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. | 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]
