bjoernager/rust
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Rollup merge of #89046 - oli-obk:fix_oflo, r=estebank

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"Fix" an overflow in byte position math

r? `@estebank`

help! I fixed the ICE only to brick the diagnostic.

I mean, it was wrong previously (using an already expanded macro span), but it is really bad now XD
This commit is contained in:
the8472 2021-09-22 19:03:22 +02:00 • committed by GitHub
commit 5948a7b407
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6 changed files with 37 additions and 10 deletions
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32
compiler/rustc_span/src/lib.rs
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@ -25,6 +25,9 @@
#[macro_use]
extern crate rustc_macros;
#[macro_use]
extern crate tracing;
use rustc_data_structures::AtomicRef;
use rustc_macros::HashStable_Generic;
use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
@ -782,13 +785,30 @@ impl Span {
/// ^^^^^^^^^^^^^^^^^
/// ```
pub fn until(self, end: Span) -> Span {
let span = self.data();
let end = end.data();
// Most of this function's body is copied from `to`.
// We can't just do `self.to(end.shrink_to_lo())`,
// because to also does some magic where it uses min/max so
// it can handle overlapping spans. Some advanced mis-use of
// `until` with different ctxts makes this visible.
let span_data = self.data();
let end_data = end.data();
// FIXME(jseyfried): `self.ctxt` should always equal `end.ctxt` here (cf. issue #23480).
// Return the macro span on its own to avoid weird diagnostic output. It is preferable to
// have an incomplete span than a completely nonsensical one.
if span_data.ctxt != end_data.ctxt {
if span_data.ctxt == SyntaxContext::root() {
return end;
} else if end_data.ctxt == SyntaxContext::root() {
return self;
}
// Both spans fall within a macro.
// FIXME(estebank): check if it is the *same* macro.
}
Span::new(
span.lo,
end.lo,
if end.ctxt == SyntaxContext::root() { end.ctxt } else { span.ctxt },
if span.parent == end.parent { span.parent } else { None },
span_data.lo,
end_data.lo,
if end_data.ctxt == SyntaxContext::root() { end_data.ctxt } else { span_data.ctxt },
if span_data.parent == end_data.parent { span_data.parent } else { None },
)
}