Switch annotations to be a slice

Author: zbraniecki

benches/simple.rs

@@ -46,7 +46,7 @@ fn create_snippet() {
             source: SOURCE,
             line_start: Some(51),
             origin: Some("src/format.rs"),
-            annotations: vec![
+            annotations: &[
                 SourceAnnotation {
                     label: "expected `Option<String>` because of return type",
                     annotation_type: AnnotationType::Warning,

examples/format.rs

@@ -40,7 +40,7 @@ fn main() {
             source,
             line_start: Some(51),
             origin: Some("src/format.rs"),
-            annotations: vec![
+            annotations: &[
                 SourceAnnotation {
                     label: "expected `Option<String>` because of return type",
                     annotation_type: AnnotationType::Warning,

src/slice.rs

@@ -5,5 +5,5 @@ pub struct Slice<'s> {
     pub source: &'s str,
     pub line_start: Option<usize>,
     pub origin: Option<&'s str>,
-    pub annotations: Vec<SourceAnnotation<'s>>,
+    pub annotations: &'s [SourceAnnotation<'s>],
 }