title: borrow of possibly uninitialized variable for match operator
body: <p>I was designing a library that would transliterate given string into English from Ukrainian, so I decided to use 'match' operator for defining statement with check of multiple conditions. But I bumped into compiler error, which is typical to Rust, but fully impossible in my situation(at least I suppose so).</p>
  
  <pre><code>
     --&gt; src/lib.rs:188:21
      |
  188 |  origin_mutated[i] = 'Y';
      |  ^^^^^^^^^^^^^^ use of possibly-uninitialized `origin_mutated`
  
  error: aborting due to previous error
  </code></pre>
  
  <p>Here is full code of a library. Please bump my nose into a problem, if I'm not seeing something obvious(because I have suspicion that it may be a bug in compiler) </p>
  
  <pre><code>pub fn transliterate(mut origin: String) -&gt; String {
      let counter: usize = origin.chars().count();
      let mut j: usize = 0;
      let mut i: usize = 0;
      let origin_vec: Vec&lt;char&gt; = origin.chars().collect();
      let mut origin_mutated: Vec&lt;char&gt;;
      if j &lt;= counter{
          while j &lt;= counter {
              match origin_vec[j] {
                  'А' =&gt; {
                      origin_mutated[i] = 'A';
                      i+=1;
                      j+=1;
                      },
                  'Б' =&gt; {
                      origin_mutated[i] = 'B';
                      j+=1;
                      i+=1;
                      },
                  'В' =&gt; {
                      origin_mutated[i] = 'V';
                      i+=1;
                      j+=1;
                      },
                  'Г' =&gt; {
                      origin_mutated[i] = 'H';
                      i+=1;
                      j+=1;
                      },
                  'Ґ' =&gt; {
                      origin_mutated[i] = 'G';
                      i+=1;
                      j+=1;
                      },
                  'Д' =&gt; {
                      origin_mutated[i] = 'D';
                      i+=1;
                      j+=1;
                      },
                  'Е' =&gt; {
                      origin_mutated[i] = 'E';
                      i+=1;
                      j+=1;
                      },
                  'Є' =&gt; {
                      origin_mutated[i] = 'Y';
                      i+=1;
                      j+=1;
                      origin_mutated[i] = 'e';
                      i+=1;
                      },
                  'Ж' =&gt; {
                      origin_mutated[i] = 'Z';
                      i+=1;
                      j+=1;
                      origin_mutated[i] = 'h';
                      i+=1;
                      },
                  'З' =&gt; {
                      origin_mutated[i] = 'Z';
                      i+=1;
                      j+=1;
                      },
                  'И' =&gt; {
                      origin_mutated[i] = 'Y';
                      i+=1;
                      j+=1;
                      },
                  'І' =&gt; {
                      origin_mutated[i] = 'I';
                      i+=1;
                      j+=1;
                      },
                  'Ї' =&gt; {
                      origin_mutated[i] = 'Y';
                      i+=1;
                      j+=1;
                      origin_mutated[i] = 'i';
                      i+=1;
                      },
                  'Й' =&gt; {
                      origin_mutated[i] = 'Y';
                      i+=1;
                      j+=1;
                      },
                  'К' =&gt; {
                      origin_mutated[i] = 'K';
                      i+=1;
                      j+=1;
                      },
                  'Л' =&gt; {
                      origin_mutated[i] = 'L';
                      i+=1;
                      j+=1;
                      },
                  'М' =&gt; {
                      origin_mutated[i] = 'M';
                      i+=1;
                      j+=1;
                      },
                  'Н' =&gt; {
                      origin_mutated[i] = 'N';
                      i+=1;
                      j+=1;
                      },
                  'О' =&gt; {
                      origin_mutated[i] = 'O';
                      i==1;
                      j+=1;
                      },
                  'П' =&gt; {
                      origin_mutated[i] = 'P';
                      i+=1;
                      j+=1;
                      },
                  'Р' =&gt; {
                      origin_mutated[i] = 'R';
                      i==1;
                      j+=1;
                      },
                  'С' =&gt; {
                      origin_mutated[i] = 'S';
                      i==1;
                      j+=1;
                      },
                  'Т' =&gt; {
                      origin_mutated[i] = 'T';
                      i==1;
                      j+=1;
                      },
                  'У' =&gt; {
                      origin_mutated[i] = 'U';
                      i+=1;
                      j+=1;
                      },
                  'Ф' =&gt; {
                      origin_mutated[i] = 'F';
                      i==1;
                      j+=1;
                      },
                  'Х' =&gt; {
                      origin_mutated[i] = 'K';
                      i+=1;
                      j==1;
                      origin_mutated[i] = 'h';
                      i+=1;
                      },
                  'Ц' =&gt; {
                      origin_mutated[i] = 'T';
                      i+=1;
                      j+=1;
                      origin_mutated[i] = 's';
                      i+=1;
                      },
                  'Ч' =&gt; {
                      origin_mutated[i] = 'C';
                      i+=1;
                      j+=1;
                      origin_mutated[i] = 'h';
                      i+=1;
                      },
                  'Ш' =&gt; {
                      origin_mutated[i] = 'S';
                      i+=1;
                      j+=1;
                      origin_mutated[i] = 'h';
                      i+=1;
                      },
                  'Щ' =&gt; {
                      origin_mutated[i] = 'S';
                      i+=1;
                      j==1;
                      origin_mutated[i] = 'h';
                      i+=1;
                      origin_mutated[i] = 'c';
                      i+=1;
                      origin_mutated[i] = 'h';
                      i+=1;
                      },
                  'Ю' =&gt; {
                      origin_mutated[i] = 'Y';
                      i+=1;
                      j+=1;
                      origin_mutated[i] = 'u';
                      i+=1;
                      },
                  'Я' =&gt; {
                      origin_mutated[i] = 'Y';
                      i+=1;
                      j+=1;
                      origin_mutated[i] = 'a';
                      i+=1;
                      },
                  _ =&gt; {
                      j+=1;
                      }
                  }
              }
          }
      else if j &gt; counter{
          origin_mutated[i] = '\n'; 
      }
      else {
          origin = origin_mutated.into_iter().collect();
      }
      //origin = origin_mutated.into_iter().collect();
      (origin)
  }
  </code></pre>