Ping. Anyone having problems with this? And the governance of the file? On Mon, Sep 12, 2022 at 1:51 PM Ulrich Drepper <drep...@redhat.com> wrote:
> After my prior inquiry into the use of python as a build tool for > maintainers didn't produce any negative comments and several active and > even enthusiastic support message I'm going forward with submitting the > patch. > > To repeat the detail, for the generation of the upcoming C++ standard > library module and the hints for missing definitions/declarations in the > std:: namespace we need a list of standard C++ APIs. The information > needed for the two use cases is different but the actual APIs overlap > almost completely and therefore it would be a bad idea to have the data > separated. > > We could opt for a file format that is easy to read in awk and writing the > appropriate scripts to transform the data into the appropriate output > format but this looks ugly, is hard to understand, and a nightmare to > maintain. On the other hand, writing the code in Python is simple and > clean. > > > Therefore, Jonathan and I worked on a CSV file which contains the > necessary information and a Python to create the gperf input file to > generate std-name-hint.h and also, in future, the complete source of the > export interface description for the standard library module. This mode is > not yet used because the module support isn't ready yet. The output file > corresponds to the hand-coded version of the export code Jonathan uses > right now. > > Note that in both of these cases the generated files are static, they > don't depend on the local configuration and therefore are checked into the > source code repository. The script only has to run if the generated files > are explicitly removed or, in maintainer mode, if the CSV file has > changed. For normal compilation from a healthy source code tree the tool > is not needed. > > > One remaining issue is the responsibility for the CSV file. The file > needs to live in the directory of the frontend and therefore nominally > changes need to be approved by the frontend maintainers. The content > entirely consists of information from the standard library, though. Any > change that doesn't break the build on one machine (i.e., the Python script > doesn't fail) will not course any problem because the output format of the > script is correct. Therefore we have been wondering whether the CSV file > should at least have shared ownership between the frontend maintainers and > the libstdc++ maintainers. > > The CSV file contain more hint information than the old hand-coded .gperf > file. So, an additional effect of this patch is the extension of the hints > that are provided but given that the lookup is now fast this shouldn't have > any negative impact. The file is not complete, though, this will come over > time and definitely before the module support is done. > > I build my complete set of compilers with this patch without problems. > > Any comments? > > 2022-09-12 Jonathan Wakely <jwak...@redhat.com> > Ulrich Drepper <drep...@redhat.com> > > contrib/ChangeLog > * gcc_update: Add rule to generate gcc/cp/std-name-hint.gperf. > > gcc/cp/ChangeLog > * Make-lang.in: Add rule to generate gcc/cp/std-name-hint.gperf. > Adjust rule to generate $(srcdir)/cp/std-name-hint.h. > Add explicit rule to depend cp/name-lookup.o on > $(srcdir)/cp/std-name-hint.h. > * cxxapi-data.csv: New file. Database of C++ APIs. > * gen-cxxapi-file.py: New file. Script to generate source code for > C++ standard library exports and to generate C++ std:: namespace > fix hints. > * std-name-hint.gperf: Regenerated. > * std-name-hint.h: Regenerated. >
