https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66572
Bug ID: 66572
Summary: [6 Regression] Bogus Wlogical-op warning for operands
coming from template instantiations
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Keywords: diagnostic
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: miyuki at gcc dot gnu.org
Target Milestone: ---
Consider this example:
$ cat ./test.cc
struct false_type
{
static constexpr bool value = false;
};
struct true_type
{
static constexpr bool value = true;
};
template<typename T>
struct is_unsigned : false_type {};
template<>
struct is_unsigned<unsigned> : true_type {};
template<typename T1, typename T2>
bool foo()
{
return is_unsigned<T1>::value && is_unsigned<T2>::value;
}
int main()
{
foo<unsigned, unsigned>();
}
$ g++ -Wlogical-op -std=c++11 ./test.cc
./test.cc: In instantiation of 'bool foo() [with T1 = unsigned int; T2 =
unsigned int]':
./test.cc:25:29: required from here
./test.cc:20:35: warning: logical 'and' of equal expressions [-Wlogical-op]
return is_unsigned<T1>::value && is_unsigned<T2>::value;
IMHO GCC should not issue this warning: in this instantiation
(is_unsigned<unsigned>::value && is_unsigned<unsigned>::value) operator && is
indeed redundant, but that is not true for general case.
