Platform/Platform-specific build defines

In the Gecko code we have a bunch of preprocessor conditions that help us conditionally compile code for specific platforms. These can get confusing so here is a handy-dandy table to help you keep them straight.

OS	Windows		OS X		Linux-gtk			Android		iOS
Product	Desktop	B2G	Desktop	B2G	Desktop	B2G	Mulet	Fennec	B2G	iOS
XP_WIN	✓	✓
XP_DARWIN			✓	✓						✓
XP_MACOSX			✓	✓
XP_IOS										✓
XP_UNIX			✓	✓	✓	✓	✓	✓	✓	✓
XP_LINUX					✓	✓	✓	✓	✓
ANDROID								✓	✓
MOZ_B2G		✓		✓		✓	✓		✓
MOZ_WIDGET_GTK					✓	✓	✓
MOZ_WIDGET_ANDROID								✓
MOZ_WIDGET_GONK									✓
MOZ_WIDGET_UIKIT										✓

Prefs files

Here is a similar table, but to see which prefs get used in which product:

OS	Windows		OS X		Linux-gtk			Android		iOS
Product	Desktop	B2G	Desktop	B2G	Desktop	B2G	Mulet	Fennec	B2G	iOS
all.js	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
firefox.js	✓		✓		✓
mobile.js								✓
b2g.js		✓		✓		✓	✓		✓
mulet.js							✓

You may also be interested in Platform/Channel-specific_build_defines