Support multiline location messages and use signature for function spans.

pkg/compiler/lib/src/io/source_file.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.io.source_file;
 
 import 'dart:math';
 import 'dart:convert' show UTF8;
 import 'dart:typed_data' show Uint8List;
 
@@ skipping 119 matching lines @@
    *
    * Use [colorize] to wrap source code text and marker characters in color
    * escape codes.
    */
   String getLocationMessage(String message, int start, int end,
                             {bool includeSourceLine: true,
                              String colorize(String text)}) {
     if (colorize == null) {
       colorize = (text) => text;
     }
-    var line = getLine(start);
-    var column = getColumn(line, start);
+    int lineStart = getLine(start);
+    int columnStart = getColumn(lineStart, start);
+    int lineEnd = getLine(end);
+    int columnEnd = getColumn(lineEnd, end);
 
-    var buf = new StringBuffer('${filename}:');
+    StringBuffer buf = new StringBuffer('${filename}:');
     if (start != end || start != 0) {
       // Line/column info is relevant.
-      buf.write('${line + 1}:${column + 1}:');
+      buf.write('${lineStart + 1}:${columnStart + 1}:');
     }
     buf.write('\n$message\n');
 
     if (start != end && includeSourceLine) {
-      String textLine = getLineText(line);
+      if (lineStart == lineEnd) {
+        String textLine = getLineText(lineStart);
 
-      int toColumn = min(column + (end-start), textLine.length);
-      buf.write(textLine.substring(0, column));
-      buf.write(colorize(textLine.substring(column, toColumn)));
-      buf.write(textLine.substring(toColumn));
+        int toColumn = min(columnStart + (end-start), textLine.length);
+        buf.write(textLine.substring(0, columnStart));
+        buf.write(colorize(textLine.substring(columnStart, toColumn)));
+        buf.write(textLine.substring(toColumn));
 
-      int i = 0;
-      for (; i < column; i++) {
-        buf.write(' ');
-      }
+        int i = 0;
+        for (; i < columnStart; i++) {
+          buf.write(' ');
+        }
 
-      for (; i < toColumn; i++) {
-        buf.write(colorize('^'));
+        for (; i < toColumn; i++) {
+          buf.write(colorize('^'));
+        }
+      } else {
+        for (int line = lineStart; line <= lineEnd; line++) {
+          String textLine = getLineText(line);
+          if (line == lineStart) {
+            buf.write(textLine.substring(0, columnStart));
+            buf.write(colorize(textLine.substring(columnStart)));
+          } else if (line == lineEnd) {
+            buf.write(colorize(textLine.substring(0, columnEnd)));
+            buf.write(textLine.substring(columnEnd));
+          } else {
+            buf.write(colorize(textLine));
+          }
+        }
       }
     }
 
     return buf.toString();
   }
 
   int get lines => lineStarts.length - 1;
 
   /// Returns the text of line  at the 0-based [index] within this source file.
   String getLineText(int index) {
@@ skipping 88 matching lines @@
   set length(int v) { }
 
   String slowText() => text;
 
   List<int> slowUtf8ZeroTerminatedBytes() {
     return _zeroTerminateIfNecessary(UTF8.encode(text));
   }
 
   String slowSubstring(int start, int end) => text.substring(start, end);
 }