error[E0425]: cannot find value `a` in this scope
  --> $DIR/typo-suggestion-named-underscore.rs:4:5
   |
LL |     a // Shouldn't suggest underscore
   |     ^ not found in this scope

error[E0405]: cannot find trait `A` in this scope
  --> $DIR/typo-suggestion-named-underscore.rs:13:11
   |
LL | fn foo<T: A>(x: T) {} // Shouldn't suggest underscore
   |           ^ not found in this scope

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0405, E0425.
For more information about an error, try `rustc --explain E0405`.