Introduce TyErr independent from TyInfer

src/librustc/hir/intravisit.rs

@@ -578,7 +578,7 @@ pub fn walk_ty<'v, V: Visitor<'v>>(visitor: &mut V, typ: &'v Ty) {
         TyTypeof(expression) => {
             visitor.visit_nested_body(expression)
         }
-        TyInfer => {}
+        TyInfer | TyErr => {}
     }
 }
 

src/librustc/hir/lowering.rs

@@ -555,6 +555,7 @@ impl<'a> LoweringContext<'a> {
     fn lower_ty(&mut self, t: &Ty) -> P<hir::Ty> {
         let kind = match t.node {
             TyKind::Infer => hir::TyInfer,
+            TyKind::Err => hir::TyErr,
             TyKind::Slice(ref ty) => hir::TySlice(self.lower_ty(ty)),
             TyKind::Ptr(ref mt) => hir::TyPtr(self.lower_mt(mt)),
             TyKind::Rptr(ref region, ref mt) => {

src/librustc/hir/mod.rs

@@ -1351,6 +1351,8 @@ pub enum Ty_ {
     /// TyInfer means the type should be inferred instead of it having been
     /// specified. This can appear anywhere in a type.
     TyInfer,
+    /// Placeholder for a type that has failed to be defined.
+    TyErr,
 }
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]

src/librustc/hir/print.rs

@@ -450,6 +450,9 @@ impl<'a> State<'a> {
             hir::TyInfer => {
                 word(&mut self.s, "_")?;
             }
+            hir::TyErr => {
+                word(&mut self.s, "?")?;
+            }
         }
         self.end()
     }

src/librustc/ich/impls_hir.rs

@@ -230,6 +230,7 @@ impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for hir::Ty {
             hir::TyTraitObject(..) |
             hir::TyImplTrait(..)   |
             hir::TyTypeof(..)      |
+            hir::TyErr             |
             hir::TyInfer           => {
                 NodeIdHashingMode::Ignore
             }
@@ -282,6 +283,7 @@ impl_stable_hash_for!(enum hir::Ty_ {
     TyTraitObject(trait_refs, lifetime),
     TyImplTrait(bounds),
     TyTypeof(body_id),
+    TyErr,
     TyInfer
 });
 

src/librustc_typeck/astconv.rs

@@ -1229,6 +1229,9 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
                 // handled specially and will not descend into this routine.
                 self.ty_infer(ast_ty.span)
             }
+            hir::TyErr => {
+                tcx.types.err
+            }
         };
 
         cache.borrow_mut().insert(ast_ty.id, result_ty);

src/librustdoc/clean/mod.rs

@@ -1805,7 +1805,7 @@ impl Clean<Type> for hir::Ty {
             }
             TyBareFn(ref barefn) => BareFunction(box barefn.clean(cx)),
             TyImplTrait(ref bounds) => ImplTrait(bounds.clean(cx)),
-            TyInfer => Infer,
+            TyInfer | TyErr => Infer,
             TyTypeof(..) => panic!("Unimplemented type {:?}", self.node),
         }
     }

src/libsyntax/ast.rs

@@ -1361,6 +1361,8 @@ pub enum TyKind {
     ImplicitSelf,
     // A macro in the type position.
     Mac(Mac),
+    /// Placeholder for a kind that has failed to be defined.
+    Err,
 }
 
 /// Inline assembly dialect.

src/libsyntax/fold.rs

@@ -358,7 +358,7 @@ pub fn noop_fold_ty<T: Folder>(t: P<Ty>, fld: &mut T) -> P<Ty> {
     t.map(|Ty {id, node, span}| Ty {
         id: fld.new_id(id),
         node: match node {
-            TyKind::Infer | TyKind::ImplicitSelf => node,
+            TyKind::Infer | TyKind::ImplicitSelf | TyKind::Err => node,
             TyKind::Slice(ty) => TyKind::Slice(fld.fold_ty(ty)),
             TyKind::Ptr(mt) => TyKind::Ptr(fld.fold_mt(mt)),
             TyKind::Rptr(region, mt) => {

src/libsyntax/parse/parser.rs

@@ -407,6 +407,25 @@ impl From<P<Expr>> for LhsExpr {
     }
 }
 
+/// Create a placeholder argument.
+fn dummy_arg(span: Span) -> Arg {
+    let spanned = Spanned {
+        span: span,
+        node: keywords::Invalid.ident()
+    };
+    let pat = P(Pat {
+        id: ast::DUMMY_NODE_ID,
+        node: PatKind::Ident(BindingMode::ByValue(Mutability::Immutable), spanned, None),
+        span: span
+    });
+    let ty = Ty {
+        node: TyKind::Err,
+        span: span,
+        id: ast::DUMMY_NODE_ID
+    };
+    Arg { ty: P(ty), pat: pat, id: ast::DUMMY_NODE_ID }
+}
+
 impl<'a> Parser<'a> {
     pub fn new(sess: &'a ParseSess,
                tokens: TokenStream,
@@ -4376,8 +4395,12 @@ impl<'a> Parser<'a> {
                             Ok(arg) => Ok(Some(arg)),
                             Err(mut e) => {
                                 e.emit();
+                                let lo = p.prev_span;
+                                // Skip every token until next possible arg or end.
                                 p.eat_to_tokens(&[&token::Comma, &token::CloseDelim(token::Paren)]);
-                                Ok(None)
+                                // Create a placeholder argument for proper arg count (#34264).
+                                let span = lo.to(p.prev_span);
+                                Ok(Some(dummy_arg(span)))
                             }
                         }
                     }

src/libsyntax/print/pprust.rs

@@ -1095,6 +1095,9 @@ impl<'a> State<'a> {
             ast::TyKind::Infer => {
                 word(&mut self.s, "_")?;
             }
+            ast::TyKind::Err => {
+                word(&mut self.s, "?")?;
+            }
             ast::TyKind::ImplicitSelf => {
                 word(&mut self.s, "Self")?;
             }

src/libsyntax/visit.rs

@@ -350,7 +350,7 @@ pub fn walk_ty<'a, V: Visitor<'a>>(visitor: &mut V, typ: &'a Ty) {
         TyKind::Typeof(ref expression) => {
             visitor.visit_expr(expression)
         }
-        TyKind::Infer | TyKind::ImplicitSelf => {}
+        TyKind::Infer | TyKind::ImplicitSelf | TyKind::Err => {}
         TyKind::Mac(ref mac) => {
             visitor.visit_mac(mac)
         }

src/test/ui/span/issue-34264.rs

@@ -0,0 +1,20 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn foo(Option<i32>, String) {}
+fn bar(x, y: usize) {}
+
+fn main() {
+    foo(Some(42), 2);
+    foo(Some(42), 2, "");
+    bar("", "");
+    bar(1, 2);
+    bar(1, 2, 3);
+}

src/test/ui/span/issue-34264.stderr

@@ -0,0 +1,49 @@
+error: expected one of `:` or `@`, found `<`
+  --> $DIR/issue-34264.rs:11:14
+   |
+11 | fn foo(Option<i32>, String) {}
+   |              ^ expected one of `:` or `@` here
+
+error: expected one of `:` or `@`, found `)`
+  --> $DIR/issue-34264.rs:11:27
+   |
+11 | fn foo(Option<i32>, String) {}
+   |                           ^ expected one of `:` or `@` here
+
+error: expected one of `:` or `@`, found `,`
+  --> $DIR/issue-34264.rs:12:9
+   |
+12 | fn bar(x, y: usize) {}
+   |         ^ expected one of `:` or `@` here
+
+error[E0061]: this function takes 2 parameters but 3 parameters were supplied
+  --> $DIR/issue-34264.rs:16:9
+   |
+11 | fn foo(Option<i32>, String) {}
+   | ------------------------------ defined here
+...
+16 |     foo(Some(42), 2, "");
+   |         ^^^^^^^^^^^^^^^ expected 2 parameters
+
+error[E0308]: mismatched types
+  --> $DIR/issue-34264.rs:17:13
+   |
+17 |     bar("", "");
+   |             ^^ expected usize, found reference
+   |
+   = note: expected type `usize`
+              found type `&'static str`
+   = help: here are some functions which might fulfill your needs:
+           - .len()
+
+error[E0061]: this function takes 2 parameters but 3 parameters were supplied
+  --> $DIR/issue-34264.rs:19:9
+   |
+12 | fn bar(x, y: usize) {}
+   | ---------------------- defined here
+...
+19 |     bar(1, 2, 3);
+   |         ^^^^^^^ expected 2 parameters
+
+error: aborting due to 3 previous errors
+