Hi *, As part of the Reproducible Builds effort , we would like to enable a new default build flag from the reproducible/fixdebugpath feature area in order to prevent issues with build paths.
From the dpkg-buildflag(1) manpage: This setting ([currently] disabled by default) adds -fdebug-prefix-map=BUILDPATH=. to CFLAGS, CXXFLAGS, OBJCFLAGS, OBJCXXFLAGS, GCJFLAGS, FFLAGS and FCFLAGS where BUILDPATH is set to the top-level directory of the package being built. This has the effect of removing the build path from any generated debug symbols. This flag is useful only since gcc-5/5.4.0-4 (#819176, ) and gcc-6 , as otherwise the produced debug symbols will lack the build path but the option itself will be saved in the resulting debug binary (in "DW_AT_producer"), only fixing the reproducibility problem halfway. Previous versions of GCC accept the -fdebug-prefix-map option but it was stored in DW_AT_producer, reducing the utility from a reproducible point of view. clang 3.8 supports the build flag and does not save the path in DW_AT_producer (although the source path gets included in the .strtab section if the source path is passed absolutely). We asked  the clang maintainers whether they would be willing to backport the -fdebug-prefix-path, but in the worst case there are only 3 clang reverse build-deps FTBFS due to this . dpkg-buildflags 1.18.10 has a restriction on the characters allowed in the build path and will automatically and silently disable the option if it finds unsafe ones. This should make it safe against unescaped characters. See #827155 for more insight on this issue. We enabled the reproducible/fixdebugpath feature in the Reproducible Builds CI one month ago and whilst we have about 3k packages yet to build we are already confident that there won't be any major regression related to this other than those 3 packages. Thus, following the dpkg team's policy  about adding a new default build flag, I'm seeking a wider discussion to see whether somebody has any concern we haven't already taken care of. I'd like to thank Daniel Kahn Gillmor for leading the implementation of this new build flag which unblocked a real problem in the Reproducible Builds world: allowing us to build packages in different build paths! Thanks for reading, Mattia  https://wiki.debian.org/ReproducibleBuilds https://reproducible-builds.org  https://bugs.debian.org/819176  https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=6ceddcd7b87911ddbb942923722af5a735dacedc  https://bugs.debian.org/819185  afl, libblocksruntime and libclc  https://wiki.debian.org/Teams/Dpkg/FAQ#Q:_Can_we_add_support_for_new_default_build_flags_to_dpkg-buildflags.3F -- regards, Mattia Rizzolo GPG Key: 66AE 2B4A FCCF 3F52 DA18 4D18 4B04 3FCD B944 4540 .''`. more about me: https://mapreri.org : :' : Launchpad user: https://launchpad.net/~mapreri `. `'` Debian QA page: https://qa.debian.org/developer.php?login=mattia `-
Description: PGP signature
_______________________________________________ Reproducible-builds mailing list Reproduciblefirstname.lastname@example.org http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/reproducible-builds