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Add catch expr to AST and disallow catch as a struct name

This commit is contained in:
Taylor Cramer 2017-02-17 15:12:47 -08:00
parent 1b19284ad9
commit d95c543722
14 changed files with 196 additions and 5 deletions
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37
src/librustc/hir/lowering.rs
View File

@ -84,6 +84,7 @@ pub struct LoweringContext<'a> {
trait_impls: BTreeMap<DefId, Vec<NodeId>>,
trait_default_impl: BTreeMap<DefId, NodeId>,
catch_scopes: Vec<NodeId>,
loop_scopes: Vec<NodeId>,
is_in_loop_condition: bool,
@ -123,6 +124,7 @@ pub fn lower_crate(sess: &Session,
trait_impls: BTreeMap::new(),
trait_default_impl: BTreeMap::new(),
exported_macros: Vec::new(),
catch_scopes: Vec::new(),
loop_scopes: Vec::new(),
is_in_loop_condition: false,
type_def_lifetime_params: DefIdMap(),
@ -261,6 +263,21 @@ impl<'a> LoweringContext<'a> {
span
}
fn with_catch_scope<T, F>(&mut self, catch_id: NodeId, f: F) -> T
where F: FnOnce(&mut LoweringContext) -> T
{
let len = self.catch_scopes.len();
self.catch_scopes.push(catch_id);
let result = f(self);
assert_eq!(len + 1, self.catch_scopes.len(),
"catch scopes should be added and removed in stack order");
self.catch_scopes.pop().unwrap();
result
}
fn with_loop_scope<T, F>(&mut self, loop_id: NodeId, f: F) -> T
where F: FnOnce(&mut LoweringContext) -> T
{
@ -295,15 +312,17 @@ impl<'a> LoweringContext<'a> {
result
}
fn with_new_loop_scopes<T, F>(&mut self, f: F) -> T
fn with_new_scopes<T, F>(&mut self, f: F) -> T
where F: FnOnce(&mut LoweringContext) -> T
{
let was_in_loop_condition = self.is_in_loop_condition;
self.is_in_loop_condition = false;
let catch_scopes = mem::replace(&mut self.catch_scopes, Vec::new());
let loop_scopes = mem::replace(&mut self.loop_scopes, Vec::new());
let result = f(self);
mem::replace(&mut self.loop_scopes, loop_scopes);
self.catch_scopes = catch_scopes;
self.loop_scopes = loop_scopes;
self.is_in_loop_condition = was_in_loop_condition;
@ -1065,7 +1084,7 @@ impl<'a> LoweringContext<'a> {
self.record_body(value, None))
}
ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
self.with_new_loop_scopes(|this| {
self.with_new_scopes(|this| {
let body = this.lower_block(body);
let body = this.expr_block(body, ThinVec::new());
let body_id = this.record_body(body, Some(decl));
@ -1665,13 +1684,17 @@ impl<'a> LoweringContext<'a> {
this.lower_opt_sp_ident(opt_ident),
hir::LoopSource::Loop))
}
ExprKind::Catch(ref body) => {
// FIXME(cramertj): Add catch to HIR
self.with_catch_scope(e.id, |this| hir::ExprBlock(this.lower_block(body)))
}
ExprKind::Match(ref expr, ref arms) => {
hir::ExprMatch(P(self.lower_expr(expr)),
arms.iter().map(|x| self.lower_arm(x)).collect(),
hir::MatchSource::Normal)
}
ExprKind::Closure(capture_clause, ref decl, ref body, fn_decl_span) => {
self.with_new_loop_scopes(|this| {
self.with_new_scopes(|this| {
this.with_parent_def(e.id, |this| {
let expr = this.lower_expr(body);
hir::ExprClosure(this.lower_capture_clause(capture_clause),
@ -2069,6 +2092,12 @@ impl<'a> LoweringContext<'a> {
// Err(err) => #[allow(unreachable_code)]
// return Carrier::from_error(From::from(err)),
// }
// FIXME(cramertj): implement breaking to catch
if !self.catch_scopes.is_empty() {
bug!("`?` in catch scopes is unimplemented")
}
let unstable_span = self.allow_internal_unstable("?", e.span);
// Carrier::translate(<expr>)

2
src/libsyntax/ast.rs
View File

@ -935,6 +935,8 @@ pub enum ExprKind {
Closure(CaptureBy, P<FnDecl>, P<Expr>, Span),
/// A block (`{ ... }`)
Block(P<Block>),
/// A catch block (`catch { ... }`)
Catch(P<Block>),
/// An assignment (`a = foo()`)
Assign(P<Expr>, P<Expr>),

6
src/libsyntax/feature_gate.rs
View File

@ -339,6 +339,9 @@ declare_features! (
// `extern "x86-interrupt" fn()`
(active, abi_x86_interrupt, "1.17.0", Some(40180)),
// Allows the `catch {...}` expression
(active, catch_expr, "1.17.0", Some(31436)),
);
declare_features! (
@ -1287,6 +1290,9 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
}
}
}
ast::ExprKind::Catch(_) => {
gate_feature_post!(&self, catch_expr, e.span, "`catch` expression is experimental");
}
_ => {}
}
visit::walk_expr(self, e);

1
src/libsyntax/fold.rs
View File

@ -1268,6 +1268,7 @@ pub fn noop_fold_expr<T: Folder>(Expr {id, node, span, attrs}: Expr, folder: &mu
};
}
ExprKind::Try(ex) => ExprKind::Try(folder.fold_expr(ex)),
ExprKind::Catch(body) => ExprKind::Catch(folder.fold_block(body)),
},
id: folder.new_id(id),
span: folder.new_span(span),

35
src/libsyntax/parse/parser.rs
View File

@ -602,6 +602,12 @@ impl<'a> Parser<'a> {
}
}
pub fn error_if_typename_is_catch(&mut self, ident: ast::Ident) {
if ident.name == keywords::Catch.name() {
self.span_err(self.span, "cannot use `catch` as the name of a type");
}
}
/// Check if the next token is `tok`, and return `true` if so.
///
/// This method will automatically add `tok` to `expected_tokens` if `tok` is not
@ -2273,6 +2279,11 @@ impl<'a> Parser<'a> {
BlockCheckMode::Unsafe(ast::UserProvided),
attrs);
}
if self.is_catch_expr() {
assert!(self.eat_keyword(keywords::Catch));
let lo = self.prev_span.lo;
return self.parse_catch_expr(lo, attrs);
}
if self.eat_keyword(keywords::Return) {
if self.token.can_begin_expr() {
let e = self.parse_expr()?;
@ -3092,6 +3103,16 @@ impl<'a> Parser<'a> {
Ok(self.mk_expr(span_lo, hi, ExprKind::Loop(body, opt_ident), attrs))
}
/// Parse a `catch {...}` expression (`catch` token already eaten)
pub fn parse_catch_expr(&mut self, span_lo: BytePos, mut attrs: ThinVec<Attribute>)
-> PResult<'a, P<Expr>>
{
let (iattrs, body) = self.parse_inner_attrs_and_block()?;
attrs.extend(iattrs);
let hi = body.span.hi;
Ok(self.mk_expr(span_lo, hi, ExprKind::Catch(body), attrs))
}
// `match` token already eaten
fn parse_match_expr(&mut self, mut attrs: ThinVec<Attribute>) -> PResult<'a, P<Expr>> {
let match_span = self.prev_span;
@ -3699,6 +3720,14 @@ impl<'a> Parser<'a> {
})
}
fn is_catch_expr(&mut self) -> bool {
self.token.is_keyword(keywords::Catch) &&
self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) &&
// prevent `while catch {} {}`, `if catch {} {} else {}`, etc.
!self.restrictions.contains(Restrictions::RESTRICTION_NO_STRUCT_LITERAL)
}
fn is_union_item(&self) -> bool {
self.token.is_keyword(keywords::Union) &&
self.look_ahead(1, |t| t.is_ident() && !t.is_any_keyword())
@ -4875,6 +4904,8 @@ impl<'a> Parser<'a> {
/// Parse struct Foo { ... }
fn parse_item_struct(&mut self) -> PResult<'a, ItemInfo> {
let class_name = self.parse_ident()?;
self.error_if_typename_is_catch(class_name);
let mut generics = self.parse_generics()?;
// There is a special case worth noting here, as reported in issue #17904.
@ -4924,6 +4955,8 @@ impl<'a> Parser<'a> {
/// Parse union Foo { ... }
fn parse_item_union(&mut self) -> PResult<'a, ItemInfo> {
let class_name = self.parse_ident()?;
self.error_if_typename_is_catch(class_name);
let mut generics = self.parse_generics()?;
let vdata = if self.token.is_keyword(keywords::Where) {
@ -5440,6 +5473,7 @@ impl<'a> Parser<'a> {
let struct_def;
let mut disr_expr = None;
let ident = self.parse_ident()?;
self.error_if_typename_is_catch(ident);
if self.check(&token::OpenDelim(token::Brace)) {
// Parse a struct variant.
all_nullary = false;
@ -5481,6 +5515,7 @@ impl<'a> Parser<'a> {
/// Parse an "enum" declaration
fn parse_item_enum(&mut self) -> PResult<'a, ItemInfo> {
let id = self.parse_ident()?;
self.error_if_typename_is_catch(id);
let mut generics = self.parse_generics()?;
generics.where_clause = self.parse_where_clause()?;
self.expect(&token::OpenDelim(token::Brace))?;

5
src/libsyntax/print/pprust.rs
View File

@ -2279,6 +2279,11 @@ impl<'a> State<'a> {
self.print_expr(e)?;
word(&mut self.s, "?")?
}
ast::ExprKind::Catch(ref blk) => {
self.head("catch")?;
space(&mut self.s)?;
self.print_block_with_attrs(&blk, attrs)?
}
}
self.ann.post(self, NodeExpr(expr))?;
self.end()

3
src/libsyntax/symbol.rs
View File

@ -221,9 +221,10 @@ declare_keywords! {
(53, Default, "default")
(54, StaticLifetime, "'static")
(55, Union, "union")
(56, Catch, "catch")
// A virtual keyword that resolves to the crate root when used in a lexical scope.
(56, CrateRoot, "{{root}}")
(57, CrateRoot, "{{root}}")
}
// If an interner exists in TLS, return it. Otherwise, prepare a fresh one.

3
src/libsyntax/visit.rs
View File

@ -779,6 +779,9 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) {
ExprKind::Try(ref subexpression) => {
visitor.visit_expr(subexpression)
}
ExprKind::Catch(ref body) => {
visitor.visit_block(body)
}
}
visitor.visit_expr_post(expression)

15
src/test/compile-fail/catch-empty-struct-name.rs Normal file
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@ -0,0 +1,15 @@
// 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.
#![allow(non_camel_case_types)]
#![allow(dead_code)]
#![feature(catch_expr)]
struct catch; //~ ERROR cannot use `catch` as the name of a type

17
src/test/compile-fail/catch-enum-variant.rs Normal file
View File

@ -0,0 +1,17 @@
// 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.
#![allow(non_camel_case_types)]
#![allow(dead_code)]
#![feature(catch_expr)]
enum Enum {
catch {} //~ ERROR cannot use `catch` as the name of a type
}

15
src/test/compile-fail/catch-struct-name.rs Normal file
View File

@ -0,0 +1,15 @@
// 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.
#![allow(non_camel_case_types)]
#![allow(dead_code)]
#![feature(catch_expr)]
struct catch {} //~ ERROR cannot use `catch` as the name of a type

15
src/test/compile-fail/catch-tuple-struct-name.rs Normal file
View File

@ -0,0 +1,15 @@
// 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.
#![allow(non_camel_case_types)]
#![allow(dead_code)]
#![feature(catch_expr)]
struct catch(); //~ ERROR cannot use `catch` as the name of a type

17
src/test/compile-fail/feature-gate-catch_expr.rs Normal file
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@ -0,0 +1,17 @@
// 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.
pub fn main() {
let catch_result = catch { //~ ERROR `catch` expression is experimental
let x = 5;
x
};
assert_eq!(catch_result, 5);
}

30
src/test/run-pass/catch-expr.rs Normal file
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@ -0,0 +1,30 @@
// 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.
#![feature(catch_expr)]
pub fn main() {
let catch_result = catch {
let x = 5;
x
};
assert_eq!(catch_result, 5);
let mut catch = true;
while catch { catch = false; }
assert_eq!(catch, false);
catch = if catch { false } else { true };
assert_eq!(catch, true);
match catch {
_ => {}
};
}