error: you assigned the result of adding something to this string. Consider using `String::push_str()` instead
  --> $DIR/string_add_assign.rs:10:9
   |
LL |         x = x + ".";
   |         ^^^^^^^^^^^
   |
   = note: `-D clippy::string-add-assign` implied by `-D warnings`

error: manual implementation of an assign operation
  --> $DIR/string_add_assign.rs:10:9
   |
LL |         x = x + ".";
   |         ^^^^^^^^^^^ help: replace it with: `x += "."`
   |
   = note: `-D clippy::assign-op-pattern` implied by `-D warnings`

error: manual implementation of an assign operation
  --> $DIR/string_add_assign.rs:19:5
   |
LL |     x = x + 1;
   |     ^^^^^^^^^ help: replace it with: `x += 1`

error: aborting due to 3 previous errors