dotnet build ignores casing of project file when setting up namespace

[JanKrivanek]

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Issue moved from dotnet/sdk#45701

• Please respond to @NeilMacMullen.

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From @NeilMacMullen on Friday, January 3, 2025 3:39:17 PM

Describe the bug

I'm not sure if this is a bug but it's certainly unexpected behaviour and caused me to waste a few hours yesterday....

dotnet build appears to use the casing of the csproj file specified in the command rather than the actual casing in the file-system. The practical impact of this is that the default-namespace for embedded resources is then incorrect and since GetManifestResourceStream is case-sensitive, applications can fail depending upon what casing was used when specifying dotnet build or dotnet publish

To Reproduce

The attached zip file contains a minimal example but the repro case is trivial...

• create a simple console application whose name is a mixture of upper and lower case (e.g. MyApp)
• Add an embedded resource (e.g. "testData.txt")
• Use the following code for Program.cs

using System.Reflection;
var embedded = Assembly.GetExecutingAssembly().GetManifestResourceNames();
foreach(var m in embedded)
    Console.WriteLine($"embedded resource '{m}'");

Build the application with expected casing of the project file then all lower-case...

➜ rm -r -force bin ;rm -r -force obj; dotnet build .\MyApp.csproj;.\bin\Debug\net9.0\myapp.exe
Restore complete (0.2s)
You are using a preview version of .NET. See: https://aka.ms/dotnet-support-policy
  MyApp succeeded (0.2s) → bin\Debug\net9.0\MyApp.dll

Build succeeded in 0.7s
embedded resource 'MyApp.testData.txt'

➜ rm -r -force bin ;rm -r -force obj; dotnet build .\myapp.csproj;.\bin\Debug\net9.0\myapp.exe
Restore complete (0.2s)
You are using a preview version of .NET. See: https://aka.ms/dotnet-support-policy
  myapp succeeded (0.2s) → bin\Debug\net9.0\myapp.dll

Build succeeded in 0.7s
embedded resource 'myapp.testData.txt'

Note the difference in output - the resource path uses the casing specified in the build line.

Somewhat unexpectedly, dotnet run manages to use the correct casing...

➜ rm -r -force bin ;rm -r -force obj; dotnet run .\myapp.csproj
embedded resource 'MyApp.testData.txt'

MyApp.zip

Further technical details

.NET SDK:
 Version:           9.0.200-preview.0.24575.35
 Commit:            81b5f040be
 Workload version:  9.0.200-manifests.1e472b70
 MSBuild version:   17.13.0-preview-24569-04+8f6b8ad0a

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.26100
 OS Platform: Windows
 RID:         win-x64
 Base Path:   C:\Program Files\dotnet\sdk\9.0.200-preview.0.24575.35\

.NET workloads installed:
 [android]
   Installation Source: SDK 9.0.200-preview.0, VS 17.13.35617.110, VS 17.12.35527.113
   Manifest Version:    35.0.24/9.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\9.0.100\microsoft.net.sdk.android\35.0.24\WorkloadManifest.json
   Install Type:              Msi

 [aspire]
   Installation Source: SDK 9.0.200-preview.0, VS 17.12.35527.113
   Manifest Version:    8.2.2/8.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.aspire\8.2.2\WorkloadManifest.json
   Install Type:              Msi

 [ios]
   Installation Source: SDK 9.0.200-preview.0, VS 17.13.35617.110, VS 17.12.35527.113
   Manifest Version:    18.2.9170/9.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\9.0.100\microsoft.net.sdk.ios\18.2.9170\WorkloadManifest.json
   Install Type:              Msi

 [maccatalyst]
   Installation Source: SDK 9.0.200-preview.0, VS 17.13.35617.110, VS 17.12.35527.113
   Manifest Version:    18.2.9170/9.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\9.0.100\microsoft.net.sdk.maccatalyst\18.2.9170\WorkloadManifest.json
   Install Type:              Msi

 [maui-windows]
   Installation Source: SDK 9.0.200-preview.0, VS 17.13.35617.110, VS 17.12.35527.113
   Manifest Version:    9.0.0/9.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\9.0.100\microsoft.net.sdk.maui\9.0.0\WorkloadManifest.json
   Install Type:              Msi

Configured to use loose manifests when installing new manifests.

Host:
  Version:      9.0.0
  Architecture: x64
  Commit:       9d5a6a9aa4

.NET SDKs installed:
  8.0.111 [C:\Program Files\dotnet\sdk]
  8.0.206 [C:\Program Files\dotnet\sdk]
  8.0.307 [C:\Program Files\dotnet\sdk]
  8.0.404 [C:\Program Files\dotnet\sdk]
  9.0.101 [C:\Program Files\dotnet\sdk]
  9.0.200-preview.0.24575.35 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 9.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 9.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 8.0.6 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 8.0.11 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 9.0.0 [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

[JanKrivanek]

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Issue moved from dotnet/sdk#45701

• Please respond to @baronfel.

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From @baronfel on Friday, January 3, 2025 3:58:21 PM

The default value for the RootNamespace is computed here:

<RootNamespace Condition=" '$(RootNamespace)' == '' ">$(MSBuildProjectName.Replace(" ", "_"))</RootNamespace>

We're using the MSBuild-engine-provided reserved property MSBuildProjectName, which is set

• in the Evaluator
• from the FullPath of the project file XML

So my suspicion is that there's some missing normalization in MSBuild itself that could/should be done here. I think it's reasonable to expect the name of the file to be its on-disk name. @JanKrivanek / @rainersigwald any objections to moving this to dotnet/msbuild?

[yuehuang010]

Might be related to #3665.