I usually compile my code with almost most warning flags on, including -Wfloat-equal. My implementation of the C++ complex fix that is not included by default is an obvious offender (see warning messages at the end).
A simple fix (and I think it is a safe one, same thing is used in the boost libraries, https://www.boost.org/doc/libs/1_72_0/boost/config/detail/suffix.hpp) that works with both GCC and clang (and most likely Intel, I'll try tomorrow) is the following: diff --git a/include/petsccxxcomplexfix.h b/include/petsccxxcomplexfix.h index d3614e8a62..3c3090215b 100644 --- a/include/petsccxxcomplexfix.h +++ b/include/petsccxxcomplexfix.h @@ -35,6 +35,10 @@ before including any PETSc include files to prevent these methods from being provided. */ +#if defined(__GNUC__) && (__GNUC__ >= 4) +#pragma GCC system_header +#endif + #define PETSC_CXX_COMPLEX_FIX(Type) \ static inline PetscComplex operator+(const PetscComplex& lhs, const Type& rhs) { return const_cast<PetscComplex&>(lhs) + PetscReal(rhs); } \ static inline PetscComplex operator+(const Type& lhs, const PetscComplex& rhs) { return PetscReal(lhs) + const_cast<PetscComplex&>(rhs); } \ Would that be an acceptable solution o we should rather implement a configure test and define PETSC_HAVE_PRAGMA_GCC_SYSTEM_HEADER ? These are the kind of errors that show up for EVERY C++ source compile if -Wfloat-equal is passed. /home/devel/petsc/dev/include/petsccxxcomplexfix.h: In function ‘bool operator==(const PetscComplex&, const PetscInt&)’: /home/devel/petsc/dev/include/petsccxxcomplexfix.h:47:134: warning: comparing floating point with == or != is unsafe [-Wfloat-equal] 47 | static inline bool operator==(const PetscComplex& lhs, const Type& rhs) { return const_cast<PetscComplex&>(lhs).imag() == PetscReal(0) && const_cast<PetscComplex&>(lhs).real() == PetscReal(rhs); } \ | ^ /home/devel/petsc/dev/include/petsccxxcomplexfix.h:60:1: note: in expansion of macro ‘PETSC_CXX_COMPLEX_FIX’ 60 | PETSC_CXX_COMPLEX_FIX(PetscInt) -- Lisandro Dalcin ============ Research Scientist Extreme Computing Research Center (ECRC) King Abdullah University of Science and Technology (KAUST) http://ecrc.kaust.edu.sa/