Bug 1006053

Summary: x86_64-linux-gnu-gcc doesn't support c++
Product: [Fedora] Fedora Reporter: Brendan Long <self>
Component: cross-gccAssignee: David Howells <dhowells>
Status: CLOSED WONTFIX QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: unspecified    
Version: 19CC: dan, dhowells, jakub, law, mjuszkie
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Hardware: i686   
OS: Linux   
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Last Closed: 2013-09-18 16:19:07 UTC Type: Bug
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Description Brendan Long 2013-09-09 22:03:25 UTC 
Description of problem:

I want to use icecream for distributed compiling, and I want my 32-bit machines to cross compile for the 64-bit machines. Unfortunately, the 64-bit version of gcc doesn't come with c++, and there's no c++ package for it.

Version-Release number of selected component (if applicable):

Fedora 19

How reproducible:

Every time.

Steps to Reproduce:

1. sudo yum install x86_64-linux-gnu-gcc
2. x86_64-linux-gnu-gcc test.cpp

Actual results:

x86_64-linux-gnu-gcc: error: test.cpp: C++ compiler not installed on this system

Expected results:

Should compile the file.

Additional info:

Installing gcc-c++ doesn't help, and there's no x86_64-linux-gnu-g++ or x86_64-linux-gnu-gcc-c++ package.
Comment 1 Brendan Long 2013-09-09 22:35:27 UTC 
Interestingly, there's even a binary called `x86_64-linux-gcc-cpp`, but it doesn't work:

> $ x86_64-linux-gnu-gcc test.cpp
> x86_64-linux-gnu-gcc: error: test.cpp: C++ compiler not installed on this system
Comment 2 Jakub Jelinek 2013-09-18 15:39:00 UTC 
*-cpp is a preprocessor, not a C++ compiler, that would be *-c++, but I bet cross-gcc is meant to support only C, it is there mainly for kernel people, building usable cross compilers for C++ requires usually more effort, you need target libraries which cross-gcc doesn't bother with.
Comment 3 David Howells 2013-09-18 16:19:07 UTC 
Jakub is right.  We don't support any userspace side at this time because of the massive multiplication factor that it would incur and the messiness it incurs.

The SRPM that builds this also builds 23 other cross-compilers RPMs at the same time in the same build.  Multiply those by the different arch variants the kernel supports (MIPS has at least 6 for example) and the different C libraries that may be available (glibc and uClibc) and you start getting huge RPM counts.

Then you need to inflate the SRPM because it needs kernel headers, glibc sources, uClibc sources and libstdc++ library sources in addition to the compiler sources.  (Does libstdc++ even build for uClibc?)

Further, there's no guarantee that we can build C++ for every cross-compiler.
Comment 4 Marcin Juszkiewicz 2013-09-24 09:04:15 UTC 
If you need C++ cross compiler then fetch source, select only required target architecture and change configure call to enable also c++ language.

I understand why there is no such one enabled.