short.Parse regression in .NET 8.0 from 7.0

[duracellko]

Description

Methods Int16.Parse and Int16.TryParse produce different result in .NET 7 and 8, when the input is decimal number. In .NET 7 numbers with decimal point are considered invalid and the methods returns error. However, in .NET 8 the methods return integer number, when input has more than 4 digits.

Reproduction Steps

Example:

short.TryParse("10000.1", NumberStyles.Number, CultureInfo.InvariantCulture, out var number);

Expected behavior

The function should return false in both .NET versions.

Actual behavior

The function returns true in .NET 8 and false in .NET 7.

Regression?

Yes, as described above.

Known Workarounds

I found the issue only in Int16. Int32 works the same in .NET 8 and 7.

Configuration

dotnet --info

.NET SDK:
Version: 8.0.100
Commit: 57efcf1350
Workload version: 8.0.100-manifests.8d38d0cc

Runtime Environment:
OS Name: Windows
OS Version: 10.0.22631
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\8.0.100\

.NET workloads installed:
Workload version: 8.0.100-manifests.8d38d0cc
[maui-windows]
Installation Source: VS 17.8.34309.116
Manifest Version: 8.0.3/8.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.maui\8.0.3\WorkloadManifest.json
Install Type: Msi

[maccatalyst]
Installation Source: VS 17.8.34309.116
Manifest Version: 17.0.8478/8.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.maccatalyst\17.0.8478\WorkloadManifest.json
Install Type: Msi

[ios]
Installation Source: VS 17.8.34309.116
Manifest Version: 17.0.8478/8.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.ios\17.0.8478\WorkloadManifest.json
Install Type: Msi

[android]
Installation Source: VS 17.8.34309.116
Manifest Version: 34.0.43/8.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.android\34.0.43\WorkloadManifest.json
Install Type: Msi

Host:
Version: 8.0.0
Architecture: x64
Commit: 5535e31

.NET SDKs installed:
8.0.100 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 6.0.25 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 7.0.14 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 8.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.25 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 7.0.14 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 6.0.25 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 7.0.14 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 8.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
x86 [C:\Program Files (x86)\dotnet]
registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
Not set

global.json file:
Not found

Learn more:
https://aka.ms/dotnet/info

Download .NET:
https://aka.ms/dotnet/download

Other information

The problem appears only for values 10000 and higher in absolute value.

[duracellko]

I created small test project for demonstration.

All .NET 7 tests are green, but 50% of .NET 8 tests are red.

Project: ParseTests.zip

[karakasa]

just FYI, you wrote Expected & Actual Behavior reversally.

[duracellko]

just FYI, you wrote Expected & Actual Behavior reversally.

Thank you. I corrected it.

[karakasa]

There may be another branch here to fail when digCount >= maxDigCount, ch != 0 and target type is integer .

runtime/src/libraries/System.Private.CoreLib/src/System/Number.Parsing.cs

Lines 269 to 287 in 47a9422

	if (digCount < maxDigCount)
	{
	number.Digits[digCount] = (byte)ch;
	if ((ch != '0') || (number.Kind != NumberBufferKind.Integer))
	{
	digEnd = digCount + 1;
	}
	}
	else if (ch != '0')
	{
	// For decimal and binary floating-point numbers, we only
	// need to store digits up to maxDigCount. However, we still
	// need to keep track of whether any additional digits past
	// maxDigCount were non-zero, as that can impact rounding
	// for an input that falls evenly between two representable
	// results.
	number.HasNonZeroTail = true;
	}

int.TryParse("2147483646.1", NumberStyles.Number, CultureInfo.InvariantCulture, out var number) also returns true.

I'm unsure if it's a bug, UB or breaking change since you are using NumberStyles.Number. Anyway, the behavior is undocumented afaik and 10000.1/1000.1 have inconsistent results.

[stephentoub]

cc: @tannergooding

[ghost]

Tagging subscribers to this area: @dotnet/area-system-numerics
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

Methods Int16.Parse and Int16.TryParse produce different result in .NET 7 and 8, when the input is decimal number. In .NET 7 numbers with decimal point are considered invalid and the methods returns error. However, in .NET 8 the methods return integer number, when input has more than 4 digits.

Reproduction Steps

Example:

short.TryParse("10000.1", NumberStyles.Number, CultureInfo.InvariantCulture, out var number);

Expected behavior

The function should return false in both .NET versions.

Actual behavior

The function returns true in .NET 8 and false in .NET 7.

Regression?

Yes, as described above.

Known Workarounds

I found the issue only in Int16. Int32 works the same in .NET 8 and 7.

Configuration

dotnet --info

.NET SDK:
Version: 8.0.100
Commit: 57efcf1350
Workload version: 8.0.100-manifests.8d38d0cc

Runtime Environment:
OS Name: Windows
OS Version: 10.0.22631
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\8.0.100\

.NET workloads installed:
Workload version: 8.0.100-manifests.8d38d0cc
[maui-windows]
Installation Source: VS 17.8.34309.116
Manifest Version: 8.0.3/8.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.maui\8.0.3\WorkloadManifest.json
Install Type: Msi

[maccatalyst]
Installation Source: VS 17.8.34309.116
Manifest Version: 17.0.8478/8.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.maccatalyst\17.0.8478\WorkloadManifest.json
Install Type: Msi

[ios]
Installation Source: VS 17.8.34309.116
Manifest Version: 17.0.8478/8.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.ios\17.0.8478\WorkloadManifest.json
Install Type: Msi

[android]
Installation Source: VS 17.8.34309.116
Manifest Version: 34.0.43/8.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.android\34.0.43\WorkloadManifest.json
Install Type: Msi

Host:
Version: 8.0.0
Architecture: x64
Commit: 5535e31

.NET SDKs installed:
8.0.100 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 6.0.25 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 7.0.14 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 8.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.25 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 7.0.14 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 6.0.25 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 7.0.14 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 8.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
x86 [C:\Program Files (x86)\dotnet]
registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
Not set

global.json file:
Not found

Learn more:
https://aka.ms/dotnet/info

Download .NET:
https://aka.ms/dotnet/download

Other information

The problem appears only for values 10000 and higher in absolute value.

Author:	duracellko
Assignees:	-
Labels:	area-System.Numerics, untriaged, needs-area-label
Milestone:	-