As explained in L1 Build Cache cmake-re mirrors code in an invariant path in the hermetic environment for the build, this mirroring can be configured as follow.

.gitignore

Mirroring doesn't overwrite .gitignored files in source mirror by default, this behaviour is to support in-source-tree generated files during the build. It happens that projects .gitignore in-source-tree generated files when files are not checked-in.

Files that are ignored by your .gitignore present in your original source tree are not ignored during source code mirroring.

The behaviour can be customized by implementing inverse .tipiignore rules.

.tipiignore

You can create an ignore file named .tipiignore in the your project. The syntax is identical to the syntax of .gitignore (official documentation for https://git-scm.com/docs/gitignore)

Target specific ignore rules using .tipiignore.<toolchain-name>

If you find the need to specify target specific rules for your build (for example to exclude a target OS specific test or example from your otherwise fully cross-platform compatible library) you can create toolchain specific .tipiignore.<toolchain-name> files in your project.

Please note that the <toolchain-name> part requires an exact match to the toolchain.

Additionally the .tipiignore rules are considered a base rule set and are applied for all toolchains even when a specific match is found: this means that rules of .tipiignore.linux-cxx17 and of .tipiignore are additive

Examples

# exclude everything except directory foo/bar
/*
!/foo
/foo/*
!/foo/bar

# exclude every .cpp ending by a number or by .swp.
[0-9].cpp
*.swp.cpp