severity 534722 normal forwarded 534722 f...@fftw.org thanks Hello Frank,
The upstream authors are included in this thread. Frank Hess wrote: > Package: libfftw3-dev > Version: 3.1.2-3.1 > Severity: important > > FFTW3 has a mis-design feature where if complex.h is included before fftw3.h > (maybe indirectly and > unintentionally through another header) then the header changes the > definition of > the "fftw_complex" types (without doing any mangling to give them different > names). Indeed, this is a documented behavior, see: http://www.fftw.org/doc/Complex-numbers.html > This means if a user doesn't include fftw3.h first, before > any possible inclusion of complex.h, then his > code may be using a different ABI than that of the libfftw3.so provided by > debian. > Or, indeed, different translation units of the user's program may be using > different > definitions of fftw_complex depending on exactly when each translation unit > included fftw3.h. This > will at the very least cause violations of the C strict aliasing rules which > can > cause mysterious crashes when optimization is turned on (unless gcc's > -fno-strict-aliasing > option is used). I have personally seen these crashes, and the problems can > also be visible when using valgrind (I saw it cause various uninitialized > memory problems > in my program which valgrind reported). Could you provide a test-case to reproduce said crashes? Also, did you use fftw_cleanup() in your programs when running through valgrind? > As a workaround, Debian should alter the fftw3.h header so it does not define > fftw_complex based on header inclusion order, but always defines fftw_complex > in > the same way it is defined when Debian compiles libfftw3.so. Except this would defeat the whole purpose of the current design. For the record, we have this in api/api.h: /* just in case: force <fftw3.h> not to use C99 complex numbers (we need this for IBM xlc because _Complex_I is treated specially and is defined even if <complex.h> is not included) */ #define FFTW_NO_Complex and this in api/fftw3.h /* If <complex.h> is included, use the C99 complex type. Otherwise define a type bit-compatible with C99 complex */ #if !defined(FFTW_NO_Complex) && defined(_Complex_I) && defined(complex) && defined(I) # define FFTW_DEFINE_COMPLEX(R, C) typedef R _Complex C #else # define FFTW_DEFINE_COMPLEX(R, C) typedef R C[2] #endif cheers, piem > > -- System Information: > Debian Release: 5.0.1 > APT prefers stable > APT policy: (500, 'stable') > Architecture: i386 (i686) > > Kernel: Linux 2.6.26-2-686 (SMP w/2 CPU cores) > Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8) > Shell: /bin/sh linked to /bin/bash > > Versions of packages libfftw3-dev depends on: > ii libc6 2.7-18 GNU C Library: Shared libraries > ii libfftw3-3 3.1.2-3.1 library for computing Fast > Fourier > > libfftw3-dev recommends no packages. > > libfftw3-dev suggests no packages. > > -- no debconf information > > > > -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
