Where is best to store ccache dependencies on GH runners?

[SJaffa]

We currently store the ccache in ${{runner.workspace}}/.ccache but the GHA syntax highlighting in VSCode complains about this, saying "Context access might be invalid", so I was wondering where is the best place to store the cache.

runner.workspace doesn't seem to exist in the runner context documentation, but we use github.workspace later on which does exist. The examples in the documentation on caching dependencies seem to just use ~ for the workspace.