1 files changed, 43 insertions, 0 deletions
diff --git a/third_party/rust/quote/src/spanned.rs b/third_party/rust/quote/src/spanned.rs
new file mode 100644
index 0000000000..f64c8f5dfe
--- /dev/null
+++ b/third_party/rust/quote/src/spanned.rs
@@ -0,0 +1,43 @@
+use crate::ToTokens;
+use proc_macro2::{Span, TokenStream};
+
+pub trait Spanned {
+    fn __span(&self) -> Span;
+}
+
+impl Spanned for Span {
+    fn __span(&self) -> Span {
+        *self
+    }
+}
+
+impl<T: ?Sized + ToTokens> Spanned for T {
+    fn __span(&self) -> Span {
+        join_spans(self.into_token_stream())
+    }
+}
+
+fn join_spans(tokens: TokenStream) -> Span {
+    #[cfg(not(needs_invalid_span_workaround))]
+    let mut iter = tokens.into_iter().map(|tt| tt.span());
+
+    #[cfg(needs_invalid_span_workaround)]
+    let mut iter = tokens.into_iter().filter_map(|tt| {
+        let span = tt.span();
+        let debug = format!("{:?}", span);
+        if debug.ends_with("bytes(0..0)") {
+            None
+        } else {
+            Some(span)
+        }
+    });
+
+    let first = match iter.next() {
+        Some(span) => span,
+        None => return Span::call_site(),
+    };
+
+    iter.fold(None, |_prev, next| Some(next))
+        .and_then(|last| first.join(last))
+        .unwrap_or(first)
+}