Directory.Build.props Enable All Errors

.editorconfig

[*.{cs,vb}]
dotnet_diagnostic.CA1062.severity = none

# IDE0022: Use block body for method
csharp_style_expression_bodied_methods = true

# IDE0032: Use auto property
dotnet_style_prefer_auto_properties = true

#CSharpier Incompatible Rules
dotnet_diagnostic.SA1009.severity = none
dotnet_diagnostic.SA1111.severity = none
dotnet_diagnostic.SA1633.severity = none
dotnet_diagnostic.SA1502.severity = none

#Don't like these
dotnet_diagnostic.SA1512.severity = none
dotnet_diagnostic.SA1623.severity = none
dotnet_diagnostic.SA1515.severity = none
dotnet_diagnostic.SA1516.severity = none

#Not sure why this is necessary
dotnet_diagnostic.CA1016.severity = none

#What's the recommendation these days?
dotnet_diagnostic.SA1309.severity = none
dotnet_diagnostic.SA1101.severity = none

#Too onerous
dotnet_diagnostic.SA1615.severity = none
dotnet_diagnostic.SA1600.severity = none
dotnet_diagnostic.SA1611.severity = none

#This is an analyzer bug when using records
dotnet_diagnostic.SA1313.severity = none

#This also seems to be a bug when using array initializers
dotnet_diagnostic.SA1010.severity = none
dotnet_diagnostic.SA1011.severity = none

# IDE0040: Add accessibility modifiers
dotnet_style_require_accessibility_modifiers = never

Directory.Build.props

<Project>
    <PropertyGroup>
        <TargetFramework>net8.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
		<WarningsNotAsErrors></WarningsNotAsErrors>
		<Deterministic>true</Deterministic>
        <LangVersion>Latest</LangVersion>
        <DebugSymbols>true</DebugSymbols>
        <EnableNETAnalyzers>true</EnableNETAnalyzers>
		<AnalysisLevel>latest</AnalysisLevel>
		<AnalysisMode>AllEnabledByDefault</AnalysisMode>
        <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
        <RunAnalyzersDuringBuild>true</RunAnalyzersDuringBuild>
		<RunAnalyzersDuringLiveAnalysis>true</RunAnalyzersDuringLiveAnalysis>
		<RunAnalyzers>true</RunAnalyzers>
		<Nullable>enable</Nullable>
		<EnforceCodeStyleInBuild>true</EnforceCodeStyleInBuild>
		<CodeAnalysisTreatWarningsAsErrors>true</CodeAnalysisTreatWarningsAsErrors>
    </PropertyGroup>

    <ItemGroup>
        <PackageReference Include="Microsoft.CodeAnalysis.NetAnalyzers" Version="8.0.0"/>
        <PackageReference Include="StyleCop.Analyzers" Version="1.1.118"/>
    </ItemGroup>

</Project>

Can you tell me why this new format exists, and why it's better than editor config

It applies to all files in a build and not just the ones matching the filter (i.e. it works like a proper replacement for .ruleset files). The format is equivalent to .editorconfig aside from section headers.