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[130.44.146.16]) by smtp.gmail.com with ESMTPSA id dm5-20020ad44e25000000b00679cf84fb78sm1236424qvb.85.2023.11.19.18.55.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Nov 2023 18:55:49 -0800 (PST) From: Jason Merrill To: gcc-patches@gcc.gnu.org Cc: libstdc++@gcc.gnu.org Subject: [PATCH RFC] c++: mangle function template constraints Date: Sun, 19 Nov 2023 21:55:47 -0500 Message-Id: <20231120025547.2938444-1-jason@redhat.com> X-Mailer: git-send-email 2.39.3 MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII"; x-default=true X-Spam-Status: No, score=-12.5 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H4,RCVD_IN_MSPIKE_WL,RCVD_IN_SORBS_WEB,SPF_HELO_NONE,SPF_NONE,TXREP,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: Tested x86_64-pc-linux-gnu. Are the library bits OK? Any comments before I push this? -- 8< -- Per https://github.com/itanium-cxx-abi/cxx-abi/issues/24 and https://github.com/itanium-cxx-abi/cxx-abi/pull/166 We need to mangle constraints to be able to distinguish between function templates that only differ in constraints. From the latter link, we want to use the template parameter mangling previously specified for lambdas to also make explicit the form of a template parameter where the argument is not a "natural" fit for it, such as when the parameter is constrained or deduced. I'm concerned about how the latter link changes the mangling for some C++98 and C++11 patterns, so I've limited template_parm_natural_p to avoid two cases found by running the testsuite with -Wabi forced on: template T f() { return V; } int main() { return f(); } template int max() { return i; } template int max() { int sub = max(); return i > sub ? i : sub; } int main() { return max<1,2,3>(); } A third C++11 pattern is changed by this patch: template