Re: 32-bit buildbot builders broken [Re: Your commit 'Build GDB as a C++ program by default' broke GDB]

[Sergio Durigan Junior <sergiodj@redhat.com>]

On Wednesday, April 27 2016, Antoine Tremblay wrote:

> Sergio Durigan Junior writes:
>
>> On Thursday, April 21 2016, Pedro Alves wrote:
>>
>>>> g++ -g -O2   -I. -I../../binutils-gdb/gdb -I../../binutils-gdb/gdb/common
>>>> -I../../binutils-gdb/gdb/config
>>> ...
>>>> -I../../binutils-gdb/gdb/../libdecnumber
>>>> -I../../binutils-gdb/gdb/gnulib/import -Ibuild-gnulib/import -DTUI=1
>>>> -I/usr/include/python2.7 -I/usr/include/python2.7 -Wall
>>>> -Wpointer-arith -Wno-unused -Wunused-value -Wunused-function
>>>> -Wno-switch -Wno-char-subscripts -Wempty-body -Wno-sign-compare
>>>> -Wno-write-strings -Wno-narrowing -Wformat-nonliteral -Werror -c -o
>>>> linux-thread-db.o -MT linux-thread-db.o -MMD -MP -MF
>>>> .deps/linux-thread-db.Tpo ../../binutils-gdb/gdb/linux-thread-db.c
>>>> In file included from ../../binutils-gdb/gdb/i386-linux-nat.c:25:0:
>>>> ../../binutils-gdb/gdb/i386-linux-nat.c: In function void fetch_regs(regcache*, int):
>>>> ../../binutils-gdb/gdb/i386-linux-nat.c:207:46: error: cast from elf_greg_t (*)[27] {aka long long unsigned int (*)[27]} to int loses precision [-fpermissive]
>>>>    if (ptrace (PTRACE_GETREGS, tid, 0, (int) &regs) < 0)
>>>
>>>
>>> ... however this error is exactly what you get if you compile with a
>>> 64-bit compiler, and forget to pass -m32 to gcc/g++.  IOW, 
>>> it compiles i386-linux-nat.c as if for a 64-bit host, which fails.
>>>
>>> So I suspect the builder is using CC="gcc -m32", and now that a C++ compiler
>>> is involved, it needs to be updated to pass CXX="g++ -m32" as well.
>>
>> Yeah, actually I was setting CFLAGS without setting CXXFLAGS for these
>> builders, so I fixed that now.  Thanks for letting me know, and sorry
>> about that.
>
> I was looking at
> http://gdb-build.sergiodj.net/builders/Fedora-x86_64-m32/builds/3499/steps/configure%20gdb/logs/stdio
>
> And it seems it builds in 64 bit, there's no --host=i386... or -m32 ?

Hey Antoine,

Thanks for the message.  So, as I said on IRC, the purpose of this
builder is to perform a 64-bit compilation of GDB (i.e., without -m32),
but run the testsuite on 32-bit mode (i.e., passing
--target_board=unix/-m32 to runtest).

Maybe the builder's name is confusing, and I apologize for that.  I
could try to add a better description of it on the page.

Cheers,

-- 
Sergio
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