Add .editorconfig file and apply dotnet-format tool

[hanabi1224]

Fix https://code.videolan.org/videolan/LibVLCSharp/issues/121 by using .editorconfig from https://github.com/dotnet/format/blob/master/.editorconfig
And apply dotnet-format tool

[hanabi1224]

@mfkl comments resolved, plz let me know if there're any other outstanding issues

[mfkl]

On your branch, typing dotnet-format gives

Unhandled exception: System.InvalidOperationException: Cannot modify an evaluated object originating in an imported file "C:\Users\Martin\.nuget\packages\msbuild.sdk.extras\1.6.46\Build\Inference.targets".
   at Microsoft.Build.Shared.ErrorUtilities.ThrowInvalidOperation(String resourceName, Object[] args)
   at Microsoft.Build.Shared.ErrorUtilities.VerifyThrowInvalidOperation(Boolean condition, String resourceName, Object arg0)
   at Microsoft.Build.Evaluation.Project.VerifyThrowInvalidOperationNotImported(ProjectRootElement otherXml)
   at Microsoft.Build.Evaluation.Project.RemoveProperty(ProjectProperty property)
   at Microsoft.CodeAnalysis.MSBuild.ProjectFile.GetProjectFileInfosAsync(CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.Worker.DoOperationAndReportProgressAsync[TResult](ProjectLoadOperation operation, String projectPath, String targetFramework, Func`1 doFunc)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.Worker.LoadProjectFileInfosAsync(String projectPath, DiagnosticReportingOptions reportingOptions, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.Worker.LoadProjectInfosFromPathAsync(String projectPath, DiagnosticReportingOptions reportingOptions, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.Worker.LoadAsync(CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.LoadSolutionInfoAsync(String solutionFilePath, IProgress`1 progress, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildWorkspace.OpenSolutionAsync(String solutionFilePath, IProgress`1 progress, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Tools.CodeFormatter.CodeFormatter.FormatWorkspaceAsync(ILogger logger, String solutionOrProjectPath, Boolean isSolution, Boolean logAllWorkspaceWarnings, Boolean saveFormattedFiles, CancellationToken cancellationToken) in /_/src/CodeFormatter.cs:line 53
   at Microsoft.CodeAnalysis.Tools.CodeFormatter.Program.Run(String workspace, String verbosity, Boolean dryRun, IConsole console) in /_/src/Program.cs:line 68
   at System.CommandLine.Invocation.CommandHandler.GetResultCodeAsync(Object value, InvocationContext context)
   at System.CommandLine.Invocation.InvocationPipeline.<>c__DisplayClass3_0.<<InvokeAsync>b__0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.CommandLine.Invocation.InvocationExtensions.<>c.<<UseParseErrorReporting>b__16_0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.CommandLine.Builder.CommandLineBuilderExtensions.<>c__DisplayClass3_0.<<UseVersionOption>b__0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.CommandLine.Invocation.InvocationExtensions.<>c.<<UseSuggestDirective>b__7_0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.CommandLine.Invocation.InvocationExtensions.<>c.<<UseDebugDirective>b__4_0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.CommandLine.Invocation.InvocationExtensions.<>c.<<UseHelp>b__14_0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.CommandLine.Invocation.InvocationExtensions.<>c.<<UseParseDirective>b__6_0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.CommandLine.Invocation.InvocationExtensions.<>c.<<RegisterWithDotnetSuggest>b__17_0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.CommandLine.Invocation.InvocationExtensions.<>c.<<UseExceptionHandler>b__5_0>d.MoveNext()

[hanabi1224]

@mfkl dotnet format tool does not seems to support custom build sdk yet, so I manually changed build sdk to Microsoft.NET.SDK before running dotnet format, then change it back : )

[mfkl]

if dotnet-format doesn't work out of the box with MSBuild.Sdk.Extras, we will probably find another way to enforce formatting. Modifying this locally each time sounds tiresome.

[hanabi1224]

Thats why i included .editorconfig as well. Both vs and vs code has extensions that support .editorconfig

[mfkl]

Sure, but I still didn't figure out how to use it with the VS extension. Either way, we will want to enforce those formatting rules in the CI so running from CLI is a must.

[hanabi1224]

@mfkl Then maybe u can use some alternative cli tools like https://github.com/editorconfig/editorconfig-core-net which seems to be better done in a separate PR

[hanabi1224]

@mfkl In my VS2017 and VS2019, when .editorconfig file is in place, it can be automatically picked up when performing formatting (Ctrl + K + D) , does that not work for you?

[mfkl]

I want this to be enforced on build, either when building with msbuild or by feeding the files to an exe. I'm not counting on contributors to think to do CTRL+K+D before each PR.

Right now, I still don't get how this works. Example:
Setting csharp_space_after_keywords_in_control_flow_statements to false does not output warnings.

[jeremyVignelles]

@hanabi1224 ; I tried your branch and did see the IDE displaying messages when I wrote int a = 0;.

@mfkl , there must be something wrong with your IDE. Did you enable the Error List window?

Now, we need to define which rules are applied on LibVLCSharp's repo, because the ones you specified are the rules defined by the dotnet-format team, but for example, I tend to disagree with this rule:

dotnet_naming_style.static_field_style.required_prefix = s_

I'd say that a default config (add/new item/editor config (.net)) would be fine for our use, but on the other hand, it would be useful to specify rules like this one (for .sh) : end_of_line = lf (and set that in .gitattributes too)

[jeremyVignelles]

Adding a .editorconfig is enough for me at that time. We can try locally, and ask for code style fixes as needed.

The automated build failure will come later, but it's not currently supported : dotnet/roslyn#33558

[hanabi1224]

@jeremyVignelles Regarding s_ prefix thing, I believed it's sth more general within netfx, https://github.com/dotnet/corefx/blob/master/Documentation/coding-guidelines/coding-style.md