Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint - #124294

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Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint#124294
tannergooding merged 2 commits into
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Description

NIndex.ToStringFromEnd() and NRange.ToString() cast nint values to uint before formatting, truncating values exceeding uint.MaxValue on 64-bit platforms:

varni=NIndex.FromEnd(unchecked((nint)(1L+uint.MaxValue)));Console.WriteLine(ni.ToString());// Prints "^0" instead of "^4294967296"

Fix

  • NIndex.cs: (uint)Value → (nuint)Value in ToStringFromEnd()
  • NRange.cs: (uint)Start.Value → (nuint)Start.Value and (uint)End.Value → (nuint)End.Value in ToString()

Tests

  • Replaced [Fact] ToStringTest with [Theory] + [InlineData] for both NIndexTests and NRangeTests
  • Added [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))] tests exercising values above uint.MaxValue

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Fix NIndex and NRange ToString truncation: cast to nuint instead of u…
9295a87
…int, add Theory tests
Co-authored-by: vcsjones <361677+vcsjones@users.noreply.github.com>
CopilotAI changed the title [WIP] Fix NIndex formatting for end index conversionFix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uintFeb 11, 2026
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Pull request overview

Fixes incorrect string formatting for NIndex/NRange on 64-bit platforms where values larger than uint.MaxValue were being truncated due to casts to uint during formatting.

Changes:

  • Update NIndex.ToStringFromEnd() to format using (nuint)Value rather than (uint)Value.
  • Update NRange.ToString() to format start/end using (nuint)Start.Value / (nuint)End.Value rather than uint.
  • Expand/adjust unit tests to cover 64-bit values above uint.MaxValue, converting prior [Fact] coverage into [Theory] + [InlineData] and adding 64-bit conditional cases.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

FileDescription
src/libraries/System.Numerics.Tensors/src/System/Buffers/NIndex.csFixes 64-bit truncation in ToStringFromEnd() by formatting via nuint.
src/libraries/System.Numerics.Tensors/src/System/Buffers/NRange.csFixes 64-bit truncation in ToString() by formatting start/end via nuint.
src/libraries/System.Numerics.Tensors/tests/NIndexTests.csAdds theory-based coverage and conditional 64-bit test cases for large values.
src/libraries/System.Numerics.Tensors/tests/NRangeTests.csAdds theory-based coverage and conditional 64-bit test cases for large range endpoints.

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@copilot please invoke the code-review skill and post your analysis/results as a comment on this PR.

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@copilot please invoke the code-review skill and post your analysis/results as a comment on this PR.

🤖 Copilot Code Review

Holistic Assessment

Motivation: The bug is real and clearly reproducible — (uint) casts truncate nint values exceeding uint.MaxValue on 64-bit platforms, causing NIndex.FromEnd(1L + uint.MaxValue).ToString() to return ^0 instead of ^4294967296. The buffer comment on line 177 ("20 for longest possible nuint value") confirms the original intent was nuint.

Approach: Changing (uint) → (nuint) is the minimal correct fix. The tests use [Theory]/[InlineData] and [ConditionalTheory] with PlatformDetection.Is64BitProcess appropriately, consistent with patterns used in NFloatTests.cs and elsewhere in the test project.

Summary: ✅ LGTM. The three cast fixes are correct, minimal, and well-tested. All findings below are positive confirmations or out-of-scope observations.

Detailed Findings

✅ Correctness — Cast fix is correct in all three locations

  • NIndex.cs:178: (uint)Value → (nuint)Value in ToStringFromEnd()
  • NRange.cs:73: (uint)Start.Value → (nuint)Start.Value in ToString()
  • NRange.cs:84: (uint)End.Value → (nuint)End.Value in ToString()

The Value property returns nint (always non-negative for valid NIndex values), so the nuint cast is safe. The stackalloc buffer was already sized for nuint (21 chars = 1 for ^ + 20 digits for max nuint on 64-bit). The non-FromEnd path (NIndex.ToString() line 172) uses Value.ToString() which calls nint.ToString() directly — no truncation issue there.

✅ Test quality — Good coverage with appropriate conditional attributes

The tests cover both fromStart and fromEnd paths, use boundary values (int.MaxValue, uint.MaxValue + 1, long.MaxValue), and correctly gate 64-bit-specific cases with [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))]. PlatformDetection is already used in other tests in this project (TensorPrimitives.Generic.cs, TensorPrimitivesTests.cs).

💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint

NRange.cs:113 uses (uint)end > (uint)length || (uint)start > (uint)end — this truncates nint values on 64-bit, which could cause incorrect bounds validation for large collections. However, this is mirrored from Range.GetOffsetAndLength (which uses int → uint, which is correct for that type) and is a separate issue from the ToString fix.

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💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint

@copilot can you open a separate PR to address this.

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💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint

@copilot can you open a separate PR to address this.

I'm not able to open new PRs. Could you open an issue for tracking the (uint) truncation in NRange.GetOffsetAndLength (line 113) so it can be picked up separately? The fix there would be changing (uint) to (nuint) for the bounds checks on end, length, and start.

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I will open a separate PR for the offset / length issue.

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tannergooding merged commit de90299 into mainFeb 12, 2026
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This one should be backported, yes?

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@tannergooding Up to you, but there are a couple of things you may want to back port when things are merged.

  1. This (Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint #124294)
  2. Fix non-dense TensorSpan handling in SequenceEqual, Fill*, Resize*, IndexOf*, and ConcatenateOnDimension #124225
  3. Fix Tensor.Reverse for tensors with length-1 dimensions #124180
  4. Fix integer overflow in TensorPrimitives IndexOf methods #124274

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I'm fine with taking them all together, but I do think we should take them for bar check at least. -- CC. @jeffhandley

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vcsjones added a commit that referenced this pull request Feb 24, 2026
@vcsjones
Fix NRange.GetOffsetAndLength truncation: cast to nuint instead of ui…
1c7e395
…nt (#124300)
## Description
`NRange.GetOffsetAndLength` casts its `nint` parameters to `uint` for
range validation. On 64-bit platforms, this truncates values larger than
`uint.MaxValue`, allowing invalid ranges to pass validation silently.
```csharp
// Before: truncates upper 32 bits on 64-bit platforms
if ((uint)end > (uint)length || (uint)start > (uint)end)
// After: correct comparison for all nint values
if ((nuint)end > (nuint)length || (nuint)start > (nuint)end)
```
For example, `start = 0x1_0000_0001` and `end = 2` with `length =
0x1_0000_0003`: the `(uint)` cast truncates start to `1`, making `1 > 2`
false and incorrectly passing validation.
**Note:** Other `(uint)` conversion issues in `NRange` (e.g.,
`ToString`) are intentionally not addressed here — those are covered by
#124294.
### Tests
- Converted existing `GetOffsetAndLengthTest` `[Fact]` to `[Theory]`
with `[InlineData]`
- Split success and exception cases into separate theory methods
- Added `[ConditionalTheory(Is64BitProcess)]` tests exercising values
above `uint.MaxValue`, including a case that directly catches the
truncation bug
<!-- START COPILOT CODING AGENT TIPS -->
---
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customizing its development environment and configuring Model Context
Protocol (MCP) servers. Learn more [Copilot coding agent
tips](https://gh.io/copilot-coding-agent-tips) in the docs.
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: vcsjones <361677+vcsjones@users.noreply.github.com>
iremyux pushed a commit to iremyux/dotnet-runtime that referenced this pull request Mar 2, 2026
@vcsjones@iremyux
Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instea…
f9bf70a
…d of uint (dotnet#124294)
## Description
`NIndex.ToStringFromEnd()` and `NRange.ToString()` cast `nint` values to
`uint` before formatting, truncating values exceeding `uint.MaxValue` on
64-bit platforms:
```csharp
var ni = NIndex.FromEnd(unchecked((nint)(1L + uint.MaxValue)));
Console.WriteLine(ni.ToString()); // Prints "^0" instead of "^4294967296"
```
### Fix
- **NIndex.cs**: `(uint)Value` → `(nuint)Value` in `ToStringFromEnd()`
- **NRange.cs**: `(uint)Start.Value` → `(nuint)Start.Value` and
`(uint)End.Value` → `(nuint)End.Value` in `ToString()`
### Tests
- Replaced `[Fact] ToStringTest` with `[Theory]` + `[InlineData]` for
both `NIndexTests` and `NRangeTests`
- Added `[ConditionalTheory(typeof(PlatformDetection),
nameof(PlatformDetection.Is64BitProcess))]` tests exercising values
above `uint.MaxValue`
<!-- START COPILOT CODING AGENT TIPS -->
---
💬 We'd love your input! Share your thoughts on Copilot coding agent in
our [2 minute survey](https://gh.io/copilot-coding-agent-survey).
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: vcsjones <361677+vcsjones@users.noreply.github.com>
iremyux pushed a commit to iremyux/dotnet-runtime that referenced this pull request Mar 2, 2026
@vcsjones@iremyux
Fix NRange.GetOffsetAndLength truncation: cast to nuint instead of ui…
2af20fd
…nt (dotnet#124300)
## Description
`NRange.GetOffsetAndLength` casts its `nint` parameters to `uint` for
range validation. On 64-bit platforms, this truncates values larger than
`uint.MaxValue`, allowing invalid ranges to pass validation silently.
```csharp
// Before: truncates upper 32 bits on 64-bit platforms
if ((uint)end > (uint)length || (uint)start > (uint)end)
// After: correct comparison for all nint values
if ((nuint)end > (nuint)length || (nuint)start > (nuint)end)
```
For example, `start = 0x1_0000_0001` and `end = 2` with `length =
0x1_0000_0003`: the `(uint)` cast truncates start to `1`, making `1 > 2`
false and incorrectly passing validation.
**Note:** Other `(uint)` conversion issues in `NRange` (e.g.,
`ToString`) are intentionally not addressed here — those are covered by
dotnet#124294.
### Tests
- Converted existing `GetOffsetAndLengthTest` `[Fact]` to `[Theory]`
with `[InlineData]`
- Split success and exception cases into separate theory methods
- Added `[ConditionalTheory(Is64BitProcess)]` tests exercising values
above `uint.MaxValue`, including a case that directly catches the
truncation bug
<!-- START COPILOT CODING AGENT TIPS -->
---
💡 You can make Copilot smarter by setting up custom instructions,
customizing its development environment and configuring Model Context
Protocol (MCP) servers. Learn more [Copilot coding agent
tips](https://gh.io/copilot-coding-agent-tips) in the docs.
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: vcsjones <361677+vcsjones@users.noreply.github.com>
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Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint - #124294
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Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint#124294
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Description
NIndex.ToStringFromEnd() and NRange.ToString() cast nint values to uint before formatting, truncating values exceeding uint.MaxValue on 64-bit platforms:
varni=NIndex.FromEnd(unchecked((nint)(1L+uint.MaxValue)));Console.WriteLine(ni.ToString());// Prints "^0" instead of "^4294967296"
Fix
  • NIndex.cs: (uint)Value → (nuint)Value in ToStringFromEnd()
  • NRange.cs: (uint)Start.Value → (nuint)Start.Value and (uint)End.Value → (nuint)End.Value in ToString()
Tests
  • Replaced [Fact] ToStringTest with [Theory] + [InlineData] for both NIndexTests and NRangeTests
  • Added [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))] tests exercising values above uint.MaxValue
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Fix NIndex and NRange ToString truncation: cast to nuint instead of u…
9295a87
…int, add Theory tests
Co-authored-by: vcsjones <361677+vcsjones@users.noreply.github.com>
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[WIP] Fix NIndex formatting for end index conversionFix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uintFeb 11, 2026
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Pull request overview
Fixes incorrect string formatting for NIndex/NRange on 64-bit platforms where values larger than uint.MaxValue were being truncated due to casts to uint during formatting.
Changes:
  • Update NIndex.ToStringFromEnd() to format using (nuint)Value rather than (uint)Value.
  • Update NRange.ToString() to format start/end using (nuint)Start.Value / (nuint)End.Value rather than uint.
  • Expand/adjust unit tests to cover 64-bit values above uint.MaxValue, converting prior [Fact] coverage into [Theory] + [InlineData] and adding 64-bit conditional cases.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.
FileDescription
src/libraries/System.Numerics.Tensors/src/System/Buffers/NIndex.csFixes 64-bit truncation in ToStringFromEnd() by formatting via nuint.
src/libraries/System.Numerics.Tensors/src/System/Buffers/NRange.csFixes 64-bit truncation in ToString() by formatting start/end via nuint.
src/libraries/System.Numerics.Tensors/tests/NIndexTests.csAdds theory-based coverage and conditional 64-bit test cases for large values.
src/libraries/System.Numerics.Tensors/tests/NRangeTests.csAdds theory-based coverage and conditional 64-bit test cases for large range endpoints.
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@copilot please invoke the code-review skill and post your analysis/results as a comment on this PR.
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@copilot please invoke the code-review skill and post your analysis/results as a comment on this PR.
🤖 Copilot Code Review
Holistic Assessment
Motivation: The bug is real and clearly reproducible — (uint) casts truncate nint values exceeding uint.MaxValue on 64-bit platforms, causing NIndex.FromEnd(1L + uint.MaxValue).ToString() to return ^0 instead of ^4294967296. The buffer comment on line 177 ("20 for longest possible nuint value") confirms the original intent was nuint.
Approach: Changing (uint) → (nuint) is the minimal correct fix. The tests use [Theory]/[InlineData] and [ConditionalTheory] with PlatformDetection.Is64BitProcess appropriately, consistent with patterns used in NFloatTests.cs and elsewhere in the test project.
Summary: ✅ LGTM. The three cast fixes are correct, minimal, and well-tested. All findings below are positive confirmations or out-of-scope observations.
Detailed Findings
✅ Correctness — Cast fix is correct in all three locations
  • NIndex.cs:178: (uint)Value → (nuint)Value in ToStringFromEnd()
  • NRange.cs:73: (uint)Start.Value → (nuint)Start.Value in ToString()
  • NRange.cs:84: (uint)End.Value → (nuint)End.Value in ToString()
The Value property returns nint (always non-negative for valid NIndex values), so the nuint cast is safe. The stackalloc buffer was already sized for nuint (21 chars = 1 for ^ + 20 digits for max nuint on 64-bit). The non-FromEnd path (NIndex.ToString() line 172) uses Value.ToString() which calls nint.ToString() directly — no truncation issue there.
✅ Test quality — Good coverage with appropriate conditional attributes
The tests cover both fromStart and fromEnd paths, use boundary values (int.MaxValue, uint.MaxValue + 1, long.MaxValue), and correctly gate 64-bit-specific cases with [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))]. PlatformDetection is already used in other tests in this project (TensorPrimitives.Generic.cs, TensorPrimitivesTests.cs).
💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
NRange.cs:113 uses (uint)end > (uint)length || (uint)start > (uint)end — this truncates nint values on 64-bit, which could cause incorrect bounds validation for large collections. However, this is mirrored from Range.GetOffsetAndLength (which uses int → uint, which is correct for that type) and is a separate issue from the ToString fix.
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💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
@copilot can you open a separate PR to address this.
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💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
@copilot can you open a separate PR to address this.
I'm not able to open new PRs. Could you open an issue for tracking the (uint) truncation in NRange.GetOffsetAndLength (line 113) so it can be picked up separately? The fix there would be changing (uint) to (nuint) for the bounds checks on end, length, and start.
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I will open a separate PR for the offset / length issue.
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This one should be backported, yes?
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@tannergooding Up to you, but there are a couple of things you may want to back port when things are merged.
  1. This (Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint #124294)
  2. Fix non-dense TensorSpan handling in SequenceEqual, Fill*, Resize*, IndexOf*, and ConcatenateOnDimension #124225
  3. Fix Tensor.Reverse for tensors with length-1 dimensions #124180
  4. Fix integer overflow in TensorPrimitives IndexOf methods #124274
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I'm fine with taking them all together, but I do think we should take them for bar check at least. -- CC. @jeffhandley
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@vcsjones
Fix NRange.GetOffsetAndLength truncation: cast to nuint instead of ui…
1c7e395
…nt (#124300)
## Description
`NRange.GetOffsetAndLength` casts its `nint` parameters to `uint` for
range validation. On 64-bit platforms, this truncates values larger than
`uint.MaxValue`, allowing invalid ranges to pass validation silently.
```csharp
// Before: truncates upper 32 bits on 64-bit platforms
if ((uint)end > (uint)length || (uint)start > (uint)end)
// After: correct comparison for all nint values
if ((nuint)end > (nuint)length || (nuint)start > (nuint)end)
```
For example, `start = 0x1_0000_0001` and `end = 2` with `length =
0x1_0000_0003`: the `(uint)` cast truncates start to `1`, making `1 > 2`
false and incorrectly passing validation.
**Note:** Other `(uint)` conversion issues in `NRange` (e.g.,
`ToString`) are intentionally not addressed here — those are covered by
#124294.
### Tests
- Converted existing `GetOffsetAndLengthTest` `[Fact]` to `[Theory]`
with `[InlineData]`
- Split success and exception cases into separate theory methods
- Added `[ConditionalTheory(Is64BitProcess)]` tests exercising values
above `uint.MaxValue`, including a case that directly catches the
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@vcsjones@iremyux
Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instea…
f9bf70a
…d of uint (dotnet#124294)
## Description
`NIndex.ToStringFromEnd()` and `NRange.ToString()` cast `nint` values to
`uint` before formatting, truncating values exceeding `uint.MaxValue` on
64-bit platforms:
```csharp
var ni = NIndex.FromEnd(unchecked((nint)(1L + uint.MaxValue)));
Console.WriteLine(ni.ToString()); // Prints "^0" instead of "^4294967296"
```
### Fix
- **NIndex.cs**: `(uint)Value` → `(nuint)Value` in `ToStringFromEnd()`
- **NRange.cs**: `(uint)Start.Value` → `(nuint)Start.Value` and
`(uint)End.Value` → `(nuint)End.Value` in `ToString()`
### Tests
- Replaced `[Fact] ToStringTest` with `[Theory]` + `[InlineData]` for
both `NIndexTests` and `NRangeTests`
- Added `[ConditionalTheory(typeof(PlatformDetection),
nameof(PlatformDetection.Is64BitProcess))]` tests exercising values
above `uint.MaxValue`
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@vcsjones@iremyux
Fix NRange.GetOffsetAndLength truncation: cast to nuint instead of ui…
2af20fd
…nt (dotnet#124300)
## Description
`NRange.GetOffsetAndLength` casts its `nint` parameters to `uint` for
range validation. On 64-bit platforms, this truncates values larger than
`uint.MaxValue`, allowing invalid ranges to pass validation silently.
```csharp
// Before: truncates upper 32 bits on 64-bit platforms
if ((uint)end > (uint)length || (uint)start > (uint)end)
// After: correct comparison for all nint values
if ((nuint)end > (nuint)length || (nuint)start > (nuint)end)
```
For example, `start = 0x1_0000_0001` and `end = 2` with `length =
0x1_0000_0003`: the `(uint)` cast truncates start to `1`, making `1 > 2`
false and incorrectly passing validation.
**Note:** Other `(uint)` conversion issues in `NRange` (e.g.,
`ToString`) are intentionally not addressed here — those are covered by
dotnet#124294.
### Tests
- Converted existing `GetOffsetAndLengthTest` `[Fact]` to `[Theory]`
with `[InlineData]`
- Split success and exception cases into separate theory methods
- Added `[ConditionalTheory(Is64BitProcess)]` tests exercising values
above `uint.MaxValue`, including a case that directly catches the
truncation bug
<!-- START COPILOT CODING AGENT TIPS -->
---
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Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint - #124294
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Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint#124294
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Description
NIndex.ToStringFromEnd() and NRange.ToString() cast nint values to uint before formatting, truncating values exceeding uint.MaxValue on 64-bit platforms:
varni=NIndex.FromEnd(unchecked((nint)(1L+uint.MaxValue)));Console.WriteLine(ni.ToString());// Prints "^0" instead of "^4294967296"
Fix
  • NIndex.cs: (uint)Value → (nuint)Value in ToStringFromEnd()
  • NRange.cs: (uint)Start.Value → (nuint)Start.Value and (uint)End.Value → (nuint)End.Value in ToString()
Tests
  • Replaced [Fact] ToStringTest with [Theory] + [InlineData] for both NIndexTests and NRangeTests
  • Added [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))] tests exercising values above uint.MaxValue
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Fix NIndex and NRange ToString truncation: cast to nuint instead of u…
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…int, add Theory tests
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[WIP] Fix NIndex formatting for end index conversionFix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uintFeb 11, 2026
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Pull request overview
Fixes incorrect string formatting for NIndex/NRange on 64-bit platforms where values larger than uint.MaxValue were being truncated due to casts to uint during formatting.
Changes:
  • Update NIndex.ToStringFromEnd() to format using (nuint)Value rather than (uint)Value.
  • Update NRange.ToString() to format start/end using (nuint)Start.Value / (nuint)End.Value rather than uint.
  • Expand/adjust unit tests to cover 64-bit values above uint.MaxValue, converting prior [Fact] coverage into [Theory] + [InlineData] and adding 64-bit conditional cases.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.
FileDescription
src/libraries/System.Numerics.Tensors/src/System/Buffers/NIndex.csFixes 64-bit truncation in ToStringFromEnd() by formatting via nuint.
src/libraries/System.Numerics.Tensors/src/System/Buffers/NRange.csFixes 64-bit truncation in ToString() by formatting start/end via nuint.
src/libraries/System.Numerics.Tensors/tests/NIndexTests.csAdds theory-based coverage and conditional 64-bit test cases for large values.
src/libraries/System.Numerics.Tensors/tests/NRangeTests.csAdds theory-based coverage and conditional 64-bit test cases for large range endpoints.
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@copilot please invoke the code-review skill and post your analysis/results as a comment on this PR.
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@copilot please invoke the code-review skill and post your analysis/results as a comment on this PR.
🤖 Copilot Code Review
Holistic Assessment
Motivation: The bug is real and clearly reproducible — (uint) casts truncate nint values exceeding uint.MaxValue on 64-bit platforms, causing NIndex.FromEnd(1L + uint.MaxValue).ToString() to return ^0 instead of ^4294967296. The buffer comment on line 177 ("20 for longest possible nuint value") confirms the original intent was nuint.
Approach: Changing (uint) → (nuint) is the minimal correct fix. The tests use [Theory]/[InlineData] and [ConditionalTheory] with PlatformDetection.Is64BitProcess appropriately, consistent with patterns used in NFloatTests.cs and elsewhere in the test project.
Summary: ✅ LGTM. The three cast fixes are correct, minimal, and well-tested. All findings below are positive confirmations or out-of-scope observations.
Detailed Findings
✅ Correctness — Cast fix is correct in all three locations
  • NIndex.cs:178: (uint)Value → (nuint)Value in ToStringFromEnd()
  • NRange.cs:73: (uint)Start.Value → (nuint)Start.Value in ToString()
  • NRange.cs:84: (uint)End.Value → (nuint)End.Value in ToString()
The Value property returns nint (always non-negative for valid NIndex values), so the nuint cast is safe. The stackalloc buffer was already sized for nuint (21 chars = 1 for ^ + 20 digits for max nuint on 64-bit). The non-FromEnd path (NIndex.ToString() line 172) uses Value.ToString() which calls nint.ToString() directly — no truncation issue there.
✅ Test quality — Good coverage with appropriate conditional attributes
The tests cover both fromStart and fromEnd paths, use boundary values (int.MaxValue, uint.MaxValue + 1, long.MaxValue), and correctly gate 64-bit-specific cases with [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))]. PlatformDetection is already used in other tests in this project (TensorPrimitives.Generic.cs, TensorPrimitivesTests.cs).
💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
NRange.cs:113 uses (uint)end > (uint)length || (uint)start > (uint)end — this truncates nint values on 64-bit, which could cause incorrect bounds validation for large collections. However, this is mirrored from Range.GetOffsetAndLength (which uses int → uint, which is correct for that type) and is a separate issue from the ToString fix.
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💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
@copilot can you open a separate PR to address this.
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💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
@copilot can you open a separate PR to address this.
I'm not able to open new PRs. Could you open an issue for tracking the (uint) truncation in NRange.GetOffsetAndLength (line 113) so it can be picked up separately? The fix there would be changing (uint) to (nuint) for the bounds checks on end, length, and start.
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I will open a separate PR for the offset / length issue.
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This one should be backported, yes?
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@tannergooding Up to you, but there are a couple of things you may want to back port when things are merged.
  1. This (Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint #124294)
  2. Fix non-dense TensorSpan handling in SequenceEqual, Fill*, Resize*, IndexOf*, and ConcatenateOnDimension #124225
  3. Fix Tensor.Reverse for tensors with length-1 dimensions #124180
  4. Fix integer overflow in TensorPrimitives IndexOf methods #124274
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I'm fine with taking them all together, but I do think we should take them for bar check at least. -- CC. @jeffhandley
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@vcsjones
Fix NRange.GetOffsetAndLength truncation: cast to nuint instead of ui…
1c7e395
…nt (#124300)
## Description
`NRange.GetOffsetAndLength` casts its `nint` parameters to `uint` for
range validation. On 64-bit platforms, this truncates values larger than
`uint.MaxValue`, allowing invalid ranges to pass validation silently.
```csharp
// Before: truncates upper 32 bits on 64-bit platforms
if ((uint)end > (uint)length || (uint)start > (uint)end)
// After: correct comparison for all nint values
if ((nuint)end > (nuint)length || (nuint)start > (nuint)end)
```
For example, `start = 0x1_0000_0001` and `end = 2` with `length =
0x1_0000_0003`: the `(uint)` cast truncates start to `1`, making `1 > 2`
false and incorrectly passing validation.
**Note:** Other `(uint)` conversion issues in `NRange` (e.g.,
`ToString`) are intentionally not addressed here — those are covered by
#124294.
### Tests
- Converted existing `GetOffsetAndLengthTest` `[Fact]` to `[Theory]`
with `[InlineData]`
- Split success and exception cases into separate theory methods
- Added `[ConditionalTheory(Is64BitProcess)]` tests exercising values
above `uint.MaxValue`, including a case that directly catches the
truncation bug
<!-- START COPILOT CODING AGENT TIPS -->
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iremyux pushed a commit
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Mar 2, 2026
@vcsjones@iremyux
Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instea…
f9bf70a
…d of uint (dotnet#124294)
## Description
`NIndex.ToStringFromEnd()` and `NRange.ToString()` cast `nint` values to
`uint` before formatting, truncating values exceeding `uint.MaxValue` on
64-bit platforms:
```csharp
var ni = NIndex.FromEnd(unchecked((nint)(1L + uint.MaxValue)));
Console.WriteLine(ni.ToString()); // Prints "^0" instead of "^4294967296"
```
### Fix
- **NIndex.cs**: `(uint)Value` → `(nuint)Value` in `ToStringFromEnd()`
- **NRange.cs**: `(uint)Start.Value` → `(nuint)Start.Value` and
`(uint)End.Value` → `(nuint)End.Value` in `ToString()`
### Tests
- Replaced `[Fact] ToStringTest` with `[Theory]` + `[InlineData]` for
both `NIndexTests` and `NRangeTests`
- Added `[ConditionalTheory(typeof(PlatformDetection),
nameof(PlatformDetection.Is64BitProcess))]` tests exercising values
above `uint.MaxValue`
<!-- START COPILOT CODING AGENT TIPS -->
---
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our [2 minute survey](https://gh.io/copilot-coding-agent-survey).
---------
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Co-authored-by: vcsjones <361677+vcsjones@users.noreply.github.com>
iremyux pushed a commit
to iremyux/dotnet-runtime
that referenced
this pull request
Mar 2, 2026
@vcsjones@iremyux
Fix NRange.GetOffsetAndLength truncation: cast to nuint instead of ui…
2af20fd
…nt (dotnet#124300)
## Description
`NRange.GetOffsetAndLength` casts its `nint` parameters to `uint` for
range validation. On 64-bit platforms, this truncates values larger than
`uint.MaxValue`, allowing invalid ranges to pass validation silently.
```csharp
// Before: truncates upper 32 bits on 64-bit platforms
if ((uint)end > (uint)length || (uint)start > (uint)end)
// After: correct comparison for all nint values
if ((nuint)end > (nuint)length || (nuint)start > (nuint)end)
```
For example, `start = 0x1_0000_0001` and `end = 2` with `length =
0x1_0000_0003`: the `(uint)` cast truncates start to `1`, making `1 > 2`
false and incorrectly passing validation.
**Note:** Other `(uint)` conversion issues in `NRange` (e.g.,
`ToString`) are intentionally not addressed here — those are covered by
dotnet#124294.
### Tests
- Converted existing `GetOffsetAndLengthTest` `[Fact]` to `[Theory]`
with `[InlineData]`
- Split success and exception cases into separate theory methods
- Added `[ConditionalTheory(Is64BitProcess)]` tests exercising values
above `uint.MaxValue`, including a case that directly catches the
truncation bug
<!-- START COPILOT CODING AGENT TIPS -->
---
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customizing its development environment and configuring Model Context
Protocol (MCP) servers. Learn more [Copilot coding agent
tips](https://gh.io/copilot-coding-agent-tips) in the docs.
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: vcsjones <361677+vcsjones@users.noreply.github.com>
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Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint - #124294
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Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint#124294
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Description
NIndex.ToStringFromEnd() and NRange.ToString() cast nint values to uint before formatting, truncating values exceeding uint.MaxValue on 64-bit platforms:
varni=NIndex.FromEnd(unchecked((nint)(1L+uint.MaxValue)));Console.WriteLine(ni.ToString());// Prints "^0" instead of "^4294967296"
Fix
  • NIndex.cs: (uint)Value → (nuint)Value in ToStringFromEnd()
  • NRange.cs: (uint)Start.Value → (nuint)Start.Value and (uint)End.Value → (nuint)End.Value in ToString()
Tests
  • Replaced [Fact] ToStringTest with [Theory] + [InlineData] for both NIndexTests and NRangeTests
  • Added [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))] tests exercising values above uint.MaxValue
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Fix NIndex and NRange ToString truncation: cast to nuint instead of u…
9295a87
…int, add Theory tests
Co-authored-by: vcsjones <361677+vcsjones@users.noreply.github.com>
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[WIP] Fix NIndex formatting for end index conversionFix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uintFeb 11, 2026
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Pull request overview
Fixes incorrect string formatting for NIndex/NRange on 64-bit platforms where values larger than uint.MaxValue were being truncated due to casts to uint during formatting.
Changes:
  • Update NIndex.ToStringFromEnd() to format using (nuint)Value rather than (uint)Value.
  • Update NRange.ToString() to format start/end using (nuint)Start.Value / (nuint)End.Value rather than uint.
  • Expand/adjust unit tests to cover 64-bit values above uint.MaxValue, converting prior [Fact] coverage into [Theory] + [InlineData] and adding 64-bit conditional cases.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.
FileDescription
src/libraries/System.Numerics.Tensors/src/System/Buffers/NIndex.csFixes 64-bit truncation in ToStringFromEnd() by formatting via nuint.
src/libraries/System.Numerics.Tensors/src/System/Buffers/NRange.csFixes 64-bit truncation in ToString() by formatting start/end via nuint.
src/libraries/System.Numerics.Tensors/tests/NIndexTests.csAdds theory-based coverage and conditional 64-bit test cases for large values.
src/libraries/System.Numerics.Tensors/tests/NRangeTests.csAdds theory-based coverage and conditional 64-bit test cases for large range endpoints.
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@copilot please invoke the code-review skill and post your analysis/results as a comment on this PR.
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@copilot please invoke the code-review skill and post your analysis/results as a comment on this PR.
🤖 Copilot Code Review
Holistic Assessment
Motivation: The bug is real and clearly reproducible — (uint) casts truncate nint values exceeding uint.MaxValue on 64-bit platforms, causing NIndex.FromEnd(1L + uint.MaxValue).ToString() to return ^0 instead of ^4294967296. The buffer comment on line 177 ("20 for longest possible nuint value") confirms the original intent was nuint.
Approach: Changing (uint) → (nuint) is the minimal correct fix. The tests use [Theory]/[InlineData] and [ConditionalTheory] with PlatformDetection.Is64BitProcess appropriately, consistent with patterns used in NFloatTests.cs and elsewhere in the test project.
Summary: ✅ LGTM. The three cast fixes are correct, minimal, and well-tested. All findings below are positive confirmations or out-of-scope observations.
Detailed Findings
✅ Correctness — Cast fix is correct in all three locations
  • NIndex.cs:178: (uint)Value → (nuint)Value in ToStringFromEnd()
  • NRange.cs:73: (uint)Start.Value → (nuint)Start.Value in ToString()
  • NRange.cs:84: (uint)End.Value → (nuint)End.Value in ToString()
The Value property returns nint (always non-negative for valid NIndex values), so the nuint cast is safe. The stackalloc buffer was already sized for nuint (21 chars = 1 for ^ + 20 digits for max nuint on 64-bit). The non-FromEnd path (NIndex.ToString() line 172) uses Value.ToString() which calls nint.ToString() directly — no truncation issue there.
✅ Test quality — Good coverage with appropriate conditional attributes
The tests cover both fromStart and fromEnd paths, use boundary values (int.MaxValue, uint.MaxValue + 1, long.MaxValue), and correctly gate 64-bit-specific cases with [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))]. PlatformDetection is already used in other tests in this project (TensorPrimitives.Generic.cs, TensorPrimitivesTests.cs).
💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
NRange.cs:113 uses (uint)end > (uint)length || (uint)start > (uint)end — this truncates nint values on 64-bit, which could cause incorrect bounds validation for large collections. However, this is mirrored from Range.GetOffsetAndLength (which uses int → uint, which is correct for that type) and is a separate issue from the ToString fix.
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💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
@copilot can you open a separate PR to address this.
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💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
@copilot can you open a separate PR to address this.
I'm not able to open new PRs. Could you open an issue for tracking the (uint) truncation in NRange.GetOffsetAndLength (line 113) so it can be picked up separately? The fix there would be changing (uint) to (nuint) for the bounds checks on end, length, and start.
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I will open a separate PR for the offset / length issue.
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This one should be backported, yes?
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@tannergooding Up to you, but there are a couple of things you may want to back port when things are merged.
  1. This (Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint #124294)
  2. Fix non-dense TensorSpan handling in SequenceEqual, Fill*, Resize*, IndexOf*, and ConcatenateOnDimension #124225
  3. Fix Tensor.Reverse for tensors with length-1 dimensions #124180
  4. Fix integer overflow in TensorPrimitives IndexOf methods #124274
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I'm fine with taking them all together, but I do think we should take them for bar check at least. -- CC. @jeffhandley
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@vcsjones
Fix NRange.GetOffsetAndLength truncation: cast to nuint instead of ui…
1c7e395
…nt (#124300)
## Description
`NRange.GetOffsetAndLength` casts its `nint` parameters to `uint` for
range validation. On 64-bit platforms, this truncates values larger than
`uint.MaxValue`, allowing invalid ranges to pass validation silently.
```csharp
// Before: truncates upper 32 bits on 64-bit platforms
if ((uint)end > (uint)length || (uint)start > (uint)end)
// After: correct comparison for all nint values
if ((nuint)end > (nuint)length || (nuint)start > (nuint)end)
```
For example, `start = 0x1_0000_0001` and `end = 2` with `length =
0x1_0000_0003`: the `(uint)` cast truncates start to `1`, making `1 > 2`
false and incorrectly passing validation.
**Note:** Other `(uint)` conversion issues in `NRange` (e.g.,
`ToString`) are intentionally not addressed here — those are covered by
#124294.
### Tests
- Converted existing `GetOffsetAndLengthTest` `[Fact]` to `[Theory]`
with `[InlineData]`
- Split success and exception cases into separate theory methods
- Added `[ConditionalTheory(Is64BitProcess)]` tests exercising values
above `uint.MaxValue`, including a case that directly catches the
truncation bug
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@vcsjones@iremyux
Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instea…
f9bf70a
…d of uint (dotnet#124294)
## Description
`NIndex.ToStringFromEnd()` and `NRange.ToString()` cast `nint` values to
`uint` before formatting, truncating values exceeding `uint.MaxValue` on
64-bit platforms:
```csharp
var ni = NIndex.FromEnd(unchecked((nint)(1L + uint.MaxValue)));
Console.WriteLine(ni.ToString()); // Prints "^0" instead of "^4294967296"
```
### Fix
- **NIndex.cs**: `(uint)Value` → `(nuint)Value` in `ToStringFromEnd()`
- **NRange.cs**: `(uint)Start.Value` → `(nuint)Start.Value` and
`(uint)End.Value` → `(nuint)End.Value` in `ToString()`
### Tests
- Replaced `[Fact] ToStringTest` with `[Theory]` + `[InlineData]` for
both `NIndexTests` and `NRangeTests`
- Added `[ConditionalTheory(typeof(PlatformDetection),
nameof(PlatformDetection.Is64BitProcess))]` tests exercising values
above `uint.MaxValue`
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@vcsjones@iremyux
Fix NRange.GetOffsetAndLength truncation: cast to nuint instead of ui…
2af20fd
…nt (dotnet#124300)
## Description
`NRange.GetOffsetAndLength` casts its `nint` parameters to `uint` for
range validation. On 64-bit platforms, this truncates values larger than
`uint.MaxValue`, allowing invalid ranges to pass validation silently.
```csharp
// Before: truncates upper 32 bits on 64-bit platforms
if ((uint)end > (uint)length || (uint)start > (uint)end)
// After: correct comparison for all nint values
if ((nuint)end > (nuint)length || (nuint)start > (nuint)end)
```
For example, `start = 0x1_0000_0001` and `end = 2` with `length =
0x1_0000_0003`: the `(uint)` cast truncates start to `1`, making `1 > 2`
false and incorrectly passing validation.
**Note:** Other `(uint)` conversion issues in `NRange` (e.g.,
`ToString`) are intentionally not addressed here — those are covered by
dotnet#124294.
### Tests
- Converted existing `GetOffsetAndLengthTest` `[Fact]` to `[Theory]`
with `[InlineData]`
- Split success and exception cases into separate theory methods
- Added `[ConditionalTheory(Is64BitProcess)]` tests exercising values
above `uint.MaxValue`, including a case that directly catches the
truncation bug
<!-- START COPILOT CODING AGENT TIPS -->
---
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customizing its development environment and configuring Model Context
Protocol (MCP) servers. Learn more [Copilot coding agent
tips](https://gh.io/copilot-coding-agent-tips) in the docs.
---------
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injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
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Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint - #124294
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Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint#124294
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Description
NIndex.ToStringFromEnd() and NRange.ToString() cast nint values to uint before formatting, truncating values exceeding uint.MaxValue on 64-bit platforms:
varni=NIndex.FromEnd(unchecked((nint)(1L+uint.MaxValue)));Console.WriteLine(ni.ToString());// Prints "^0" instead of "^4294967296"
Fix
  • NIndex.cs: (uint)Value → (nuint)Value in ToStringFromEnd()
  • NRange.cs: (uint)Start.Value → (nuint)Start.Value and (uint)End.Value → (nuint)End.Value in ToString()
Tests
  • Replaced [Fact] ToStringTest with [Theory] + [InlineData] for both NIndexTests and NRangeTests
  • Added [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))] tests exercising values above uint.MaxValue
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Fix NIndex and NRange ToString truncation: cast to nuint instead of u…
9295a87
…int, add Theory tests
Co-authored-by: vcsjones <361677+vcsjones@users.noreply.github.com>
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[WIP] Fix NIndex formatting for end index conversionFix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uintFeb 11, 2026
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Pull request overview
Fixes incorrect string formatting for NIndex/NRange on 64-bit platforms where values larger than uint.MaxValue were being truncated due to casts to uint during formatting.
Changes:
  • Update NIndex.ToStringFromEnd() to format using (nuint)Value rather than (uint)Value.
  • Update NRange.ToString() to format start/end using (nuint)Start.Value / (nuint)End.Value rather than uint.
  • Expand/adjust unit tests to cover 64-bit values above uint.MaxValue, converting prior [Fact] coverage into [Theory] + [InlineData] and adding 64-bit conditional cases.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.
FileDescription
src/libraries/System.Numerics.Tensors/src/System/Buffers/NIndex.csFixes 64-bit truncation in ToStringFromEnd() by formatting via nuint.
src/libraries/System.Numerics.Tensors/src/System/Buffers/NRange.csFixes 64-bit truncation in ToString() by formatting start/end via nuint.
src/libraries/System.Numerics.Tensors/tests/NIndexTests.csAdds theory-based coverage and conditional 64-bit test cases for large values.
src/libraries/System.Numerics.Tensors/tests/NRangeTests.csAdds theory-based coverage and conditional 64-bit test cases for large range endpoints.
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@copilot please invoke the code-review skill and post your analysis/results as a comment on this PR.
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@copilot please invoke the code-review skill and post your analysis/results as a comment on this PR.
🤖 Copilot Code Review
Holistic Assessment
Motivation: The bug is real and clearly reproducible — (uint) casts truncate nint values exceeding uint.MaxValue on 64-bit platforms, causing NIndex.FromEnd(1L + uint.MaxValue).ToString() to return ^0 instead of ^4294967296. The buffer comment on line 177 ("20 for longest possible nuint value") confirms the original intent was nuint.
Approach: Changing (uint) → (nuint) is the minimal correct fix. The tests use [Theory]/[InlineData] and [ConditionalTheory] with PlatformDetection.Is64BitProcess appropriately, consistent with patterns used in NFloatTests.cs and elsewhere in the test project.
Summary: ✅ LGTM. The three cast fixes are correct, minimal, and well-tested. All findings below are positive confirmations or out-of-scope observations.
Detailed Findings
✅ Correctness — Cast fix is correct in all three locations
  • NIndex.cs:178: (uint)Value → (nuint)Value in ToStringFromEnd()
  • NRange.cs:73: (uint)Start.Value → (nuint)Start.Value in ToString()
  • NRange.cs:84: (uint)End.Value → (nuint)End.Value in ToString()
The Value property returns nint (always non-negative for valid NIndex values), so the nuint cast is safe. The stackalloc buffer was already sized for nuint (21 chars = 1 for ^ + 20 digits for max nuint on 64-bit). The non-FromEnd path (NIndex.ToString() line 172) uses Value.ToString() which calls nint.ToString() directly — no truncation issue there.
✅ Test quality — Good coverage with appropriate conditional attributes
The tests cover both fromStart and fromEnd paths, use boundary values (int.MaxValue, uint.MaxValue + 1, long.MaxValue), and correctly gate 64-bit-specific cases with [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))]. PlatformDetection is already used in other tests in this project (TensorPrimitives.Generic.cs, TensorPrimitivesTests.cs).
💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
NRange.cs:113 uses (uint)end > (uint)length || (uint)start > (uint)end — this truncates nint values on 64-bit, which could cause incorrect bounds validation for large collections. However, this is mirrored from Range.GetOffsetAndLength (which uses int → uint, which is correct for that type) and is a separate issue from the ToString fix.
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💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
@copilot can you open a separate PR to address this.
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💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
@copilot can you open a separate PR to address this.
I'm not able to open new PRs. Could you open an issue for tracking the (uint) truncation in NRange.GetOffsetAndLength (line 113) so it can be picked up separately? The fix there would be changing (uint) to (nuint) for the bounds checks on end, length, and start.
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I will open a separate PR for the offset / length issue.
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This one should be backported, yes?
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@tannergooding Up to you, but there are a couple of things you may want to back port when things are merged.
  1. This (Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint #124294)
  2. Fix non-dense TensorSpan handling in SequenceEqual, Fill*, Resize*, IndexOf*, and ConcatenateOnDimension #124225
  3. Fix Tensor.Reverse for tensors with length-1 dimensions #124180
  4. Fix integer overflow in TensorPrimitives IndexOf methods #124274
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I'm fine with taking them all together, but I do think we should take them for bar check at least. -- CC. @jeffhandley
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@vcsjones
Fix NRange.GetOffsetAndLength truncation: cast to nuint instead of ui…
1c7e395
…nt (#124300)
## Description
`NRange.GetOffsetAndLength` casts its `nint` parameters to `uint` for
range validation. On 64-bit platforms, this truncates values larger than
`uint.MaxValue`, allowing invalid ranges to pass validation silently.
```csharp
// Before: truncates upper 32 bits on 64-bit platforms
if ((uint)end > (uint)length || (uint)start > (uint)end)
// After: correct comparison for all nint values
if ((nuint)end > (nuint)length || (nuint)start > (nuint)end)
```
For example, `start = 0x1_0000_0001` and `end = 2` with `length =
0x1_0000_0003`: the `(uint)` cast truncates start to `1`, making `1 > 2`
false and incorrectly passing validation.
**Note:** Other `(uint)` conversion issues in `NRange` (e.g.,
`ToString`) are intentionally not addressed here — those are covered by
#124294.
### Tests
- Converted existing `GetOffsetAndLengthTest` `[Fact]` to `[Theory]`
with `[InlineData]`
- Split success and exception cases into separate theory methods
- Added `[ConditionalTheory(Is64BitProcess)]` tests exercising values
above `uint.MaxValue`, including a case that directly catches the
truncation bug
<!-- START COPILOT CODING AGENT TIPS -->
---
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customizing its development environment and configuring Model Context
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iremyux pushed a commit
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Mar 2, 2026
@vcsjones@iremyux
Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instea…
f9bf70a
…d of uint (dotnet#124294)
## Description
`NIndex.ToStringFromEnd()` and `NRange.ToString()` cast `nint` values to
`uint` before formatting, truncating values exceeding `uint.MaxValue` on
64-bit platforms:
```csharp
var ni = NIndex.FromEnd(unchecked((nint)(1L + uint.MaxValue)));
Console.WriteLine(ni.ToString()); // Prints "^0" instead of "^4294967296"
```
### Fix
- **NIndex.cs**: `(uint)Value` → `(nuint)Value` in `ToStringFromEnd()`
- **NRange.cs**: `(uint)Start.Value` → `(nuint)Start.Value` and
`(uint)End.Value` → `(nuint)End.Value` in `ToString()`
### Tests
- Replaced `[Fact] ToStringTest` with `[Theory]` + `[InlineData]` for
both `NIndexTests` and `NRangeTests`
- Added `[ConditionalTheory(typeof(PlatformDetection),
nameof(PlatformDetection.Is64BitProcess))]` tests exercising values
above `uint.MaxValue`
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Fix NRange.GetOffsetAndLength truncation: cast to nuint instead of ui…
2af20fd
…nt (dotnet#124300)
## Description
`NRange.GetOffsetAndLength` casts its `nint` parameters to `uint` for
range validation. On 64-bit platforms, this truncates values larger than
`uint.MaxValue`, allowing invalid ranges to pass validation silently.
```csharp
// Before: truncates upper 32 bits on 64-bit platforms
if ((uint)end > (uint)length || (uint)start > (uint)end)
// After: correct comparison for all nint values
if ((nuint)end > (nuint)length || (nuint)start > (nuint)end)
```
For example, `start = 0x1_0000_0001` and `end = 2` with `length =
0x1_0000_0003`: the `(uint)` cast truncates start to `1`, making `1 > 2`
false and incorrectly passing validation.
**Note:** Other `(uint)` conversion issues in `NRange` (e.g.,
`ToString`) are intentionally not addressed here — those are covered by
dotnet#124294.
### Tests
- Converted existing `GetOffsetAndLengthTest` `[Fact]` to `[Theory]`
with `[InlineData]`
- Split success and exception cases into separate theory methods
- Added `[ConditionalTheory(Is64BitProcess)]` tests exercising values
above `uint.MaxValue`, including a case that directly catches the
truncation bug
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Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint - #124294
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Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint#124294
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Description
NIndex.ToStringFromEnd() and NRange.ToString() cast nint values to uint before formatting, truncating values exceeding uint.MaxValue on 64-bit platforms:
varni=NIndex.FromEnd(unchecked((nint)(1L+uint.MaxValue)));Console.WriteLine(ni.ToString());// Prints "^0" instead of "^4294967296"
Fix
  • NIndex.cs: (uint)Value → (nuint)Value in ToStringFromEnd()
  • NRange.cs: (uint)Start.Value → (nuint)Start.Value and (uint)End.Value → (nuint)End.Value in ToString()
Tests
  • Replaced [Fact] ToStringTest with [Theory] + [InlineData] for both NIndexTests and NRangeTests
  • Added [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))] tests exercising values above uint.MaxValue
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Fix NIndex and NRange ToString truncation: cast to nuint instead of u…
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…int, add Theory tests
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[WIP] Fix NIndex formatting for end index conversionFix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uintFeb 11, 2026
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Pull request overview
Fixes incorrect string formatting for NIndex/NRange on 64-bit platforms where values larger than uint.MaxValue were being truncated due to casts to uint during formatting.
Changes:
  • Update NIndex.ToStringFromEnd() to format using (nuint)Value rather than (uint)Value.
  • Update NRange.ToString() to format start/end using (nuint)Start.Value / (nuint)End.Value rather than uint.
  • Expand/adjust unit tests to cover 64-bit values above uint.MaxValue, converting prior [Fact] coverage into [Theory] + [InlineData] and adding 64-bit conditional cases.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.
FileDescription
src/libraries/System.Numerics.Tensors/src/System/Buffers/NIndex.csFixes 64-bit truncation in ToStringFromEnd() by formatting via nuint.
src/libraries/System.Numerics.Tensors/src/System/Buffers/NRange.csFixes 64-bit truncation in ToString() by formatting start/end via nuint.
src/libraries/System.Numerics.Tensors/tests/NIndexTests.csAdds theory-based coverage and conditional 64-bit test cases for large values.
src/libraries/System.Numerics.Tensors/tests/NRangeTests.csAdds theory-based coverage and conditional 64-bit test cases for large range endpoints.
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@copilot please invoke the code-review skill and post your analysis/results as a comment on this PR.
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@copilot please invoke the code-review skill and post your analysis/results as a comment on this PR.
🤖 Copilot Code Review
Holistic Assessment
Motivation: The bug is real and clearly reproducible — (uint) casts truncate nint values exceeding uint.MaxValue on 64-bit platforms, causing NIndex.FromEnd(1L + uint.MaxValue).ToString() to return ^0 instead of ^4294967296. The buffer comment on line 177 ("20 for longest possible nuint value") confirms the original intent was nuint.
Approach: Changing (uint) → (nuint) is the minimal correct fix. The tests use [Theory]/[InlineData] and [ConditionalTheory] with PlatformDetection.Is64BitProcess appropriately, consistent with patterns used in NFloatTests.cs and elsewhere in the test project.
Summary: ✅ LGTM. The three cast fixes are correct, minimal, and well-tested. All findings below are positive confirmations or out-of-scope observations.
Detailed Findings
✅ Correctness — Cast fix is correct in all three locations
  • NIndex.cs:178: (uint)Value → (nuint)Value in ToStringFromEnd()
  • NRange.cs:73: (uint)Start.Value → (nuint)Start.Value in ToString()
  • NRange.cs:84: (uint)End.Value → (nuint)End.Value in ToString()
The Value property returns nint (always non-negative for valid NIndex values), so the nuint cast is safe. The stackalloc buffer was already sized for nuint (21 chars = 1 for ^ + 20 digits for max nuint on 64-bit). The non-FromEnd path (NIndex.ToString() line 172) uses Value.ToString() which calls nint.ToString() directly — no truncation issue there.
✅ Test quality — Good coverage with appropriate conditional attributes
The tests cover both fromStart and fromEnd paths, use boundary values (int.MaxValue, uint.MaxValue + 1, long.MaxValue), and correctly gate 64-bit-specific cases with [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))]. PlatformDetection is already used in other tests in this project (TensorPrimitives.Generic.cs, TensorPrimitivesTests.cs).
💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
NRange.cs:113 uses (uint)end > (uint)length || (uint)start > (uint)end — this truncates nint values on 64-bit, which could cause incorrect bounds validation for large collections. However, this is mirrored from Range.GetOffsetAndLength (which uses int → uint, which is correct for that type) and is a separate issue from the ToString fix.
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💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
@copilot can you open a separate PR to address this.
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💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
@copilot can you open a separate PR to address this.
I'm not able to open new PRs. Could you open an issue for tracking the (uint) truncation in NRange.GetOffsetAndLength (line 113) so it can be picked up separately? The fix there would be changing (uint) to (nuint) for the bounds checks on end, length, and start.
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I will open a separate PR for the offset / length issue.
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This one should be backported, yes?
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@tannergooding Up to you, but there are a couple of things you may want to back port when things are merged.
  1. This (Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint #124294)
  2. Fix non-dense TensorSpan handling in SequenceEqual, Fill*, Resize*, IndexOf*, and ConcatenateOnDimension #124225
  3. Fix Tensor.Reverse for tensors with length-1 dimensions #124180
  4. Fix integer overflow in TensorPrimitives IndexOf methods #124274
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I'm fine with taking them all together, but I do think we should take them for bar check at least. -- CC. @jeffhandley
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@vcsjones
Fix NRange.GetOffsetAndLength truncation: cast to nuint instead of ui…
1c7e395
…nt (#124300)
## Description
`NRange.GetOffsetAndLength` casts its `nint` parameters to `uint` for
range validation. On 64-bit platforms, this truncates values larger than
`uint.MaxValue`, allowing invalid ranges to pass validation silently.
```csharp
// Before: truncates upper 32 bits on 64-bit platforms
if ((uint)end > (uint)length || (uint)start > (uint)end)
// After: correct comparison for all nint values
if ((nuint)end > (nuint)length || (nuint)start > (nuint)end)
```
For example, `start = 0x1_0000_0001` and `end = 2` with `length =
0x1_0000_0003`: the `(uint)` cast truncates start to `1`, making `1 > 2`
false and incorrectly passing validation.
**Note:** Other `(uint)` conversion issues in `NRange` (e.g.,
`ToString`) are intentionally not addressed here — those are covered by
#124294.
### Tests
- Converted existing `GetOffsetAndLengthTest` `[Fact]` to `[Theory]`
with `[InlineData]`
- Split success and exception cases into separate theory methods
- Added `[ConditionalTheory(Is64BitProcess)]` tests exercising values
above `uint.MaxValue`, including a case that directly catches the
truncation bug
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@vcsjones@iremyux
Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instea…
f9bf70a
…d of uint (dotnet#124294)
## Description
`NIndex.ToStringFromEnd()` and `NRange.ToString()` cast `nint` values to
`uint` before formatting, truncating values exceeding `uint.MaxValue` on
64-bit platforms:
```csharp
var ni = NIndex.FromEnd(unchecked((nint)(1L + uint.MaxValue)));
Console.WriteLine(ni.ToString()); // Prints "^0" instead of "^4294967296"
```
### Fix
- **NIndex.cs**: `(uint)Value` → `(nuint)Value` in `ToStringFromEnd()`
- **NRange.cs**: `(uint)Start.Value` → `(nuint)Start.Value` and
`(uint)End.Value` → `(nuint)End.Value` in `ToString()`
### Tests
- Replaced `[Fact] ToStringTest` with `[Theory]` + `[InlineData]` for
both `NIndexTests` and `NRangeTests`
- Added `[ConditionalTheory(typeof(PlatformDetection),
nameof(PlatformDetection.Is64BitProcess))]` tests exercising values
above `uint.MaxValue`
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our [2 minute survey](https://gh.io/copilot-coding-agent-survey).
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iremyux pushed a commit
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Mar 2, 2026
@vcsjones@iremyux
Fix NRange.GetOffsetAndLength truncation: cast to nuint instead of ui…
2af20fd
…nt (dotnet#124300)
## Description
`NRange.GetOffsetAndLength` casts its `nint` parameters to `uint` for
range validation. On 64-bit platforms, this truncates values larger than
`uint.MaxValue`, allowing invalid ranges to pass validation silently.
```csharp
// Before: truncates upper 32 bits on 64-bit platforms
if ((uint)end > (uint)length || (uint)start > (uint)end)
// After: correct comparison for all nint values
if ((nuint)end > (nuint)length || (nuint)start > (nuint)end)
```
For example, `start = 0x1_0000_0001` and `end = 2` with `length =
0x1_0000_0003`: the `(uint)` cast truncates start to `1`, making `1 > 2`
false and incorrectly passing validation.
**Note:** Other `(uint)` conversion issues in `NRange` (e.g.,
`ToString`) are intentionally not addressed here — those are covered by
dotnet#124294.
### Tests
- Converted existing `GetOffsetAndLengthTest` `[Fact]` to `[Theory]`
with `[InlineData]`
- Split success and exception cases into separate theory methods
- Added `[ConditionalTheory(Is64BitProcess)]` tests exercising values
above `uint.MaxValue`, including a case that directly catches the
truncation bug
<!-- START COPILOT CODING AGENT TIPS -->
---
💡 You can make Copilot smarter by setting up custom instructions,
customizing its development environment and configuring Model Context
Protocol (MCP) servers. Learn more [Copilot coding agent
tips](https://gh.io/copilot-coding-agent-tips) in the docs.
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: vcsjones <361677+vcsjones@users.noreply.github.com>
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Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint - #124294
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Merged
Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint#124294
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Description
NIndex.ToStringFromEnd() and NRange.ToString() cast nint values to uint before formatting, truncating values exceeding uint.MaxValue on 64-bit platforms:
varni=NIndex.FromEnd(unchecked((nint)(1L+uint.MaxValue)));Console.WriteLine(ni.ToString());// Prints "^0" instead of "^4294967296"
Fix
  • NIndex.cs: (uint)Value → (nuint)Value in ToStringFromEnd()
  • NRange.cs: (uint)Start.Value → (nuint)Start.Value and (uint)End.Value → (nuint)End.Value in ToString()
Tests
  • Replaced [Fact] ToStringTest with [Theory] + [InlineData] for both NIndexTests and NRangeTests
  • Added [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))] tests exercising values above uint.MaxValue
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Fix NIndex and NRange ToString truncation: cast to nuint instead of u…
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[WIP] Fix NIndex formatting for end index conversionFix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uintFeb 11, 2026
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Pull request overview
Fixes incorrect string formatting for NIndex/NRange on 64-bit platforms where values larger than uint.MaxValue were being truncated due to casts to uint during formatting.
Changes:
  • Update NIndex.ToStringFromEnd() to format using (nuint)Value rather than (uint)Value.
  • Update NRange.ToString() to format start/end using (nuint)Start.Value / (nuint)End.Value rather than uint.
  • Expand/adjust unit tests to cover 64-bit values above uint.MaxValue, converting prior [Fact] coverage into [Theory] + [InlineData] and adding 64-bit conditional cases.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.
FileDescription
src/libraries/System.Numerics.Tensors/src/System/Buffers/NIndex.csFixes 64-bit truncation in ToStringFromEnd() by formatting via nuint.
src/libraries/System.Numerics.Tensors/src/System/Buffers/NRange.csFixes 64-bit truncation in ToString() by formatting start/end via nuint.
src/libraries/System.Numerics.Tensors/tests/NIndexTests.csAdds theory-based coverage and conditional 64-bit test cases for large values.
src/libraries/System.Numerics.Tensors/tests/NRangeTests.csAdds theory-based coverage and conditional 64-bit test cases for large range endpoints.
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@copilot please invoke the code-review skill and post your analysis/results as a comment on this PR.
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@copilot please invoke the code-review skill and post your analysis/results as a comment on this PR.
🤖 Copilot Code Review
Holistic Assessment
Motivation: The bug is real and clearly reproducible — (uint) casts truncate nint values exceeding uint.MaxValue on 64-bit platforms, causing NIndex.FromEnd(1L + uint.MaxValue).ToString() to return ^0 instead of ^4294967296. The buffer comment on line 177 ("20 for longest possible nuint value") confirms the original intent was nuint.
Approach: Changing (uint) → (nuint) is the minimal correct fix. The tests use [Theory]/[InlineData] and [ConditionalTheory] with PlatformDetection.Is64BitProcess appropriately, consistent with patterns used in NFloatTests.cs and elsewhere in the test project.
Summary: ✅ LGTM. The three cast fixes are correct, minimal, and well-tested. All findings below are positive confirmations or out-of-scope observations.
Detailed Findings
✅ Correctness — Cast fix is correct in all three locations
  • NIndex.cs:178: (uint)Value → (nuint)Value in ToStringFromEnd()
  • NRange.cs:73: (uint)Start.Value → (nuint)Start.Value in ToString()
  • NRange.cs:84: (uint)End.Value → (nuint)End.Value in ToString()
The Value property returns nint (always non-negative for valid NIndex values), so the nuint cast is safe. The stackalloc buffer was already sized for nuint (21 chars = 1 for ^ + 20 digits for max nuint on 64-bit). The non-FromEnd path (NIndex.ToString() line 172) uses Value.ToString() which calls nint.ToString() directly — no truncation issue there.
✅ Test quality — Good coverage with appropriate conditional attributes
The tests cover both fromStart and fromEnd paths, use boundary values (int.MaxValue, uint.MaxValue + 1, long.MaxValue), and correctly gate 64-bit-specific cases with [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))]. PlatformDetection is already used in other tests in this project (TensorPrimitives.Generic.cs, TensorPrimitivesTests.cs).
💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
NRange.cs:113 uses (uint)end > (uint)length || (uint)start > (uint)end — this truncates nint values on 64-bit, which could cause incorrect bounds validation for large collections. However, this is mirrored from Range.GetOffsetAndLength (which uses int → uint, which is correct for that type) and is a separate issue from the ToString fix.
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💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
@copilot can you open a separate PR to address this.
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💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
@copilot can you open a separate PR to address this.
I'm not able to open new PRs. Could you open an issue for tracking the (uint) truncation in NRange.GetOffsetAndLength (line 113) so it can be picked up separately? The fix there would be changing (uint) to (nuint) for the bounds checks on end, length, and start.
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I will open a separate PR for the offset / length issue.
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This one should be backported, yes?
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@tannergooding Up to you, but there are a couple of things you may want to back port when things are merged.
  1. This (Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint #124294)
  2. Fix non-dense TensorSpan handling in SequenceEqual, Fill*, Resize*, IndexOf*, and ConcatenateOnDimension #124225
  3. Fix Tensor.Reverse for tensors with length-1 dimensions #124180
  4. Fix integer overflow in TensorPrimitives IndexOf methods #124274
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I'm fine with taking them all together, but I do think we should take them for bar check at least. -- CC. @jeffhandley
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@vcsjones
Fix NRange.GetOffsetAndLength truncation: cast to nuint instead of ui…
1c7e395
…nt (#124300)
## Description
`NRange.GetOffsetAndLength` casts its `nint` parameters to `uint` for
range validation. On 64-bit platforms, this truncates values larger than
`uint.MaxValue`, allowing invalid ranges to pass validation silently.
```csharp
// Before: truncates upper 32 bits on 64-bit platforms
if ((uint)end > (uint)length || (uint)start > (uint)end)
// After: correct comparison for all nint values
if ((nuint)end > (nuint)length || (nuint)start > (nuint)end)
```
For example, `start = 0x1_0000_0001` and `end = 2` with `length =
0x1_0000_0003`: the `(uint)` cast truncates start to `1`, making `1 > 2`
false and incorrectly passing validation.
**Note:** Other `(uint)` conversion issues in `NRange` (e.g.,
`ToString`) are intentionally not addressed here — those are covered by
#124294.
### Tests
- Converted existing `GetOffsetAndLengthTest` `[Fact]` to `[Theory]`
with `[InlineData]`
- Split success and exception cases into separate theory methods
- Added `[ConditionalTheory(Is64BitProcess)]` tests exercising values
above `uint.MaxValue`, including a case that directly catches the
truncation bug
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@vcsjones@iremyux
Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instea…
f9bf70a
…d of uint (dotnet#124294)
## Description
`NIndex.ToStringFromEnd()` and `NRange.ToString()` cast `nint` values to
`uint` before formatting, truncating values exceeding `uint.MaxValue` on
64-bit platforms:
```csharp
var ni = NIndex.FromEnd(unchecked((nint)(1L + uint.MaxValue)));
Console.WriteLine(ni.ToString()); // Prints "^0" instead of "^4294967296"
```
### Fix
- **NIndex.cs**: `(uint)Value` → `(nuint)Value` in `ToStringFromEnd()`
- **NRange.cs**: `(uint)Start.Value` → `(nuint)Start.Value` and
`(uint)End.Value` → `(nuint)End.Value` in `ToString()`
### Tests
- Replaced `[Fact] ToStringTest` with `[Theory]` + `[InlineData]` for
both `NIndexTests` and `NRangeTests`
- Added `[ConditionalTheory(typeof(PlatformDetection),
nameof(PlatformDetection.Is64BitProcess))]` tests exercising values
above `uint.MaxValue`
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Mar 2, 2026
@vcsjones@iremyux
Fix NRange.GetOffsetAndLength truncation: cast to nuint instead of ui…
2af20fd
…nt (dotnet#124300)
## Description
`NRange.GetOffsetAndLength` casts its `nint` parameters to `uint` for
range validation. On 64-bit platforms, this truncates values larger than
`uint.MaxValue`, allowing invalid ranges to pass validation silently.
```csharp
// Before: truncates upper 32 bits on 64-bit platforms
if ((uint)end > (uint)length || (uint)start > (uint)end)
// After: correct comparison for all nint values
if ((nuint)end > (nuint)length || (nuint)start > (nuint)end)
```
For example, `start = 0x1_0000_0001` and `end = 2` with `length =
0x1_0000_0003`: the `(uint)` cast truncates start to `1`, making `1 > 2`
false and incorrectly passing validation.
**Note:** Other `(uint)` conversion issues in `NRange` (e.g.,
`ToString`) are intentionally not addressed here — those are covered by
dotnet#124294.
### Tests
- Converted existing `GetOffsetAndLengthTest` `[Fact]` to `[Theory]`
with `[InlineData]`
- Split success and exception cases into separate theory methods
- Added `[ConditionalTheory(Is64BitProcess)]` tests exercising values
above `uint.MaxValue`, including a case that directly catches the
truncation bug
<!-- START COPILOT CODING AGENT TIPS -->
---
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customizing its development environment and configuring Model Context
Protocol (MCP) servers. Learn more [Copilot coding agent
tips](https://gh.io/copilot-coding-agent-tips) in the docs.
---------
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Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint - #124294
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Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint#124294
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Description
NIndex.ToStringFromEnd() and NRange.ToString() cast nint values to uint before formatting, truncating values exceeding uint.MaxValue on 64-bit platforms:
varni=NIndex.FromEnd(unchecked((nint)(1L+uint.MaxValue)));Console.WriteLine(ni.ToString());// Prints "^0" instead of "^4294967296"
Fix
  • NIndex.cs: (uint)Value → (nuint)Value in ToStringFromEnd()
  • NRange.cs: (uint)Start.Value → (nuint)Start.Value and (uint)End.Value → (nuint)End.Value in ToString()
Tests
  • Replaced [Fact] ToStringTest with [Theory] + [InlineData] for both NIndexTests and NRangeTests
  • Added [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))] tests exercising values above uint.MaxValue
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Fix NIndex and NRange ToString truncation: cast to nuint instead of u…
9295a87
…int, add Theory tests
Co-authored-by: vcsjones <361677+vcsjones@users.noreply.github.com>
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[WIP] Fix NIndex formatting for end index conversionFix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uintFeb 11, 2026
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Pull request overview
Fixes incorrect string formatting for NIndex/NRange on 64-bit platforms where values larger than uint.MaxValue were being truncated due to casts to uint during formatting.
Changes:
  • Update NIndex.ToStringFromEnd() to format using (nuint)Value rather than (uint)Value.
  • Update NRange.ToString() to format start/end using (nuint)Start.Value / (nuint)End.Value rather than uint.
  • Expand/adjust unit tests to cover 64-bit values above uint.MaxValue, converting prior [Fact] coverage into [Theory] + [InlineData] and adding 64-bit conditional cases.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.
FileDescription
src/libraries/System.Numerics.Tensors/src/System/Buffers/NIndex.csFixes 64-bit truncation in ToStringFromEnd() by formatting via nuint.
src/libraries/System.Numerics.Tensors/src/System/Buffers/NRange.csFixes 64-bit truncation in ToString() by formatting start/end via nuint.
src/libraries/System.Numerics.Tensors/tests/NIndexTests.csAdds theory-based coverage and conditional 64-bit test cases for large values.
src/libraries/System.Numerics.Tensors/tests/NRangeTests.csAdds theory-based coverage and conditional 64-bit test cases for large range endpoints.
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@copilot please invoke the code-review skill and post your analysis/results as a comment on this PR.
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@copilot please invoke the code-review skill and post your analysis/results as a comment on this PR.
🤖 Copilot Code Review
Holistic Assessment
Motivation: The bug is real and clearly reproducible — (uint) casts truncate nint values exceeding uint.MaxValue on 64-bit platforms, causing NIndex.FromEnd(1L + uint.MaxValue).ToString() to return ^0 instead of ^4294967296. The buffer comment on line 177 ("20 for longest possible nuint value") confirms the original intent was nuint.
Approach: Changing (uint) → (nuint) is the minimal correct fix. The tests use [Theory]/[InlineData] and [ConditionalTheory] with PlatformDetection.Is64BitProcess appropriately, consistent with patterns used in NFloatTests.cs and elsewhere in the test project.
Summary: ✅ LGTM. The three cast fixes are correct, minimal, and well-tested. All findings below are positive confirmations or out-of-scope observations.
Detailed Findings
✅ Correctness — Cast fix is correct in all three locations
  • NIndex.cs:178: (uint)Value → (nuint)Value in ToStringFromEnd()
  • NRange.cs:73: (uint)Start.Value → (nuint)Start.Value in ToString()
  • NRange.cs:84: (uint)End.Value → (nuint)End.Value in ToString()
The Value property returns nint (always non-negative for valid NIndex values), so the nuint cast is safe. The stackalloc buffer was already sized for nuint (21 chars = 1 for ^ + 20 digits for max nuint on 64-bit). The non-FromEnd path (NIndex.ToString() line 172) uses Value.ToString() which calls nint.ToString() directly — no truncation issue there.
✅ Test quality — Good coverage with appropriate conditional attributes
The tests cover both fromStart and fromEnd paths, use boundary values (int.MaxValue, uint.MaxValue + 1, long.MaxValue), and correctly gate 64-bit-specific cases with [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))]. PlatformDetection is already used in other tests in this project (TensorPrimitives.Generic.cs, TensorPrimitivesTests.cs).
💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
NRange.cs:113 uses (uint)end > (uint)length || (uint)start > (uint)end — this truncates nint values on 64-bit, which could cause incorrect bounds validation for large collections. However, this is mirrored from Range.GetOffsetAndLength (which uses int → uint, which is correct for that type) and is a separate issue from the ToString fix.
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💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
@copilot can you open a separate PR to address this.
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💡 Out-of-scope observation — NRange.GetOffsetAndLength has a similar (uint) cast on nint
@copilot can you open a separate PR to address this.
I'm not able to open new PRs. Could you open an issue for tracking the (uint) truncation in NRange.GetOffsetAndLength (line 113) so it can be picked up separately? The fix there would be changing (uint) to (nuint) for the bounds checks on end, length, and start.
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I will open a separate PR for the offset / length issue.
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This one should be backported, yes?
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@tannergooding Up to you, but there are a couple of things you may want to back port when things are merged.
  1. This (Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instead of uint #124294)
  2. Fix non-dense TensorSpan handling in SequenceEqual, Fill*, Resize*, IndexOf*, and ConcatenateOnDimension #124225
  3. Fix Tensor.Reverse for tensors with length-1 dimensions #124180
  4. Fix integer overflow in TensorPrimitives IndexOf methods #124274
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I'm fine with taking them all together, but I do think we should take them for bar check at least. -- CC. @jeffhandley
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@vcsjones
Fix NRange.GetOffsetAndLength truncation: cast to nuint instead of ui…
1c7e395
…nt (#124300)
## Description
`NRange.GetOffsetAndLength` casts its `nint` parameters to `uint` for
range validation. On 64-bit platforms, this truncates values larger than
`uint.MaxValue`, allowing invalid ranges to pass validation silently.
```csharp
// Before: truncates upper 32 bits on 64-bit platforms
if ((uint)end > (uint)length || (uint)start > (uint)end)
// After: correct comparison for all nint values
if ((nuint)end > (nuint)length || (nuint)start > (nuint)end)
```
For example, `start = 0x1_0000_0001` and `end = 2` with `length =
0x1_0000_0003`: the `(uint)` cast truncates start to `1`, making `1 > 2`
false and incorrectly passing validation.
**Note:** Other `(uint)` conversion issues in `NRange` (e.g.,
`ToString`) are intentionally not addressed here — those are covered by
#124294.
### Tests
- Converted existing `GetOffsetAndLengthTest` `[Fact]` to `[Theory]`
with `[InlineData]`
- Split success and exception cases into separate theory methods
- Added `[ConditionalTheory(Is64BitProcess)]` tests exercising values
above `uint.MaxValue`, including a case that directly catches the
truncation bug
<!-- START COPILOT CODING AGENT TIPS -->
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customizing its development environment and configuring Model Context
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Co-authored-by: vcsjones <361677+vcsjones@users.noreply.github.com>
iremyux pushed a commit
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Mar 2, 2026
@vcsjones@iremyux
Fix NIndex/NRange ToString truncation on 64-bit: cast to nuint instea…
f9bf70a
…d of uint (dotnet#124294)
## Description
`NIndex.ToStringFromEnd()` and `NRange.ToString()` cast `nint` values to
`uint` before formatting, truncating values exceeding `uint.MaxValue` on
64-bit platforms:
```csharp
var ni = NIndex.FromEnd(unchecked((nint)(1L + uint.MaxValue)));
Console.WriteLine(ni.ToString()); // Prints "^0" instead of "^4294967296"
```
### Fix
- **NIndex.cs**: `(uint)Value` → `(nuint)Value` in `ToStringFromEnd()`
- **NRange.cs**: `(uint)Start.Value` → `(nuint)Start.Value` and
`(uint)End.Value` → `(nuint)End.Value` in `ToString()`
### Tests
- Replaced `[Fact] ToStringTest` with `[Theory]` + `[InlineData]` for
both `NIndexTests` and `NRangeTests`
- Added `[ConditionalTheory(typeof(PlatformDetection),
nameof(PlatformDetection.Is64BitProcess))]` tests exercising values
above `uint.MaxValue`
<!-- START COPILOT CODING AGENT TIPS -->
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our [2 minute survey](https://gh.io/copilot-coding-agent-survey).
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Co-authored-by: vcsjones <361677+vcsjones@users.noreply.github.com>
iremyux pushed a commit
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that referenced
this pull request
Mar 2, 2026
@vcsjones@iremyux
Fix NRange.GetOffsetAndLength truncation: cast to nuint instead of ui…
2af20fd
…nt (dotnet#124300)
## Description
`NRange.GetOffsetAndLength` casts its `nint` parameters to `uint` for
range validation. On 64-bit platforms, this truncates values larger than
`uint.MaxValue`, allowing invalid ranges to pass validation silently.
```csharp
// Before: truncates upper 32 bits on 64-bit platforms
if ((uint)end > (uint)length || (uint)start > (uint)end)
// After: correct comparison for all nint values
if ((nuint)end > (nuint)length || (nuint)start > (nuint)end)
```
For example, `start = 0x1_0000_0001` and `end = 2` with `length =
0x1_0000_0003`: the `(uint)` cast truncates start to `1`, making `1 > 2`
false and incorrectly passing validation.
**Note:** Other `(uint)` conversion issues in `NRange` (e.g.,
`ToString`) are intentionally not addressed here — those are covered by
dotnet#124294.
### Tests
- Converted existing `GetOffsetAndLengthTest` `[Fact]` to `[Theory]`
with `[InlineData]`
- Split success and exception cases into separate theory methods
- Added `[ConditionalTheory(Is64BitProcess)]` tests exercising values
above `uint.MaxValue`, including a case that directly catches the
truncation bug
<!-- START COPILOT CODING AGENT TIPS -->
---
💡 You can make Copilot smarter by setting up custom instructions,
customizing its development environment and configuring Model Context
Protocol (MCP) servers. Learn more [Copilot coding agent
tips](https://gh.io/copilot-coding-agent-tips) in the docs.
---------
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