fix: Ensure empty sources have one "line"

Muscraft · Muscraft · commit 23242144f51c · 2025-06-24T13:24:21.000-06:00
diff --git a/src/renderer/source_map.rs b/src/renderer/source_map.rs
@@ -11,6 +11,21 @@ pub(crate) struct SourceMap<'a> {
 
 impl<'a> SourceMap<'a> {
     pub(crate) fn new(source: &'a str, line_start: usize) -> Self {
+        // Empty sources do have a "line", but it is empty, so we need to add
+        // a line with an empty string to the source map.
+        if source.is_empty() {
+            return Self {
+                lines: vec![LineInfo {
+                    line: "",
+                    line_index: line_start,
+                    start_byte: 0,
+                    end_byte: 0,
+                    end_line_size: 0,
+                }],
+                source,
+            };
+        }
+
         let mut current_index = 0;
 
         let mut mapping = vec![];
diff --git a/tests/formatter.rs b/tests/formatter.rs
@@ -303,6 +303,7 @@ fn test_only_source() {
 error: 
  --> file.rs
   |
+1 |
 "#]];
     let renderer = Renderer::plain();
     assert_data_eq!(renderer.render(input), expected);
diff --git a/tests/rustc_tests.rs b/tests/rustc_tests.rs
@@ -2682,7 +2682,6 @@ LL | | */
 }
 
 #[test]
-#[should_panic(expected = "called `Option::unwrap()` on a `None` value")]
 fn mismatched_types1() {
     // tests/ui/include-macros/mismatched-types.rs
 

Original file line number	Diff line number	Diff line change
`@@ -303,6 +303,7 @@ fn test_only_source() {`
`303`	`303`	`error:`
`304`	`304`	`--> file.rs`
`305`	`305`	`\|`
	`306`	`+1 \|`
`306`	`307`	`"#]];`
`307`	`308`	`let renderer = Renderer::plain();`
`308`	`309`	`assert_data_eq!(renderer.render(input), expected);`
Original file line number	Diff line number	Diff line change
`@@ -2682,7 +2682,6 @@ LL \| \| */`
`2682`	`2682`	`}`
`2683`	`2683`
`2684`	`2684`	`#[test]`
`2685`		-#[should_panic(expected = "called `Option::unwrap()` on a `None` value")]
`2686`	`2685`	`fn mismatched_types1() {`
`2687`	`2686`	`// tests/ui/include-macros/mismatched-types.rs`
`2688`	`2687`