error[E0425]: cannot find value `x` in this scope
  --> $DIR/while-let-typo.rs:4:16
   |
LL |     while Some(x) = foo {}
   |                ^ not found in this scope
   |
help: you might have meant to use pattern matching
   |
LL |     while let Some(x) = foo {}
   |           +++

error[E0425]: cannot find value `x` in this scope
  --> $DIR/while-let-typo.rs:8:11
   |
LL |     while x = 5 {}
   |           ^ not found in this scope
   |
help: you might have meant to use pattern matching
   |
LL |     while let x = 5 {}
   |           +++

error[E0308]: mismatched types
  --> $DIR/while-let-typo.rs:6:11
   |
LL |     while 3 = foo {}
   |           ^^^^^^^ expected `bool`, found `()`

error[E0070]: invalid left-hand side of assignment
  --> $DIR/while-let-typo.rs:7:19
   |
LL |     while Some(3) = foo {}
   |                -  ^
   |                |
   |                cannot assign to this expression
   |
help: you might have meant to use pattern destructuring
   |
LL |     while let Some(3) = foo {}
   |           +++

error: aborting due to 4 previous errors

Some errors have detailed explanations: E0070, E0308, E0425.
For more information about an error, try `rustc --explain E0070`.