Allow running simple .exe files without .runtimeconfig.json

It is currently impossible to execute simple console applications (.exe) compiled against net472 using dotnet myapp.exe.

The output we get is something along these lines:

Cannot use file stream for [/Users/builder/azdo/_work/1/s/setup/MacSetup/build/packages/binarycompatchecker/1.0.20/tools/BinaryCompatChecker.deps.json]: No such file or directory
A fatal error was encountered. The library 'libhostpolicy.dylib' required to execute the application was not found in '/Users/builder/azdo/_work/1/s/setup/MacSetup/build/packages/binarycompatchecker/1.0.20/tools/'.
Failed to run as a self-contained app.
The application was run as a self-contained app because '/Users/builder/azdo/_work/1/s/setup/MacSetup/build/packages/binarycompatchecker/1.0.20/tools/BinaryCompatChecker.runtimeconfig.json' was not found.
If this should be a framework-dependent app, add the '/Users/builder/azdo/_work/1/s/setup/MacSetup/build/packages/binarycompatchecker/1.0.20/tools/BinaryCompatChecker.runtimeconfig.json' file and specify the appropriate framework.

This is not user friendly at all. The expectation is that for most programs compiled against net472 they should just run by prepending dotnet. Forcing to add a .runtimeconfig.json sounds like a sound requirement in theory, but in practice this adds friction to the 90% case (simplest scenario).

[KirillOsenkov]

Just pick the latest available Core runtime and hope for the best. There are situations where you have an existing tool compiled for net472 that you want to run on Mac. You can run on Mono without problems, but you can’t run on dotnet for an artificial reason/limitation.

I don’t think dotnet some.exe should work for native binaries, but that’s not the scenario I care about. In 90% cases you can run .NET Framework apps just fine if you manually add a .runtimeconfig.json file. I think it’s silly to have this artificial impediment.

[abatishchev]

And the other cases?

Doesn’t matter. If in 90% it’ll work - it’s already a huge win for the customers.

Following this logic, nothing needs any improvement ever if there will be always a corner case which won’t be fixed/improved.

Catering to ~90% of customers sounds to me like a good reason for a change.