Hi all. I'd like to express my concerns about the proposed change. CMake strongly discourages using `file(GLOB)` to find source files, since file additions then do not automatically trigger a buildsystem regeneration. So well-behaved projects, which do not feed such outputs to add_*() commands, will now pay a performance penalty for a feature only introduced for the sake of the ill-behaved ones.
In our setup, we have a large CMake-language framework built on top of "vanilla" CMake (partly for historical reasons, but partly to support our particular workflow), and we're always struggling with keeping the time of CMake processing down. Adding unnecessary overhead would be bad news for us. Can we instead make the feature optional? Even opt-out would be good enough, even thought there technically already is an opt-in, namely `list(SORT)` (which is even mentioned in the docs). Petr On 14 May 2016 at 12:30, Reiner Herrmann <rei...@reiner-h.de> wrote: > file(GLOB ...) is often used to find source files. As it uses > readdir(), the list of files will be unsorted. > This list is often passed directly to add_executable / add_library. > Linking binaries with an unsorted list will make it unreproducible, > which means that the produced binary will differ depending on the > unpredictable readdir() order. > > To solve those reproducibility issues in a lot of programs (which > don't explicitely sort the list manually), this change sorts the > resulting list of the file GLOB command. > > A more detailed rationale about reproducible builds is available at: > https://reproducible-builds.org/ > --- > Help/command/file.rst | 3 +-- > Source/cmFileCommand.cxx | 1 + > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/Help/command/file.rst b/Help/command/file.rst > index 96ac6c7..a502134 100644 > --- a/Help/command/file.rst > +++ b/Help/command/file.rst > @@ -103,8 +103,7 @@ Generate a list of files that match the > ``<globbing-expressions>`` and > store it into the ``<variable>``. Globbing expressions are similar to > regular expressions, but much simpler. If ``RELATIVE`` flag is > specified, the results will be returned as relative paths to the given > -path. No specific order of results is defined. If order is important > then > -sort the list explicitly (e.g. using the :command:`list(SORT)` command). > +path. The file list will be sorted. > > By default ``GLOB`` lists directories - directories are omited in result > if > ``LIST_DIRECTORIES`` is set to false. > diff --git a/Source/cmFileCommand.cxx b/Source/cmFileCommand.cxx > index 6b6b913..4efa550 100644 > --- a/Source/cmFileCommand.cxx > +++ b/Source/cmFileCommand.cxx > @@ -1026,6 +1026,7 @@ bool > cmFileCommand::HandleGlobCommand(std::vector<std::string> const& args, > > std::vector<std::string>::size_type cc; > std::vector<std::string>& files = g.GetFiles(); > + std::sort(files.begin(), files.end()); > for ( cc = 0; cc < files.size(); cc ++ ) > { > if ( !first ) > -- > 2.8.1 > > -- > > Powered by www.kitware.com > > Please keep messages on-topic and check the CMake FAQ at: > http://www.cmake.org/Wiki/CMake_FAQ > > Kitware offers various services to support the CMake community. For more > information on each offering, please visit: > > CMake Support: http://cmake.org/cmake/help/support.html > CMake Consulting: http://cmake.org/cmake/help/consulting.html > CMake Training Courses: http://cmake.org/cmake/help/training.html > > Visit other Kitware open-source projects at > http://www.kitware.com/opensource/opensource.html > > Follow this link to subscribe/unsubscribe: > http://public.kitware.com/mailman/listinfo/cmake-developers >
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