False positives with -Wconstant-logical-operand in template code #10583
Description
| Bugzilla Link | 10211 |
| Resolution | DUPLICATE |
| Resolved on | Nov 07, 2018 00:22 |
| Version | trunk |
| OS | All |
| CC | @DougGregor |
Extended Description
-Wconstant-logical-operand warns about code where the constant argument was instantiated from a template. This is idiomatically acceptable code. It comes up a lot in e.g. Eigen:
http://eigen.tuxfamily.org/index.php?title=Main_Page
Anyone verifying this should probably do a test compile with some Eigen files, e.g. 2.0.15's test/geometry.cpp [note: clang -I.. -D test_geometry], but here's a short reduction of a few cases we should get:
template class A {
unsigned count() { return 0; }
bool test1() { return (count() && int(T::SomeBit)); }
enum {
SomeBit = T::SomeBit
};
bool test2() { return (count() && int(SomeBit)); }
};
struct B { enum { SomeBit = true }; };
template class A;
The warning doesn't trigger here without the function-style casts.