How to configure NCrunch so that it can build a Blazor project

Question

When NCrunch (version 4.2.0.7) tries to build a Blazor project (version 3.0.0-preview9), it produces the following error:

packages\microsoft.aspnetcore.blazor.build\3.0.0-preview9.19465.2\targets\Blazor.MonoRuntime.targets (441, 5): The command "dotnet "C:\Users\Rodolfo.nuget\packages\microsoft.aspnetcore.blazor.mono\3.0.0-preview9.19462.2\build\netstandard1.0../../tools/illink/illink.dll" -l none --disable-opt unreachablebodies --verbose --strip-security true --exclude-feature com --exclude-feature sre -v false -c link -u link -b true -d (... lots of files here...) exited with code -532462766.

How can I get NCrunch to build Blazor projects?

Disclaimer: I'm writing this question after not finding a single answer online, including SO. I have already found the solution and intend to answer the question myself in order to - hopefully - help someone else.

Answer 1

UPDATE (2023-09-04): the Custom Build variables mentioned in the original post have changed.

1. Since Blazor General Availability, a variable IsWasmProject=false is required.
2. Since Visual Studio 17.7, a variable SelfContained=true is required (see https://stackoverflow.com/a/77036175/257372 for details)

---

Original post TL;DR

1. Go to the NCrunch Configuration for the Blazor project.
2. Add a Custom build property named BlazorLinkOnBuild (as of 3.2.0-preview3, renamed to BlazorWebAssemblyEnableLinking) with a value of false.

---

Full explanation ... in case the details change.

In line 441 of the .targets file mentioned in the error message you will find the Exec command that causes the error:

<Exec Command="dotnet &quot;$(MonoLinkerPath)&quot; $(_BlazorLinkerAdditionalOptions) @(_BlazorFolderLookupPaths, ' ') -o &quot;$(BlazorIntermediateLinkerOutputPath)&quot; @(_BlazorAssemblyDescriptorFiles, ' ') @(_BlazorAssembliesToLink, ' ')"  />

This command is wrapped in the following target:

<Target
  Name="_LinkBlazorApplication"
  Condition="$(_BlazorShouldLinkApplicationAssemblies) != ''"
  Inputs="$(BlazorBuildLinkerInputsCache);
          @(IntermediateAssembly);
          @(_BlazorDependencyInput);
          @(BlazorLinkerDescriptor)"
  Outputs="$(BlazorIntermediateLinkerResultFilePath)"
>

Which means the Exec will only be executed if the _BlazorShouldLinkApplicationAssemblies property is not empty. Searching the .targets file for where this internal property is set, you will find this PropertyGroup (line 152):

<PropertyGroup Label="Build properties">
  <_BlazorShouldLinkApplicationAssemblies Condition="$(BlazorLinkOnBuild) == 'false'"></_BlazorShouldLinkApplicationAssemblies>
  <_BlazorShouldLinkApplicationAssemblies Condition="$(BlazorLinkOnBuild) == 'true'">true</_BlazorShouldLinkApplicationAssemblies>
  <_BlazorBuiltInBclLinkerDescriptor>$(MSBuildThisFileDirectory)BuiltInBclLinkerDescriptor.xml</_BlazorBuiltInBclLinkerDescriptor>
</PropertyGroup>

This is why setting the BlazorLinkOnBuild (as of 3.2.0-preview3, renamed to BlazorWebAssemblyEnableLinking) to false allows NCrunch to build the project.