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Auto merge of #40043 - petrochenkov:objpars, r=nikomatsakis 

Refactor parsing of trait object types

Bugs are fixed and code is cleaned up.

User visible changes:
- `ty` matcher in macros accepts trait object types like `Write + Send` (https://github.com/rust-lang/rust/issues/39080)
- Buggy priority of `+` in trait object types starting with `for` is fixed (https://github.com/rust-lang/rust/issues/39317). `&for<'a> Trait<'a> + Send` is now parsed as `(&for<'a> Trait<'a>) + Send` and requires parens `&(for<'a> Trait<'a> + Send)`. For comparison, `&Send + for<'a> Trait<'a>` was parsed like this since [Nov 27, 2014](https://github.com/rust-lang/rust/pull/19298).
- Trailing `+`s are supported in trait objects, like in other bounds.
- Better error reporting for trait objects starting with `?Sized`.

Fixes https://github.com/rust-lang/rust/issues/39080
Fixes https://github.com/rust-lang/rust/issues/39317 [breaking-change]
Closes https://github.com/rust-lang/rust/issues/39298
cc https://github.com/rust-lang/rust/issues/39085 (fixed, then reverted https://github.com/rust-lang/rust/pull/40043#issuecomment-286570653)
cc https://github.com/rust-lang/rust/issues/39318 (fixed, then reverted https://github.com/rust-lang/rust/pull/40043#issuecomment-284493890)

r? @nikomatsakis
This commit is contained in:
bors 2017-03-22 02:00:16 +00:00
parent 50c4e3e8d0 b5e889791a
commit 8c4f2c64c6
21 changed files with 294 additions and 267 deletions
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12
src/libsyntax/ast.rs
View File

@ -17,7 +17,7 @@ pub use self::PathParameters::*;
pub use symbol::Symbol as Name;
pub use util::ThinVec;
use syntax_pos::{mk_sp, Span, DUMMY_SP, ExpnId};
use syntax_pos::{mk_sp, BytePos, Span, DUMMY_SP, ExpnId};
use codemap::{respan, Spanned};
use abi::Abi;
use ext::hygiene::SyntaxContext;
@ -1716,6 +1716,16 @@ pub struct PolyTraitRef {
pub span: Span,
}
impl PolyTraitRef {
pub fn new(lifetimes: Vec<LifetimeDef>, path: Path, lo: BytePos, hi: BytePos) -> Self {
PolyTraitRef {
bound_lifetimes: lifetimes,
trait_ref: TraitRef { path: path, ref_id: DUMMY_NODE_ID },
span: mk_sp(lo, hi),
}
}
}
#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
pub enum Visibility {
Public,

2
src/libsyntax/ext/expand.rs
View File

@ -657,7 +657,7 @@ impl<'a> Parser<'a> {
}
ExpansionKind::Expr => Expansion::Expr(self.parse_expr()?),
ExpansionKind::OptExpr => Expansion::OptExpr(Some(self.parse_expr()?)),
ExpansionKind::Ty => Expansion::Ty(self.parse_ty_no_plus()?),
ExpansionKind::Ty => Expansion::Ty(self.parse_ty()?),
ExpansionKind::Pat => Expansion::Pat(self.parse_pat()?),
})
}

2
src/libsyntax/ext/quote.rs
View File

@ -414,7 +414,7 @@ pub fn parse_arm_panic(parser: &mut Parser) -> Arm {
}
pub fn parse_ty_panic(parser: &mut Parser) -> P<Ty> {
panictry!(parser.parse_ty_no_plus())
panictry!(parser.parse_ty())
}
pub fn parse_stmt_panic(parser: &mut Parser) -> Option<Stmt> {

2
src/libsyntax/ext/tt/macro_parser.rs
View File

@ -512,7 +512,7 @@ fn parse_nt<'a>(p: &mut Parser<'a>, sp: Span, name: &str) -> Nonterminal {
},
"pat" => token::NtPat(panictry!(p.parse_pat())),
"expr" => token::NtExpr(panictry!(p.parse_expr())),
"ty" => token::NtTy(panictry!(p.parse_ty_no_plus())),
"ty" => token::NtTy(panictry!(p.parse_ty())),
// this could be handled like a token, since it is one
"ident" => match p.token {
token::Ident(sn) => {

404
src/libsyntax/parse/parser.rs
View File

@ -41,7 +41,7 @@ use ast::{BinOpKind, UnOp};
use ast::RangeEnd;
use {ast, attr};
use codemap::{self, CodeMap, Spanned, spanned, respan};
use syntax_pos::{self, Span, Pos, BytePos, mk_sp};
use syntax_pos::{self, Span, BytePos, mk_sp};
use errors::{self, DiagnosticBuilder};
use parse::{self, classify, token};
use parse::common::SeqSep;
@ -1116,57 +1116,13 @@ impl<'a> Parser<'a> {
self.check_keyword(keywords::Extern)
}
pub fn get_lifetime(&mut self) -> ast::Ident {
fn get_label(&mut self) -> ast::Ident {
match self.token {
token::Lifetime(ref ident) => *ident,
_ => self.bug("not a lifetime"),
}
}
pub fn parse_for_in_type(&mut self) -> PResult<'a, TyKind> {
/*
Parses whatever can come after a `for` keyword in a type.
The `for` hasn't been consumed.
- for <'lt> [unsafe] [extern "ABI"] fn (S) -> T
- for <'lt> path::foo(a, b) + Trait + 'a
*/
let lo = self.span.lo;
let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
// examine next token to decide to do
if self.token_is_bare_fn_keyword() {
self.parse_ty_bare_fn(lifetime_defs)
} else {
let hi = self.span.hi;
let trait_ref = self.parse_trait_ref()?;
let poly_trait_ref = PolyTraitRef { bound_lifetimes: lifetime_defs,
trait_ref: trait_ref,
span: mk_sp(lo, hi)};
let other_bounds = if self.eat(&token::BinOp(token::Plus)) {
self.parse_ty_param_bounds()?
} else {
Vec::new()
};
let all_bounds =
Some(TraitTyParamBound(poly_trait_ref, TraitBoundModifier::None)).into_iter()
.chain(other_bounds)
.collect();
Ok(ast::TyKind::TraitObject(all_bounds))
}
}
pub fn parse_impl_trait_type(&mut self) -> PResult<'a, TyKind> {
// Parses whatever can come after a `impl` keyword in a type.
// The `impl` has already been consumed.
Ok(ast::TyKind::ImplTrait(self.parse_ty_param_bounds()?))
}
pub fn parse_ty_path(&mut self) -> PResult<'a, TyKind> {
Ok(TyKind::Path(None, self.parse_path(PathStyle::Type)?))
}
/// parse a TyKind::BareFn type:
pub fn parse_ty_bare_fn(&mut self, lifetime_defs: Vec<LifetimeDef>)
-> PResult<'a, TyKind> {
@ -1347,84 +1303,9 @@ impl<'a> Parser<'a> {
}
}
/// Parse a type.
// Parse a type
pub fn parse_ty(&mut self) -> PResult<'a, P<Ty>> {
let lo = self.span.lo;
let lhs = self.parse_ty_no_plus()?;
if !self.eat(&token::BinOp(token::Plus)) {
return Ok(lhs);
}
let mut bounds = self.parse_ty_param_bounds()?;
// In type grammar, `+` is treated like a binary operator,
// and hence both L and R side are required.
if bounds.is_empty() {
let prev_span = self.prev_span;
self.span_err(prev_span,
"at least one type parameter bound \
must be specified");
}
let mut lhs = lhs.unwrap();
if let TyKind::Paren(ty) = lhs.node {
// We have to accept the first bound in parens for backward compatibility.
// Example: `(Bound) + Bound + Bound`
lhs = ty.unwrap();
}
if let TyKind::Path(None, path) = lhs.node {
let poly_trait_ref = PolyTraitRef {
bound_lifetimes: Vec::new(),
trait_ref: TraitRef { path: path, ref_id: lhs.id },
span: lhs.span,
};
let poly_trait_ref = TraitTyParamBound(poly_trait_ref, TraitBoundModifier::None);
bounds.insert(0, poly_trait_ref);
} else {
let mut err = struct_span_err!(self.sess.span_diagnostic, lhs.span, E0178,
"expected a path on the left-hand side \
of `+`, not `{}`",
pprust::ty_to_string(&lhs));
err.span_label(lhs.span, &format!("expected a path"));
let hi = bounds.iter().map(|x| match *x {
TraitTyParamBound(ref tr, _) => tr.span.hi,
RegionTyParamBound(ref r) => r.span.hi,
}).max_by_key(|x| x.to_usize());
let full_span = hi.map(|hi| Span {
lo: lhs.span.lo,
hi: hi,
expn_id: lhs.span.expn_id,
});
match (&lhs.node, full_span) {
(&TyKind::Rptr(ref lifetime, ref mut_ty), Some(full_span)) => {
let ty_str = pprust::to_string(|s| {
use print::pp::word;
use print::pprust::PrintState;
word(&mut s.s, "&")?;
s.print_opt_lifetime(lifetime)?;
s.print_mutability(mut_ty.mutbl)?;
s.popen()?;
s.print_type(&mut_ty.ty)?;
s.print_bounds(" +", &bounds)?;
s.pclose()
});
err.span_suggestion(full_span, "try adding parentheses (per RFC 438):",
ty_str);
}
_ => {
help!(&mut err,
"perhaps you forgot parentheses? (per RFC 438)");
}
}
err.emit();
}
let sp = mk_sp(lo, self.prev_span.hi);
let sum = TyKind::TraitObject(bounds);
Ok(P(Ty {id: ast::DUMMY_NODE_ID, node: sum, span: sp}))
self.parse_ty_common(true)
}
/// Parse a type in restricted contexts where `+` is not permitted.
@ -1432,15 +1313,17 @@ impl<'a> Parser<'a> {
/// `+` is prohibited to maintain operator priority (P(+) < P(&)).
/// Example 2: `value1 as TYPE + value2`
/// `+` is prohibited to avoid interactions with expression grammar.
pub fn parse_ty_no_plus(&mut self) -> PResult<'a, P<Ty>> {
fn parse_ty_no_plus(&mut self) -> PResult<'a, P<Ty>> {
self.parse_ty_common(false)
}
fn parse_ty_common(&mut self, allow_plus: bool) -> PResult<'a, P<Ty>> {
maybe_whole!(self, NtTy, |x| x);
let lo = self.span.lo;
let t = if self.eat(&token::OpenDelim(token::Paren)) {
// (t) is a parenthesized ty
// (t,) is the type of a tuple with only one field,
// of type t
let node = if self.eat(&token::OpenDelim(token::Paren)) {
// `(TYPE)` is a parenthesized type.
// `(TYPE,)` is a tuple with a single field of type TYPE.
let mut ts = vec![];
let mut last_comma = false;
while self.token != token::CloseDelim(token::Paren) {
@ -1452,81 +1335,162 @@ impl<'a> Parser<'a> {
break;
}
}
self.expect(&token::CloseDelim(token::Paren))?;
if ts.len() == 1 && !last_comma {
TyKind::Paren(ts.into_iter().nth(0).unwrap())
let ty = ts.into_iter().nth(0).unwrap().unwrap();
match ty.node {
// Accept `(Trait1) + Trait2 + 'a` for backward compatibility (#39318).
TyKind::Path(None, ref path)
if allow_plus && self.token == token::BinOp(token::Plus) => {
self.bump(); // `+`
let pt = PolyTraitRef::new(Vec::new(), path.clone(), lo, self.prev_span.hi);
let mut bounds = vec![TraitTyParamBound(pt, TraitBoundModifier::None)];
bounds.append(&mut self.parse_ty_param_bounds()?);
TyKind::TraitObject(bounds)
}
_ => TyKind::Paren(P(ty))
}
} else {
TyKind::Tup(ts)
}
} else if self.eat(&token::Not) {
// Never type `!`
TyKind::Never
} else if self.eat(&token::BinOp(token::Star)) {
// STAR POINTER (bare pointer?)
// Raw pointer
TyKind::Ptr(self.parse_ptr()?)
} else if self.eat(&token::OpenDelim(token::Bracket)) {
// VECTOR
// Array or slice
let t = self.parse_ty()?;
// Parse the `; e` in `[ i32; e ]`
// where `e` is a const expression
// Parse optional `; EXPR` in `[TYPE; EXPR]`
let t = match self.maybe_parse_fixed_length_of_vec()? {
None => TyKind::Slice(t),
Some(suffix) => TyKind::Array(t, suffix)
Some(suffix) => TyKind::Array(t, suffix),
};
self.expect(&token::CloseDelim(token::Bracket))?;
t
} else if self.check(&token::BinOp(token::And)) ||
self.check(&token::AndAnd) {
// BORROWED POINTER
} else if self.check(&token::BinOp(token::And)) || self.check(&token::AndAnd) {
// Reference
self.expect_and()?;
self.parse_borrowed_pointee()?
} else if self.check_keyword(keywords::For) {
// FIXME `+` has incorrect priority in trait object types starting with `for` (#39317).
self.parse_for_in_type()?
} else if self.eat_keyword(keywords::Impl) {
// FIXME figure out priority of `+` in `impl Trait1 + Trait2` (#34511).
self.parse_impl_trait_type()?
} else if self.token_is_bare_fn_keyword() {
// BARE FUNCTION
self.parse_ty_bare_fn(Vec::new())?
} else if self.eat_keyword_noexpect(keywords::Typeof) {
// TYPEOF
// `typeof(EXPR)`
// In order to not be ambiguous, the type must be surrounded by parens.
self.expect(&token::OpenDelim(token::Paren))?;
let e = self.parse_expr()?;
self.expect(&token::CloseDelim(token::Paren))?;
TyKind::Typeof(e)
} else if self.eat(&token::Underscore) {
// A type to be inferred `_`
TyKind::Infer
} else if self.eat_lt() {
// Qualified path
let (qself, path) = self.parse_qualified_path(PathStyle::Type)?;
TyKind::Path(Some(qself), path)
} else if self.token.is_path_start() {
// Simple path
let path = self.parse_path(PathStyle::Type)?;
if self.eat(&token::Not) {
// MACRO INVOCATION
// Macro invocation in type position
let (_, tts) = self.expect_delimited_token_tree()?;
let hi = self.span.hi;
TyKind::Mac(spanned(lo, hi, Mac_ { path: path, tts: tts }))
TyKind::Mac(spanned(lo, self.span.hi, Mac_ { path: path, tts: tts }))
} else {
// NAMED TYPE
TyKind::Path(None, path)
// Just a type path or bound list (trait object type) starting with a trait.
// `Type`
// `Trait1 + Trait2 + 'a`
if allow_plus && self.eat(&token::BinOp(token::Plus)) {
let poly_trait = PolyTraitRef::new(Vec::new(), path, lo, self.prev_span.hi);
let mut bounds = vec![TraitTyParamBound(poly_trait, TraitBoundModifier::None)];
bounds.append(&mut self.parse_ty_param_bounds()?);
TyKind::TraitObject(bounds)
} else {
TyKind::Path(None, path)
}
}
} else if self.eat(&token::Underscore) {
// TYPE TO BE INFERRED
TyKind::Infer
} else if self.token_is_bare_fn_keyword() {
// Function pointer type
self.parse_ty_bare_fn(Vec::new())?
} else if self.check_keyword(keywords::For) {
// Function pointer type or bound list (trait object type) starting with a poly-trait.
// `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T`
// `for<'lt> Trait1<'lt> + Trait2 + 'a`
let lo = self.span.lo;
let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
if self.token_is_bare_fn_keyword() {
self.parse_ty_bare_fn(lifetime_defs)?
} else {
let path = self.parse_path(PathStyle::Type)?;
let poly_trait = PolyTraitRef::new(lifetime_defs, path, lo, self.prev_span.hi);
let mut bounds = vec![TraitTyParamBound(poly_trait, TraitBoundModifier::None)];
if allow_plus && self.eat(&token::BinOp(token::Plus)) {
bounds.append(&mut self.parse_ty_param_bounds()?)
}
TyKind::TraitObject(bounds)
}
} else if self.eat_keyword(keywords::Impl) {
// FIXME: figure out priority of `+` in `impl Trait1 + Trait2` (#34511).
TyKind::ImplTrait(self.parse_ty_param_bounds()?)
} else if self.check(&token::Question) {
// Bound list (trait object type)
// Bound lists starting with `'lt` are not currently supported (#40043)
TyKind::TraitObject(self.parse_ty_param_bounds_common(allow_plus)?)
} else {
let msg = format!("expected type, found {}", self.this_token_descr());
return Err(self.fatal(&msg));
};
let sp = mk_sp(lo, self.prev_span.hi);
Ok(P(Ty {id: ast::DUMMY_NODE_ID, node: t, span: sp}))
let span = mk_sp(lo, self.prev_span.hi);
let ty = Ty { node: node, span: span, id: ast::DUMMY_NODE_ID };
// Try to recover from use of `+` with incorrect priority.
self.maybe_recover_from_bad_type_plus(allow_plus, &ty)?;
Ok(P(ty))
}
pub fn parse_borrowed_pointee(&mut self) -> PResult<'a, TyKind> {
// look for `&'lt` or `&'foo ` and interpret `foo` as the region name:
let opt_lifetime = self.eat_lifetime();
let mutbl = self.parse_mutability()?;
fn maybe_recover_from_bad_type_plus(&mut self, allow_plus: bool, ty: &Ty) -> PResult<'a, ()> {
// Do not add `+` to expected tokens.
if !allow_plus || self.token != token::BinOp(token::Plus) {
return Ok(())
}
self.bump(); // `+`
let bounds = self.parse_ty_param_bounds()?;
let sum_span = mk_sp(ty.span.lo, self.prev_span.hi);
let mut err = struct_span_err!(self.sess.span_diagnostic, ty.span, E0178,
"expected a path on the left-hand side of `+`, not `{}`", pprust::ty_to_string(&ty));
err.span_label(ty.span, &format!("expected a path"));
match ty.node {
TyKind::Rptr(ref lifetime, ref mut_ty) => {
let sum_with_parens = pprust::to_string(|s| {
use print::pp::word;
use print::pprust::PrintState;
word(&mut s.s, "&")?;
s.print_opt_lifetime(lifetime)?;
s.print_mutability(mut_ty.mutbl)?;
s.popen()?;
s.print_type(&mut_ty.ty)?;
s.print_bounds(" +", &bounds)?;
s.pclose()
});
err.span_suggestion(sum_span, "try adding parentheses:", sum_with_parens);
}
TyKind::Ptr(..) | TyKind::BareFn(..) => {
help!(&mut err, "perhaps you forgot parentheses?");
}
_ => {}
}
err.emit();
Ok(())
}
fn parse_borrowed_pointee(&mut self) -> PResult<'a, TyKind> {
let opt_lifetime = if self.check_lifetime() { Some(self.expect_lifetime()) } else { None };
let mutbl = self.parse_mutability();
let ty = self.parse_ty_no_plus()?;
return Ok(TyKind::Rptr(opt_lifetime, MutTy { ty: ty, mutbl: mutbl }));
}
@ -1927,30 +1891,28 @@ impl<'a> Parser<'a> {
}
}
/// Parse single lifetime 'a or nothing.
pub fn eat_lifetime(&mut self) -> Option<Lifetime> {
fn check_lifetime(&mut self) -> bool {
self.expected_tokens.push(TokenType::Lifetime);
self.token.is_lifetime()
}
/// Parse single lifetime 'a or panic.
fn expect_lifetime(&mut self) -> Lifetime {
match self.token {
token::Lifetime(ident) => {
self.bump();
Some(Lifetime {
id: ast::DUMMY_NODE_ID,
span: self.prev_span,
name: ident.name
})
}
_ => {
self.expected_tokens.push(TokenType::Lifetime);
None
Lifetime { name: ident.name, span: self.prev_span, id: ast::DUMMY_NODE_ID }
}
_ => self.span_bug(self.span, "not a lifetime")
}
}
/// Parse mutability (`mut` or nothing).
pub fn parse_mutability(&mut self) -> PResult<'a, Mutability> {
fn parse_mutability(&mut self) -> Mutability {
if self.eat_keyword(keywords::Mut) {
Ok(Mutability::Mutable)
Mutability::Mutable
} else {
Ok(Mutability::Immutable)
Mutability::Immutable
}
}
@ -2207,7 +2169,7 @@ impl<'a> Parser<'a> {
return self.parse_while_expr(None, lo, attrs);
}
if self.token.is_lifetime() {
let label = Spanned { node: self.get_lifetime(),
let label = Spanned { node: self.get_label(),
span: self.span };
let lo = self.span.lo;
self.bump();
@ -2230,7 +2192,7 @@ impl<'a> Parser<'a> {
if self.eat_keyword(keywords::Continue) {
let ex = if self.token.is_lifetime() {
let ex = ExprKind::Continue(Some(Spanned{
node: self.get_lifetime(),
node: self.get_label(),
span: self.span
}));
self.bump();
@ -2267,7 +2229,7 @@ impl<'a> Parser<'a> {
} else if self.eat_keyword(keywords::Break) {
let lt = if self.token.is_lifetime() {
let spanned_lt = Spanned {
node: self.get_lifetime(),
node: self.get_label(),
span: self.span
};
self.bump();
@ -2700,7 +2662,7 @@ impl<'a> Parser<'a> {
}
token::BinOp(token::And) | token::AndAnd => {
self.expect_and()?;
let m = self.parse_mutability()?;
let m = self.parse_mutability();
let e = self.parse_prefix_expr(None);
let (span, e) = self.interpolated_or_expr_span(e)?;
hi = span.hi;
@ -3422,7 +3384,7 @@ impl<'a> Parser<'a> {
token::BinOp(token::And) | token::AndAnd => {
// Parse &pat / &mut pat
self.expect_and()?;
let mutbl = self.parse_mutability()?;
let mutbl = self.parse_mutability();
if let token::Lifetime(ident) = self.token {
return Err(self.fatal(&format!("unexpected lifetime `{}` in pattern", ident)));
}
@ -3449,7 +3411,7 @@ impl<'a> Parser<'a> {
pat = self.parse_pat_ident(BindingMode::ByValue(Mutability::Mutable))?;
} else if self.eat_keyword(keywords::Ref) {
// Parse ref ident @ pat / ref mut ident @ pat
let mutbl = self.parse_mutability()?;
let mutbl = self.parse_mutability();
pat = self.parse_pat_ident(BindingMode::ByRef(mutbl))?;
} else if self.eat_keyword(keywords::Box) {
// Parse box pat
@ -4069,30 +4031,32 @@ impl<'a> Parser<'a> {
// BOUND = TY_BOUND | LT_BOUND
// LT_BOUND = LIFETIME (e.g. `'a`)
// TY_BOUND = [?] [for<LT_PARAM_DEFS>] SIMPLE_PATH (e.g. `?for<'a: 'b> m::Trait<'a>`)
fn parse_ty_param_bounds(&mut self) -> PResult<'a, TyParamBounds>
{
fn parse_ty_param_bounds_common(&mut self, allow_plus: bool) -> PResult<'a, TyParamBounds> {
let mut bounds = Vec::new();
loop {
let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None };
if let Some(lifetime) = self.eat_lifetime() {
if self.check_lifetime() {
if let Some(question_span) = question {
self.span_err(question_span,
"`?` may only modify trait bounds, not lifetime bounds");
}
bounds.push(RegionTyParamBound(lifetime));
} else {if self.check_keyword(keywords::For) || self.check_path() {
let poly_trait_ref = self.parse_poly_trait_ref()?;
bounds.push(RegionTyParamBound(self.expect_lifetime()));
} else if self.check_keyword(keywords::For) || self.check_path() {
let lo = self.span.lo;
let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
let path = self.parse_path(PathStyle::Type)?;
let poly_trait = PolyTraitRef::new(lifetime_defs, path, lo, self.prev_span.hi);
let modifier = if question.is_some() {
TraitBoundModifier::Maybe
} else {
TraitBoundModifier::None
};
bounds.push(TraitTyParamBound(poly_trait_ref, modifier));
bounds.push(TraitTyParamBound(poly_trait, modifier));
} else {
break
}}
}
if !self.eat(&token::BinOp(token::Plus)) {
if !allow_plus || !self.eat(&token::BinOp(token::Plus)) {
break
}
}
@ -4100,12 +4064,16 @@ impl<'a> Parser<'a> {
return Ok(bounds);
}
fn parse_ty_param_bounds(&mut self) -> PResult<'a, TyParamBounds> {
self.parse_ty_param_bounds_common(true)
}
// Parse bounds of a type parameter `BOUND + BOUND + BOUND` without trailing `+`.
// BOUND = LT_BOUND (e.g. `'a`)
fn parse_lt_param_bounds(&mut self) -> Vec<Lifetime> {
let mut lifetimes = Vec::new();
while let Some(lifetime) = self.eat_lifetime() {
lifetimes.push(lifetime);
while self.check_lifetime() {
lifetimes.push(self.expect_lifetime());
if !self.eat(&token::BinOp(token::Plus)) {
break
@ -4150,7 +4118,8 @@ impl<'a> Parser<'a> {
let mut seen_ty_param = false;
loop {
let attrs = self.parse_outer_attributes()?;
if let Some(lifetime) = self.eat_lifetime() {
if self.check_lifetime() {
let lifetime = self.expect_lifetime();
// Parse lifetime parameter.
let bounds = if self.eat(&token::Colon) {
self.parse_lt_param_bounds()
@ -4166,7 +4135,7 @@ impl<'a> Parser<'a> {
self.span_err(self.prev_span,
"lifetime parameters must be declared prior to type parameters");
}
} else {if self.check_ident() {
} else if self.check_ident() {
// Parse type parameter.
ty_params.push(self.parse_ty_param(attrs)?);
seen_ty_param = true;
@ -4178,7 +4147,7 @@ impl<'a> Parser<'a> {
&format!("trailing attribute after {} parameters", param_kind));
}
break
}}
}
if !self.eat(&token::Comma) {
break
@ -4224,14 +4193,14 @@ impl<'a> Parser<'a> {
let mut seen_type = false;
let mut seen_binding = false;
loop {
if let Some(lifetime) = self.eat_lifetime() {
if self.check_lifetime() && self.look_ahead(1, |t| t != &token::BinOp(token::Plus)) {
// Parse lifetime argument.
lifetimes.push(lifetime);
lifetimes.push(self.expect_lifetime());
if seen_type || seen_binding {
self.span_err(self.prev_span,
"lifetime parameters must be declared prior to type parameters");
}
} else {if self.check_ident() && self.look_ahead(1, |t| t == &token::Eq) {
} else if self.check_ident() && self.look_ahead(1, |t| t == &token::Eq) {
// Parse associated type binding.
let lo = self.span.lo;
let ident = self.parse_ident()?;
@ -4254,7 +4223,7 @@ impl<'a> Parser<'a> {
seen_type = true;
} else {
break
}}
}
if !self.eat(&token::Comma) {
break
@ -4299,7 +4268,8 @@ impl<'a> Parser<'a> {
loop {
let lo = self.span.lo;
if let Some(lifetime) = self.eat_lifetime() {
if self.check_lifetime() && self.look_ahead(1, |t| t != &token::BinOp(token::Plus)) {
let lifetime = self.expect_lifetime();
// Bounds starting with a colon are mandatory, but possibly empty.
self.expect(&token::Colon)?;
let bounds = self.parse_lt_param_bounds();
@ -4310,7 +4280,7 @@ impl<'a> Parser<'a> {
bounds: bounds,
}
));
} else {if self.check_type() {
} else if self.check_type() {
// Parse optional `for<'a, 'b>`.
// This `for` is parsed greedily and applies to the whole predicate,
// the bounded type can have its own `for` applying only to it.
@ -4348,7 +4318,7 @@ impl<'a> Parser<'a> {
}
} else {
break
}}
}
if !self.eat(&token::Comma) {
break
@ -4453,13 +4423,13 @@ impl<'a> Parser<'a> {
} else if self.look_ahead(1, |t| t.is_lifetime()) &&
isolated_self(self, 2) {
self.bump();
let lt = self.eat_lifetime().expect("not a lifetime");
let lt = self.expect_lifetime();
(SelfKind::Region(Some(lt), Mutability::Immutable), expect_ident(self))
} 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.eat_lifetime().expect("not a lifetime");
let lt = self.expect_lifetime();
self.bump();
(SelfKind::Region(Some(lt), Mutability::Mutable), expect_ident(self))
} else {
@ -4852,14 +4822,6 @@ impl<'a> Parser<'a> {
}
}
/// Parse a::B<String,i32>
fn parse_trait_ref(&mut self) -> PResult<'a, TraitRef> {
Ok(TraitRef {
path: self.parse_path(PathStyle::Type)?,
ref_id: ast::DUMMY_NODE_ID,
})
}
fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<LifetimeDef>> {
if self.eat_keyword(keywords::For) {
self.expect_lt()?;
@ -4875,18 +4837,6 @@ impl<'a> Parser<'a> {
}
}
/// Parse for<'l> a::B<String,i32>
fn parse_poly_trait_ref(&mut self) -> PResult<'a, PolyTraitRef> {
let lo = self.span.lo;
let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
Ok(PolyTraitRef {
bound_lifetimes: lifetime_defs,
trait_ref: self.parse_trait_ref()?,
span: mk_sp(lo, self.prev_span.hi),
})
}
/// Parse struct Foo { ... }
fn parse_item_struct(&mut self) -> PResult<'a, ItemInfo> {
let class_name = self.parse_ident()?;

44
src/libsyntax/parse/token.rs
View File

@ -103,6 +103,21 @@ fn ident_can_begin_expr(ident: ast::Ident) -> bool {
].contains(&ident.name)
}
fn ident_can_begin_type(ident: ast::Ident) -> bool {
let ident_token: Token = Ident(ident);
!ident_token.is_any_keyword() ||
ident_token.is_path_segment_keyword() ||
[
keywords::For.name(),
keywords::Impl.name(),
keywords::Fn.name(),
keywords::Unsafe.name(),
keywords::Extern.name(),
keywords::Typeof.name(),
].contains(&ident.name)
}
#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Hash, Debug)]
pub enum Token {
/* Expression-operator symbols. */
@ -182,23 +197,21 @@ impl Token {
/// Returns `true` if the token can appear at the start of an expression.
pub fn can_begin_expr(&self) -> bool {
match *self {
OpenDelim(..) => true,
Ident(ident) => ident_can_begin_expr(ident),
Literal(..) => true,
Not => true,
BinOp(Minus) => true,
BinOp(Star) => true,
BinOp(And) => true,
BinOp(Or) => true, // in lambda syntax
OrOr => true, // in lambda syntax
AndAnd => true, // double borrow
Ident(ident) => ident_can_begin_expr(ident), // value name or keyword
OpenDelim(..) => true, // tuple, array or block
Literal(..) => true, // literal
Not => true, // operator not
BinOp(Minus) => true, // unary minus
BinOp(Star) => true, // dereference
BinOp(Or) | OrOr => true, // closure
BinOp(And) => true, // reference
AndAnd => true, // double reference
DotDot | DotDotDot => true, // range notation
Lt | BinOp(Shl) => true, // associated path
ModSep => true,
Pound => true, // for expression attributes
ModSep => true, // global path
Pound => true, // expression attributes
Interpolated(ref nt) => match **nt {
NtExpr(..) => true,
NtIdent(..) => true,
NtBlock(..) => true,
NtPath(..) => true,
_ => false,
@ -210,19 +223,20 @@ impl Token {
/// Returns `true` if the token can appear at the start of a type.
pub fn can_begin_type(&self) -> bool {
match *self {
Ident(ident) => ident_can_begin_type(ident), // type name or keyword
OpenDelim(Paren) => true, // tuple
OpenDelim(Bracket) => true, // array
Ident(..) => true, // type name or keyword
Underscore => true, // placeholder
Not => true, // never
BinOp(Star) => true, // raw pointer
BinOp(And) => true, // reference
AndAnd => true, // double reference
Question => true, // maybe bound in trait object
Lifetime(..) => true, // lifetime bound in trait object
Lt | BinOp(Shl) => true, // associated path
ModSep => true, // global path
Interpolated(ref nt) => match **nt {
NtTy(..) => true,
NtIdent(..) => true,
NtPath(..) => true,
_ => false,
},

3
src/test/compile-fail/E0178.rs
View File

@ -17,15 +17,12 @@ struct Bar<'a> {
x: &'a Foo + 'a,
//~^ ERROR E0178
//~| NOTE expected a path
//~| ERROR at least one non-builtin trait is required for an object type
y: &'a mut Foo + 'a,
//~^ ERROR E0178
//~| NOTE expected a path
//~| ERROR at least one non-builtin trait is required for an object type
z: fn() -> Foo + 'a,
//~^ ERROR E0178
//~| NOTE expected a path
//~| ERROR at least one non-builtin trait is required for an object type
}
fn main() {

2
src/test/compile-fail/issue-34334.rs
View File

@ -9,7 +9,7 @@
// except according to those terms.
fn main () {
let sr: Vec<(u32, _, _) = vec![]; //~ ERROR expected one of `+`, `,`, or `>`, found `=`
let sr: Vec<(u32, _, _) = vec![]; //~ ERROR expected one of `,` or `>`, found `=`
let sr2: Vec<(u32, _, _)> = sr.iter().map(|(faction, th_sender, th_receiver)| {}).collect();
//~^ ERROR cannot find value `sr` in this scope
}

4
src/test/compile-fail/privacy/restricted/tuple-struct-fields/test.rs
View File

@ -11,6 +11,6 @@
mod foo {
type T = ();
struct S1(pub(foo) (), pub(T), pub(crate) (), pub(((), T)));
struct S2(pub((foo)) ()); //~ ERROR expected one of `+` or `,`, found `(`
//~| ERROR expected one of `+`, `;`, or `where`, found `(`
struct S2(pub((foo)) ()); //~ ERROR expected `,`, found `(`
//~| ERROR expected one of `;` or `where`, found `(`
}

4
src/test/compile-fail/privacy/restricted/tuple-struct-fields/test2.rs
View File

@ -12,8 +12,8 @@ macro_rules! define_struct {
($t:ty) => {
struct S1(pub $t);
struct S2(pub (foo) ());
struct S3(pub $t ()); //~ ERROR expected one of `+` or `,`, found `(`
//~| ERROR expected one of `+`, `;`, or `where`, found `(`
struct S3(pub $t ()); //~ ERROR expected `,`, found `(`
//~| ERROR expected one of `;` or `where`, found `(`
}
}

4
src/test/compile-fail/privacy/restricted/tuple-struct-fields/test3.rs
View File

@ -12,8 +12,8 @@ macro_rules! define_struct {
($t:ty) => {
struct S1(pub($t));
struct S2(pub (foo) ());
struct S3(pub($t) ()); //~ ERROR expected one of `+` or `,`, found `(`
//~| ERROR expected one of `+`, `;`, or `where`, found `(`
struct S3(pub($t) ()); //~ ERROR expected `,`, found `(`
//~| ERROR expected one of `;` or `where`, found `(`
}
}

19
src/test/compile-fail/trait-object-macro-matcher.rs Normal file
View File

@ -0,0 +1,19 @@
// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// `ty` matcher accepts trait object types
macro_rules! m {
($t: ty) => ( let _: $t; )
}
fn main() {
m!(Copy + Send + 'static); //~ ERROR the trait `std::marker::Copy` cannot be made into an object
}

3
src/test/compile-fail/trait-object-reference-without-parens-suggestion.rs
View File

@ -13,10 +13,9 @@ fn main() {
//~^ ERROR expected a path
//~| HELP try adding parentheses
//~| SUGGESTION let _: &(Copy + 'static);
//~| ERROR at least one non-builtin trait is required for an object type
//~| ERROR the trait `std::marker::Copy` cannot be made into an object
let _: &'static Copy + 'static;
//~^ ERROR expected a path
//~| HELP try adding parentheses
//~| SUGGESTION let _: &'static (Copy + 'static);
//~| ERROR at least one non-builtin trait is required for an object type
}

2
src/test/parse-fail/bounds-obj-parens.rs
View File

@ -10,6 +10,6 @@
// compile-flags: -Z parse-only
type A = Box<(Fn(D::Error) -> E) + 'static + Send + Sync>; // OK
type A = Box<(Fn(D::Error) -> E) + 'static + Send + Sync>; // OK (but see #39318)
FAIL //~ ERROR

2
src/test/parse-fail/issue-17904.rs
View File

@ -13,6 +13,6 @@
struct Baz<U> where U: Eq(U); //This is parsed as the new Fn* style parenthesis syntax.
struct Baz<U> where U: Eq(U) -> R; // Notice this parses as well.
struct Baz<U>(U) where U: Eq; // This rightfully signals no error as well.
struct Foo<T> where T: Copy, (T); //~ ERROR expected one of `+`, `:`, `==`, or `=`, found `;`
struct Foo<T> where T: Copy, (T); //~ ERROR expected one of `:`, `==`, or `=`, found `;`
fn main() {}

2
src/test/parse-fail/removed-syntax-ptr-lifetime.rs
View File

@ -10,4 +10,4 @@
// compile-flags: -Z parse-only
type bptr = &lifetime/isize; //~ ERROR expected one of `!`, `(`, `+`, `::`, `;`, or `<`, found `/`
type bptr = &lifetime/isize; //~ ERROR expected one of `!`, `(`, `::`, `;`, or `<`, found `/`

2
src/test/parse-fail/removed-syntax-uniq-mut-ty.rs
View File

@ -10,4 +10,4 @@
// compile-flags: -Z parse-only
type mut_box = Box<mut isize>; //~ ERROR expected type, found keyword `mut`
type mut_box = Box<mut isize>; //~ ERROR expected one of `>`, lifetime, or type, found `mut`

6
src/test/parse-fail/trailing-plus-in-bounds.rs
View File

@ -13,7 +13,7 @@
use std::fmt::Debug;
fn main() {
let x: Box<Debug+> = box 3 as Box<Debug+>;
//~^ ERROR at least one type parameter bound must be specified
//~^^ ERROR at least one type parameter bound must be specified
let x: Box<Debug+> = box 3 as Box<Debug+>; // Trailing `+` is OK
}
FAIL //~ ERROR

20
src/test/parse-fail/trait-object-macro-matcher.rs Normal file
View File

@ -0,0 +1,20 @@
// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// A single lifetime is not parsed as a type.
// `ty` matcher in particular doesn't accept a single lifetime
macro_rules! m {
($t: ty) => ( let _: $t; )
}
fn main() {
m!('static); //~ ERROR expected type, found `'static`
}

19
src/test/parse-fail/trait-object-polytrait-priority.rs Normal file
View File

@ -0,0 +1,19 @@
// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
trait Trait<'a> {}
fn main() {
let _: &for<'a> Trait<'a> + 'static;
//~^ ERROR expected a path on the left-hand side of `+`, not `& for<'a>Trait<'a>`
//~| NOTE expected a path
//~| HELP try adding parentheses
//~| SUGGESTION &( for<'a>Trait<'a> + 'static)
}

3
src/test/run-pass/issue-28279.rs
View File

@ -18,7 +18,7 @@ fn test1() -> Rc<for<'a> Fn(&'a usize) + 'static> {
}
}
fn test2() -> *mut for<'a> Fn(&'a usize) + 'static {
fn test2() -> *mut (for<'a> Fn(&'a usize) + 'static) {
if let Some(_) = Some(1) {
loop{}
} else {
@ -27,4 +27,3 @@ fn test2() -> *mut for<'a> Fn(&'a usize) + 'static {
}
fn main() {}