- Boost - lists.boost.org

Linker Error During Compilation of Function
by Mottengte, Rajeev Kumar 11 Aug '05

11 Aug '05

Hi I am getting linker errors during compilation of functions which is returning object of class boost::archive::text_iarchive. The error is "In Copy constructor 'boost::archive::basic_text_iprimitive<> ..... boost::scoped_ptr<T> is private. So I changed the scoped_ptr to public manually in the scoped_ptr.hpp file. After that I am getting an error undefined reference to boost::scoped_ptr<std::locale>. Can any body tell me how to resolve this problem. Rgds Rajeev

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Re: [boost] alignment problem in proposed any alternative
by Martin Bonner 11 Aug '05

11 Aug '05

----Original Message---- From: christopher diggins [mailto:cdiggins@videotron.ca] Sent: 11 August 2005 14:00 To: boost(a)lists.boost.org Subject: Re: [boost] alignment problem in proposed any alternative [snip] > 3.9(2) says: > For any complete POD object type T, whether or not the object holds a > valid value of type T, the underlying > bytes (1.7) making up the object can be copied into an array of char > or unsigned char.36) If the content of the array of char or unsigned > char is copied back into the object, the object shall subsequently > hold its original value. > > This has nothing to do with void* and char*, but rather with all > POD's. > > This clearly implies char arrays are stringently aligned. Err, no it doesn't. It says that you can store the bits of a POD object into a char array, and then load the bits back into the same (correctly aligned) POD object. It does *NOT* say that you can use the address of the char array as if it were the address of the POD object. For example: #include <assert.h> int main() { long pod = 3141L; char pad; char c[sizeof(pod)]; memcpy( c, &pod, sizeof(pod) ); pod = 42L; memcpy( &pod, c, sizeof(pod) ); assert (pod == 3141L); // 3.9(2) requires this assert to pass. // nothing requires THIS assert to pass, and on some systems it fail // because c is not suitable aligned. assert ( *reinterpret_cast<long*>(&c[0]) == 3141L ); return 0; } -- Martin Bonner Martin.Bonner(a)Pitechnology.com Pi Technology, Milton Hall, Ely Road, Milton, Cambridge, CB4 6WZ, ENGLAND Tel: +44 (0)1223 441434

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thread library mutexes in Windows 95
by Jorge Lodos 11 Aug '05

11 Aug '05

Hi I'm trying to use the the boost::thread::mutex class in a Windows 95 project. Since the generated .lib files for the thread library include InterlockedCompareExchange (used in try_mutex::call_once) I was left with the option of adding the mutex.cpp and the exceptions.cpp files to my project and compiling them separately. Building the program included at the end, MSCV 7.1 gives the following linker errors: Compiling... Mutex.cpp Linking... mutex1.obj : error LNK2019: unresolved external symbol "void __cdecl boost::call_once(void (__cdecl*)(void),long &)" (?call_once@boost@@YAXP6AXXZAAJ@Z) referenced in function "bool __cdecl `anonymous namespace'::has_TryEnterCriticalSection(void)" (?has_TryEnterCriticalSection@?A0x5deb84cd@@YA_NXZ) mutex1.obj : error LNK2019: unresolved external symbol "int __cdecl boost::xtime_get(struct boost::xtime *,int)" (?xtime_get@boost@@YAHPAUxtime@1@H@Z) referenced in function "private: bool __thiscall boost::timed_mutex::do_timedlock(struct boost::xtime const &)" (?do_timedlock@timed_mutex@boost@@AAE_NABUxtime@2@@Z) Debug/Mutex.exe : fatal error LNK1120: 2 unresolved externals call_once is called in try_mutex constructor, while xtime_get is called in timed_mutex::do_timedlock. Nor try_mutex or timed_mutex are used at all. This was confirmed by commenting out the whole implementation for both in mutex.cpp, in which case the program links without problems. Just commenting out the lines m_critical_section = has_TryEnterCriticalSection(); in the try_mutex constructor and boost::xtime_get(&cur, boost::TIME_UTC); in timed_mutex::do_timedlock makes the program link. I originally expected the linker will remove all try_mutex and timed_muted implementation but it does not. Can someone give any ideas on how to use boost::mutex in a MSCV 7.1 project for Windows 95 without having to modify the original files? Is there a reason for the linker not to remove all the code for try_mutex and timed_mutex? Thanks in advance. Best regards Jorge #define BOOST_THREAD_NO_LIB #include <boost/thread/mutex.hpp> // mutex.cpp and exceptions.cpp compiled with // BOOST_THREAD_NO_LIB preprocessor option. // This must be enforced, since they both #include // <boost/thread/detail/config.hpp> int main(int argc, char *argv[ ]) { boost::mutex mymutex; boost::mutex::scoped_lock scoped_lock(mymutex); }

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Boost regression notification (2005-08-11)
by Douglas Gregor 11 Aug '05

11 Aug '05

Boost regression test failures ------------------------------ Report time: 2005-08-11T14:40:23Z This report lists all regression test failures on release platforms. Detailed report: http://engineering.meta-comm.com/boost-regression/CVS-RC_1_33_0/developer/i… 0 failure in 0 library:

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[1.33 RC2/serialization] New failures on Intel 8.1
by Stefan Slapeta 11 Aug '05

11 Aug '05

Hi, the latest changes seem to cause new failures on Intel 8.1 ("internal failure...") that are once again related to the buggy debug info generation in this compiler version. After investigating, I'm afraid I can't offer anything but to mark them as expected :-( Stefan

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Re: [boost] alignment problem in proposed any alternative
by felipe 11 Aug '05

11 Aug '05

> Date: Thu, 11 Aug 2005 09:00:20 -0400 > From: christopher diggins <cdiggins(a)videotron.ca> > Subject: Re: [boost] alignment problem in proposed any alternative > To: boost(a)lists.boost.org > Message-ID: <004c01c59e74$a17a7800$2b792518@heronnest> > Content-Type: text/plain; format=flowed; charset=iso-8859-1; > reply-type=original > ----- Original Message ----- > From: "felipe" <pbr(a)taric.es> > To: <boost(a)lists.boost.org> > Sent: Thursday, August 11, 2005 4:09 AM > Subject: Re: [boost] alignment problem in proposed any alternative > >> Nope, this is totally wrong! chars and arrays of type char are >> generally >> the least aligned objects. You can demonstrate that this doesn't work >> with something like this: >> >> void blah() >> { >> char c[/* some number */]; >> any<8> a((double)1.0); >> std::cout << &a << std::endl; >> } > That code is completely misleading, yhe question is not what the address > of > a is! > Well, let me clarify: /*############ BEGIN ########*/ #include <iostream> #include <boost/type_traits.hpp> template<int buffer_size> struct any { char c; // this offsets buffer by one-byte.. because for the // compiler, chars only need byte alignment char buffer[buffer_size]; // ... template<typename T> any(const T& x) { if (boost::is_pod<T>::value && (sizeof(T) <= buffer_size)) { memcpy(buffer, &x, sizeof(T)); } else { // new and stuff } } }; int main(int argc, char **argv) { any<8> blah((double)1.0); std::cout << (void *)&blah.buffer << std::endl; return 0; } /*##### END ########*/ Output of the program on Pentium/Win2k/Visual C++ 6.0: 0x22ef01 This is obviously NOT a good place for a double, unless you are going to memcpy everything, which would be a needlessly inefficient design. Right, the Pentium lets me slide (with some extra instructions to keep away idle cycles), but don't try it on an Alpha! Have you not read the articles by Alexandrescu in CUJ? These are pretty old and yet they explore all of this stuff. What you should do is make the buffer a union of a minimal size object (e.g. your char array) and a minimum alignment object (e.g. a double in the example above). The compiler then adjusts alignment for the latter, while guaranteeing space for the former. Another thing, your proposal shies away from objects with constructors, etc. Why? You can use the placement new operator and get a much cleaner implementation. You know, something like this: template<typename T> any(const T& x) { .. new(&buffer[0]) T(x); // instead of memcpy hope this helps -- Using Opera's revolutionary e-mail client: http://www.opera.com/m2/

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Self Contained Transportable Class :
by Mottengte, Rajeev Kumar 11 Aug '05

11 Aug '05

Hi I am trying to create a self contained transportable class which can be migrated to any machine by calling a member function in it. I am having the socket stream implementation which derives the transportable boost class. In the serialize function of the boost class, I am trying to get the string stream and trying to call network marshal function of the base class. How can I get the stream ( I am using a string stream ) from the archive class inside the serialize function. Rgds Rajeev

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Re: [boost] alignment problem in proposed any alternative
by felipe 11 Aug '05

11 Aug '05

Nope, this is totally wrong! chars and arrays of type char are generally the least aligned objects. You can demonstrate that this doesn't work with something like this: void blah() { char c[/* some number */]; any<8> a((double)1.0); std::cout << &a << std::endl; } Tweak the size of c[] until you get &a % 8 != 0. Some compilers optimize stack layout, over-aligning data, but this is true only for SOME compilers on SOME processors with SOME optimization settings. (You can also experiment by defining an additional char variable before the buffer in your any. Where does &a.buffer lie?) I think you are misreading 3.9.2: it is talking about pointers, namely that void * and char * have the same storage and alignment requirements. On Wed, 10 Aug 2005 20:27:16 +0200, <boost-request(a)lists.boost.org> wrote: > From: "christopher diggins" <cdiggins(a)videotron.ca> > To: "Boost mailing list" <boost(a)lists.boost.org> > Sent: Wednesday, August 10, 2005 1:30 AM > Subject: [boost] alignment problem in proposed any alternative >> The question I have is whether in practice though are there are any >> compilers which have stricter alignment requirements on small types (<= >> sizeof(void*)) than a void pointer. In other words, is it possible with >> any >> known compiler to actually throw the runtime error ? > Now a moot point, see below. > >> Unfortunately there is another problem, I am not an expert in >> interepreting >> the standard, but AFAICT placement new is guaranteed to return a pointer >> to >> properly aligned memory (3.7.3.1 / 2) which I leverage to check that >> alignment occured. Apparently not every STL implementation does in fact >> do >> that (I believe at least dinkumware is guilty of that). > Apparently I am wrong about this! 18.4.1.3 provides an exception. (I > wonder > why I missed the exception 15 chapters later?) > Anyway it turns out we can guarantee alignment by simply using a char > buffer. According to 3.9/2 the following automatically has no alignment > problems: > template<int buffer_size> > struct any { > char buffer[buffer_size]; > ... > template<typename T> > any(const T& x) { > if (boost::is_pod<T>::value && (sizeof(T) <= buffer_size)) { > memcpy(buffer, &T, N); > } > else { > // new and stuff > } > } > } > Christopher Diggins -- Using Opera's revolutionary e-mail client: http://www.opera.com/m2/

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[1.33.0] Release candidate #2 is available
by Douglas Gregor 11 Aug '05

11 Aug '05

Boost 1.33.0 release candidate #2 is now available at the usual place: http://www.osl.iu.edu/~dgregor/boost-1.33.0/ Please build it, test it, and report back to the mailing list. If no major problems are found before August 9th, this release candidate will become Boost 1.33.0. Doug Gregor 1.33.0 Release Manager

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Compilation error with regex only with -O3 on gcc
by robert kraus 11 Aug '05

11 Aug '05

Hi, when I compile with: -O0 to -O2 my programs compile and work fine, but when I switch to -O3 I get compilation errors (shortened, see below). Is this my fault (maybe I shouldnt use optimizations? thank you very much for your answers ido fedora core 4,gcc version: Target: i386-redhat-linux Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-libgcj-multifile --enable-languages=c,c++,objc,java,f95,ada --enable-java-awt=gtk --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre --host=i386-redhat-linux Thread model: posix gcc version 4.0.1 20050727 (Red Hat 4.0.1-5) boost: boost-devel-1.32.0-6 Errors: Building file: ../src/Parser.cpp Invoking: GCC C++ Compiler g++ -DDEBUG -O3 -g3 -pedantic -Wall -c -fmessage-length=0 -osrc/Parser.o ../src/Parser.cpp /usr/include/boost/regex/v4/regex_compile.hpp: In member function ‘boost::re_detail::re_syntax_base* boost::reg_expression<charT, traits, Allocator>::compile_set_simple(boost::re_detail::re_syntax_base*, long unsigned int, bool) [with charT = char, traits = boost::regex_traits<char>, Allocator = std::allocator<char>]’: /usr/include/boost/regex/v4/regex_compile.hpp:1635: instantiated from ‘unsigned int boost::reg_expression<charT, traits, Allocator>::set_expression(const charT*, const charT*, boost::regex_constants::syntax_option_type) [with charT = char, traits = boost::regex_traits<char>, Allocator = std::allocator<char>]’ /usr/include/boost/regex/v4/basic_regex.hpp:238: instantiated from ‘unsigned int boost::reg_expression<charT, traits, Allocator>::set_expression(const charT*, boost::regex_constants::syntax_option_type) [with charT = char, traits = boost::regex_traits<char>, Allocator = std::allocator<char>]’ /usr/include/boost/regex/v4/regex_compile.hpp:110: instantiated from ‘boost::reg_expression<charT, traits, Allocator>::reg_expression(const charT*, boost::regex_constants::syntax_option_type, const Allocator&) [with charT = char, traits = boost::regex_traits<char>, Allocator = std::allocator<char>]’ /usr/include/boost/regex/v4/basic_regex.hpp:340: instantiated from ‘boost::basic_regex<charT, traits, Allocator>::basic_regex(const charT*, typename boost::reg_expression<charT, traits, Allocator>::flag_type, const Allocator&) [with charT = char, traits = boost::regex_traits<char>, Allocator = std::allocator<char>]’ ../src/Parser.cpp:16: instantiated from here __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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