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Rollup merge of #23475 - nikomatsakis:closure-ret-syntax, r=acrichto

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Require braces when a closure has an explicit return type. This is a [breaking-change]: instead of a closure like `|| -> i32 22`, prefer `|| -> i32 { 22 }`.

Fixes #23420.
This commit is contained in:
Manish Goregaokar
2015-03-19 06:08:56 +05:30
parent c7392be968 c225824bde
commit a32bb1bcc4
9 changed files with 52 additions and 22 deletions
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36
src/libsyntax/parse/parser.rs
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@@ -2099,10 +2099,7 @@ impl<'a> Parser<'a> {
}
},
token::OpenDelim(token::Brace) => {
self.bump();
let blk = self.parse_block_tail(lo, DefaultBlock);
return self.mk_expr(blk.span.lo, blk.span.hi,
ExprBlock(blk));
return self.parse_block_expr(lo, DefaultBlock);
},
token::BinOp(token::Or) | token::OrOr => {
return self.parse_lambda_expr(CaptureByRef);
@@ -2998,19 +2995,30 @@ impl<'a> Parser<'a> {
{
let lo = self.span.lo;
let decl = self.parse_fn_block_decl();
let body = self.parse_expr();
let fakeblock = P(ast::Block {
id: ast::DUMMY_NODE_ID,
stmts: vec![],
span: body.span,
expr: Some(body),
rules: DefaultBlock,
});
let body = match decl.output {
DefaultReturn(_) => {
// If no explicit return type is given, parse any
// expr and wrap it up in a dummy block:
let body_expr = self.parse_expr();
P(ast::Block {
id: ast::DUMMY_NODE_ID,
stmts: vec![],
span: body_expr.span,
expr: Some(body_expr),
rules: DefaultBlock,
})
}
_ => {
// If an explicit return type is given, require a
// block to appear (RFC 968).
self.parse_block()
}
};
self.mk_expr(
lo,
fakeblock.span.hi,
ExprClosure(capture_clause, decl, fakeblock))
body.span.hi,
ExprClosure(capture_clause, decl, body))
}
pub fn parse_else_expr(&mut self) -> P<Expr> {