large enum field values" {
13251325 try expect(@intFromEnum(e) == std.math.maxInt(i128));
13261326 }
13271327}
1328
1329test "comptime @enumFromInt with signed arithmetic" {
1330 const E = enum(i8) { foo = -1, bar = 0 };
1331 const x: E = @enumFromInt(@as(i8, -1) * 0);
1332 comptime assert(x == .bar);
1333 comptime assert(@intFromEnum(x) == 0);
1334}