Overview

This PR implements support for path transformers (specified using the CODEQL_PATH_TRANSFORMER environment variable) in the C# extractor. Paths are transformed in the following places:

• When populating the files relation.
• When populating the folders relation.
• When adding files to the source archive.
• When creating TRAP files.

While it is strictly speaking not needed for TRAP files, it maintains the invariant that each source code file in the source archive is mapped to a .trap.gz file at the same relative location.

Testing

macOS

I have tested locally on macOS with this transformer file

#src
/<path-to-codeql-checkout>/csharp/autobuilder//

and this build command

CODEQL_PATH_TRANSFORMER=<path-to-transformer-file> codeql database create --language=csharp --keep-trap --command "dotnet build csharp/CSharp.sln /t:rebuild /p:UseSharedCompilation=false" -- db

Windows

I have tested locally on Windows with this transformer file

#src
C:\<path-to-codeql-checkout>\csharp\autobuilder//

and this build command

set CODEQL_PATH_TRANSFORMER=<path-to-transformer-file>
codeql database create --language=csharp --keep-trap --command "dotnet build csharp/CSharp.sln /t:rebuild /p:UseSharedCompilation=false" -- db

Review

Commit-by-commit review is suggested.