Keep track of parse errors in mods and don't emit resolve errors for paths involving them

When we expand a `mod foo;` and parse `foo.rs`, we now track whether that file had an unrecovered parse error that reached the end of the file. If so, we keep that information around. When resolving a path like `foo::bar`, we do not emit any errors for "`bar` not found in `foo`", as we know that the parse error might have caused `bar` to not be parsed and accounted for.

When this happens in an existing project, every path referencing `foo` would be an irrelevant compile error. Instead, we now skip emitting anything until `foo.rs` is fixed. Tellingly enough, we didn't have any test for errors caused by `mod` expansion.

Fix #97734.

Author: estebank

src/items.rs

@@ -3597,7 +3597,7 @@ pub(crate) fn rewrite_extern_crate(
 pub(crate) fn is_mod_decl(item: &ast::Item) -> bool {
     !matches!(
         item.kind,
-        ast::ItemKind::Mod(_, ast::ModKind::Loaded(_, ast::Inline::Yes, _))
+        ast::ItemKind::Mod(_, ast::ModKind::Loaded(_, ast::Inline::Yes, _, _))
     )
 }
 

src/modules.rs

@@ -316,12 +316,11 @@ impl<'ast, 'psess, 'c> ModResolver<'ast, 'psess> {
             self.directory = directory;
         }
         match (sub_mod.ast_mod_kind, sub_mod.items) {
-            (Some(Cow::Borrowed(ast::ModKind::Loaded(items, _, _))), _) => {
+            (Some(Cow::Borrowed(ast::ModKind::Loaded(items, _, _, _))), _) => {
                 self.visit_mod_from_ast(items)
             }
-            (Some(Cow::Owned(ast::ModKind::Loaded(items, _, _))), _) | (_, Cow::Owned(items)) => {
-                self.visit_mod_outside_ast(items)
-            }
+            (Some(Cow::Owned(ast::ModKind::Loaded(items, _, _, _))), _)
+            | (_, Cow::Owned(items)) => self.visit_mod_outside_ast(items),
             (_, _) => Ok(()),
         }
     }

src/visitor.rs

@@ -927,7 +927,7 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
         let ident_str = rewrite_ident(&self.get_context(), ident).to_owned();
         self.push_str(&ident_str);
 
-        if let ast::ModKind::Loaded(ref items, ast::Inline::Yes, ref spans) = mod_kind {
+        if let ast::ModKind::Loaded(ref items, ast::Inline::Yes, ref spans, _) = mod_kind {
             let ast::ModSpans {
                 inner_span,
                 inject_use_span: _,