internal: Report macro definition errors on the definition

crates/ide-diagnostics/src/handlers/macro_error.rs

@@ -9,6 +9,16 @@ pub(crate) fn macro_error(ctx: &DiagnosticsContext<'_>, d: &hir::MacroError) ->
     Diagnostic::new("macro-error", d.message.clone(), display_range).experimental()
 }
 
+// Diagnostic: macro-error
+//
+// This diagnostic is shown for macro expansion errors.
+pub(crate) fn macro_def_error(ctx: &DiagnosticsContext<'_>, d: &hir::MacroDefError) -> Diagnostic {
+    // Use more accurate position if available.
+    let display_range =
+        ctx.resolve_precise_location(&d.node.clone().map(|it| it.syntax_node_ptr()), d.name);
+    Diagnostic::new("macro-def-error", d.message.clone(), display_range).experimental()
+}
+
 #[cfg(test)]
 mod tests {
     use crate::{
@@ -188,6 +198,7 @@ fn f() {
       "#,
         );
     }
+
     #[test]
     fn dollar_crate_in_builtin_macro() {
         check_diagnostics(
@@ -209,6 +220,24 @@ macro_rules! outer {
 fn f() {
     outer!();
 } //^^^^^^^^ error: leftover tokens
+"#,
+        )
+    }
+
+    #[test]
+    fn def_diagnostic() {
+        check_diagnostics(
+            r#"
+macro_rules! foo {
+           //^^^ error: expected subtree
+    f => {};
+}
+
+fn f() {
+    foo!();
+  //^^^ error: invalid macro definition: expected subtree
+
+}
 "#,
         )
     }