Get the project building again

Cargo.lock

@@ -1583,9 +1583,8 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.56"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2b63bdb0cd06f1f4dedf69b254734f9b45af66e4a031e42a7480257d9898b435"
+version = "1.0.67"
+source = "git+https://github.com/tonyg/proc-macro2?branch=repair_span_start_end#e1af85d3dd6ad595cedc0c344418ab0a60f1ce72"
 dependencies = [
  "unicode-ident",
 ]

Cargo.toml

@@ -25,3 +25,9 @@ strip = true
 
 [profile.bench]
 debug = true
+
+[patch.crates-io]
+# Unfortunately, until [1] is fixed (perhaps via [2]), we have to use a patched proc-macro2.
+# [1]: https://github.com/dtolnay/proc-macro2/issues/402
+# [2]: https://github.com/dtolnay/proc-macro2/pull/407
+proc-macro2 = { git = "https://github.com/tonyg/proc-macro2", branch = "repair_span_start_end" }