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Date: Fri, 07 May 2010 07:14:00 -0000
Subject: [Bug c++/44021]  New: Templates with -Wtype-limits produces warnings.
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-Wtype-limits should not produce warnings in the following example:

template<class integer>
bool foo(integer x)
{
        if(x >= 0)
        {
                // Do something here if integer is positive.
                return false;
        }
        else if(x < 0) // Used else if() here instead of just else to get 2nd
warning.
        {
                // Do something else here if integer is negative.
                return true;
        }
}

int main()
{
        foo<unsigned int>(3);
        foo<int>(3);
        return 0;
}

The first line in the main() function, together with -Wtype-limits (or
-Wextra), produces these warnings:

        warning: comparison of unsigned expression >= 0 is always true
        warning: comparison of unsigned expression < 0 is always false

While these warnings makes sense for all other cases, they should not occur for
comparison of template types, since it does not easily allow for warning-free
templates which can handle unsigned and signed integers and have different
behavior for negative numbers.

Disabling the warning with -Wno-type-limits works as a temporary solution, but
this also makes finding potential bugs in non-template code more difficult.

Regards,
Jason.


-- 
           Summary: Templates with -Wtype-limits produces warnings.
           Product: gcc
           Version: 4.3.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: crossroads0000 at googlemail dot com
 GCC build triplet: x86_64-linux-elf
  GCC host triplet: x86_64-linux-elf
GCC target triplet: x86_64-linux-elf


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44021