1535219 - Remove XP_WIN32 preprocessor macro

Status: NEW

(Firefox Build System :: General, enhancement)

Description

[Nicholas Nethercote [inactive]]

XP_WIN32 is a synonym for XP_WIN. It's not used much. We should remove it.

But there's a wrinkle with NSS -- the meanings of XP_WIN and XP_WIN32 are subtly different when building NSS outside of Firefox's build system.

Within Firefox's build system:

• XP_WIN, XP_WIN32, WIN32, and _WINDOWS are defined on all Windows builds

But secport.h within NSS does the following:

• defines XP_WIN if _WINDOWS is defined
  • So it's always defined within Firefox's build system
  • Otherwise, I'm not sure when _WINDOWS is defined
• defines XP_WIN32 if _WIN32 or WIN32 is defined
  • True on any Win32 machine

We can easily change all occurrences of XP_WIN32 within Firefox to XP_WIN,
excluding the ones in NSS.

As for NSS, it seems like things could be cleaned up, but I'm not certain how.
Key questions:

• When is _WINDOWS defined? It's not listed at
  https://docs.microsoft.com/en-us/cpp/preprocessor/predefined-macros?view=vs-2017.
• Does NSS still support non-32-bit versions of Windows?
• Are XP_WIN and XP_WIN32 effectively synonymous within NSS?