error[E0381]: used binding `blah` is possibly-uninitialized
  --> $DIR/E0381-duplicated-label.rs:11:33
   |
LL |             let blah: Option<String>;
   |                 ---- binding declared here but left uninitialized
LL |             if true {
LL |                 blah = Some("".to_string());
   |                 ---- binding initialized here in some conditions
LL |             }
LL |             if let Some(blah) = blah.as_ref() {
   |                                 ^^^^ `blah` used here but it is possibly-uninitialized

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0381`.