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fix: reject overflowing division precision #472

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Merged
mwoss merged 2 commits into from
Oct 18, 2026
Merged

fix: reject overflowing division precision #472

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d56f107
fix: reject overflowing division precision
yuefdev Oct 18, 2026
96888f7
Fold the MinInt32 check into the existing overflow check
mwoss Oct 18, 2026
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2 changes: 1 addition & 1 deletion decimal.go
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Original file line number Diff line number Diff line change
Expand Up @@ -796,7 +796,7 @@ func (d Decimal) quoRem(d2 Decimal, precision int32, bb *big.Int) (Decimal, Deci
}
scale := -precision
e := int64(d.exp) - int64(d2.exp) - int64(scale)
if e > math.MaxInt32 || e < math.MinInt32 {
if precision == math.MinInt32 || e > math.MaxInt32 || e < math.MinInt32 {
panic("overflow in decimal QuoRem")
}
if bb == nil {
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10 changes: 10 additions & 0 deletions decimal_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2542,6 +2542,16 @@ func TestDecimal_Overflow(t *testing.T) {
if !didPanic(func() { New(1, math.MaxInt32).Mul(New(1, math.MaxInt32)) }) {
t.Fatalf("should have gotten an overflow panic")
}
// -math.MinInt32 wraps back to itself as an int32.
if !didPanic(func() { New(1, math.MinInt32).QuoRem(New(1, 0), math.MinInt32) }) {
t.Fatalf("should have gotten an overflow panic")
}
if !didPanic(func() { New(1, math.MinInt32).DivRound(New(1, 0), math.MinInt32) }) {
t.Fatalf("should have gotten an overflow panic")
}
if q, _ := New(1, math.MaxInt32).QuoRem(New(1, 0), math.MinInt32+1); !q.Equal(New(1, math.MaxInt32)) {
t.Fatalf("precision math.MinInt32+1 should still work, got %s", q)
}
}

func TestDecimal_ExtremeValues(t *testing.T) {
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