Not generating correct forward declarations for functions marked with extern C

[pfeerick]

Just adding this an issue to be reviewed, as it arose when trying to get some code working with a third party core. It would appear that the arduino-builder does not generation declarations for functions marked with extern C. Code that worked with 1.6.5 (and I believe also 1.6.6) stopped working on 1.6.7 or 1.6.8 with c++ linkage errors as mentioned at esp8266/Arduino#1759.

igrr ended up having to do the workaround committed at esp8266/Arduino@7307640 in order to allow the code to work on Arduino 1.6.8, and you can see from the commit the lines that were removed which worked prior to arduino-builder.

[facchinm]

Hi @pfeerick , the issue should be solved in nightly as #128 was merged. Also, @igrr already reported it here #126, so I believe I can close this one 😄

[pfeerick]

lol... no worries... no wonder nothing jumped out at me for it as it was a closed issue! So since this is in the nightly/hourly build, does that mean it should appear in the next IDE stable release?

[facchinm]

Yep 😄