[cfe-dev] Bug 23307 - clang fails to compile rstudio-0.98.1103/src/cpp/session/modules/SessionHTMLPreview.cpp against libc++

[Richard Smith]

On Wed, Apr 22, 2015 at 12:54 PM, Jack Howarth <
howarth.mailing.lists at gmail.com> wrote:

>     Can one of the libc++ experts take a peak at...
>
> https://llvm.org/bugs/show_bug.cgi?id=23307
>
> I am unclear why clang++ with libstdc++ tolerates the following code from
> rstudio 0.98.1103...
>
> const char* const MAGIC_GUID = "12861c30b10411e1afa60800200c9a66";
> const char* const FIGURE_DIR = "figure-compile-notebook-12861c30b";
>
> bool okToGenerateFile(const FilePath& rmdPath,
>                       const std::string& extension,
>                       std::string* pErrMsg)
> {
>    FilePath filePath = rmdPath.parent().complete(
>                                     rmdPath.stem() + extension);
>
>    if (filePath.exists())
>    {
>       boost::shared_ptr<std::istream> pStr;
>       Error error = filePath.open_r(&pStr);
>       if (error)
>       {
>          *pErrMsg = "Error opening file: " + error.summary();
>          return false;
>       }
>
>       std::string magicGuid(MAGIC_GUID);
>       std::istreambuf_iterator<char> eod;
>       if (eod == std::search(std::istreambuf_iterator<char>(*pStr),
>                              eod,
>

std::search requires a ForwardIterator. std::istreambuf_iterator is only an
InputIterator.
If you build with -D_GLIBCXX_CONCEPT_CHECKS then the libstdc++ build will
also fail.


>                              magicGuid.begin(),
>                              magicGuid.end()))
>
> but clang++ with libc++ errors on the above if statement as...
>
> # clang++ -DBOOST_ASIO_DISABLE_KQUEUE -DBOOST_ENABLE_ASSERT_HANDLER
> -DBOOST_SIGNALS_NO_DEPRECATION_WARNING -std=c++11 -stdlib=libc++ -O3
> -DNDEBUG -c SessionHTMLPreview.ii
> In file included from
> /sw/src/fink.build/rstudio-desktop-0.98.1103-5/rstudio-0.98.1103/src/cpp/session/modules/SessionHTMLPreview.cpp:17:
> In file included from
> /sw/src/fink.build/rstudio-desktop-0.98.1103-5/rstudio-0.98.1103/src/cpp/session/modules/SessionHTMLPreview.hpp:25:
> In file included from
> /sw/src/fink.build/rstudio-desktop-0.98.1103-5/rstudio-0.98.1103/src/cpp/core/include/core/json/Json.hpp:19:
> In file included from
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/string:439:
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/algorithm:1572:12:
> error: no matching function for call to
>       '__search'
>     return std::__1::__search<typename
> add_lvalue_reference<_BinaryPredicate>::type>
>
>  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/algorithm:1586:22:
> note: in instantiation of function
>       template specialization
> 'std::__1::search<std::__1::istreambuf_iterator<char,
> std::__1::char_traits<char> >, std::__1::__wrap_iter<char *>,
>       std::__1::__equal_to<char, char> >' requested here
>     return std::__1::search(__first1, __last1, __first2, __last2,
> __equal_to<__v1, __v2>());
>                      ^
> /sw/src/fink.build/rstudio-desktop-0.98.1103-5/rstudio-0.98.1103/src/cpp/session/modules/SessionHTMLPreview.cpp:555:23:
> note: in instantiation of function template
>       specialization 'std::__1::search<std::__1::istreambuf_iterator<char,
> std::__1::char_traits<char> >, std::__1::__wrap_iter<char *> >' requested
> here
>       if (eod == std::search(std::istreambuf_iterator<char>(*pStr),
>                       ^
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/algorithm:1456:1:
> note: candidate function [with
>       _BinaryPredicate = std::__1::__equal_to<char, char> &,
> _RandomAccessIterator1 = std::__1::istreambuf_iterator<char,
> std::__1::char_traits<char> >,
>       _RandomAccessIterator2 = std::__1::__wrap_iter<char *>] not viable:
> no known conversion from 'typename
> std::iterator_traits<istreambuf_iterator<char,
>       char_traits<char> > >::iterator_category' (aka
> 'std::__1::input_iterator_tag') to 'std::__1::random_access_iterator_tag'
> for 6th argument
> __search(_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1,
> ^
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/algorithm:1419:1:
> note: candidate function [with
>       _BinaryPredicate = std::__1::__equal_to<char, char> &,
> _ForwardIterator1 = std::__1::istreambuf_iterator<char,
> std::__1::char_traits<char> >,
>       _ForwardIterator2 = std::__1::__wrap_iter<char *>] not viable: no
> known conversion from 'typename
> std::iterator_traits<istreambuf_iterator<char,
>       char_traits<char> > >::iterator_category' (aka
> 'std::__1::input_iterator_tag') to 'std::__1::forward_iterator_tag' for 6th
> argument
> __search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
> ^
> 1 error generated.
>
> Is this a valid error or a glitch in clang++/libc++?
>             Jack
>
> _______________________________________________
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> cfe-dev at cs.uiuc.edu
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>
>
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