Add fix for tabs. Move error unit tests->ui tests

Author: Jonathan Turner

src/librustc_errors/styled_buffer.rs

@@ -26,10 +26,27 @@ impl StyledBuffer {
         }
     }
 
-    pub fn render(&self) -> Vec<Vec<StyledString>> {
+    pub fn copy_tabs(&mut self, row: usize) {
+        if row < self.text.len() {
+            for i in row+1..self.text.len() {
+                for j in 0..self.text[i].len() {
+                    if self.text[row].len() > j &&
+                       self.text[row][j] == '\t' &&
+                       self.text[i][j] == ' ' {
+                        self.text[i][j] = '\t';
+                    }
+                }
+            }
+        }
+    }
+
+    pub fn render(&mut self) -> Vec<Vec<StyledString>> {
         let mut output: Vec<Vec<StyledString>> = vec![];
         let mut styled_vec: Vec<StyledString> = vec![];
 
+        //before we render, do a little patch-up work to support tabs
+        self.copy_tabs(3);
+
         for (row, row_style) in self.text.iter().zip(&self.styles) {
             let mut current_style = Style::NoStyle;
             let mut current_text = String::new();
@@ -78,11 +95,7 @@ impl StyledBuffer {
         } else {
             let mut i = self.text[line].len();
             while i < col {
-                let s = match self.text[0].get(i) {
-                    Some(&'\t') => '\t',
-                    _ => ' ',
-                };
-                self.text[line].push(s);
+                self.text[line].push(' ');
                 self.styles[line].push(Style::NoStyle);
                 i += 1;
             }