r193887 - Disable -Wtautological-constant-out-of-range-compare in template instantiations.

[Richard Smith]

Maybe you want to close PR8682? =)


On Fri, Nov 1, 2013 at 2:19 PM, Richard Trieu <rtrieu at google.com> wrote:

> Author: rtrieu
> Date: Fri Nov  1 16:19:43 2013
> New Revision: 193887
>
> URL: http://llvm.org/viewvc/llvm-project?rev=193887&view=rev
> Log:
> Disable -Wtautological-constant-out-of-range-compare in template
> instantiations.
>
> Modified:
>     cfe/trunk/lib/Sema/SemaChecking.cpp
>     cfe/trunk/test/SemaCXX/compare.cpp
>
> Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=193887&r1=193886&r2=193887&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaChecking.cpp Fri Nov  1 16:19:43 2013
> @@ -4806,6 +4806,10 @@ static void DiagnoseOutOfRangeComparison
>                                           Expr *Constant, Expr *Other,
>                                           llvm::APSInt Value,
>                                           bool RhsConstant) {
> +  // Disable warning in template instantiations.
> +  if (!S.ActiveTemplateInstantiations.empty())
> +    return;
> +
>    // 0 values are handled later by CheckTrivialUnsignedComparison().
>    if (Value == 0)
>      return;
>
> Modified: cfe/trunk/test/SemaCXX/compare.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/compare.cpp?rev=193887&r1=193886&r2=193887&view=diff
>
> ==============================================================================
> --- cfe/trunk/test/SemaCXX/compare.cpp (original)
> +++ cfe/trunk/test/SemaCXX/compare.cpp Fri Nov  1 16:19:43 2013
> @@ -355,3 +355,29 @@ void test9(int x) {
>    };
>    (void)((E)x == 1);
>  }
> +
> +namespace templates {
> +  template<class T> T max();
> +
> +  template<> constexpr int max<int>() { return 2147483647; };
> +
> +  template<typename T>
> +  bool less_than_max(short num, T value) {
> +    const T vmax = max<T>();
> +    return (vmax >= num);  // no warning
> +  }
> +
> +  template<typename T>
> +  bool less_than_max(short num) {
> +    // This should trigger one warning on the template pattern, and not a
> +    // warning per specialization.
> +    return num < max<int>();  // expected-warning{{comparison of constant
> 2147483647 with expression of type 'short' is always true}}
> +  }
> +
> +  void test10(short num, int x) {
> +    less_than_max(num, x);
> +    less_than_max<int>(num);
> +    less_than_max<long>(num);
> +    less_than_max<short>(num);
> +  }
> +}
>
>
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