Merge pull request microsoft#7307 from zhengbli/fixFormatOnEnter

Avoid removing indentation on a new line as trailing white spaces

Author: zhengbli

src/services/formatting/formatting.ts

@@ -72,12 +72,20 @@ namespace ts.formatting {
  if (line === 0) {
  return [];
  }
- // get the span for the previous\current line
+ // After the enter key, the cursor is now at a new line. The new line may or may not contain non-whitespace characters.
+ // If the new line has only whitespaces, we won't want to format this line, because that would remove the indentation as
+ // trailing whitespaces. So the end of the formatting span should be the later one between:
+ // 1. the end of the previous line
+ // 2. the last non-whitespace character in the current line
+ let endOfFormatSpan = getEndLinePosition(line, sourceFile);
+ while (isWhiteSpace(sourceFile.text.charCodeAt(endOfFormatSpan)) && !isLineBreak(sourceFile.text.charCodeAt(endOfFormatSpan))) {
+ endOfFormatSpan--;
+ }
  let span = {
  // get start position for the previous line
  pos: getStartPositionOfLine(line - 1, sourceFile),
- // get end position for the current line (end value is exclusive so add 1 to the result)
- end: getEndLinePosition(line, sourceFile) + 1
+ // end value is exclusive so add 1 to the result
+ end: endOfFormatSpan + 1
  }
  return formatSpan(span, sourceFile, options, rulesProvider, FormattingRequestKind.FormatOnEnter);
  }