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

[Andreas Färber]

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,
Andreas

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