Re: [Qemu-devel] [PATCH v2] configure: Make C++ test work with --enable-werror

[Peter Maydell]

On 6 March 2014 19:55, Andreas Färber <address@hidden> wrote:
> Am 25.02.2014 19:27, schrieb Peter Maydell:
>> gcc's C++ compiler complains about being passed some -W options
>> which make sense for C but not for C++. This means we mustn't try
>> a C++ compile with QEMU_CFLAGS, but only with a filtered version
>> that removes the offending options. This filtering was already being
>> done for uses of C++ in the build itself, but was omitted for the
>> "does C++ work?" configure test. This only showed up when doing
>> builds which explicitly enabled -Werror with --enable-werror,
>> because the "do the compilers work" tests were mistakenly placed
>> above the "default werror based on whether compiling from git" code.
>> Another error in this category is that clang warns if you ask it to
>> compile C++ code from a file named "foo.c". Further, because we
>> were running do_cc in a subshell in the condition part of an "if",
>> the error_exit inside do_compiler wouldn't terminate configure and
>> we would plunge on regardless. Fix this complex of errors:
>>
>> 1. Move the default-werror code up so that there are no invocations
>> of compile_object and friends between it and the point where we
>> set $werror explicitly based on the --enable-werror command line
>> option.
>>
>> 2. Provide a mechanism for filtering QEMU_CFLAGS to create
>> QEMU_CXXFLAGS, and use it for the test we run here.
>>
>> 3. Provide a do_cxx function to run a test with the C++ compiler
>> rather than doing cute tricks with subshells and do_cc.
>>
>> 4. Use a new temporary file TMPCXX for the C++ program fragment.
>>
>> Signed-off-by: Peter Maydell <address@hidden>
>
> Still works for my --enable-werror setup,
>
> Tested-by: Andreas Färber <address@hidden>

Thanks; applied directly to master as a buildfix.

-- PMM