feat(graphical): Inherit source code to causes (#401)

src/handlers/graphical.rs

@@ -218,9 +218,18 @@ impl GraphicalReportHandler {
         f: &mut impl fmt::Write,
         diagnostic: &(dyn Diagnostic),
     ) -> fmt::Result {
+        self.render_report_inner(f, diagnostic, diagnostic.source_code())
+    }
+
+    fn render_report_inner(
+        &self,
+        f: &mut impl fmt::Write,
+        diagnostic: &(dyn Diagnostic),
+        parent_src: Option<&dyn SourceCode>,
+    ) -> fmt::Result {
+        let src = diagnostic.source_code().or(parent_src);
         self.render_header(f, diagnostic)?;
-        self.render_causes(f, diagnostic)?;
+        self.render_causes(f, diagnostic, src)?;
-        let src = diagnostic.source_code();
         self.render_snippets(f, diagnostic, src)?;
         self.render_footer(f, diagnostic)?;
         self.render_related(f, diagnostic, src)?;
@@ -278,7 +287,14 @@ impl GraphicalReportHandler {
         Ok(())
     }
 
-    fn render_causes(&self, f: &mut impl fmt::Write, diagnostic: &(dyn Diagnostic)) -> fmt::Result {
+    fn render_causes(
+        &self,
+        f: &mut impl fmt::Write,
+        diagnostic: &(dyn Diagnostic),
+        parent_src: Option<&dyn SourceCode>,
+    ) -> fmt::Result {
+        let src = diagnostic.source_code().or(parent_src);
+
         let (severity_style, severity_icon) = match diagnostic.severity() {
             Some(Severity::Error) | None => (self.theme.styles.error, &self.theme.characters.error),
             Some(Severity::Warning) => (self.theme.styles.warning, &self.theme.characters.warning),
@@ -356,7 +372,7 @@ impl GraphicalReportHandler {
                         inner_renderer.with_cause_chain = false;
                         // Since everything from here on is indented, shrink the virtual terminal
                         inner_renderer.termwidth -= rest_indent.width();
-                        inner_renderer.render_report(&mut inner, diag)?;
+                        inner_renderer.render_report_inner(&mut inner, diag, src)?;
 
                         // If there was no header, remove the leading newline
                         let inner = inner.trim_start_matches('\n');
@@ -410,8 +426,8 @@ impl GraphicalReportHandler {
                     Some(Severity::Advice) => write!(f, "Advice: ")?,
                 };
                 inner_renderer.render_header(f, rel)?;
-                inner_renderer.render_causes(f, rel)?;
                 let src = rel.source_code().or(parent_src);
+                inner_renderer.render_causes(f, rel, src)?;
                 inner_renderer.render_snippets(f, rel, src)?;
                 inner_renderer.render_footer(f, rel)?;
                 inner_renderer.render_related(f, rel, src)?;

tests/test_diagnostic_source_macro.rs

@@ -299,3 +299,53 @@ fn test_nested_cause_chains_for_related_errors_are_output() {
 
     assert_eq!(expected, out);
 }
+
+#[cfg(feature = "fancy-no-backtrace")]
+#[derive(Debug, miette::Diagnostic, thiserror::Error)]
+#[error("A case1 error happened")]
+enum NestedEnumError {
+    Case1 {
+        #[source_code]
+        code: String,
+        #[diagnostic_source]
+        the_other_err: Case1Inner,
+    },
+}
+
+#[derive(Debug, miette::Diagnostic, thiserror::Error)]
+#[error("I am the inner error")]
+struct Case1Inner {
+    #[label("inner-label")]
+    label: (usize, usize),
+}
+
+#[cfg(feature = "fancy-no-backtrace")]
+#[test]
+fn source_is_inherited_to_causes() {
+    let diag = NestedEnumError::Case1 {
+        code: String::from("this is the parent source"),
+        the_other_err: Case1Inner { label: (8, 3) },
+    };
+    let mut out = String::new();
+    miette::GraphicalReportHandler::new_themed(miette::GraphicalTheme::unicode_nocolor())
+        .with_width(80)
+        .with_footer("Yooo, a footer".to_string())
+        .render_report(&mut out, &diag)
+        .unwrap();
+    println!("{}", out);
+
+    let expected = r#"
+  × A case1 error happened
+  ╰─▶   × I am the inner error
+         ╭────
+       1 │ this is the parent source
+         ·         ─┬─
+         ·          ╰── inner-label
+         ╰────
+      
+
+  Yooo, a footer
+"#;
+
+    assert_eq!(expected, out);
+}