Allow let bindings everywhere

src/test/ui/error-codes/E0010-teach.rs

@@ -14,5 +14,6 @@
 #![allow(warnings)]
 
 const CON : Box<i32> = box 0; //~ ERROR E0010
+//~^ ERROR contains unimplemented expression type
 
 fn main() {}

src/test/ui/error-codes/E0010-teach.stderr

@@ -6,6 +6,16 @@ LL | const CON : Box<i32> = box 0; //~ ERROR E0010
    |
    = note: The value of statics and constants must be known at compile time, and they live for the entire lifetime of a program. Creating a boxed value allocates memory on the heap at runtime, and therefore cannot be done at compile time.
 
-error: aborting due to previous error
+error[E0019]: constant contains unimplemented expression type
+  --> $DIR/E0010-teach.rs:16:28
+   |
+LL | const CON : Box<i32> = box 0; //~ ERROR E0010
+   |                            ^
+   |
+   = note: A function call isn't allowed in the const's initialization expression because the expression's value must be known at compile-time.
+   = note: Remember: you can't use a function call inside a const's initialization expression! However, you can use it anywhere else.
 
-For more information about this error, try `rustc --explain E0010`.
+error: aborting due to 2 previous errors
+
+Some errors occurred: E0010, E0019.
+For more information about an error, try `rustc --explain E0010`.

src/test/ui/error-codes/E0010.rs

@@ -12,5 +12,6 @@
 #![allow(warnings)]
 
 const CON : Box<i32> = box 0; //~ ERROR E0010
+//~^ ERROR contains unimplemented expression type
 
 fn main() {}

src/test/ui/error-codes/E0010.stderr

@@ -4,6 +4,13 @@ error[E0010]: allocations are not allowed in constants
 LL | const CON : Box<i32> = box 0; //~ ERROR E0010
    |                        ^^^^^ allocation not allowed in constants
 
-error: aborting due to previous error
+error[E0019]: constant contains unimplemented expression type
+  --> $DIR/E0010.rs:14:28
+   |
+LL | const CON : Box<i32> = box 0; //~ ERROR E0010
+   |                            ^
 
-For more information about this error, try `rustc --explain E0010`.
+error: aborting due to 2 previous errors
+
+Some errors occurred: E0010, E0019.
+For more information about an error, try `rustc --explain E0010`.