Extend ItemTree pretty-printing to include attributes even when a cfg
expression evaluates to false, emitting explicit `cfg(cfg_expr)` marker
after the attributes.
This improves testability of ItemTree attribute handling by exposing
more information in pretty-printed output.
Basically, we switch to expanding cfg_attr in AST form, filter irrelevant attributes from the item tree, and move hir-def attributes (non-item-tree) to be flag-based.
The main motivation is memory usage, although this also simplifies the code, and fixes some bugs around handling of `cfg_attr`s.
Now that they're const it's no longer needed.
Nothing manual was performed: only a regexp search of `sym::([\w][\w\d]*)\.clone\(\)` and replace by `sym::$1`.
I expected this to be faster (due to less allocations and better cache locality), but benchmarked it is not (neither it is slower). Memory usage, however, drops by ~50mb (of `analysis-stats .`). I guess tt construction is just not hot.
This also simplifies using even less memory for token trees by compressing equal span, which I plan to do right after.
Some workflows are more easily expressed with a flat tt, while some are better expressed with a tree. With the right helpers, though (which was mostly a matter of trial and error), even the worst workflows become very easy indeed.
This will mean users opting to not activate `cfg(test)` will lose IDE experience on them, which is quite unfortunate, but this is unavoidable if we want to avoid false positives on e.g. diagnostics. The real fix is to provide IDE experience even for cfg'ed out code, but this is out of scope for this PR.
Partially fixes#15656 . When a crate graph is extended which is the case when new workspaces are added to the project
the rules for deduplication were too strict. One problem that arises from this is that in certain conditions
when we see the same crate having different `CrateOrigin`s the first form would be maintained. This approach however
results in some unwanted results such as making renaming forbidden as this has been recently only made available for
local crates. The given example in #15656 can still not be resolved with this PR as that involves taking inconsistencies
between dependencies into consideration. This will be addressed in a future PR.
This makes code more readale and concise,
moving all format arguments like `format!("{}", foo)`
into the more compact `format!("{foo}")` form.
The change was automatically created with, so there are far less change
of an accidental typo.
```
cargo clippy --fix -- -A clippy::all -W clippy::uninlined_format_args
```
