In .NET 6 timeframe we intend to improve on the following aspects of developer inner loop productivity based on feedback regarding common pain points:

• Reduce manual steps needed for unit testing of private coreclr dev bits from 4 to 1
• Coreclr up-to-date check takes < 5s on an average dev machine
• Local build time
• Local build reliability and consistency
• Telemetry

Unit testing

• Define a msbuild hooks that allows you to replace the runtime and host inside a retail dotnet sdk install. This will enable 'overriding' runtime components with private developer flies.
• Produce a dev-inner loop based off of single file. The single file host includes various runtime components compiled into a static library. This removes the need of manual patching of files.
• Build on top of the prototype to extend to other areas of the runtime, such as using different libraries.

Local build time

• (P1) Improve local build by switching over to Ninja on Windows, Improve coreclr windows native build time #33872
• (Incremental, P1) Investigate reducing complexity of test build / execution; Proposal revise CoreCLR test build/run design to reduce complexity #36295

Local build reliability and consistency (5 weeks total)

• (1 week, P2) Failure in build-runtime.cmd related to missing UCRT in Windows; build-runtime.cmd fails when the latest version in C:\Program Files (x86)\Windows Kits\10\Lib does not contain ucrt #42774
• (2 days, P1) Failure in enforcepgo doesn't fail the build; If the enforcepgo script fails, it doesn't fail the CoreCLR build #35089
• (2 days, P2) Sharing violation reading pgd file in parallel coreclr local builds; Sharing violation reading pgd file during concurrent local coreclr builds (windows x86 release) #46018
• (2 days, P2) Spurious mkdir error message during Linux build; mkdir error message from bash function setup_dirs #34342
• (2 days) installer.tasks.dll not found in local runtime build; runtime build failure: "GenerateFileVersionProps" task could not be loaded because installer.tasks.dll not found #46020
• (2 days, P1) Obsolete warnings in clean build; Obsolete warnings on clean build #39976
• (2 days, P1) Test run files should be arch/OS distinguished; coreclr test run files TestRun.html and TestRun.xml should be os/arch/flavor distinguished #1737
• (1 week, P2) Enable more MSVC warnings; Tracking issue: enable more MSVC warnings #42767
• (1 week, P2) Per-component (coreclr, libraries, installer, mono?) cmake args; Support per-component (coreclr, installer, etc) cmake args #42711

Documentation (2 days total)

• (2 days, P1) Build doesn't see libs subset even though it's been built; "The 'libs' subset must be built before building this project" when subset has been built #36528