StructField -> FieldDef ("field definition")
Field -> ExprField ("expression field", not "field expression")
FieldPat -> PatField ("pattern field", not "field pattern")
Also rename visiting and other methods working on them.
Improve suggestion for tuple struct pattern matching errors.
Closes#80174
This change allows numbers to be parsed as field names when pattern matching on structs, which allows us to provide better error messages when tuple structs are matched using a struct pattern.
r? ``@estebank``
Reduce log level used by tracing instrumentation from info to debug
Restore log level to debug to avoid make info log level overly verbose (the uses of instrument attribute modified there, were for the most part a replacement for `debug!`; one use was novel).
Currently, when a user uses a struct pattern to pattern match on
a tuple struct, the errors we emit generally suggest adding fields
using their field names, which are numbers. However, numbers are
not valid identifiers, so the suggestions, which use the shorthand
notation, are not valid syntax. This commit changes those errors
to suggest using the actual tuple struct pattern syntax instead,
which is a more actionable suggestion.
In #76612, suggestions were added for missing fields in
patterns. However, the suggestions are being inserted just at the end
of the last field in the pattern—before any trailing comma after the
last field. This resulted in the "if you don't care about missing
fields" suggestion to recommend code with a trailing comma after the
field ellipsis (`..,`), which is actually not legal ("`..` must be at
the end and cannot have a trailing comma")!
Incidentally, the doc-comment on `error_unmentioned_fields` was using
`you_cant_use_this_field` as an example field name (presumably
copy-paste inherited from the description of Issue #76077), but
the present author found this confusing, because unmentioned fields
aren't necessarily unusable.
The suggested code in the diff this commit introduces to
`destructuring-assignment/struct_destructure_fail.stderr` doesn't
work, but it didn't work beforehand, either (because of the "found
reserved identifier `_`" thing), so you can't really call it a
regression; it could be fixed in a separate PR.
Resolves#78511.
For example, this code:
struct S(i32, f32);
let S(x) = S(0, 1.0);
will make the compiler suggest either:
let S(x, _) = S(0, 1.0);
or:
let S(x, ..) = S(0, 1.0);
rustc_ast currently has a few dependencies on rustc_lexer. Ideally, an AST
would not have any dependency its lexer, for minimizing unnecessarily
design-time dependencies. Breaking this dependency would also have practical
benefits, since modifying rustc_lexer would not trigger a rebuild of rustc_ast.
This commit does not remove the rustc_ast --> rustc_lexer dependency,
but it does remove one of the sources of this dependency, which is the
code that handles fuzzy matching between symbol names for making suggestions
in diagnostics. Since that code depends only on Symbol, it is easy to move
it to rustc_span. It might even be best to move it to a separate crate,
since other tools such as Cargo use the same algorithm, and have simply
contain a duplicate of the code.
This changes the signature of find_best_match_for_name so that it is no
longer generic over its input. I checked the optimized binaries, and this
function was duplicated at nearly every call site, because most call sites
used short-lived iterator chains, generic over Map and such. But there's
no good reason for a function like this to be generic, since all it does
is immediately convert the generic input (the Iterator impl) to a concrete
Vec<Symbol>. This has all of the costs of generics (duplicated method bodies)
with no benefit.
Changing find_best_match_for_name to be non-generic removed about 10KB of
code from the optimized binary. I know it's a drop in the bucket, but we have
to start reducing binary size, and beginning to tame over-use of generics
is part of that.
Implement destructuring assignment for tuples
This is the first step towards implementing destructuring assignment (RFC: https://github.com/rust-lang/rfcs/pull/2909, tracking issue: #71126). This PR is the first part of #71156, which was split up to allow for easier review.
Quick summary: This change allows destructuring the LHS of an assignment if it's a (possibly nested) tuple.
It is implemented via a desugaring (AST -> HIR lowering) as follows:
```rust
(a,b) = (1,2)
```
... becomes ...
```rust
{
let (lhs0,lhs1) = (1,2);
a = lhs0;
b = lhs1;
}
```
Thanks to `@varkor` who helped with the implementation, particularly around default binding modes.
r? `@petrochenkov`
give *even better* suggestion when matching a const range
notice that the err already has "constant defined here"
so this is now *exceedingly clear*
extension to #76222
r? @estebank
This commit adjusts the missing field diagnostic logic for struct
patterns in typeck to improve the diagnostic when the missing fields are
inaccessible.
Signed-off-by: David Wood <david@davidtw.co>
Vadim Petrochenkov
klensy
Dylan DPC
Reese Williams
bors
Jonas Schievink
Esteban Küber
Tomasz Miąsko
Zack M. Davis
Camelid
LeSeulArtichaut
Arlie Davis
Mara Bos
oli
Bastian Kauschke
Fabian Zaiser
ankushduacodes
varkor
Ralf Jung
Gus Wynn
Matthias Krüger
David Wood
mark