Partial template specialization based on “signed-ness” of integer type?

Question

Given:

template
inline bool f( T n ) {
  return n >= 0 && n <= 100;
}   

When used with an unsigned

Answer 1

Is there any clever way not to do the comparison n >= 0 when T is an unsigned type? I tried adding a partial template specialization:

The optimizer should drop the code for the compare since it detected the condition.

For Clang, add -Wno-tautological-compare to squash the warning. For GCC/G++, add -Wno-type-limits to squash the warning.

If you are using a compiler that support pragma diagnostic {push|pop} you can:

#if (GCC_VERSION >= 40600) || (LLVM_CLANG_VERSION >= 10700) || (APPLE_CLANG_VERSION >= 20000)
# define GCC_DIAGNOSTIC_AVAILABLE 1
#endif    

#if MSC_VERSION
# pragma warning(push)
# pragma warning(disable: 4389)
#endif

#if GCC_DIAGNOSTIC_AVAILABLE
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wsign-compare"
# if (LLVM_CLANG_VERSION >= 20800) || (APPLE_CLANG_VERSION >= 30000)
#  pragma GCC diagnostic ignored "-Wtautological-compare"
# elif (GCC_VERSION >= 40300)
#  pragma GCC diagnostic ignored "-Wtype-limits"
# endif
#endif

template
inline bool f( T n ) {
  return n >= 0 && n <= 100;
}

#if GCC_DIAGNOSTIC_AVAILABLE
# pragma GCC diagnostic pop
#endif

#if MSC_VERSION
# pragma warning(pop)
#endif

Also see Comparison is always false due to limited range…