84 lines
3.3 KiB
Markdown
84 lines
3.3 KiB
Markdown
How to update a third party library to a newer version
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======================================================
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0. Introduction
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---------------
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wxWidgets includes several third party libraries, i.e. libraries which are
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used by wxWidgets and distributed with it but which we don't maintain nor even
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modify, inasmuch as possible, ourselves. These libraries are developed by
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their maintainers and from time to time we need to replace the versions used
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by wxWidgets with newer versions.
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1. Submodules
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-------------
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All third party libraries are managed using Git submodules. This includes
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3rdparty/catch and expat, jpeg, png, tiff and zlib subdirectories of src.
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As always with submodules, updating a library involves updating its sources in
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the submodule, pushing this submodule out and then committing the changes in
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the top-level repository.
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2. Updating the submodule
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-------------------------
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All submodules use `master` branch for the upstream master and `wx` for the
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version used by wxWidgets. To update the latter, just merge the appropriate
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commit from master into `wx`, e.g.
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$ cd src/expat
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$ git checkout wx
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$ git merge R_x_y_z # For the latest x.y.z release
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After resolving any conflicts, commit the result, test the build under MSW and
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under Unix using `--disable-sys-libs` configure option, and push the updated
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branch out. Notice that you may want to use the ssh GitHub repository URL
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instead of the default (because more convenient for checking them out) HTTPS
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one:
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$ git push --set-upstream git@github.com:wxWidgets/libexpat.git wx
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3. Generating build files (libexpat, libtiff)
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---------------------------------------------
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We include the generated build files of libexpat and libtiff. For libexpat run
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`buildconf.sh`. For libtiff run `autogen.sh`. Commit the changes.
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4. Updating the main repository
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-------------------------------
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If there are any changes to the source files used by the library, update the
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corresponding `build/bakefiles/$lib.bkl` file (e.g. `expat.bkl` for Expat) and
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rerun bakefile to regenerate most of the makefiles and project files. Currently
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you will need to update `build/msw/wx_wx$lib.vcxproj{,.filters}` files
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manually.
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Commit these changes and the submodule and create a PR to test them as usual.
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5. Special instructions for libpng
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----------------------------------
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We use a special hack for libpng as we want to prefix all its symbols with
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`wx_` but don't want to use its build system which makes this easily possible
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(perhaps we should, but for now we don't). So, when upgrading libpng, you need
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to perform an extra step after merging the new version (and before committing
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your changes):
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Create a temporary build directory and run libpng configure from it using
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`--with-libpng-prefix=wx_` option. Then run `make pnglibconf.h pngprefix.h`
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to create these files in the build directory. Next, search for the line
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containing `PNG_ZLIB_VERNUM` in the `pnglibconf.h` and set it to 0 to disable
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zlib version checks (this looks dangerous but seems to be unavoidable with the
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current build system). And then, finally, copy these files to src/png
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subdirectory of the wxWidgets source tree, overwriting the versions there.
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Notice that config.h generated by libpng configure is not used, we build it
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without `-DHAVE_CONFIG_H` as it works just fine without it on any ANSI C system
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(i.e. anywhere by now).
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