`dotnet project convert` works incorrectly for target framework other than default base framework `net10.0`

[egvijayanand]

Describe the bug

dotnet project convert works incorrectly for target framework other than default base framework net10.0

To Reproduce

A WinForms sample and it works correctly with dotnet run Forms.cs (assuming the file is saved as Forms.cs)

#:property TargetFramework net10.0-windows
#:property UseWindowsForms true
#:property OutputType WinExe

Application.Run(new Form() { Text = "Hello C#" });

When tried to convert it to a project with the command dotnet project convert Forms.cs, the output contains duplicated content.

The default property of the base target framework is always included which is incorrect and it should be based on the file input.

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net10.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <PropertyGroup>
    <TargetFramework>net10.0-windows</TargetFramework>
    <UseWindowsForms>true</UseWindowsForms>
    <OutputType>WinExe</OutputType>
  </PropertyGroup>

</Project>

Exceptions (if any)

None.

Further technical details

• 10.0.100-preview.4.25258.110
• CLI

[jjonescz]

The default property of the base target framework is always included which is incorrect and it should be based on the file input.

The generated csproj works though, right? The latter TargetFramework property should overwrite the former.

That being said, yes, we should probably make user-defined properties overwrite the built-in ones. Note that might be a slight breaking change from existing behavior: currently, #:property TargetFramework $(TargetFramework);net472 results in effectively TargetFramework=net10;net472 whereas afterwards it will result in TargetFramework=;net472.