Fix RootNamespace handling for dashes and starting digits in project names

[Copilot]

The .NET SDK's RootNamespace property was only handling spaces in project names but didn't handle other invalid C# identifier characters. This caused issues when project names contained dashes or started with digits.

Changes Made

Extended the RootNamespace transformation logic in Microsoft.NET.Sdk.props to:

1. Replace both spaces AND dashes with underscores
2. Add an underscore prefix if the project name starts with a digit
3. Include defensive programming to handle edge cases

Examples

Project Name	Old Behavior	New Behavior
13-monkeys	13-monkeys ❌	_13_monkeys ✅
my-project	my-project ❌	my_project ✅
Project Name With Spaces	Project_Name_With_Spaces ✅	Project_Name_With_Spaces ✅
normalproject	normalproject ✅	normalproject ✅

Testing

Added comprehensive tests covering:

• Project names with dashes only
• Project names starting with digits only
• Project names with both dashes and starting digits
• Verification that existing space handling is preserved

The implementation uses MSBuild property functions with appropriate safety checks to prevent errors on edge cases like empty strings.

Fixes #49327.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• 7tjvsblobprodcus341.vsblob.vsassets.io
  • Triggering command: dotnet test test/Microsoft.NET.Build.Tests/Microsoft.NET.Build.Tests.csproj --filter FullyQualifiedName~It_makes_RootNamespace_safe_when_project_name_has_spaces --no-build --verbosity normal (dns block)
• c78vsblobprodcus322.vsblob.vsassets.io
  • Triggering command: dotnet test test/Microsoft.NET.Build.Tests/Microsoft.NET.Build.Tests.csproj --filter FullyQualifiedName~It_makes_RootNamespace_safe_when_project_name_has_spaces --no-build --verbosity normal (dns block)
• d0svsblobprodcus381.vsblob.vsassets.io
  • Triggering command: dotnet test test/Microsoft.NET.Build.Tests/Microsoft.NET.Build.Tests.csproj --filter FullyQualifiedName~It_makes_RootNamespace_safe_when_project_name_has_spaces --no-build --verbosity normal (dns block)
• jd4vsblobprodcus366.vsblob.vsassets.io
  • Triggering command: dotnet test test/Microsoft.NET.Build.Tests/Microsoft.NET.Build.Tests.csproj --filter FullyQualifiedName~It_makes_RootNamespace_safe_when_project_name_has_spaces --no-build --verbosity normal (dns block)
• l49vsblobprodcus358.vsblob.vsassets.io
  • Triggering command: dotnet test test/Microsoft.NET.Build.Tests/Microsoft.NET.Build.Tests.csproj --filter FullyQualifiedName~It_makes_RootNamespace_safe_when_project_name_has_spaces --no-build --verbosity normal (dns block)
• uy6vsblobprodcus34.vsblob.vsassets.io
  • Triggering command: dotnet test test/Microsoft.NET.Build.Tests/Microsoft.NET.Build.Tests.csproj --filter FullyQualifiedName~It_makes_RootNamespace_safe_when_project_name_has_spaces --no-build --verbosity normal (dns block)
• vb4vsblobprodcus33.vsblob.vsassets.io
  • Triggering command: dotnet test test/Microsoft.NET.Build.Tests/Microsoft.NET.Build.Tests.csproj --filter FullyQualifiedName~It_makes_RootNamespace_safe_when_project_name_has_spaces --no-build --verbosity normal (dns block)
• x3yvsblobprodcus370.vsblob.vsassets.io
  • Triggering command: /home/REDACTED/work/sdk/sdk/.dotnet/dotnet msbuild /m /nologo /clp:Summary /v:minimal /nr:true /warnaserror /p:TreatWarningsAsErrors=true /p:ContinuousIntegrationBuild=false /home/REDACTED/work/sdk/sdk/artifacts/toolset/restore.proj /t:__WriteToolsetLocation /clp:ErrorsOnly;NoSummary /p:__ToolsetLocationOutputFile=/home/REDACTED/work/sdk/sdk/artifacts/toolset/10.0.0-beta.25304.106.txt (dns block)
  • Triggering command: dotnet test test/Microsoft.NET.Build.Tests/Microsoft.NET.Build.Tests.csproj --filter FullyQualifiedName~It_makes_RootNamespace_safe_when_project_name_has_spaces --no-build --verbosity normal (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to my firewall allow list

[marcpopMSFT]

@copilot in MSBuild, you can use character functions. In this case, you should be able to use $([System.Char]::IsDigit()) on the first character rather than comparing against each possible digit

[Copilot]

@copilot in MSBuild, you can use character functions. In this case, you should be able to use $([System.Char]::IsDigit()) on the first character rather than comparing against each possible digit

Updated to use $([System.Char]::IsDigit()) instead of manually checking each digit. This makes the code much cleaner and more maintainable. Commit 841b1fe.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• x3yvsblobprodcus370.vsblob.vsassets.io
  • Triggering command: dotnet test test/Microsoft.NET.Build.Tests/Microsoft.NET.Build.Tests.csproj --filter FullyQualifiedName~RootNamespace --no-build --verbosity normal (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to my firewall allow list

[Copilot]

Pull Request Overview

This PR enhances the RootNamespace transformation logic to handle project names with dashes and those starting with a digit.

• Replaces spaces and dashes with underscores in the RootNamespace property.
• Prefixes the RootNamespace with an underscore when the project name starts with a digit.
• Adds comprehensive tests to validate the new behavior.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
test/Microsoft.NET.Build.Tests/GivenThatWeWantToBuildALibrary.cs	Added tests covering project names with dashes, starting digits, and both combined.
src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.props	Updated RootNamespace property transformation with additional conditional properties to handle dashes and starting digits.

Comments suppressed due to low confidence (1)

src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.props:47

• [nitpick] Adding a clarifying comment about the rationale behind overriding RootNamespace when the first character is a digit would help future maintainers understand the multi-step transformation logic.

    <RootNamespace Condition=" '$(_ImplicitRootNamespace)' == 'true' AND '$(_IsFirstCharDigit)' == 'true' ">_$(RootNamespace)</RootNamespace>

[Copilot]

[nitpick] Consider extracting the common GetPropertyValue logic from the three tests into a shared helper method to reduce duplication and improve maintainability.