Implement source chains

A SourceSpan can now contain a child SourceSpan, ad infinitum, in order
to represent a chain of locations. The report_source_issue function
has been changed to print the entire chain, instead of just one
SourceSpan.

The report_source_issue function has also been changed to correctly
print SourceSpans that extend across multiple source lines.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/tokeniser.rs b/src/tokeniser.rs
index e09a439..0061e7a 100644
--- a/src/tokeniser.rs
+++ b/src/tokeniser.rs
@@ -221,7 +221,7 @@ impl Tokeniser {
         };
 
         let string = self.get_chars(&self.start, &self.end).iter().collect();
-        SourceSpan { string, in_merged, in_source }
+        SourceSpan { string, in_merged, in_source, child: None }
     }
 }