Why not just EnforceCodeStyleInBuild?

EnforceCodeStyleInBuild = true in your project tells the .NET SDK to run the Roslyn style analyzers inside CoreCompile and report IDE0055 and the code style rules as build diagnostics. It is the right thing to set. Curb is designed to work with it, not instead of it.

With EnforceCodeStyleInBuild = true and no formatter in the build, every mechanically unformatted file reports IDE0055. A developer who forgot to run dotnet format sees build errors — and to fix them, they have to run the command, check the output, commit again, and wait for CI to rerun. For a CI pipeline that runs tests after the build, the whole suite gets blocked on a missing semicolon.

Curb runs at BeforeTargets="CoreCompile". By the time CoreCompile evaluates the analyzers, Curb has already rewritten every file it can format. The only IDE0055 diagnostics that survive are things Curb has not implemented — which are reported explicitly rather than silently skipped.

The MSBuild smoketest verifies both directions: building the sample with Curb in the path must succeed even with EnforceCodeStyleInBuild = true and deliberately misformatted source; building without Curb must report IDE0055 errors. Only the pair proves anything.

Curb handles syntax-level code style — braces, expression bodies, modifier order, namespace declarations, using placement. It does not handle semantic rules: var decisions, naming conventions, unused members. Those genuinely need a compilation.

With both EnforceCodeStyleInBuild and Curb in place, the analyzer output you see in a build is the semantic remainder — things worth discussing, not things a formatter should have caught. That is what the split is for.

If a file should not be formatted by Curb, use generated_code = true or dotnet_diagnostic.IDE0055.severity = none in your .editorconfig. Curb honours both and skips the file. The analyzers still run unless you configure their severity separately.

Curb itself can produce build diagnostics through the MSBuild integration:

CURB0002 is always an error. A formatter that could not verify its own work has verified nothing, and a quiet warning would hide that.

The .editorconfig diagnostics (CURB1001–CURB1007) appear in curb print-config output and in the build log, not as MSBuild diagnostics.