clean up logic

Author: estebank

src/librustc/query/mod.rs

@@ -398,6 +398,16 @@ rustc_queries! {
                 typeck_tables.map(|tables| &*tcx.arena.alloc(tables))
             }
         }
+        query diagnostic_only_typeck_tables_of(key: DefId) -> &'tcx ty::TypeckTables<'tcx> {
+            cache_on_disk_if { key.is_local() }
+            load_cached(tcx, id) {
+                let typeck_tables: Option<ty::TypeckTables<'tcx>> = tcx
+                    .queries.on_disk_cache
+                    .try_load_query_result(tcx, id);
+
+                typeck_tables.map(|tables| &*tcx.arena.alloc(tables))
+            }
+        }
     }
 
     Other {

src/librustc_typeck/astconv.rs

@@ -2770,30 +2770,15 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         let tcx = self.tcx();
 
         // We proactively collect all the infered type params to emit a single error per fn def.
-        let mut placeholder_types = vec![];
-        let mut output_placeholder_types = vec![];
-
-        let input_tys = decl.inputs.iter().map(|a| {
-            let mut visitor = PlaceholderHirTyCollector::new();
-            visitor.visit_ty(&a);
-            if visitor.0.is_empty() || self.allow_ty_infer() {
-                self.ty_of_arg(a, None)
-            } else {
-                placeholder_types.extend(visitor.0);
-                tcx.types.err
-            }
-        });
+        let mut visitor = PlaceholderHirTyCollector::new();
+        for ty in &decl.inputs {
+            visitor.visit_ty(ty);
+        }
+        let input_tys = decl.inputs.iter().map(|a| self.ty_of_arg(a, None));
         let output_ty = match decl.output {
             hir::Return(ref output) => {
-                let mut visitor = PlaceholderHirTyCollector::new();
                 visitor.visit_ty(output);
-                let is_infer = if let hir::TyKind::Infer = output.kind { true } else { false };
-                if (is_infer || !visitor.0.is_empty()) && !self.allow_ty_infer() {
-                    output_placeholder_types.extend(visitor.0);
-                    tcx.types.err
-                } else {
-                    self.ast_ty_to_ty(output)
-                }
+                self.ast_ty_to_ty(output)
             }
             hir::DefaultReturn(..) => tcx.mk_unit(),
         };
@@ -2803,15 +2788,15 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         let bare_fn_ty =
             ty::Binder::bind(tcx.mk_fn_sig(input_tys, output_ty, decl.c_variadic, unsafety, abi));
 
-        placeholder_types.extend(output_placeholder_types);
-
-        crate::collect::placeholder_type_error(
-            tcx,
-            ident_span.unwrap_or(DUMMY_SP),
-            generic_params,
-            placeholder_types,
-            ident_span.is_some(),
-        );
+        if !self.allow_ty_infer() {
+            crate::collect::placeholder_type_error(
+                tcx,
+                ident_span.unwrap_or(DUMMY_SP),
+                generic_params,
+                visitor.0,
+                ident_span.is_some(),
+            );
+        }
 
         // Find any late-bound regions declared in return type that do
         // not appear in the arguments. These are not well-formed.

src/librustc_typeck/check/mod.rs

@@ -756,6 +756,7 @@ pub fn provide(providers: &mut Providers<'_>) {
     *providers = Providers {
         typeck_item_bodies,
         typeck_tables_of,
+        diagnostic_only_typeck_tables_of,
         has_typeck_tables,
         adt_destructor,
         used_trait_imports,
@@ -941,7 +942,26 @@ where
     val.fold_with(&mut FixupFolder { tcx })
 }
 
-fn typeck_tables_of(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::TypeckTables<'_> {
+fn typeck_tables_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> &ty::TypeckTables<'tcx> {
+    let fallback = move || tcx.type_of(def_id);
+    typeck_tables_of_with_fallback(tcx, def_id, fallback)
+}
+
+/// Used only to get `TypeckTables` for type inference during error recovery.
+/// Currently only used for type inference of `static`s and `const`s to avoid type cycle errors.
+fn diagnostic_only_typeck_tables_of<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    def_id: DefId,
+) -> &ty::TypeckTables<'tcx> {
+    let fallback = move || tcx.types.err;
+    typeck_tables_of_with_fallback(tcx, def_id, fallback)
+}
+
+fn typeck_tables_of_with_fallback<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    def_id: DefId,
+    fallback: impl Fn() -> Ty<'tcx> + 'tcx,
+) -> &'tcx ty::TypeckTables<'tcx> {
     // Closures' tables come from their outermost function,
     // as they are part of the same "inference environment".
     let outer_def_id = tcx.closure_base_def_id(def_id);
@@ -990,7 +1010,7 @@ fn typeck_tables_of(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::TypeckTables<'_> {
                     hir::TyKind::Infer => Some(AstConv::ast_ty_to_ty(&fcx, ty)),
                     _ => None,
                 })
-                .unwrap_or_else(|| tcx.type_of(def_id));
+                .unwrap_or_else(fallback);
             let expected_type = fcx.normalize_associated_types_in(body.value.span, &expected_type);
             fcx.require_type_is_sized(expected_type, body.value.span, traits::ConstSized);
 

src/librustc_typeck/collect.rs

@@ -160,15 +160,7 @@ crate fn placeholder_type_error(
             format!(", {}", type_name),
         ));
     }
-    let mut err = struct_span_err!(
-        tcx.sess,
-        placeholder_types.clone(),
-        E0121,
-        "the type placeholder `_` is not allowed within types on item signatures",
-    );
-    for span in &placeholder_types {
-        err.span_label(*span, "not allowed in type signatures");
-    }
+    let mut err = bad_placeholder_type(tcx, placeholder_types);
     if suggest {
         err.multipart_suggestion(
             "use type parameters instead",
@@ -184,14 +176,8 @@ fn reject_placeholder_type_signatures_in_item(tcx: TyCtxt<'tcx>, item: &'tcx hir
         hir::ItemKind::Union(_, generics)
         | hir::ItemKind::Enum(_, generics)
         | hir::ItemKind::Struct(_, generics) => (&generics.params[..], true),
-        hir::ItemKind::Static(ty, ..) => {
-            if let hir::TyKind::Infer = ty.kind {
-                return; // We handle it elsewhere to attempt to suggest an appropriate type.
-            } else {
-                (&[][..], false)
-            }
-        }
         hir::ItemKind::TyAlias(_, generics) => (&generics.params[..], false),
+        // hir::ItemKind::Static(ty, ..) => {
         // hir::ItemKind::Fn(..) |
         // hir::ItemKind::Const(..) => {} // We handle these elsewhere to suggest appropriate type.
         _ => return,
@@ -255,15 +241,21 @@ impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
 ///////////////////////////////////////////////////////////////////////////
 // Utility types and common code for the above passes.
 
-fn bad_placeholder_type(tcx: TyCtxt<'tcx>, span: Span) -> errors::DiagnosticBuilder<'tcx> {
-    let mut diag = struct_span_err!(
+fn bad_placeholder_type(
+    tcx: TyCtxt<'tcx>,
+    mut spans: Vec<Span>,
+) -> errors::DiagnosticBuilder<'tcx> {
+    spans.sort();
+    let mut err = struct_span_err!(
         tcx.sess,
-        span,
+        spans.clone(),
         E0121,
         "the type placeholder `_` is not allowed within types on item signatures",
     );
-    diag.span_label(span, "not allowed in type signatures");
-    diag
+    for span in spans {
+        err.span_label(span, "not allowed in type signatures");
+    }
+    err
 }
 
 impl ItemCtxt<'tcx> {
@@ -298,7 +290,7 @@ impl AstConv<'tcx> for ItemCtxt<'tcx> {
     }
 
     fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
-        self.tcx().sess.delay_span_bug(span, "bad placeholder type, but no error was emitted");
+        self.tcx().sess.delay_span_bug(span, "bad placeholder type");
         self.tcx().types.err
     }
 
@@ -308,7 +300,7 @@ impl AstConv<'tcx> for ItemCtxt<'tcx> {
         _: Option<&ty::GenericParamDef>,
         span: Span,
     ) -> &'tcx Const<'tcx> {
-        bad_placeholder_type(self.tcx(), span).emit();
+        bad_placeholder_type(self.tcx(), vec![span]).emit();
 
         self.tcx().consts.err
     }
@@ -1233,7 +1225,7 @@ fn infer_placeholder_type(
     span: Span,
     item_ident: Ident,
 ) -> Ty<'_> {
-    let ty = tcx.typeck_tables_of(def_id).node_type(body_id.hir_id);
+    let ty = tcx.diagnostic_only_typeck_tables_of(def_id).node_type(body_id.hir_id);
 
     // If this came from a free `const` or `static mut?` item,
     // then the user may have written e.g. `const A = 42;`.
@@ -1253,7 +1245,7 @@ fn infer_placeholder_type(
             .emit();
         }
         None => {
-            let mut diag = bad_placeholder_type(tcx, span);
+            let mut diag = bad_placeholder_type(tcx, vec![span]);
             if ty != tcx.types.err {
                 diag.span_suggestion(
                     span,
@@ -1284,12 +1276,8 @@ fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
             }
             TraitItemKind::Const(ref ty, body_id) => body_id
                 .and_then(|body_id| {
-                    if let hir::TyKind::Infer = ty.kind {
+                    if is_infer_ty(ty) {
                         Some(infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident))
-                    } else if is_infer_ty(ty) {
-                        // Infering this would cause a cycle error.
-                        tcx.sess.delay_span_bug(ty.span, "`_` placeholder but no error emitted");
-                        Some(tcx.types.err)
                     } else {
                         None
                     }
@@ -1307,12 +1295,8 @@ fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
                 tcx.mk_fn_def(def_id, substs)
             }
             ImplItemKind::Const(ref ty, body_id) => {
-                if let hir::TyKind::Infer = ty.kind {
+                if is_infer_ty(ty) {
                     infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
-                } else if is_infer_ty(ty) {
-                    // Infering this would cause a cycle error.
-                    tcx.sess.delay_span_bug(ty.span, "`_` placeholder but no error emitted");
-                    tcx.types.err
                 } else {
                     icx.to_ty(ty)
                 }
@@ -1336,12 +1320,8 @@ fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
         Node::Item(item) => {
             match item.kind {
                 ItemKind::Static(ref ty, .., body_id) | ItemKind::Const(ref ty, body_id) => {
-                    if let hir::TyKind::Infer = ty.kind {
+                    if is_infer_ty(ty) {
                         infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident)
-                    } else if is_infer_ty(ty) {
-                        // Infering this would cause a cycle error.
-                        tcx.sess.delay_span_bug(ty.span, "`_` placeholder but no error emitted");
-                        tcx.types.err
                     } else {
                         icx.to_ty(ty)
                     }
@@ -1818,7 +1798,7 @@ crate fn is_infer_ty(ty: &hir::Ty<'_>) -> bool {
         hir::TyKind::Slice(ty) | hir::TyKind::Array(ty, _) => is_infer_ty(ty),
         hir::TyKind::Tup(tys)
             if !tys.is_empty()
-                && tys.iter().all(|ty| match ty.kind {
+                && tys.iter().any(|ty| match ty.kind {
                     hir::TyKind::Infer => true,
                     _ => false,
                 }) =>
@@ -1858,12 +1838,14 @@ fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
             match get_infer_ret_ty(&sig.decl.output) {
                 Some(ty) => {
                     let fn_sig = tcx.typeck_tables_of(def_id).liberated_fn_sigs()[hir_id];
-                    let mut diag = bad_placeholder_type(tcx, ty.span);
+                    let mut visitor = PlaceholderHirTyCollector::new();
+                    visitor.visit_ty(ty);
+                    let mut diag = bad_placeholder_type(tcx, visitor.0);
                     let ret_ty = fn_sig.output();
                     if ret_ty != tcx.types.err {
                         diag.span_suggestion(
                             ty.span,
-                            "replace this with the correct return type",
+                            "replace with the correct return type",
                             ret_ty.to_string(),
                             Applicability::MaybeIncorrect,
                         );

src/test/ui/error-codes/E0121.stderr

@@ -5,7 +5,7 @@ LL | fn foo() -> _ { 5 }
    |             ^
    |             |
    |             not allowed in type signatures
-   |             help: replace this with the correct return type: `i32`
+   |             help: replace with the correct return type: `i32`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
   --> $DIR/E0121.rs:3:13

src/test/ui/typeck/typeck_type_placeholder_item.rs

@@ -30,6 +30,7 @@ fn test7(x: _) { let _x: usize = x; }
 
 fn test8(_f: fn() -> _) { }
 //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+//~| ERROR the type placeholder `_` is not allowed within types on item signatures
 
 struct Test9;
 
@@ -79,6 +80,7 @@ pub fn main() {
 
     fn fn_test8(_f: fn() -> _) { }
     //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+    //~| ERROR the type placeholder `_` is not allowed within types on item signatures
 
     struct FnTest9;
 
@@ -128,4 +130,4 @@ trait T {
     //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
     fn assoc_fn_test3() -> _;
     //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
-}
+}