Consider these expples
{ 92 }
async { 92 }
'a: { 92 }
#[a] { 92 }
Previously the tree for them were
BLOCK_EXPR
{ ... }
EFFECT_EXPR
async
BLOCK_EXPR
{ ... }
EFFECT_EXPR
'a:
BLOCK_EXPR
{ ... }
BLOCK_EXPR
#[a]
{ ... }
As you see, it gets progressively worse :) The last two items are
especially odd. The last one even violates the balanced curleys
invariant we have (#10357) The new approach is to say that the stuff in
`{}` is stmt_list, and the block is stmt_list + optional modifiers
BLOCK_EXPR
STMT_LIST
{ ... }
BLOCK_EXPR
async
STMT_LIST
{ ... }
BLOCK_EXPR
'a:
STMT_LIST
{ ... }
BLOCK_EXPR
#[a]
STMT_LIST
{ ... }
Originally we tried to maintain the invariant that `{}` always match.
That is, that in the parse tree the pair of corresponding `{}` is always
first and last tokens of some nodes.
We had the code to validate that, but apparently it's been broken for
**years** since we introduced tokens/nodes split. Fixing it now makes
some tests fail.
It's unclear if we want to keep this invariant: there's a strong
motivation for breaking it in the following case:
```
use std::{ // unclosed paren
fn main() {
}
} // don't actually want to pair up this with the one from `use`
```
So let's fix the code, but disable it for the time being
The code here is intentionally dense and does exactly what is written.
Explaining semantic difference between Rust 2015 and 2018 doesn't help
with understanding syntax. Better to just add more targeted tests.
Group related stuff together, use only on path for parsing extern blocks
(they actually have modifiers).
Perhaps we should get rid of items_without_modifiers altogether? Better
to handle these kinds on diagnostics in validation layer...
9944: internal: introduce in-place indenting API r=matklad a=iDawer
Introduce `edit_in_place::Indent` that uses mutable tree API and intended to replace `edit::AstNodeEdit`.
Closes#9903
Co-authored-by: Dawer <7803845+iDawer@users.noreply.github.com>
9814: Generate default impl when converting `#[derive(Debug)]` to manual impl r=yoshuawuyts a=yoshuawuyts
This patch makes it so when you convert `#[derive(Debug)]` to a manual impl, a default body is provided that's equivalent to the original output of `#[derive(Debug)]`. This should make it drastically easier to write custom `Debug` impls, especially when all you want to do is quickly omit a single field which is `!Debug`.
This is implemented for enums, record structs, tuple structs, empty structs - and it sets us up to implement variations on this in the future for other traits (like `PartialEq` and `Hash`).
Thanks!
## Codegen diff
This is the difference in codegen for record structs with this patch:
```diff
struct Foo {
bar: String,
}
impl fmt::Debug for Foo {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
- todo!();
+ f.debug_struct("Foo").field("bar", &self.bar).finish()
}
}
```
Co-authored-by: Irina Shestak <shestak.irina@gmail.com>
Co-authored-by: Yoshua Wuyts <yoshuawuyts@gmail.com>
Co-authored-by: Yoshua Wuyts <yoshuawuyts+github@gmail.com>
* Keep codegen adjacent to the relevant crates.
* Remove codgen deps from xtask, speeding-up from-source installation.
This regresses the release process a bit, as it now needs to run the
tests (and, by extension, compile the code).
9455: feat: Handle not let if expressions in replace_if_let_with_match r=Veykril a=Veykril
Transforms bare `if cond {}` into `_ if cond` guard patterns in the match as long as at least one `if let` is in the if chain, otherwise the assist wont be applicable.
bors r+
Co-authored-by: Lukas Wirth <lukastw97@gmail.com>
This story begins in #8384, where we added a smart test for our syntax
highting, which run the algorithm on synthetic files of varying length
in order to guesstimate if the complexity is O(N^2) or O(N)-ish.
The test turned out to be pretty effective, and flagged #9031 as a
change that makes syntax highlighting accidentally quadratic. There was
much rejoicing, for the time being.
Then, lnicola asked an ominous question[1]: "Are we sure that the time
is linear right now?"
Of course it turned out that our sophisticated non-linearity detector
*was* broken, and that our syntax highlighting *was* quadratic.
Investigating that, many brave hearts dug deeper and deeper into the
guts of rust-analyzer, only to get lost in a maze of traits delegating
to traits delegating to macros.
Eventually, matklad managed to peel off all layers of abstraction one by
one, until almost nothing was left. In fact, the issue was discovered in
the very foundation of the rust-analyzer -- in the syntax trees.
Worse, it was not a new problem, but rather a well-know, well-understood
and event (almost) well-fixed (!) performance bug.
The problem lies within `SyntaxNodePtr` type -- a light-weight "address"
of a node in a syntax tree [3]. Such pointers are used by rust-analyzer all
other the place to record relationships between IR nodes and the
original syntax.
Internally, the pointer to a syntax node is represented by node's range.
To "dereference" the pointer, you traverse the syntax tree from the
root, looking for the node with the right range. The inner loop of this
search is finding a node's child whose range contains the specified
range. This inner loop was implemented by naive linear search over all
the children. For wide trees, dereferencing a single `SyntaxNodePtr` was
linear. The problem with wide trees though is that they contain a lot of
nodes! And dereferencing pointers to all the nodes is quadratic in the
size of the file!
The solution to this problem is to speed up the children search --
rather than doing a linear lookup, we can use binary search to locate
the child with the desired interval.
Doing this optimization was one of the motivations (or rather, side
effects) of #6857. That's why `rowan` grew the useful
`child_or_token_at_range` method which does exactly this binary search.
But looks like we've never actually switch to this method? Oups.
Lesson learned: do not leave broken windows in the fundamental infra.
Otherwise, you'll have to repeatedly re-investigate the issue, by
digging from the top of the Everest down to the foundation!
[1]: https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Frust-analyzer/topic/.60syntax_highlighting_not_quadratic.60.20failure/near/240811501
[2]: https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Frust-analyzer/topic/Syntax.20highlighting.20is.20quadratic
[3]: https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Frust-analyzer/topic/Syntax.20highlighting.20is.20quadratic/near/243412392
