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	FxOS TV
Product	Desktop	B2G	Mulet	Desktop	B2G	Mulet	Desktop	B2G	Mulet	Fennec	B2G	iOS	FxOS TV
XP_WIN	✓	✓	✓										??
XP_DARWIN				✓	✓	✓						✓	??
XP_MACOSX				✓	✓	✓							??
XP_IOS												✓	??
XP_UNIX				✓	✓	✓	✓	✓	✓	✓	✓	✓	??
XP_LINUX							✓	✓	✓	✓	✓		??
ANDROID										✓	✓		??
MOZ_WIDGET_GTK							✓	✓	✓				??
MOZ_WIDGET_ANDROID										✓			??
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	Desktop	Desktop	Fennec	GeckoView	iOS
all.js	✓	✓	✓	✓	??	✓
firefox.js	✓	✓	✓		??
mobile.js				✓	??

Reftest conditions

Here is another table that tells you what conditions are true on various platforms for use in reftest.list conditions.

OS	Windows		OS X		Linux-gtk			Android		iOS
Product	Desktop	B2G	Desktop	B2G	Desktop	B2G	Mulet	Fennec	B2G	iOS
B2G									✓
B2GDT		✓		✓		✓
Android								✓
cocoaWidget			✓	✓
gtkWidget					✓	✓	✓
qtWidget
winWidget	✓	✓
Mulet							✓

Mochitest conditions

Here is another table that tells you what different condition values are on various platforms for use in mochitest.ini/a11y.ini/chrome.ini/browser.ini conditions.

OS	Windows		OS X		Linux-gtk			Android		iOS
Product	Desktop	B2G	Desktop	B2G	Desktop	B2G	Mulet	Fennec	B2G	iOS
os	win	??	mac	??	linux	??	??	android	b2g	??
toolkit	windows	??	cocoa	??	gtk2 or gtk3	??	??	android	gonk	??
buildapp	??	??	??	??	??	??	mulet	??	b2g	??

You may also be interested in Platform/Channel-specific_build_defines