Remove SpanlessEq 🎃

The new solution is slightly hacky, but way more flexible. All types that implement PartialEq can now be compared spanlessly in tests by manipulating a thread-local boolean that is read in Span's PartialEq implementation.

1 files changed, 28 insertions, 1 deletions

diff --git a/src/syntax/span.rs b/src/syntax/span.rs
index c93f5c1e..923d13c2 100644
--- a/src/syntax/span.rs
+++ b/src/syntax/span.rs
@@ -3,9 +3,23 @@
 use std::fmt::{self, Debug, Formatter};
 use std::ops::{Add, Sub};
 
+#[cfg(test)]
+use std::cell::Cell;
+
 #[cfg(feature = "serialize")]
 use serde::Serialize;
 
+#[cfg(test)]
+thread_local! {
+    static CMP_SPANS: Cell<bool> = Cell::new(true);
+}
+
+/// When set to `false` comparisons with `PartialEq` ignore spans.
+#[cfg(test)]
+pub(crate) fn set_cmp(cmp: bool) {
+    CMP_SPANS.with(|cell| cell.set(cmp));
+}
+
 /// Span offsetting.
 pub trait Offset {
     /// Offset all spans contained in `Self` by the given position.
@@ -85,7 +99,7 @@ impl<T: Debug> Debug for Spanned<T> {
 }
 
 /// Locates a slice of source code.
-#[derive(Copy, Clone, Eq, PartialEq, Hash)]
+#[derive(Copy, Clone, Hash)]
 #[cfg_attr(feature = "serialize", derive(Serialize))]
 pub struct Span {
     /// The inclusive start position.
@@ -131,6 +145,19 @@ impl Offset for Span {
     }
 }
 
+impl Eq for Span {}
+
+impl PartialEq for Span {
+    fn eq(&self, other: &Self) -> bool {
+        #[cfg(test)]
+        if !CMP_SPANS.with(Cell::get) {
+            return true;
+        }
+
+        self.start == other.start && self.end == other.end
+    }
+}
+
 impl Debug for Span {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         write!(f, "<{:?}-{:?}>", self.start, self.end)