Add default strategy for selecting primary label. Change attribute syntax to #[label(primary)].

miette-derive/src/label.rs

@@ -25,6 +25,7 @@ struct Label {
 
 struct LabelAttr {
     label: Option<Display>,
+    primary: bool,
 }
 
 impl Parse for LabelAttr {
@@ -41,10 +42,22 @@ impl Parse for LabelAttr {
             }
         });
         let la = input.lookahead1();
-        let label = if la.peek(syn::token::Paren) {
+        let (primary, label) = if la.peek(syn::token::Paren) {
-            // #[label("{}", x)]
+            // #[label(primary?, "{}", x)]
             let content;
             parenthesized!(content in input);
+
+            let primary = if content.peek(syn::Ident) {
+                let ident: syn::Ident = content.parse()?;
+                if ident != "primary" {
+                    return Err(syn::Error::new(input.span(), "Invalid argument to label() attribute. The argument must be a literal string or the keyword `primary`."));
+                }
+                let _ = content.parse::<Token![,]>();
+                true
+            } else {
+                false
+            };
+
             if content.peek(syn::LitStr) {
                 let fmt = content.parse()?;
                 let args = if content.is_empty() {
@@ -57,22 +70,27 @@ impl Parse for LabelAttr {
                     args,
                     has_bonus_display: false,
                 };
-                Some(display)
+                (primary, Some(display))
+            } else if !primary {
+                return Err(syn::Error::new(input.span(), "Invalid argument to label() attribute. The argument must be a literal string or the keyword `primary`."));
             } else {
-                return Err(syn::Error::new(input.span(), "Invalid argument to label() attribute. The first argument must be a literal string."));
+                (primary, None)
             }
         } else if la.peek(Token![=]) {
             // #[label = "blabla"]
             input.parse::<Token![=]>()?;
-            Some(Display {
+            (
-                fmt: input.parse()?,
+                false,
-                args: TokenStream::new(),
+                Some(Display {
-                has_bonus_display: false,
+                    fmt: input.parse()?,
-            })
+                    args: TokenStream::new(),
+                    has_bonus_display: false,
+                }),
+            )
         } else {
-            None
+            (false, None)
         };
-        Ok(LabelAttr { label })
+        Ok(LabelAttr { label, primary })
     }
 }
 
@@ -91,16 +109,7 @@ impl Labels {
         let mut labels = Vec::new();
         for (i, field) in fields.iter().enumerate() {
             for attr in &field.attrs {
-                let is_label = attr.path().is_ident("label");
+                if attr.path().is_ident("label") {
-                let is_primary_label = attr.path().is_ident("primary_label");
-                if is_label || is_primary_label {
-                    if is_primary_label && labels.iter().any(|l: &Label| l.primary) {
-                        return Err(syn::Error::new(
-                            field.span(),
-                            "Cannot have more than one primary label.",
-                        ));
-                    }
-
                     let span = if let Some(ident) = field.ident.clone() {
                         syn::Member::Named(ident)
                     } else {
@@ -110,13 +119,21 @@ impl Labels {
                         })
                     };
                     use quote::ToTokens;
-                    let LabelAttr { label } =
+                    let LabelAttr { label, primary } =
                         syn::parse2::<LabelAttr>(attr.meta.to_token_stream())?;
+
+                    if primary && labels.iter().any(|l: &Label| l.primary) {
+                        return Err(syn::Error::new(
+                            field.span(),
+                            "Cannot have more than one primary label.",
+                        ));
+                    }
+
                     labels.push(Label {
                         label,
                         span,
                         ty: field.ty.clone(),
-                        primary: is_primary_label,
+                        primary,
                     });
                 }
             }

src/handlers/graphical.rs

@@ -391,7 +391,10 @@ impl GraphicalReportHandler {
     ) -> fmt::Result {
         let (contents, lines) = self.get_lines(source, context.inner())?;
 
-        let primary_label = labels.iter().find(|label| label.primary());
+        let primary_label = labels
+            .iter()
+            .find(|label| label.primary())
+            .or_else(|| labels.first());
 
         // sorting is your friend
         let labels = labels

src/miette_diagnostic.rs

@@ -252,7 +252,7 @@ impl MietteDiagnostic {
     /// ```
     pub fn and_labels(mut self, labels: impl IntoIterator<Item = LabeledSpan>) -> Self {
         let mut all_labels = self.labels.unwrap_or_default();
-        all_labels.extend(labels.into_iter());
+        all_labels.extend(labels);
         self.labels = Some(all_labels);
         self
     }

tests/graphical.rs

@@ -86,7 +86,7 @@ fn single_line_highlight_span_full_line() {
     println!("Error: {}", out);
 
     let expected = r#"  × oops!
-   ╭─[issue:1:1]
+   ╭─[issue:2:1]
  1 │ source
  2 │ text
    · ──┬─
@@ -120,7 +120,7 @@ fn single_line_with_wide_char() -> Result<(), MietteError> {
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:2:7]
  1 │ source
  2 │   👼🏼text
    ·     ───┬──
@@ -159,7 +159,7 @@ fn single_line_with_two_tabs() -> Result<(), MietteError> {
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:2:3]
  1 │ source
  2 │         text
    ·         ──┬─
@@ -198,7 +198,7 @@ fn single_line_with_tab_in_middle() -> Result<(), MietteError> {
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:2:8]
  1 │ source
  2 │ text =  text
    ·         ──┬─
@@ -235,7 +235,7 @@ fn single_line_highlight() -> Result<(), MietteError> {
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:2:3]
  1 │ source
  2 │   text
    ·   ──┬─
@@ -270,7 +270,7 @@ fn external_source() -> Result<(), MietteError> {
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:2:3]
  1 │ source
  2 │   text
    ·   ──┬─
@@ -343,7 +343,7 @@ fn single_line_highlight_offset_end_of_line() -> Result<(), MietteError> {
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:1:7]
  1 │ source
    ·       ▲
    ·       ╰── this bit here
@@ -379,7 +379,7 @@ fn single_line_highlight_include_end_of_line() -> Result<(), MietteError> {
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:2:3]
  1 │ source
  2 │   text
    ·   ──┬──
@@ -416,7 +416,7 @@ fn single_line_highlight_include_end_of_line_crlf() -> Result<(), MietteError> {
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:2:3]
  1 │ source
  2 │   text
    ·   ──┬──
@@ -453,7 +453,7 @@ fn single_line_highlight_with_empty_span() -> Result<(), MietteError> {
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:2:3]
  1 │ source
  2 │   text
    ·   ▲
@@ -490,7 +490,7 @@ fn single_line_highlight_no_label() -> Result<(), MietteError> {
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:2:3]
  1 │ source
  2 │   text
    ·   ────
@@ -526,7 +526,7 @@ fn single_line_highlight_at_line_start() -> Result<(), MietteError> {
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:2:1]
  1 │ source
  2 │ text
    · ──┬─
@@ -569,7 +569,7 @@ fn multiple_same_line_highlights() -> Result<(), MietteError> {
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:2:3]
  1 │ source
  2 │   text text text text text
    ·   ──┬─ ──┬─      ──┬─
@@ -616,7 +616,7 @@ fn multiple_same_line_highlights_with_tabs_in_middle() -> Result<(), MietteError
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:2:3]
  1 │ source
  2 │   text text text    text text
    ·   ──┬─ ──┬─         ──┬─
@@ -655,7 +655,7 @@ fn multiline_highlight_adjacent() -> Result<(), MietteError> {
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:2:3]
  1 │     source
  2 │ ╭─▶   text
  3 │ ├─▶     here
@@ -969,7 +969,7 @@ fn related() -> Result<(), MietteError> {
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:2:3]
  1 │ source
  2 │   text
    ·   ──┬─
@@ -1031,7 +1031,7 @@ fn related_source_code_propagation() -> Result<(), MietteError> {
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:2:3]
  1 │ source
  2 │   text
    ·   ──┬─
@@ -1136,7 +1136,7 @@ fn related_severity() -> Result<(), MietteError> {
     let expected = r#"oops::my::bad
 
   × oops!
-   ╭─[bad_file.rs:1:1]
+   ╭─[bad_file.rs:2:3]
  1 │ source
  2 │   text
    ·   ──┬─
@@ -1201,7 +1201,7 @@ fn zero_length_eol_span() {
     println!("Error: {}", out);
 
     let expected = r#"  × oops!
-   ╭─[issue:1:1]
+   ╭─[issue:2:1]
  1 │ this is the first line
  2 │ this is the second line
    · ▲
@@ -1220,22 +1220,27 @@ fn primary_label() {
     struct MyBad {
         #[source_code]
         src: NamedSource,
-        #[primary_label("The root cause")]
+        #[label]
-        bad_bit: SourceSpan,
+        first_label: SourceSpan,
+        #[label(primary, "nope")]
+        second_label: SourceSpan,
     }
     let err = MyBad {
         src: NamedSource::new("issue", "this is the first line\nthis is the second line"),
-        bad_bit: (24, 4).into(),
+        first_label: (2, 4).into(),
+        second_label: (24, 4).into(),
     };
     let out = fmt_report(err.into());
     println!("Error: {}", out);
 
+    // line 2 should be the primary, not line 1
     let expected = r#"  × oops!
    ╭─[issue:2:2]
  1 │ this is the first line
+   ·   ────
  2 │ this is the second line
    ·  ──┬─
-   ·    ╰── The root cause
+   ·    ╰── nope
    ╰────
 "#
     .to_string();

tests/test_diagnostic_source_macro.rs

@@ -91,7 +91,7 @@ fn test_diagnostic_source_pass_extra_info() {
     println!("Error: {}", out);
     let expected = r#"  × TestError
   ╰─▶   × A complex error happened
-         ╭─[1:1]
+         ╭─[1:2]
        1 │ Hello
          ·  ──┬─
          ·    ╰── here