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[217.227.102.54]) by smtp.gmail.com with ESMTPSA id u1-20020a1709063b8100b00a4324ae24dbsm6792405ejf.62.2024.03.05.22.48.32 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 Mar 2024 22:48:32 -0800 (PST) Received-SPF: pass client-ip=2a00:1450:4864:20::52e; envelope-from=gerd.moellmann@gmail.com; helo=mail-ed1-x52e.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:316848 Archived-At: Symbols are currently encoded as words with tag = 0 (= Lisp_Symbol enumerator), that when untagged are an offset from lispsym (the array of built-in symbols), not a pointer to some structure like it is done for other Lisp types. That makes the word 0x0 = Qnil, 0x1 = Qt, and so on. My question comes from playing with another GC library, where this unique encoding is, well, quite inconvenient. So, I'd like to ask two questions: - Does someone remember the reasons why this has been done? - Is there something that relies on this? Maybe something that relies on 0x0 being a valid Lisp_Object? Thanks!