bug#42448: Issue with Qemu Binfmt and CMake not detecting compiler.

bug#42448: Issue with Qemu Binfmt and CMake not detecting compiler.

[Brett Gilio]

Hey all,

Opening a bug report as per a request following this issue identified
at: https://lists.gnu.org/archive/html/guix-devel/2020-07/msg00124.html.

To recap, when running

--8<---------------cut here---------------start------------->8---
./pre-inst-env guix build --system=armhf-linux swi-prolog
--8<---------------cut here---------------end--------------->8---

the configure phase is failing to identify the C/CXX compiler
toolchains to compile a test CMake file. There is a variety of
CMakeError.log and other object outputs that populate the build
directory when ran with --keep-failed.

This seems to be reported before, but subsequently patched at
https://issues.guix.gnu.org/38454#3. This only occurs when using the
Qemu method of compiling on a foreign architecture, and is not present
when natively compiling on true hardware.

Thanks,
Brett Gilio

bug#42448: A possible solution

[Brett Gilio]

As Marius Bakke pointed out on IRC, this issue is related to a change in
CMake where after 3.15 they removed the explicit `#define
_FILE_OFFSET_BITS 64`. The solution solution to this is to add

--8<---------------cut here---------------start------------->8---
CFLAGS="-D_FILE_OFFSET_BITS=64"
CXXFLAGS="-D_FILE_OFFSET_BITS=64"
--8<---------------cut here---------------end--------------->8---

to CMakes compilation procedure. This is a core-updates change. I will
leave this issue open for now in case this needs more
investigation. Since I am just coming off of a haitus I think there are
changes to the core-updates and staging procedures so I dont think I am
comfortable making this change myself.

Brett Gilio