This is a developer QoL improvement, where running codegen will skip
writing (and especially formatting) any files that were not changed.
**Why?** While code generation in itself was pretty much instant, QL
formatting of generated code was starting to take a long time. This made
unconditionally running codegen quite annoying, for example before each
test run as part of an IDE workflow or as part of the pre-commit hook.
**How?** This was not completely straightforward as we could not work
with the contents of the file prior to code generation as that was
already post-processed by the QL formatting, so we had no chance of
comparing the output of template rendering with that. We therefore store
the hashes of the files _prior_ to QL formatting in a checked-in file
(`swift/ql/.generated.list`). We can therefore load those hashes at
the beginning of code generation, use them to compare the template
rendering output and update them in this special registry file.
**What else?** We also extend this mechanism to detect accidental
modification of generated files in a more robust way. Before this patch,
we were doing it with a rough regexp based heuristic. Now, we just store
the hashes of the files _after_ QL formatting in the same checked file,
so we can check that and stop generation if a generated file was
modified, or a stub was modified without removing the `// generated`
header.
Java's regular strings are formatted as they appear in source, but we don't easily have this information available in Kotlin. During annotation extraction however it guesses a source rendering because the source is not necessarily available. By formatting to match the annotation extractor, we prepare to ensure consistency with a Java database
when extracting annotations as seen by Kotlin.
In https://github.com/github/codeql/pull/8641, `localFlowExit` was
changed to use `Stage2::readStepCand` instead of `read`, which means
that the big-step relation is broken up less. This causes test result
changes. Nothing is lost from the `select` clause, but some results may
have fewer paths, and fewer nodes and edges are output in the test
results.
In the `subpaths` section, the last node is now printed without its type
if it is the sink of the path.
This comes from the commit "Dataflow: Bugfix: include subpaths ending at
a sink. " in https://github.com/github/codeql/pull/7526
