Auto merge of #42887 - GuillaumeGomez:remove-err-methods, r=nikomatsakis

Remove err methods

To be merged after #42519.

cc @Susurrus @QuietMisdreavus

Author: bors

src/librustc/infer/mod.rs

@@ -1191,28 +1191,6 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
     // types using one of these methods, and should not call span_err directly for such
     // errors.
 
-    pub fn type_error_message<M>(&self,
-                                 sp: Span,
-                                 mk_msg: M,
-                                 actual_ty: Ty<'tcx>)
-        where M: FnOnce(String) -> String,
-    {
-        self.type_error_struct(sp, mk_msg, actual_ty).emit();
-    }
-
-    // FIXME: this results in errors without an error code. Deprecate?
-    pub fn type_error_struct<M>(&self,
-                                sp: Span,
-                                mk_msg: M,
-                                actual_ty: Ty<'tcx>)
-                                -> DiagnosticBuilder<'tcx>
-        where M: FnOnce(String) -> String,
-    {
-        self.type_error_struct_with_diag(sp, |actual_ty| {
-            self.tcx.sess.struct_span_err(sp, &mk_msg(actual_ty))
-        }, actual_ty)
-    }
-
     pub fn type_error_struct_with_diag<M>(&self,
                                           sp: Span,
                                           mk_diag: M,

src/librustc_typeck/check/cast.rs

@@ -239,12 +239,10 @@ impl<'a, 'gcx, 'tcx> CastCheck<'tcx> {
         }
 
         let tstr = fcx.ty_to_string(self.cast_ty);
-        let mut err =
-            fcx.type_error_struct(self.span,
-                                  |actual| {
-                                      format!("cast to unsized type: `{}` as `{}`", actual, tstr)
-                                  },
-                                  self.expr_ty);
+        let mut err = type_error_struct!(fcx.tcx.sess, self.span, self.expr_ty, E0620,
+                                         "cast to unsized type: `{}` as `{}`",
+                                         fcx.resolve_type_vars_if_possible(&self.expr_ty),
+                                         tstr);
         match self.expr_ty.sty {
             ty::TyRef(_, ty::TypeAndMut { mutbl: mt, .. }) => {
                 let mtstr = match mt {

src/librustc_typeck/check/mod.rs

@@ -4716,9 +4716,9 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             // If not, error.
             if alternative.is_ty_var() || alternative.references_error() {
                 if !self.is_tainted_by_errors() {
-                    self.type_error_message(sp, |_actual| {
-                        "the type of this value must be known in this context".to_string()
-                    }, ty);
+                    type_error_struct!(self.tcx.sess, sp, ty, E0619,
+                                       "the type of this value must be known in this context")
+                        .emit();
                 }
                 self.demand_suptype(sp, self.tcx.types.err, ty);
                 ty = self.tcx.types.err;

src/librustc_typeck/diagnostics.rs

@@ -4665,6 +4665,67 @@ i_am_a_function();
 ```
 "##,
 
+E0619: r##"
+The type-checker needed to know the type of an expression, but that type had not
+yet been inferred.
+
+Erroneous code example:
+
+```compile_fail,E0619
+let mut x = vec![];
+match x.pop() {
+    Some(v) => {
+        // Here, the type of `v` is not (yet) known, so we
+        // cannot resolve this method call:
+        v.to_uppercase(); // error: the type of this value must be known in
+                          //        this context
+    }
+    None => {}
+}
+```
+
+Type inference typically proceeds from the top of the function to the bottom,
+figuring out types as it goes. In some cases -- notably method calls and
+overloadable operators like `*` -- the type checker may not have enough
+information *yet* to make progress. This can be true even if the rest of the
+function provides enough context (because the type-checker hasn't looked that
+far ahead yet). In this case, type annotations can be used to help it along.
+
+To fix this error, just specify the type of the variable. Example:
+
+```
+let mut x: Vec<String> = vec![]; // We precise the type of the vec elements.
+match x.pop() {
+    Some(v) => {
+        v.to_uppercase(); // Since rustc now knows the type of the vec elements,
+                          // we can use `v`'s methods.
+    }
+    None => {}
+}
+```
+"##,
+
+E0620: r##"
+A cast to an unsized type was attempted.
+
+Erroneous code example:
+
+```compile_fail,E0620
+let x = &[1_usize, 2] as [usize]; // error: cast to unsized type: `&[usize; 2]`
+                                  //        as `[usize]`
+```
+
+In Rust, some types don't have a known size at compile-time. For example, in a
+slice type like `[u32]`, the number of elements is not known at compile-time and
+hence the overall size cannot be computed. As a result, such types can only be
+manipulated through a reference (e.g., `&T` or `&mut T`) or other pointer-type
+(e.g., `Box` or `Rc`). Try casting to a reference instead:
+
+```
+let x = &[1_usize, 2] as &[usize]; // ok!
+```
+"##,
+
 }
 
 register_diagnostics! {
@@ -4736,5 +4797,4 @@ register_diagnostics! {
     E0568, // auto-traits can not have predicates,
     E0588, // packed struct cannot transitively contain a `[repr(align)]` struct
     E0592, // duplicate definitions with name `{}`
-    E0619, // intrinsic must be a function
 }

src/test/compile-fail/E0619.rs

@@ -0,0 +1,18 @@
+// 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 main() {
+    let x;
+
+    match x {
+        (..) => {} //~ ERROR E0619
+        _ => {}
+    }
+}

src/test/compile-fail/E0620.rs

@@ -0,0 +1,13 @@
+// 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 main() {
+    let _foo = &[1_usize, 2] as [usize]; //~ ERROR E0620
+}