Account for proc_macro::Span layout change between 1.31 and 1.32

Author: dtolnay

Cargo.toml

@@ -25,6 +25,7 @@ unicode-ident = "1.0"
 
 [dev-dependencies]
 quote = { version = "1.0", default_features = false }
+rustversion = "1"
 
 [features]
 proc-macro = []

tests/test_size.rs

@@ -2,6 +2,7 @@ extern crate proc_macro;
 
 use std::mem;
 
+#[rustversion::attr(before(1.32), ignore)]
 #[test]
 fn test_proc_macro_span_size() {
     assert_eq!(mem::size_of::<proc_macro::Span>(), 4);
@@ -22,6 +23,7 @@ fn test_proc_macro2_fallback_span_size_with_locations() {
     assert_eq!(mem::size_of::<Option<proc_macro2::Span>>(), 12);
 }
 
+#[rustversion::attr(before(1.32), ignore)]
 #[cfg_attr(not(all(wrap_proc_macro, not(span_locations))), ignore)]
 #[test]
 fn test_proc_macro2_wrapper_span_size_without_locations() {