Prevent impossible combinations in ast::ModKind.

`ModKind::Loaded` has an `inline` field and a `had_parse_error` field.
If the `inline` field is `Inline::Yes` then `had_parse_error` must be
`Ok(())`.

This commit moves the `had_parse_error` field into the `Inline::No`
variant. This makes it impossible to create the nonsensical combination
of `inline == Inline::Yes` and `had_parse_error = Err(_)`.

Author: nnethercote

compiler/rustc_ast/src/ast.rs

@@ -3137,7 +3137,7 @@ impl FnRetTy {
 #[derive(Clone, Copy, PartialEq, Encodable, Decodable, Debug, Walkable)]
 pub enum Inline {
     Yes,
-    No,
+    No { had_parse_error: Result<(), ErrorGuaranteed> },
 }
 
 /// Module item kind.
@@ -3147,7 +3147,7 @@ pub enum ModKind {
     /// or with definition outlined to a separate file `mod foo;` and already loaded from it.
     /// The inner span is from the first token past `{` to the last token until `}`,
     /// or from the first to the last token in the loaded file.
-    Loaded(ThinVec<Box<Item>>, Inline, ModSpans, Result<(), ErrorGuaranteed>),
+    Loaded(ThinVec<Box<Item>>, Inline, ModSpans),
     /// Module with definition outlined to a separate file `mod foo;` but not yet loaded from it.
     Unloaded,
 }

compiler/rustc_ast_lowering/src/item.rs

@@ -251,7 +251,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             ItemKind::Mod(_, ident, mod_kind) => {
                 let ident = self.lower_ident(*ident);
                 match mod_kind {
-                    ModKind::Loaded(items, _, spans, _) => {
+                    ModKind::Loaded(items, _, spans) => {
                         hir::ItemKind::Mod(ident, self.lower_mod(items, spans))
                     }
                     ModKind::Unloaded => panic!("`mod` items should have been loaded by now"),

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -1169,7 +1169,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                     self.dcx().emit_err(errors::UnsafeItem { span, kind: "module" });
                 }
                 // Ensure that `path` attributes on modules are recorded as used (cf. issue #35584).
-                if !matches!(mod_kind, ModKind::Loaded(_, Inline::Yes, _, _))
+                if !matches!(mod_kind, ModKind::Loaded(_, Inline::Yes, _))
                     && !attr::contains_name(&item.attrs, sym::path)
                 {
                     self.check_mod_file_item_asciionly(*ident);

compiler/rustc_builtin_macros/src/test_harness.rs

@@ -141,7 +141,7 @@ impl<'a> MutVisitor for TestHarnessGenerator<'a> {
         if let ast::ItemKind::Mod(
             _,
             _,
-            ModKind::Loaded(.., ast::ModSpans { inner_span: span, .. }, _),
+            ModKind::Loaded(.., ast::ModSpans { inner_span: span, .. }),
         ) = item.kind
         {
             let prev_tests = mem::take(&mut self.tests);

compiler/rustc_expand/src/expand.rs

@@ -799,7 +799,8 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                                     ItemKind::Mod(
                                         _,
                                         _,
-                                        ModKind::Unloaded | ModKind::Loaded(_, Inline::No, _, _),
+                                        ModKind::Unloaded
+                                            | ModKind::Loaded(_, Inline::No { .. }, _),
                                     )
                                 ) =>
                         {
@@ -1004,7 +1005,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             fn visit_item(&mut self, item: &'ast ast::Item) {
                 match &item.kind {
                     ItemKind::Mod(_, _, mod_kind)
-                        if !matches!(mod_kind, ModKind::Loaded(_, Inline::Yes, _, _)) =>
+                        if !matches!(mod_kind, ModKind::Loaded(_, Inline::Yes, _)) =>
                     {
                         feature_err(
                             self.sess,
@@ -1315,7 +1316,7 @@ impl InvocationCollectorNode for Box<ast::Item> {
         let ItemKind::Mod(_, ident, ref mut mod_kind) = node.kind else { unreachable!() };
         let ecx = &mut collector.cx;
         let (file_path, dir_path, dir_ownership) = match mod_kind {
-            ModKind::Loaded(_, inline, _, _) => {
+            ModKind::Loaded(_, inline, _) => {
                 // Inline `mod foo { ... }`, but we still need to push directories.
                 let (dir_path, dir_ownership) = mod_dir_path(
                     ecx.sess,
@@ -1329,7 +1330,7 @@ impl InvocationCollectorNode for Box<ast::Item> {
                 // This lets `parse_external_mod` catch cycles if it's self-referential.
                 let file_path = match inline {
                     Inline::Yes => None,
-                    Inline::No => mod_file_path_from_attr(ecx.sess, &attrs, &dir_path),
+                    Inline::No { .. } => mod_file_path_from_attr(ecx.sess, &attrs, &dir_path),
                 };
                 node.attrs = attrs;
                 (file_path, dir_path, dir_ownership)
@@ -1365,7 +1366,7 @@ impl InvocationCollectorNode for Box<ast::Item> {
                     );
                 }
 
-                *mod_kind = ModKind::Loaded(items, Inline::No, spans, had_parse_error);
+                *mod_kind = ModKind::Loaded(items, Inline::No { had_parse_error }, spans);
                 node.attrs = attrs;
                 if node.attrs.len() > old_attrs_len {
                     // If we loaded an out-of-line module and added some inner attributes,

compiler/rustc_expand/src/module.rs

@@ -120,7 +120,7 @@ pub(crate) fn mod_dir_path(
 
             (dir_path, dir_ownership)
         }
-        Inline::No => {
+        Inline::No { .. } => {
             // FIXME: This is a subset of `parse_external_mod` without actual parsing,
             // check whether the logic for unloaded, loaded and inline modules can be unified.
             let file_path = mod_file_path(sess, ident, attrs, &module.dir_path, dir_ownership)

compiler/rustc_lint/src/builtin.rs

@@ -3097,7 +3097,7 @@ impl EarlyLintPass for SpecialModuleName {
             if let ast::ItemKind::Mod(
                 _,
                 ident,
-                ast::ModKind::Unloaded | ast::ModKind::Loaded(_, ast::Inline::No, _, _),
+                ast::ModKind::Unloaded | ast::ModKind::Loaded(_, ast::Inline::No { .. }, _),
             ) = item.kind
             {
                 if item.attrs.iter().any(|a| a.has_name(sym::path)) {

compiler/rustc_parse/src/parser/item.rs

@@ -43,7 +43,7 @@ impl<'a> Parser<'a> {
             self.expect(exp!(OpenBrace))?;
             let (inner_attrs, items, inner_span) = self.parse_mod(exp!(CloseBrace))?;
             attrs.extend(inner_attrs);
-            ModKind::Loaded(items, Inline::Yes, inner_span, Ok(()))
+            ModKind::Loaded(items, Inline::Yes, inner_span)
         };
         Ok(ItemKind::Mod(safety, ident, mod_kind))
     }

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -11,7 +11,7 @@ use std::sync::Arc;
 use rustc_ast::visit::{self, AssocCtxt, Visitor, WalkItemKind};
 use rustc_ast::{
     self as ast, AssocItem, AssocItemKind, Block, ConstItem, Delegation, Fn, ForeignItem,
-    ForeignItemKind, Item, ItemKind, NodeId, StaticItem, StmtKind, TyAlias,
+    ForeignItemKind, Inline, Item, ItemKind, NodeId, StaticItem, StmtKind, TyAlias,
 };
 use rustc_attr_parsing as attr;
 use rustc_attr_parsing::AttributeParser;
@@ -801,7 +801,8 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
             ItemKind::Mod(_, ident, ref mod_kind) => {
                 self.r.define_local(parent, ident, TypeNS, res, vis, sp, expansion);
 
-                if let ast::ModKind::Loaded(_, _, _, Err(_)) = mod_kind {
+                if let ast::ModKind::Loaded(_, Inline::No { had_parse_error: Err(_) }, _) = mod_kind
+                {
                     self.r.mods_with_parse_errors.insert(def_id);
                 }
                 self.parent_scope.module = self.r.new_local_module(

compiler/rustc_resolve/src/diagnostics.rs

@@ -3434,7 +3434,7 @@ impl<'tcx> visit::Visitor<'tcx> for UsePlacementFinder {
 
     fn visit_item(&mut self, item: &'tcx ast::Item) {
         if self.target_module == item.id {
-            if let ItemKind::Mod(_, _, ModKind::Loaded(items, _inline, mod_spans, _)) = &item.kind {
+            if let ItemKind::Mod(_, _, ModKind::Loaded(items, _inline, mod_spans)) = &item.kind {
                 let inject = mod_spans.inject_use_span;
                 if is_span_suitable_for_use_injection(inject) {
                     self.first_legal_span = Some(inject);