Wrap std::numeric_limits<T>::max() in parenthesis

[bjornblissing]

The windows.h header file defines the macro max. If the max macro is include it will lead to name collisions with the std::numeric_limits::max() function.

One solution is to define NOMINMAX before the inclusion of windows.h. However, that might be a demanding task for a large codebase. Defining the NOMINMAX as global define may also break previous code.

Another to solution to the problem is to wrap the numeric_limits function in parenthesis to instruct the compiler to treat it as a function and not a macro.

This commit wraps the std::numeric_limits::max() calls in the public interfacing header files, with parenthesis.

[wolfpld]

Another to solution to the problem is to wrap the numeric_limits function in parenthesis to instruct the compiler to treat it as a function and not a macro.

Can you point me to a relevant section in the language standard that has an explanation for this behavior?

[bjornblissing]

I am not that well-versed in how to interpret C++-standard language. But I guess that by wrapping the library indentifier protects it from macro substitution in during phase 4 of the lexer.

The C99 standard is a bit more clear:

7.1.4 Use of library functions
Any function declared in a header may be additionally implemented as a function-like macro defined in the header, so if a library function is declared explicitly when its header is included, one of the techniques shown below can be used to ensure the declaration is not affected by such a macro. Any macro definition of a function can be suppressed locally by enclosing the name of the function in parentheses, because the name is then not followed by the left parenthesis that indicates expansion of a macro function name. For the same syntactic reason, it is permitted to take the address of a library function even if it is also defined as a macro.

This is the official recommendation from Microsoft on how to handle name conflicts between library code and macros:
https://learn.microsoft.com/en-us/cpp/c-runtime-library/recommendations-for-choosing-between-functions-and-macros

The solution works for all compilers I have checked:
https://godbolt.org/z/1P73o8TvK

The pattern can already be found in Tracy repo:
Once here:

tracy/server/tracy_robin_hood.h

Line 2131 in 84eff4b

if (ROBIN_HOOD_LIKELY(maxElements <= (std::numeric_limits<size_t>::max)() / 100)) {

And extensive use in this file:

tracy/import-chrome/src/json.hpp

Line 4018 in 84eff4b

return static_cast<CommonType>(val) <= static_cast<CommonType>((std::numeric_limits<OfType>::max)());

[wolfpld]

Thanks!