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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id t19sm7868809ejc.62.2021.01.25.00.04.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 25 Jan 2021 00:04:35 -0800 (PST) Subject: Re: [PATCH v7 05/11] osdep: build with non-working system() function To: Peter Maydell , Joelle van Dyne References: <20210122201113.63788-1-j@getutm.app> <20210122201113.63788-6-j@getutm.app> From: Paolo Bonzini Message-ID: <59a773e4-b277-a8a2-b496-d95b515718e2@redhat.com> Date: Mon, 25 Jan 2021 09:04:34 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.25, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: QEMU Developers Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 23/01/21 14:45, Peter Maydell wrote: > On Sat, 23 Jan 2021 at 03:18, Joelle van Dyne wrote: > On Fri, Jan 22, 2021 at 3:17 PM Peter Maydell wrote: >>> Can we do the "does system() exist?" check in meson.build ? > >>> config_host_data.set('HAVE_SYSTEM_FUNCTION', cc.has_function('system')) > >> Unfortunately, this doesn't work for iOS, which defines system() but >> throws a compile time error if you try to call it. > > That's odd -- as far as I can tell the meson implementation > of has_function() does what I expected it to do, ie > "try to compile and link a little program that uses the > function, and see if it successfully links": > https://github.com/mesonbuild/meson/blob/39ede12aa5b27376341df85bc9ec254913f044bd/mesonbuild/compilers/mixins/clike.py#L791 > There's some initial cleverness there too, so I guess some > part of that must be what's tripping us up. > > In any case, I think we should be doing new checks in > meson.build, not configure. Paolo, what's the right > way to do a meson "really compile this program and > check it built" test? One possibility is that you have to specify the #include in the "prefix" argument of cc.has_function for the test to behave as the QEMU code? If cc.has_function doesn't work, there's cc.compiles() and cc.links(). Paolo