Forbid type ascriptions of place expressions in lvalue contexts

src/test/ui/coercion/coerce-expect-unsized-ascribed.rs

@@ -1,29 +1,29 @@
 // A version of coerce-expect-unsized that uses type ascription.
 // Doesn't work so far, but supposed to work eventually
 
+// check-pass
+
 #![feature(box_syntax, type_ascription)]
 
 use std::fmt::Debug;
 
 pub fn main() {
-    let _ = box { [1, 2, 3] }: Box<[i32]>; //~ ERROR mismatched types
-    let _ = box if true { [1, 2, 3] } else { [1, 3, 4] }: Box<[i32]>; //~ ERROR mismatched types
+    let _ = box { [1, 2, 3] }: Box<[i32]>;
+    let _ = box if true { [1, 2, 3] } else { [1, 3, 4] }: Box<[i32]>;
     let _ = box match true { true => [1, 2, 3], false => [1, 3, 4] }: Box<[i32]>;
-    //~^ ERROR mismatched types
-    let _ = box { |x| (x as u8) }: Box<dyn Fn(i32) -> _>; //~ ERROR mismatched types
-    let _ = box if true { false } else { true }: Box<dyn Debug>; //~ ERROR mismatched types
-    let _ = box match true { true => 'a', false => 'b' }: Box<dyn Debug>; //~ ERROR mismatched types
+    let _ = box { |x| (x as u8) }: Box<dyn Fn(i32) -> _>;
+    let _ = box if true { false } else { true }: Box<dyn Debug>;
+    let _ = box match true { true => 'a', false => 'b' }: Box<dyn Debug>;
 
-    let _ = &{ [1, 2, 3] }: &[i32]; //~ ERROR mismatched types
-    let _ = &if true { [1, 2, 3] } else { [1, 3, 4] }: &[i32]; //~ ERROR mismatched types
+    let _ = &{ [1, 2, 3] }: &[i32];
+    let _ = &if true { [1, 2, 3] } else { [1, 3, 4] }: &[i32];
     let _ = &match true { true => [1, 2, 3], false => [1, 3, 4] }: &[i32];
-    //~^ ERROR mismatched types
-    let _ = &{ |x| (x as u8) }: &dyn Fn(i32) -> _; //~ ERROR mismatched types
-    let _ = &if true { false } else { true }: &dyn Debug; //~ ERROR mismatched types
-    let _ = &match true { true => 'a', false => 'b' }: &dyn Debug; //~ ERROR mismatched types
+    let _ = &{ |x| (x as u8) }: &dyn Fn(i32) -> _;
+    let _ = &if true { false } else { true }: &dyn Debug;
+    let _ = &match true { true => 'a', false => 'b' }: &dyn Debug;
 
-    let _ = Box::new([1, 2, 3]): Box<[i32]>; //~ ERROR mismatched types
-    let _ = Box::new(|x| (x as u8)): Box<dyn Fn(i32) -> _>; //~ ERROR mismatched types
+    let _ = Box::new([1, 2, 3]): Box<[i32]>;
+    let _ = Box::new(|x| (x as u8)): Box<dyn Fn(i32) -> _>;
 
     let _ = vec![
         Box::new(|x| (x as u8)),

src/test/ui/coercion/type-ascription/coerce-array-repeat-in-fn-arg.rs

@@ -1,10 +1,9 @@
 #![feature(type_ascription)]
 
-// build-pass
-
 fn foo(_arg : [&[u32];3]) {}
 
 fn main() {
   let arr = [4,5,6];
   foo([&arr : &[u32]; 3]);
+  //~^ ERROR type ascriptions are not
 }

src/test/ui/coercion/type-ascription/coerce-array-repeat-in-fn-arg.stderr

@@ -0,0 +1,8 @@
+error: type ascriptions are not allowed in lvalue contexts
+  --> $DIR/coerce-array-repeat-in-fn-arg.rs:7:8
+   |
+LL |   foo([&arr : &[u32]; 3]);
+   |        ^^^^^^^^^^^^^
+
+error: aborting due to previous error
+

src/test/ui/coercion/type-ascription/coerce-enum-variant.rs

@@ -1,5 +1,3 @@
-// build-pass
-
 #![feature(type_ascription)]
 
 enum Foo<'a> {
@@ -10,4 +8,5 @@ enum Foo<'a> {
 fn main() {
   let arr = [4,5,6];
   let temp = Foo::A((10, &arr : &[u32]));
+  //~^ ERROR type ascriptions are not
 }

src/test/ui/coercion/type-ascription/coerce-enum-variant.stderr

@@ -0,0 +1,8 @@
+error: type ascriptions are not allowed in lvalue contexts
+  --> $DIR/coerce-enum-variant.rs:10:26
+   |
+LL |   let temp = Foo::A((10, &arr : &[u32]));
+   |                          ^^^^^^^^^^^^^
+
+error: aborting due to previous error
+

src/test/ui/coercion/type-ascription/coerce-struct-fields-pass-in-let-stmt.rs

@@ -1,8 +1,6 @@
 // Here we test for coercions in struct fields of nested type ascriptions
 // inside a tuple using an unsized coercion and a coercion from &mut -> &
 
-// run-pass
-
 #![feature(type_ascription)]
 
 use std::any::type_name;
@@ -26,4 +24,5 @@ fn main() {
   let tup = (9, (3, &arr : &[u32]), &mut bar);
   assert_eq!(type_of(tup), "(i32, (i32, &[u32]), &mut coerce_struct_fields_pass_in_let_stmt::Bar)");
   let _ = Foo { _a : (9, (3, &arr : &[u32]), &mut bar) };
+  //~^ ERROR type ascriptions are not
 }

src/test/ui/coercion/type-ascription/coerce-struct-fields-pass-in-let-stmt.stderr

@@ -0,0 +1,8 @@
+error: type ascriptions are not allowed in lvalue contexts
+  --> $DIR/coerce-struct-fields-pass-in-let-stmt.rs:26:30
+   |
+LL |   let _ = Foo { _a : (9, (3, &arr : &[u32]), &mut bar) };
+   |                              ^^^^^^^^^^^^^
+
+error: aborting due to previous error
+

src/test/ui/coercion/type-ascription/coerce-to-unsized-in-return-expr.rs

@@ -1,9 +1,8 @@
-// build-pass
-
 #![feature(type_ascription)]
 
 fn foo<'a>(arg : &'a [u32; 3]) -> &'a [u32] {
   arg : &[u32]
+  //~^ ERROR type ascriptions are not
 }
 
 fn main() {

src/test/ui/coercion/type-ascription/coerce-to-unsized-in-return-expr.stderr

@@ -0,0 +1,8 @@
+error: type ascriptions are not allowed in lvalue contexts
+  --> $DIR/coerce-to-unsized-in-return-expr.rs:4:3
+   |
+LL |   arg : &[u32]
+   |   ^^^^^^^^^^^^
+
+error: aborting due to previous error
+

src/test/ui/coercion/type-ascription/coerce-union-field.rs

@@ -1,5 +1,3 @@
-// build-pass
-
 #![feature(type_ascription)]
 
 union Foo<'a> {
@@ -11,4 +9,6 @@ fn main() {
   let arr = [4,5,6];
   let x = &mut 26;
   let _ = Foo { f1: (x : &u32, (5, &arr : &[u32])) };
+  //~^ ERROR type ascriptions
+  //~^^ ERROR type ascriptions
 }

src/test/ui/coercion/type-ascription/coerce-union-field.stderr

@@ -0,0 +1,19 @@
+error: type ascriptions are not allowed in lvalue contexts
+  --> $DIR/coerce-union-field.rs:11:22
+   |
+LL |   let _ = Foo { f1: (x : &u32, (5, &arr : &[u32])) };
+   |                      ^^^^^^^^
+   |
+help: try to use the type ascription when creating the local variable
+   |
+LL | let x: &u32 = &mut 26;
+   | ^^^^^^^^^^^
+
+error: type ascriptions are not allowed in lvalue contexts
+  --> $DIR/coerce-union-field.rs:11:36
+   |
+LL |   let _ = Foo { f1: (x : &u32, (5, &arr : &[u32])) };
+   |                                    ^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+

src/test/ui/mir/mir_ascription_coercion.rs

@@ -1,4 +1,3 @@
-// run-pass
 // Tests that the result of type ascription has adjustments applied
 
 #![feature(type_ascription)]
@@ -7,4 +6,5 @@ fn main() {
     let x = [1, 2, 3];
     // The RHS should coerce to &[i32]
     let _y : &[i32] = &x : &[i32; 3];
+    //~^ ERROR type ascriptions
 }

src/test/ui/mir/mir_ascription_coercion.stderr

@@ -0,0 +1,8 @@
+error: type ascriptions are not allowed in lvalue contexts
+  --> $DIR/mir_ascription_coercion.rs:8:23
+   |
+LL |     let _y : &[i32] = &x : &[i32; 3];
+   |                       ^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+

src/test/ui/nll/user-annotations/type_ascription_static_lifetime.rs

@@ -3,5 +3,6 @@
 
 fn main() {
     let x = 22_u32;
-    let y: &u32 = &x: &'static u32; //~ ERROR E0597
+    let y: &u32 = &x: &'static u32; 
+    //~^ ERROR type ascriptions are not
 }

src/test/ui/nll/user-annotations/type_ascription_static_lifetime.stderr

@@ -1,14 +1,8 @@
-error[E0597]: `x` does not live long enough
+error: type ascriptions are not allowed in lvalue contexts
   --> $DIR/type_ascription_static_lifetime.rs:6:19
    |
-LL |     let y: &u32 = &x: &'static u32;
-   |                   ^^--------------
-   |                   |
-   |                   borrowed value does not live long enough
-   |                   type annotation requires that `x` is borrowed for `'static`
-LL | }
-   | - `x` dropped here while still borrowed
+LL |     let y: &u32 = &x: &'static u32; 
+   |                   ^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0597`.