1 files changed, 42 insertions, 0 deletions
diff --git a/quote/src/spanned.rs b/quote/src/spanned.rs
new file mode 100644
index 0000000..55168bd
--- /dev/null
+++ b/quote/src/spanned.rs
@@ -0,0 +1,42 @@
+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 {
+    let mut iter = tokens.into_iter().filter_map(|tt| {
+        // FIXME: This shouldn't be required, since optimally spans should
+        // never be invalid. This filter_map can probably be removed when
+        // https://github.com/rust-lang/rust/issues/43081 is resolved.
+        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)
+}