From c9fe0938767c8803330367806db8ba1ce81c7843 Mon Sep 17 00:00:00 2001
From: Oli Scherer <git-spam-no-reply9815368754983@oli-obk.de>
Date: Mon, 20 Sep 2021 15:39:16 +0000
Subject: [PATCH] Avoid the overflow with rustc+debugassertions in issue-44406
---
compiler/rustc_span/src/lib.rs | 29 +++++++++++++++++++++------
src/test/ui/parser/issue-44406.stderr | 2 +-
2 files changed, 24 insertions(+), 7 deletions(-)
diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs
index ae685ffe974..21cfa78a6e4 100644
--- a/compiler/rustc_span/src/lib.rs
+++ b/compiler/rustc_span/src/lib.rs
@@ -785,13 +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 },
)
}
diff --git a/src/test/ui/parser/issue-44406.stderr b/src/test/ui/parser/issue-44406.stderr
index 862026408ef..a37a806a157 100644
--- a/src/test/ui/parser/issue-44406.stderr
+++ b/src/test/ui/parser/issue-44406.stderr
@@ -26,7 +26,7 @@ LL | bar { }
help: if `bar` is a function, use the arguments directly
|
LL - bar(baz: $rest)
-LL + bar(true);
+LL + bar(: $rest)
|
error: aborting due to 2 previous errors