Nodes in the dependency graph.
Contains variant => str representations for constructing DepNode groups for tests.
A dep-node filter goes from a user-defined string to a query over nodes. Right now the format is like this:
A “work product” is an intermediate result that we save into the incremental directory for later re-use. The primary example are the object files that we save for each partition at code generation time.
A “work product” corresponds to a
.o (or other) file that we
save in between runs. These IDs do not have a
DefId but rather
some independent path or string that persists between runs without
the need to be mapped or unmapped. (This ensures we can serialize
them even in the absence of a tcx.)