https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101795
Bug ID: 101795
Summary: (x > QNaNf) is not a constant expression
Product: gcc
Version: 11.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: jonas.rahlf.basf at gmail dot com
Target Milestone: ---
Somehow (x > QNaNf) is not a constant expression, according to g++. I could not
find anything in the c++ standard that would support this behaviour.
Both clang and MSVC compile (x > QNaNf) as a constant expression.
Interestingly, (x == QNaNf) seems to work fine with g++.
Example:
#include <limits>
constexpr bool canCompile = std::numeric_limits<float>::quiet_NaN() > 1;
Compiler output: error: '(+QNaNf > 1.0e+0f)' is not a constant expression
See also: https://godbolt.org/z/vW651jPYh
No extra compile options needed.
I noticed this when attempting to compile std::lerp(a,b,NaN) (which is supposed
to be constexpr) as a constant expression.
