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ICE: wrong-structured lhs for follow check with macro #21350
Description
Fiddling with some code from JeanSprouts on IRC,
fn main() {
macro_rules! dispatch(
$($id:expr, $name:ident, $parser:expr, $conda:ident, $condb:expr),+
=> {
general_dispatch!(
id,
start,
size,
$(
($id, $name, {
header.$name = match $parser.0 {
$conda if $condb => $conda,
_ => {
return Err(ParserError::Incompatible);
},
}
}),
)+
)
}
);
dispatch!(
(0x4286, EBMLVersion, try!(self.parse_uint(size)), n, n == 1),
(0x42F7, EBMLReadVersion, try!(self.parse_uint(size)), n, n == 1),
(0x42F2, EBMLMaxIDLength, try!(self.parse_uint(size)), n, n == 4),
(0x42F3, EBMLMaxSizeLength, try!(self.parse_uint(size)), n, n == 8),
(0x4282, DocType, try!(self.parse_string(size)), s, s == "matroska"),
(0x4287, DocTypeVersion, try!(self.parse_uint(size)), n, n <= 2),
(0x4285, DocTypeReadVersion, try!(self.parse_uint(size)), n, n <= 2)
);
}failed on playpen with:
<anon>:2:5: 23:7 error: internal compiler error: wrong-structured lhs for follow check
<anon>:2 macro_rules! dispatch(
<anon>:3
<anon>:4 $($id:expr, $name:ident, $parser:expr, $conda:ident, $condb:expr),+
<anon>:5 => {
<anon>:6 general_dispatch!(
<anon>:7 id,
...
note: the compiler unexpectedly panicked. this is a bug.
Activity
jdm commentedon Jan 18, 2015
Presumably we're getting a
TtSequencehere. @cmr is this just something we should have a better error for?emberian commentedon Jan 18, 2015
Nope, this isn't a legitimate error. I just didn't find a case where this could happen, so I didn't handle it. I'll fix it.
emberian commentedon Jan 18, 2015
(A workaround is to wrap the lhs in parens)
Auto merge of #21364 - cmr:fix-ttseq-ice, r=alexcrichton