Merge branch 'hotfix/v3.5.4' into develop

* hotfix/v3.5.4:
  Fix preprocessor for Arduino sketch when function returns certain type // Resolve #1683

HISTORY.rst

@@ -25,6 +25,8 @@ PlatformIO 3.0
 * Removed "date&time" when processing project with `platformio run <http://docs.platformio.org/page/userguide/cmd_run.html>`__ command
   (`issue #1343 <https://github.com/platformio/platformio-core/issues/1343>`_)
 * Fixed issue with invalid LD script if path contains space
+* Fixed preprocessor for Arduino sketch when function returns certain type
+  (`issue #1683 <https://github.com/platformio/platformio-core/issues/1683>`_)
 
 3.5.3 (2018-06-01)
 ~~~~~~~~~~~~~~~~~~

platformio/builder/tools/piomisc.py

@@ -33,7 +33,7 @@ class InoToCPPConverter(object):
     PROTOTYPE_RE = re.compile(
         r"""^(
         (?:template\<.*\>\s*)?      # template
-        ([a-z_\d]+\*?\s+){1,2}      # return type
+        ([a-z_\d\&]+\*?\s+){1,2}      # return type
         ([a-z_\d]+\s*)              # name of prototype
         \([a-z_,\.\*\&\[\]\s\d]*\)  # arguments
         )\s*\{                      # must end with {