improve span context in @extend, removing some potential panics

src/parse/mod.rs

@@ -753,7 +753,7 @@ impl<'a> Parser<'a> {
                 compound.components.first().unwrap(),
                 &extend_rule,
                 &None,
-                Some(self.span_before),
+                self.span_before,
             )
         }
 

src/selector/extend/extension.rs

@@ -28,20 +28,24 @@ pub(crate) struct Extension {
     pub media_context: Option<Vec<CssMediaQuery>>,
 
     /// The span in which `extender` was defined.
-    // todo: no `Option<>`
-    pub span: Option<Span>,
+    pub span: Span,
 
     pub left: Option<Box<Extension>>,
     pub right: Option<Box<Extension>>,
 }
 
 impl Extension {
-    pub fn one_off(extender: ComplexSelector, specificity: Option<i32>, is_original: bool) -> Self {
+    pub fn one_off(
+        extender: ComplexSelector,
+        specificity: Option<i32>,
+        is_original: bool,
+        span: Span,
+    ) -> Self {
         Self {
             specificity: specificity.unwrap_or_else(|| extender.max_specificity()),
             extender,
             target: None,
-            span: None,
+            span,
             is_optional: true,
             is_original,
             media_context: None,
@@ -60,7 +64,7 @@ impl Extension {
             return;
         }
 
-        // Err(("You may not @extend selectors across media queries.", self.span.unwrap()).into())
+        // Err(("You may not @extend selectors across media queries.", self.span).into())
     }
 
     #[allow(clippy::missing_const_for_fn)]

src/selector/extend/merged.rs

@@ -19,20 +19,25 @@ impl MergedExtension {
     /// extender and target.
     pub fn merge(left: Extension, right: Extension) -> SassResult<Extension> {
         if left.extender != right.extender || left.target != right.target {
-            todo!("we need a span to throw a proper error")
-            //     return Err((format!("{} and {} aren't the same extension.", left, right), ))
+            return Err((
+                format!(
+                    "{} and {} aren't the same extension.",
+                    left.extender, right.extender
+                ),
+                left.span.merge(right.span),
+            )
+                .into());
         }
 
         if left.media_context.is_some()
             && right.media_context.is_some()
             && left.media_context != right.media_context
         {
-            todo!()
-            // throw SassException(
-            //     "From ${left.span.message('')}\n"
-            //     "You may not @extend the same selector from within different media "
-            //     "queries.",
-            //     right.span);
+            return Err((
+                "You may not @extend the same selector from within different media queries.",
+                right.span,
+            )
+                .into());
         }
 
         if right.is_optional && right.media_context.is_none() {
@@ -61,44 +66,5 @@ impl MergedExtension {
             left: None,
             right: None,
         }
-        // : super(left.extender, left.target, left.extenderSpan, left.span,
-        //     left.mediaContext ?? right.mediaContext,
-        //     specificity: left.specificity, optional: true);
-    }
-
-    /// Returns all leaf-node `Extension`s in the tree or `MergedExtension`s.
-    #[allow(dead_code, unused_mut, clippy::unused_self)]
-    pub fn unmerge(mut self) -> Vec<Extension> {
-        todo!()
-        /*  Iterable<Extension> unmerge() sync* {
-            if (left is MergedExtension) {
-              yield* (left as MergedExtension).unmerge();
-            } else {
-              yield left;
-            }
-
-            if (right is MergedExtension) {
-              yield* (right as MergedExtension).unmerge();
-            } else {
-              yield right;
-            }
-          }
-        */
     }
 }
-/*
-class MergedExtension extends Extension {
-  /// One of the merged extensions.
-  final Extension left;
-
-  /// The other merged extension.
-  final Extension right;
-
-  MergedExtension._(this.left, this.right)
-      : super(left.extender, left.target, left.extenderSpan, left.span,
-            left.mediaContext ?? right.mediaContext,
-            specificity: left.specificity, optional: true);
-
-
-}
-*/

src/selector/extend/mod.rs

@@ -154,7 +154,12 @@ impl Extender {
         let extenders: IndexMap<ComplexSelector, Extension> = source
             .components
             .into_iter()
-            .map(|complex| (complex.clone(), Extension::one_off(complex, None, false)))
+            .map(|complex| {
+                (
+                    complex.clone(),
+                    Extension::one_off(complex, None, false, span),
+                )
+            })
             .collect();
 
         let compound_targets = targets
@@ -164,7 +169,7 @@ impl Extender {
                 if complex.components.len() == 1 {
                     Ok(complex.components.first().unwrap().as_compound().clone())
                 } else {
-                    Err(("Can't extend complex selector $complex.", span).into())
+                    Err((format!("Can't extend complex selector {}.", complex), span).into())
                 }
             })
             .collect::<SassResult<Vec<CompoundSelector>>>()?;
@@ -745,6 +750,7 @@ impl Extender {
             },
             specificity,
             true,
+            self.span,
         )
     }
 
@@ -762,6 +768,7 @@ impl Extender {
             },
             specificity,
             true,
+            self.span,
         )
     }
 
@@ -949,7 +956,7 @@ impl Extender {
         target: &SimpleSelector,
         extend: &ExtendRule,
         media_context: &Option<Vec<CssMediaQuery>>,
-        span: Option<Span>,
+        span: Span,
     ) {
         let selectors = self.selectors.get(target).cloned();
         let existing_extensions = self.extensions_by_extender.get(target).cloned();