On 10 April 2026 at 16:51, Kurt Hornik wrote: | >>>>> Dirk Eddelbuettel writes: | | > Hi Helmut, | | > I will CC Kurt Hornik from the upstream team for R, he is the principal | > author of the extensive autoconf etc pieces for R. | | > On 30 March 2026 at 18:27, Helmut Grohne wrote: | > | Source: r-base | > | Version: 4.5.3-1 | > | Tags: patch | > | User: [email protected] | > | Usertags: cross-satisfiability ftcbfs | > | | > | r-base fails to cross build from source for a pile of reasons. | > | | > | Initially, its Build-Depends cannot be satisfied. This is due to "gcc", | > | "g++" and "gfortran". For supporting cross compilation, toolchain | > | dependencies need to be translated and declare what architecture they | > | are being used for. In case of gcc and g++, both the build and host | > | architecture toolchain is implied in build-essential. The version | > | constraint is satisfied in oldoldstable. I suggest dropping them. | | > Yes. I recall us having email about this before but for some reason it stuck. | | > R is in pre-release for R 4.6.0 so I can easily try a few builds (up until | > the release on April 24). | | > | gfortran is used to compile Fortran code for the host architecture. | > | Hence, it should be suffixed -for-host. Once doing so, you may no longer | > | assume presence of unprefixed tools such as "gfortran". Instead, | > | ${DEB_HOST_GNU_TYPE}-gfortran must be used. This leads to the second | > | problem. | > | | > | Use of bare tools. debian/rules uses bare tool names such as gcc, g++ | > | and gfortran in several places. Those compile for the build | | > It's an old file, and some/most of the shenanigans were/are needed ... | | > | architecture, but the package is supposed to be built for the host | > | architecture. Those tools all need to be prefixed with a host | > | architecture triplet. Fortunately, dpkg has a buildtools.mk file that | > | can be included to supply all those tools. | > | | > | In the attached patch, I opt for replacing the variable names for tools | > | with those used by buildtools.mk. For instance, compiler becomes CC and | > | cxxcompiler becomes CXX. This also happens to match what the upstream | > | build system expects. | | > I appreciate this and will fold it in. | | > | Last but not least, for cross building an autotools project one needs to | > | pass --build and --host to configure. Since the package does not use | > | dh_auto_configure, this must be done explicitly. | > | | > | You can find all of the necessary changes in the attached patch. Once | > | applying it, r-base will not cross build. The upstream build system uses | > | a pile of AC_RUN_IFELSE checks and any of them makes a cross build fail. | | > Kurt, this is your corner. | | Thanks. Not much I can do about this: R-admin has forever said | | The @file{configure} script has other generic options added by | @command{autoconf} and which are not supported for @R{}: in particular | building for one architecture on a different host is not possible. | | Is there a case for cross-building?
It is my understanding that some Debian architectures use it but Helmut will know more and may chime in. I also lost track of what happens with Windows and R but at some point didn't some of the MSys replacement / update work involve building under Linux with gcc cross compilers? Either way, this should be addressable as Debian surely hits other upstream sources using autoconf so I have some hope that between all of us we may just be missing a small step to facilitate this. Dirk | -k | | > | most of them are cached, so a cross builder may supply a result via the | > | environment. Going from there to a full cross build is another piece, | > | but the attached patch at least makes Build-Depends satisfiable and | > | proceeds to the configure step. | | > Following April 24, R gets into a new annual cycle. With your assistance, | > maybe upstream (and the Debian package) can (finally) to cross-build and | > repeated builds. | | > Dirk | | > | Helmut | > | x[DELETED ATTACHMENT r-base_4.5.3-1.1.debdiff, plain text] | | > -- | > dirk.eddelbuettel.com | @eddelbuettel | [email protected] -- dirk.eddelbuettel.com | @eddelbuettel | [email protected] Sponsor me for Tour de Shore 2026! Donate at https://www.pledgereg.com/536435 More about the ride at https://dirk.eddelbuettel.com/blog/2026/04/03#sponsor_tour_de_shore_2026
