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Promote Int128/UInt128 arithmetic overflow to Double#27602

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KirtiRamchandani:fix/int128-overflow-promotion-26677
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Promote Int128/UInt128 arithmetic overflow to Double#27602
KirtiRamchandani wants to merge 1 commit into
PowerShell:masterfrom
KirtiRamchandani:fix/int128-overflow-promotion-26677

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Summary

Fixes [Int128] and [UInt128] arithmetic overflow silently wrapping instead of promoting to [double] like [Int64].

Problem

[Int128]::MaxValue + [Int128]::MaxValue  # wrapped instead of promoting
([Int128]::MaxValue + [Int128]::MaxValue).GetType().Name  # was Int128, should be Double

Fix

  • Recognize Int128/UInt128 as numeric types
  • Add Int128Ops/UInt128Ops with BigInteger overflow detection
  • Route binary numeric operations through the custom numeric pipeline
  • Add Pester tests in ArithmeticOperators.Tests.ps1

Fixes #26677

Route Int128 and UInt128 through the numeric operations pipeline with
dedicated overflow handling, matching Int64 behavior instead of relying
on native wrapping operators.

Fixes PowerShell#26677
@KirtiRamchandani KirtiRamchandani marked this pull request as ready for review June 15, 2026 07:13
@KirtiRamchandani KirtiRamchandani requested a review from a team as a code owner June 15, 2026 07:13
Copilot AI review requested due to automatic review settings June 15, 2026 07:13

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Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds Int128/UInt128 support to PowerShell numeric type handling and binary operator binding, including overflow behavior (promotion to Double) and targeted tests.

Changes:

  • Introduces Int128Ops / UInt128Ops implementations for arithmetic and comparisons.
  • Updates numeric type classification/helpers and type lists to include Int128 / UInt128.
  • Adds Pester tests validating overflow promotion to Double (and non-overflow preservation for Int128).

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 9 comments.

Show a summary per file
File Description
test/powershell/Language/Operators/ArithmeticOperators.Tests.ps1 Adds tests for overflow promotion behavior for 64/128-bit integer arithmetic.
src/System.Management.Automation/utils/ExtensionMethods.cs Extends numeric-type helpers to treat Int128/UInt128 as numeric/integer.
src/System.Management.Automation/engine/runtime/Operations/NumericOps.cs Adds operator implementations for Int128 and UInt128.
src/System.Management.Automation/engine/runtime/Binding/Binders.cs Routes binary numeric ops to the new 128-bit operator implementations.
src/System.Management.Automation/engine/LanguagePrimitives.cs Includes Int128/UInt128 in numeric/integer type arrays used in conversions.

Comment on lines +2447 to +2456
else if (target.LimitType.IsInt128Type() || arg.LimitType.IsInt128Type())
{
opImplType = typeof(Int128Ops);
argType = typeof(Int128);
}
else if (target.LimitType.IsUInt128Type() || arg.LimitType.IsUInt128Type())
{
opImplType = typeof(UInt128Ops);
argType = typeof(UInt128);
}
Comment on lines +399 to +408
internal static object Add(Int128 lhs, Int128 rhs)
{
System.Numerics.BigInteger biResult = (System.Numerics.BigInteger)lhs + (System.Numerics.BigInteger)rhs;
if (biResult >= Int128.MinValue && biResult <= Int128.MaxValue)
{
return (Int128)biResult;
}

return (double)biResult;
}
Comment on lines +397 to +400
internal static class Int128Ops
{
internal static object Add(Int128 lhs, Int128 rhs)
{
return (double)biResult;
}

internal static object Sub(Int128 lhs, Int128 rhs)
return (double)biResult;
}

internal static object Multiply(Int128 lhs, Int128 rhs)
return (double)biResult;
}

internal static object Divide(Int128 lhs, Int128 rhs)
return (double)lhs / (double)rhs;
}

internal static object Remainder(Int128 lhs, Int128 rhs)
return lhs % rhs;
}

internal static object CompareEq(Int128 lhs, Int128 rhs) { return (lhs == rhs) ? Boxed.True : Boxed.False; }
# Copyright (c) Microsoft Corporation.
# Licensed under the MIT License.

Describe "Arithmetic overflow promotion" -Tags "CI","RequireAdminOnWindows" {
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PowerShell v7 (7.5.4) mis-handles [Int128] overflow

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