Closes#17841.
The majority of the work should be done, e.g. trait and inherent impls, different forms of UFCS syntax, defaults, and cross-crate usage. It's probably enough to replace the constants in `f32`, `i8`, and so on, or close to good enough.
There is still some significant functionality missing from this commit:
- ~~Associated consts can't be used in match patterns at all. This is simply because I haven't updated the relevant bits in the parser or `resolve`, but it's *probably* not hard to get working.~~
- Since you can't select an impl for trait-associated consts until partway through type-checking, there are some problems with code that assumes that you can check constants earlier. Associated consts that are not in inherent impls cause ICEs if you try to use them in array sizes or match ranges. For similar reasons, `check_static_recursion` doesn't check them properly, so the stack goes ka-blooey if you use an associated constant that's recursively defined. That's a bit trickier to solve; I'm not entirely sure what the best approach is yet.
- Dealing with consts associated with type parameters will raise some new issues (e.g. if you have a `T: Int` type parameter and want to use `<T>::ZERO`). See rust-lang/rfcs#865.
- ~~Unused associated consts don't seem to trigger the `dead_code` lint when they should. Probably easy to fix.~~
Also, this is the first time I've been spelunking in rustc to such a large extent, so I've probably done some silly things in a couple of places.
Remove the name "multi-line string literal" since the rule appears to affect each line-break individually rather than the whole string literal. Re-word, and remove the stray reference to raw strings.
A user in IRC was having trouble because they used `main.rs` when they were trying
to migrate a library. The `[[lib]]` key is not easily found, and the `main.rs`/`lib.rs`
distinction doesn't seem to exist in trpl
r? @steveklabnik
Improve example for as_string and add example for as_vec
Provide a better example of `as_string` / `DerefString`'s unique capabilities.
Use an example where (for an unspecified reason) you need a &String, and
show how `as_string` solves the problem without needing an allocation.
The minus sign ‘−’ is the same width as the plus sign ‘+’, so the button’s transition between the two symbols will look slightly smoother.
If you don’t want to use literal Unicode characters, I can change ‘−’ to `\u2212`. I’m not starting with that suggestion because ‘−’ is easier to read and understand, and if I used `\u2212`, it would probably be necessary to also comment the usage on each line to explain what character is being used.
Fix `make_command_line` for the case of backslashes at the end of an
argument requiring quotes. We must encode the command and arguments
such that `CommandLineToArgvW` recovers them in the spawned process.
Simplify the logic by using a running count of backslashes as they
are encountered instead of looking ahead for quotes following them.
Extend `test_make_command_line` to additionally cover:
* a leading quote in an argument that requires quotes,
* a backslash before a quote in an argument that requires quotes,
* a backslash at the end of an argument that requires quotes, and
* a backslash at the end of an argument that does not require quotes.
Remove the name "multi-line string literal" since the rule appears to affect each line-break individually rather than the whole string literal. Re-word, and remove the stray reference to raw strings.
So that if people accidentally delete the character, they won’t re-type it as a hyphen, which would cause bugs.
I changed ‘+’ too, even though it won’t be re-typed incorrectly, so that it is easier to see when plus is used as a symbol for the button, and when it is used as an operator in code. It also makes it clearer that the use of an entity for minus is on purpose, so people won’t be tempted to replace the entity incorrectly with a hyphen character.
I figure I'd start easy with fixing a simple documentation bug. This is also a test to see that I got everything right w r t the fork/pull request process.
This changes the `ToTokens` implementations for expressions, statements, etc. with almost-trivial ones that produce `Interpolated(*Nt(...))` pseudo-tokens. In this way, quasiquote now works the same way as macros do: already-parsed AST fragments are used as-is, not reparsed.
The `ToSource` trait is removed. Quasiquote no longer involves pretty-printing at all, which removes the need for the `encode_with_hygiene` hack. All associated machinery is removed.
New `Nonterminal`s are added: NtArm, NtImplItem, and NtTraitItem. These are just for quasiquote, not macros.
`ToTokens` is no longer implemented for `Arg` (although this could be added again) and `Generics` (which I don't think makes sense).
This breaks any compiler extensions that relied on the ability of `ToTokens` to turn AST fragments back into inspectable token trees. For this reason, this closes#16987.
As such, this is a [breaking-change].
Fixes#16472.
Fixes#15962.
Fixes#17397.
Fixes#16617.
An actual typeck error is the cause of many failed compilations but an
unrelated bug is being reported instead. It is triggered because a typeck
error is presumably not yet identified during compiler execution, which
would normally bypass an invariant in the presence of other errors. In
this particular situation, we delay the reporting of the bug until
abort_if_errors().
Closes#23827, closes#24356, closes#23041, closes#22897, closes#23966,
closes#24013, and closes#23729
**There is at least one situation where this bug may still be genuinely
triggered (#23437).**
Transplant the relevant changes (turns out to be all of them) to `grammar.md`, and remove all grammar talk from `reference.md`. Sorry for the chaos.
The second commit, further below, goes over the comments and whitespace sections.
r? @steveklabnik
This changes the `ToTokens` implementations for expressions, statements,
etc. with almost-trivial ones that produce `Interpolated(*Nt(...))`
pseudo-tokens. In this way, quasiquote now works the same way as macros
do: already-parsed AST fragments are used as-is, not reparsed.
The `ToSource` trait is removed. Quasiquote no longer involves
pretty-printing at all, which removes the need for the
`encode_with_hygiene` hack. All associated machinery is removed.
A new `Nonterminal` is added, NtArm, which the parser now interpolates.
This is just for quasiquote, not macros (although it could be in the
future).
`ToTokens` is no longer implemented for `Arg` (although this could be
added again) and `Generics` (which I don't think makes sense).
This breaks any compiler extensions that relied on the ability of
`ToTokens` to turn AST fragments back into inspectable token trees. For
this reason, this closes#16987.
As such, this is a [breaking-change].
Fixes#16472.
Fixes#15962.
Fixes#17397.
Fixes#16617.
At https://doc.rust-lang.org/book/vectors.html, there should be a link to
Generics page but the link address is ommitted and thus link is not functioning
well. So I added a link definition to the vectors.md.
r? @steveklabnik
