In today's cross-platform C++ (or C) world we have:

Data model  | short |   int |   long | long long | pointers/size_t  | Sample operating systems
... 
LLP64/IL32P64   16      32      32     64           64                Microsoft Windows (x86-64 and IA-64)
LP64/I32LP64    16      32      64     64           64                Most Unix and Unix-like systems, e.g. Solaris, Linux, BSD, and OS X; z/OS
...

What this means today, is that for any "common" (signed) integer, int will suffice and can possibly still be used as the default integer type when writing C++ application code. It will also - for current practical purposes - have a consistent size across platforms.

Iff a use case requires at least 64 bits, we can today use long long, though possibly using one of the bitness-specifying types or the __int64type might make more sense.

This leaves longin the middle, and we're considering outright banning the use of long from our application code.

Would this make sense, or is there a case for using long in modern C++ (or C) code that has to run cross platform? (platform being desktop, mobile devices, but not things like microcontrollers, DSPs etc.)

Possibly interesting background links:

• What does the C++ standard state the size of int, long type to be?
• Why did the Win64 team choose the LLP64 model?
• 64-Bit Programming Models: Why LP64? (somewhat aged)
• Is long guaranteed to be at least 32 bits? (This addresses the comment discussion below. Answer.)