Fix line numbers in checkstyle output

[calebcartwright]

Resolves #1386

[calebcartwright]

Actually there's more going wrong here than I realized 🤔

The current checkstyle output generated from formatting tests/writemode/source/fn-single-line.rs is way off on the calcs for both the line_number and line_number_orig values in the Mismatch :

<?xml version="1.0" encoding="UTF-8"?>
<checkstyle version="4.3">
  <file name="tests/writemode/source/fn-single-line.rs">
    <error line="2" original_line="2" severity="warning" message="Should be `fn foo_expr() { 1 }`" />
    <error line="2" original_line="2" severity="warning" message="Should be `fn foo_stmt() { foo(); }`" />
    <error line="2" original_line="2" severity="warning" message="Should be `fn foo_decl_local() { let z = 5; }`" />
    <error line="2" original_line="2" severity="warning" message="Should be `fn foo_decl_item(x: &amp;mut i32) { x = 3; }`" />
    <error line="2" original_line="2" severity="warning" message="Should be `fn empty() {}`" />
    <error line="2" original_line="2" severity="warning" message="Should be `fn foo_return() -&gt; String { &quot;yay&quot; }`" />
    <error line="2" original_line="2" severity="warning" message="Should be `fn foo_where() -&gt; T`" />
    <error line="2" original_line="2" severity="warning" message="Should be `where`" />
    <error line="2" original_line="2" severity="warning" message="Should be `    T: Sync,`" />
    <error line="2" original_line="2" severity="warning" message="Should be `{`" />
    <error line="52" original_line="61" severity="warning" message="Should be `fn lots_of_space() { 1 }`" />
    <error line="59" original_line="70" severity="warning" message="Should be `    fn dummy(&amp;self) {}`" />
    <error line="59" original_line="70" severity="warning" message="Should be `trait CoolerTypes {`" />
    <error line="59" original_line="70" severity="warning" message="Should be `    fn dummy(&amp;self) {}`" />
    <error line="59" original_line="70" severity="warning" message="Should be `fn Foo&lt;T&gt;()`" />
    <error line="59" original_line="70" severity="warning" message="Should be `where`" />
    <error line="59" original_line="70" severity="warning" message="Should be `    T: Bar,`" />
    <error line="59" original_line="70" severity="warning" message="Should be `{`" />
  </file>
</checkstyle>

[calebcartwright]

I decided to keep things simple here, and just fix the offset line numbers. Below is an example of the checkstyle output that is now emitted (pretty printed for ease of view). See above for what this same output looked like before.

My recommendation is that anyone wanting a more complex output (line numbers from the before/after versions of the file, start/end line numbers, etc.) should instead use the new json emit mode added in #3735 as the json format should be easier to work with.

<?xml version="1.0" encoding="UTF-8"?>
<checkstyle version="4.3">
  <file name="tests/writemode/source/fn-single-line.rs">
    <error line="5" severity="warning" message="Should be `fn foo_expr() { 1 }`" />
    <error line="7" severity="warning" message="Should be `fn foo_stmt() { foo(); }`" />
    <error line="9" severity="warning" message="Should be `fn foo_decl_local() { let z = 5; }`" />
    <error line="11" severity="warning" message="Should be `fn foo_decl_item(x: &amp;mut i32) { x = 3; }`" />
    <error line="13" severity="warning" message="Should be `fn empty() {}`" />
    <error line="15" severity="warning" message="Should be `fn foo_return() -&gt; String { &quot;yay&quot; }`" />
    <error line="17" severity="warning" message="Should be `fn foo_where() -&gt; T`" />
    <error line="18" severity="warning" message="Should be `where`" />
    <error line="19" severity="warning" message="Should be `    T: Sync,`" />
    <error line="20" severity="warning" message="Should be `{`" />
    <error line="55" severity="warning" message="Should be `fn lots_of_space() { 1 }`" />
    <error line="60" severity="warning" message="Should be `    fn dummy(&amp;self) {}`" />
    <error line="63" severity="warning" message="Should be `trait CoolerTypes {`" />
    <error line="64" severity="warning" message="Should be `    fn dummy(&amp;self) {}`" />
    <error line="67" severity="warning" message="Should be `fn Foo&lt;T&gt;()`" />
    <error line="68" severity="warning" message="Should be `where`" />
    <error line="69" severity="warning" message="Should be `    T: Bar,`" />
    <error line="70" severity="warning" message="Should be `{`" />
  </file>
</checkstyle>

[topecongiro]

Sorry for the late review on this one. Thank you for your works!

[calebcartwright]

Sorry for the late review on this one. Thank you for your works!

No worries, and my pleasure! I'm still pretty new to Rust but I find working with rustfmt is both fun and helping me learn. I'm keeping an eye out for any issues I think I can help with, but please also let me know if there's anything in particular I can do to help!