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Rollup merge of #60393 - estebank:pat-sugg, r=oli-obk

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Do not suggest incorrect syntax on pattern type error due to borrow

Fix #55174.
This commit is contained in:
Mazdak Farrokhzad 2019-05-03 16:24:59 +02:00 committed by GitHub
commit 3e536e8ac6
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GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 151 additions and 17 deletions
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57
src/librustc_typeck/check/_match.rs
View File

@ -1,8 +1,8 @@
use crate::check::{FnCtxt, Expectation, Diverges, Needs};
use crate::check::coercion::CoerceMany;
use crate::util::nodemap::FxHashMap;
use errors::Applicability;
use rustc::hir::{self, PatKind};
use errors::{Applicability, DiagnosticBuilder};
use rustc::hir::{self, PatKind, Pat};
use rustc::hir::def::{Def, CtorKind};
use rustc::hir::pat_util::EnumerateAndAdjustIterator;
use rustc::infer;
@ -377,15 +377,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
// Look for a case like `fn foo(&foo: u32)` and suggest
// `fn foo(foo: &u32)`
if let Some(mut err) = err {
if let PatKind::Binding(..) = inner.node {
if let Ok(snippet) = tcx.sess.source_map()
.span_to_snippet(pat.span)
{
err.help(&format!("did you mean `{}: &{}`?",
&snippet[1..],
expected));
}
}
self.borrow_pat_suggestion(&mut err, &pat, &inner, &expected);
err.emit();
}
(rptr_ty, inner_ty)
@ -517,6 +509,49 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
// subtyping.
}
fn borrow_pat_suggestion(
&self,
err: &mut DiagnosticBuilder<'_>,
pat: &Pat,
inner: &Pat,
expected: Ty<'tcx>,
) {
let tcx = self.tcx;
if let PatKind::Binding(..) = inner.node {
let parent_id = tcx.hir().get_parent_node_by_hir_id(pat.hir_id);
let parent = tcx.hir().get_by_hir_id(parent_id);
debug!("inner {:?} pat {:?} parent {:?}", inner, pat, parent);
match parent {
hir::Node::Item(hir::Item { node: hir::ItemKind::Fn(..), .. }) |
hir::Node::ForeignItem(hir::ForeignItem {
node: hir::ForeignItemKind::Fn(..), ..
}) |
hir::Node::TraitItem(hir::TraitItem { node: hir::TraitItemKind::Method(..), .. }) |
hir::Node::ImplItem(hir::ImplItem { node: hir::ImplItemKind::Method(..), .. }) => {
// this pat is likely an argument
if let Ok(snippet) = tcx.sess.source_map().span_to_snippet(inner.span) {
// FIXME: turn into structured suggestion, will need a span that also
// includes the the arg's type.
err.help(&format!("did you mean `{}: &{}`?", snippet, expected));
}
}
hir::Node::Expr(hir::Expr { node: hir::ExprKind::Match(..), .. }) |
hir::Node::Pat(_) => {
// rely on match ergonomics or it might be nested `&&pat`
if let Ok(snippet) = tcx.sess.source_map().span_to_snippet(inner.span) {
err.span_suggestion(
pat.span,
"you can probably remove the explicit borrow",
snippet,
Applicability::MaybeIncorrect,
);
}
}
_ => {} // don't provide suggestions in other cases #55175
}
}
}
pub fn check_dereferencable(&self, span: Span, expected: Ty<'tcx>, inner: &hir::Pat) -> bool {
if let PatKind::Binding(..) = inner.node {
if let Some(mt) = self.shallow_resolve(expected).builtin_deref(true) {

12
src/test/ui/destructure-trait-ref.stderr
View File

@ -20,21 +20,25 @@ error[E0308]: mismatched types
--> $DIR/destructure-trait-ref.rs:31:10
|
LL | let &&x = &1isize as &T;
| ^^ expected trait T, found reference
| ^^
| |
| expected trait T, found reference
| help: you can probably remove the explicit borrow: `x`
|
= note: expected type `dyn T`
found type `&_`
= help: did you mean `x: &dyn T`?
error[E0308]: mismatched types
--> $DIR/destructure-trait-ref.rs:36:11
|
LL | let &&&x = &(&1isize as &T);
| ^^ expected trait T, found reference
| ^^
| |
| expected trait T, found reference
| help: you can probably remove the explicit borrow: `x`
|
= note: expected type `dyn T`
found type `&_`
= help: did you mean `x: &dyn T`?
error[E0308]: mismatched types
--> $DIR/destructure-trait-ref.rs:41:13

6
src/test/ui/mismatched_types/issue-38371.stderr
View File

@ -12,11 +12,13 @@ error[E0308]: mismatched types
--> $DIR/issue-38371.rs:18:9
|
LL | fn agh(&&bar: &u32) {
| ^^^^ expected u32, found reference
| ^^^^
| |
| expected u32, found reference
| help: you can probably remove the explicit borrow: `bar`
|
= note: expected type `u32`
found type `&_`
= help: did you mean `bar: &u32`?
error[E0308]: mismatched types
--> $DIR/issue-38371.rs:21:8

41
src/test/ui/suggestions/match-ergonomics.rs Normal file
View File

@ -0,0 +1,41 @@
fn main() {
let x = vec![1i32];
match &x[..] {
[&v] => {}, //~ ERROR mismatched types
_ => {},
}
match x {
[&v] => {}, //~ ERROR expected an array or slice
_ => {},
}
match &x[..] {
[v] => {},
_ => {},
}
match &x[..] {
&[v] => {},
_ => {},
}
match x {
[v] => {}, //~ ERROR expected an array or slice
_ => {},
}
let y = 1i32;
match &y {
&v => {},
_ => {},
}
match y {
&v => {}, //~ ERROR mismatched types
_ => {},
}
match &y {
v => {},
_ => {},
}
match y {
v => {},
_ => {},
}
if let [&v] = &x[..] {} //~ ERROR mismatched types
}

52
src/test/ui/suggestions/match-ergonomics.stderr Normal file
View File

@ -0,0 +1,52 @@
error[E0308]: mismatched types
--> $DIR/match-ergonomics.rs:4:10
|
LL | [&v] => {},
| ^^
| |
| expected i32, found reference
| help: you can probably remove the explicit borrow: `v`
|
= note: expected type `i32`
found type `&_`
error[E0529]: expected an array or slice, found `std::vec::Vec<i32>`
--> $DIR/match-ergonomics.rs:8:9
|
LL | [&v] => {},
| ^^^^ pattern cannot match with input type `std::vec::Vec<i32>`
error[E0529]: expected an array or slice, found `std::vec::Vec<i32>`
--> $DIR/match-ergonomics.rs:20:9
|
LL | [v] => {},
| ^^^ pattern cannot match with input type `std::vec::Vec<i32>`
error[E0308]: mismatched types
--> $DIR/match-ergonomics.rs:29:9
|
LL | &v => {},
| ^^
| |
| expected i32, found reference
| help: you can probably remove the explicit borrow: `v`
|
= note: expected type `i32`
found type `&_`
error[E0308]: mismatched types
--> $DIR/match-ergonomics.rs:40:13
|
LL | if let [&v] = &x[..] {}
| ^^
| |
| expected i32, found reference
| help: you can probably remove the explicit borrow: `v`
|
= note: expected type `i32`
found type `&_`
error: aborting due to 5 previous errors
Some errors have detailed explanations: E0308, E0529.
For more information about an error, try `rustc --explain E0308`.