fixes #1264

compiler/lexer.nim

@@ -537,6 +537,10 @@ proc getString(L: var TLexer, tok: var TToken, rawMode: bool) =
     tok.tokType = tkTripleStrLit # long string literal:
     inc(pos, 2)               # skip ""
     # skip leading newline:
+    if buf[pos] in {' ', '\t'}:
+      var newpos = pos+1
+      while buf[newpos] in {' ', '\t'}: inc newpos
+      if buf[newpos] in {CR, LF}: pos = newpos
     pos = handleCRLF(L, pos)
     buf = L.buf
     while true: 

doc/manual.txt

@@ -263,15 +263,16 @@ String literals can also be delimited by three double quotes
 ``"""`` ... ``"""``.
 Literals in this form may run for several lines, may contain ``"`` and do not
 interpret any escape sequences.
-For convenience, when the opening ``"""`` is immediately followed by a newline,
-the newline is not included in the string. The ending of the string literal is
-defined by the pattern ``"""[^"]``, so this:
-  
+For convenience, when the opening ``"""`` is followed by a newline (there may
+be whitespace between the opening ``"""`` and the newline),
+the newline (and the preceding whitespace) is not included in the string. The
+ending of the string literal is defined by the pattern ``"""[^"]``, so this:
+
 .. code-block:: nimrod 
   """"long string within quotes""""
-  
+
 Produces::
-  
+
   "long string within quotes"