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Require body of else-less if expressions to be a value-less block

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For consistency with other constructs that could not possibly return a
value (say, loops).
This commit is contained in:
Marijn Haverbeke 2011-09-16 16:57:54 +02:00
parent 66153436c9
commit 133d36f452
8 changed files with 21 additions and 17 deletions
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2
src/comp/syntax/parse/lexer.rs
View file

@ -194,7 +194,7 @@ fn scan_dec_digits_with_prefix(rdr: reader) -> str {
rdr.bump();
}
let digits = scan_dec_digits(rdr);
if negative { str::unshift_char(digits, '-') }
if negative { str::unshift_char(digits, '-'); }
ret digits;
}

14
src/comp/syntax/parse/parser.rs
View file

@ -28,6 +28,7 @@ type parser =
fn swap(token::token, uint, uint);
fn look_ahead(uint) -> token::token;
fn fatal(str) -> ! ;
fn span_fatal(span, str) -> ! ;
fn warn(str);
fn restrict(restriction);
fn get_restriction() -> restriction;
@ -99,7 +100,10 @@ fn new_parser(sess: parse_sess, cfg: ast::crate_cfg, rdr: lexer::reader,
ret buffer[distance - 1u].tok;
}
fn fatal(m: str) -> ! {
codemap::emit_error(some(self.get_span()), m, sess.cm);
self.span_fatal(self.get_span(), m);
}
fn span_fatal(sp: span, m: str) -> ! {
codemap::emit_error(some(sp), m, sess.cm);
fail;
}
fn warn(m: str) {
@ -1270,6 +1274,9 @@ fn parse_if_expr_1(p: parser) ->
let elexpr = parse_else_expr(p);
els = some(elexpr);
hi = elexpr.span.hi;
} else if !option::is_none(thn.node.expr) {
let sp = option::get(thn.node.expr).span;
p.span_fatal(sp, "if without else can not return a value");
}
ret {cond: cond, then: thn, els: els, lo: lo, hi: hi};
}
@ -1658,10 +1665,7 @@ fn parse_block_no_value(p: parser) -> ast::blk {
let blk = parse_block(p);
if !option::is_none(blk.node.expr) {
let sp = option::get(blk.node.expr).span;
codemap::emit_error(some(sp),
"this block must not return a value",
p.get_sess().cm);
fail;
p.span_fatal(sp, "this block must not return a value");
}
ret blk;
}