Fix case where AST failed to parse to give better errors

Author: GuillaumeGomez

src/librustdoc/doctest.rs

@@ -603,6 +603,11 @@ impl DocTest {
         // If `test_id` is `None`, it means we're generating code for a code example "run" link.
         test_id: Option<&str>,
     ) -> (String, usize) {
+        if self.failed_ast {
+            // If the AST failed to compile, no need to go generate a complete doctest, the error
+            // will be better this way.
+            return (self.everything_else.clone(), 0);
+        }
         let mut line_offset = 0;
         let mut prog = String::with_capacity(
             self.test_code.len() + self.crate_attrs.len() + self.crates.len(),
@@ -942,11 +947,10 @@ pub(crate) fn make_test(
                 Ok(p) => p,
                 Err(errs) => {
                     errs.into_iter().for_each(|err| err.cancel());
-                    return (found_main, found_extern_crate, found_macro, true);
+                    return (found_main, found_extern_crate, found_macro);
                 }
             };
 
-            let mut has_errors = false;
             loop {
                 match parser.parse_item(ForceCollect::No) {
                     Ok(Some(item)) => {
@@ -977,7 +981,6 @@ pub(crate) fn make_test(
                     Ok(None) => break,
                     Err(e) => {
                         e.cancel();
-                        has_errors = true;
                         break;
                     }
                 }
@@ -987,14 +990,13 @@ pub(crate) fn make_test(
                 parser.maybe_consume_incorrect_semicolon(&[]);
             }
 
-            has_errors = has_errors || psess.dcx.has_errors_or_delayed_bugs().is_some();
             // Reset errors so that they won't be reported as compiler bugs when dropping the
             // dcx. Any errors in the tests will be reported when the test file is compiled,
             // Note that we still need to cancel the errors above otherwise `Diag` will panic on
             // drop.
             psess.dcx.reset_err_count();
 
-            (found_main, found_extern_crate, found_macro, has_errors)
+            (found_main, found_extern_crate, found_macro)
         })
     });
 
@@ -1003,7 +1005,7 @@ pub(crate) fn make_test(
         Ignore::None => false,
         Ignore::Some(ref ignores) => ignores.iter().any(|s| target_str.contains(s)),
     };
-    let Ok((mut main_fn_span, already_has_extern_crate, found_macro, has_errors)) = result else {
+    let Ok((mut main_fn_span, already_has_extern_crate, found_macro)) = result else {
         // If the parser panicked due to a fatal error, pass the test code through unchanged.
         // The error will be reported during compilation.
         return DocTest {
@@ -1059,7 +1061,7 @@ pub(crate) fn make_test(
         lang_string,
         line,
         file,
-        failed_ast: has_errors,
+        failed_ast: false,
         rustdoc_test_options,
         outdir,
         test_id,