Currently, when two tokens must be glued together, this function duplicates
large chunks of the existing streams. This can cause quadratic behaviour.
This commit changes the function so that it overwrites the last token with a
glued token, which avoids the quadratic behaviour. This removes the need for
`TokenStreamBuilder::push_all_but_{first,last}_tree`.
The commit also restructures `push` somewhat, by removing
`TokenStream::{first_tree_and_joint,last_tree_if_joint}` in favour of more
pattern matching and some comments. This makes the code shorter, and in my
opinion, more readable.
Currently, this function creates a new empty stream, and then appends
the elements from each given stream onto that stream. This can cause
quadratic behaviour.
This commit changes the function so that it modifies the first stream
(which can be long) by extending it with the elements from the
subsequent streams (which are almost always short), which avoids the
quadratic behaviour.
It's the same as `InferCtxt::commit_unconditionally()` except that it
is passed a snapshot and has a worse name.
The commit also changes `commit_unconditionally()` to receive a
snapshot, for consistency with `commit_if_ok()` and `probe()`.
Rollup of 8 pull requests
Successful merges:
- #64726 (rewrite documentation for unimplemented! to clarify use)
- #65040 (syntax: more cleanups in item and function signature parsing)
- #65046 (Make `Cell::new` method come first in documentation)
- #65098 (Add long error explanation for E0561)
- #65150 (Suggest dereferencing boolean reference when used in 'if' or 'while')
- #65154 (Fix const generic arguments not displaying in types mismatch diagnostic)
- #65181 (fix bug in folding for constants)
- #65187 (use 'invalid argument' for vxWorks)
Failed merges:
- #65179 (Add long error explanation for E0567)
r? @ghost
fix bug in folding for constants
These was a bug in the folding for constants that caused it to overlook bound regions. This branch includes some other little things that I did while trying to track the bug down.
r? @oli-obk
Make `Cell::new` method come first in documentation
Methods to create a thing usually comes first in `std` documentation, and `Cell` has been an exception. Also, `T: Copy` specialized methods should not be on top of the page. (This had led me to miss that most of its methods are not bounded by `Copy`...)
rewrite documentation for unimplemented! to clarify use
The current docs for `unimplemented!` seem to miss the point of this macro.
> This can be useful if you are prototyping and are just looking to have your code type-check, or if you're implementing a trait that requires multiple methods, and you're only planning on using one of them.
You could also return a `()` if you just want your code to type-check.
I think `unimplemented!` is useful for when you want your program to exit when it reaches an unimplemented area.
I rewrote the explanation and gave examples of both forms of this macro that I think clarify its use a little better.
