bjoernager/rust
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Suggest not mutably borrowing a mutable reference

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This commit is concerned with the case where the user tries to mutably
borrow a mutable reference, thereby triggering an error. Instead of the
existing suggestion to make the binding mutable, the compiler will now
suggest to avoid borrowing altogether.
This commit is contained in:
Yaron Tausky 2018-05-25 20:33:15 +02:00
parent aa094a43cc
commit 3303e6847b
6 changed files with 114 additions and 39 deletions
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42
src/libsyntax/parse/parser.rs
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@ -5190,36 +5190,36 @@ impl<'a> Parser<'a> {
// Only a limited set of initial token sequences is considered self parameters, anything
// else is parsed as a normal function parameter list, so some lookahead is required.
let eself_lo = self.span;
let (eself, eself_ident) = match self.token {
let (eself, eself_ident, eself_hi) = match self.token {
token::BinOp(token::And) => {
// &self
// &mut self
// &'lt self
// &'lt mut self
// &not_self
if isolated_self(self, 1) {
(if isolated_self(self, 1) {
self.bump();
(SelfKind::Region(None, Mutability::Immutable), expect_ident(self))
SelfKind::Region(None, Mutability::Immutable)
} else if self.look_ahead(1, |t| t.is_keyword(keywords::Mut)) &&
isolated_self(self, 2) {
self.bump();
self.bump();
(SelfKind::Region(None, Mutability::Mutable), expect_ident(self))
SelfKind::Region(None, Mutability::Mutable)
} else if self.look_ahead(1, |t| t.is_lifetime()) &&
isolated_self(self, 2) {
self.bump();
let lt = self.expect_lifetime();
(SelfKind::Region(Some(lt), Mutability::Immutable), expect_ident(self))
SelfKind::Region(Some(lt), Mutability::Immutable)
} else if self.look_ahead(1, |t| t.is_lifetime()) &&
self.look_ahead(2, |t| t.is_keyword(keywords::Mut)) &&
isolated_self(self, 3) {
self.bump();
let lt = self.expect_lifetime();
self.bump();
(SelfKind::Region(Some(lt), Mutability::Mutable), expect_ident(self))
SelfKind::Region(Some(lt), Mutability::Mutable)
} else {
return Ok(None);
}
}, expect_ident(self), self.prev_span)
}
token::BinOp(token::Star) => {
// *self
@ -5227,43 +5227,45 @@ impl<'a> Parser<'a> {
// *mut self
// *not_self
// Emit special error for `self` cases.
if isolated_self(self, 1) {
(if isolated_self(self, 1) {
self.bump();
self.span_err(self.span, "cannot pass `self` by raw pointer");
(SelfKind::Value(Mutability::Immutable), expect_ident(self))
SelfKind::Value(Mutability::Immutable)
} else if self.look_ahead(1, |t| t.is_mutability()) &&
isolated_self(self, 2) {
self.bump();
self.bump();
self.span_err(self.span, "cannot pass `self` by raw pointer");
(SelfKind::Value(Mutability::Immutable), expect_ident(self))
SelfKind::Value(Mutability::Immutable)
} else {
return Ok(None);
}
}, expect_ident(self), self.prev_span)
}
token::Ident(..) => {
if isolated_self(self, 0) {
// self
// self: TYPE
let eself_ident = expect_ident(self);
if self.eat(&token::Colon) {
let eself_hi = self.prev_span;
(if self.eat(&token::Colon) {
let ty = self.parse_ty()?;
(SelfKind::Explicit(ty, Mutability::Immutable), eself_ident)
SelfKind::Explicit(ty, Mutability::Immutable)
} else {
(SelfKind::Value(Mutability::Immutable), eself_ident)
}
SelfKind::Value(Mutability::Immutable)
}, eself_ident, eself_hi)
} else if self.token.is_keyword(keywords::Mut) &&
isolated_self(self, 1) {
// mut self
// mut self: TYPE
self.bump();
let eself_ident = expect_ident(self);
if self.eat(&token::Colon) {
let eself_hi = self.prev_span;
(if self.eat(&token::Colon) {
let ty = self.parse_ty()?;
(SelfKind::Explicit(ty, Mutability::Mutable), eself_ident)
SelfKind::Explicit(ty, Mutability::Mutable)
} else {
(SelfKind::Value(Mutability::Mutable), eself_ident)
}
SelfKind::Value(Mutability::Mutable)
}, eself_ident, eself_hi)
} else {
return Ok(None);
}
@ -5271,7 +5273,7 @@ impl<'a> Parser<'a> {
_ => return Ok(None),
};
let eself = codemap::respan(eself_lo.to(self.prev_span), eself);
let eself = codemap::respan(eself_lo.to(eself_hi), eself);
Ok(Some(Arg::from_self(eself, eself_ident)))
}