Instead of simple numbering, we hash important bits, like the name of the item.
This will allow for much better incrementality, e.g. when you add an item. Currently, this invalidates the IDs of all following items, which invalidates pretty much everything.
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`.
Specifically, #18744 was the PR that was supposed to fix the old bug, but it fixed it incorrectly (and didn't add a test!) The underlying reason was that we marked metavariables in expansions as joint if they were joint in the macro call, which is incorrect.
This wrong fix causes other bug, #19497, which this PR fixes by removing the old (incorrect) fix.
More correctly, *also* per-token. Because as it turns out, while the top-level edition affects parsing (I think), the per-token edition affects escaping of identifiers/keywords.
We should immediately mark them as finished, on the first entry.
The funny (or sad) part was that this bug was pre-existing, but previously to #18327, it was causing us to generate bindings non-stop, 65535 of them, until we get to the hardcoded repetition limit, and then throw it all away. And it was so Blazingly Fast that nobody noticed.
With #18327 however, this is still what happens, except that now instead of *merging* the fragments into the result, we write them on-demand. Meaning that when we hit the limit, we've already written all previous entries. This is a minor change, I thought for myself when I was writing this, and it's actually for the better, so who cares. Minor change? Not so fast. This caused us to emit 65535 repetitions, all of which the MBE infra needs to handle when calling other macros with the expansion, and convert to rowan tree etc., which resulted a *massive* hang.
The test (and also `analysis-stats`) used to crash with stack overflow on this macro, because we were dropping some crazily deep rowan tree. Now they work properly. Because I am lazy, and also because I could not find the exact conditions that causes a macro match but with a missing binding, I just copied all macros from tracing. Easy.
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.
feat: Support the `${concat(...)}` metavariable expression
I didn't follow rustc precisely, because I think it does some things wrongly (or they are FIXME), but I only allowed more code, not less. So we're all fine.
Closes#18145.
I didn't follow rustc precisely, because I think it does some things wrongly (or they are FIXME), but I only allowed more code, not less. So we're all fine.
fix: Get rid of `$crate` in expansions shown to the user
Be it "Expand Macro Recursively", "Inline macro" or few other things.
We replace it with the crate name, as should've always been.
Probably fixes some issues, but I don't know what they are.
