fix: Make span_to_lines return at least one line

src/renderer/source_map.rs

@@ -124,7 +124,7 @@ impl<'a> SourceMap<'a> {
             if start >= line_info.end_byte {
                 continue;
             }
-            if end <= line_info.start_byte {
+            if end < line_info.start_byte {
                 break;
             }
             lines.push(line_info);

tests/rustc_tests.rs

@@ -2964,3 +2964,82 @@ LL | /// This is a long line that contains a <http://link.com>
         .term_width(10);
     assert_data_eq!(renderer.render(input), expected);
 }
+
+#[test]
+fn array_into_iter() {
+    let source1 = r#"#![allow(unused)]
+fn main() {
+[1, 2, 3].into_iter().for_each(|n| { *n; });
+}
+"#;
+    let source2 = r#"[1, 2, 3].into_iter().for_each(|n| { *n; });
+"#;
+
+    let long_title1 ="this method call resolves to `<&[T; N] as IntoIterator>::into_iter` (due to backwards compatibility), but will resolve to `<[T; N] as IntoIterator>::into_iter` in Rust 2021";
+    let long_title2 = "for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/IntoIterator-for-arrays.html>";
+    let long_title3 = "or use `IntoIterator::into_iter(..)` instead of `.into_iter()` to explicitly iterate by value";
+
+    let input = Level::WARNING
+        .header(long_title1)
+        .group(
+            Group::new()
+                .element(
+                    Snippet::source(source1)
+                        .origin("lint_example.rs")
+                        .fold(true)
+                        .annotation(AnnotationKind::Primary.span(40..49)),
+                )
+                .element(Level::WARNING.title("this changes meaning in Rust 2021"))
+                .element(Level::NOTE.title(long_title2))
+                .element(Level::NOTE.title("`#[warn(array_into_iter)]` on by default")),
+        )
+        .group(
+            Group::new()
+                .element(
+                    Level::HELP.title("use `.iter()` instead of `.into_iter()` to avoid ambiguity"),
+                )
+                .element(
+                    Snippet::source(source2)
+                        .origin("lint_example.rs")
+                        .line_start(3)
+                        .fold(true)
+                        .patch(Patch::new(10..19, "iter")),
+                ),
+        )
+        .group(
+            Group::new()
+                .element(Level::HELP.title(long_title3))
+                .element(
+                    Snippet::source(source2)
+                        .origin("lint_example.rs")
+                        .line_start(3)
+                        .fold(true)
+                        .patch(Patch::new(0..0, "IntoIterator::into_iter("))
+                        .patch(Patch::new(9..21, ")")),
+                ),
+        );
+
+    let expected = str![[r#"
+warning: this method call resolves to `<&[T; N] as IntoIterator>::into_iter` (due to backwards compatibility), but will resolve to `<[T; N] as IntoIterator>::into_iter` in Rust 2021
+ --> lint_example.rs:3:11
+  |
+3 | [1, 2, 3].into_iter().for_each(|n| { *n; });
+  |           ^^^^^^^^^
+  |
+  = warning: this changes meaning in Rust 2021
+  = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/IntoIterator-for-arrays.html>
+  = note: `#[warn(array_into_iter)]` on by default
+help: use `.iter()` instead of `.into_iter()` to avoid ambiguity
+  |
+3 - [1, 2, 3].into_iter().for_each(|n| { *n; });
+3 + [1, 2, 3].iter().for_each(|n| { *n; });
+  |
+help: or use `IntoIterator::into_iter(..)` instead of `.into_iter()` to explicitly iterate by value
+  |
+3 - [1, 2, 3].into_iter().for_each(|n| { *n; });
+3 + IntoIterator::into_iter([1, 2, 3]).for_each(|n| { *n; });
+  |
+"#]];
+    let renderer = Renderer::plain();
+    assert_data_eq!(renderer.render(input), expected);
+}