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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.googlemail.com with ESMTPSA id h21-20020a170906829500b006cef3dcd067sm8458024ejx.174.2022.03.15.10.29.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 15 Mar 2022 10:29:51 -0700 (PDT) Message-ID: Date: Tue, 15 Mar 2022 18:29:50 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH experiment 00/16] C++20 coroutine backend Content-Language: en-US To: Peter Maydell , Stefan Hajnoczi References: <20220314093203.1420404-1-pbonzini@redhat.com> <4528e387-8016-0774-9c8b-532a75566d9d@redhat.com> From: Paolo Bonzini In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Host-Lookup-Failed: Reverse DNS lookup failed for 2a00:1450:4864:20::630 (failed) Received-SPF: pass client-ip=2a00:1450:4864:20::630; envelope-from=paolo.bonzini@gmail.com; helo=mail-ej1-x630.google.com X-Spam_score_int: 0 X-Spam_score: -0.1 X-Spam_bar: / X-Spam_report: (-0.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FORGED_FROMDOMAIN=0.249, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.249, NICE_REPLY_A=-0.001, PDS_HP_HELO_NORDNS=0.659, RCVD_IN_DNSWL_NONE=-0.0001, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, hreitz@redhat.com, berrange@redhat.com, qemu-devel@nongnu.org, qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 3/15/22 15:24, Peter Maydell wrote: > On Tue, 15 Mar 2022 at 14:09, Stefan Hajnoczi wrote: >> Also, once C++ is available people will >> start submitting C++ patches simply because they are more comfortable >> with C++ (especially one-time/infrequent contributors). > > This to my mind is the major argument against using C++ > for coroutines... I agree on the need for a policy, but _what_ C++ are they going to be contributing that we should be scared of? We're talking about: * major features contributed by one-time/infrequent participants (which is already a once-in-a-year thing or so, at least for me) * ... in an area where there are no examples of using C++ in the tree (or presumably the maintainer would be comfortable reviewing it) * ... but yet C++ offer killer features (right now there's only C++ coroutines and fpu/) * ... and where the one-time contributor has put enough investment in using these killer C++ features, that telling them to remove the features would amount to a rewrite. That does not seem to be a common situation, and not even a problematic one if it were to happen. Paolo