<div dir="ltr">Hi,<div><br></div><div>Xcode seems to think that [some] builtins can be used from Swift. It autocompletes popcount for example, and command-clicking the function opens a bona fide interface file, with the following declaration (among others):<br><div><br></div><div><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(187,44,162)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(187,44,162)">func</span><span style="font-variant-ligatures:no-common-ligatures"> __builtin_popcount(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(187,44,162)">_</span><span style="font-variant-ligatures:no-common-ligatures">: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">UInt32</span><span style="font-variant-ligatures:no-common-ligatures">) -&gt; </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Int32</span></p></div><div><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)"><br></span></div><div>However, when I try to compile code that uses that function, I get an unresolved identifier compiler error.</div><div><br></div><div>I guess I need to import some module, but which one?</div><div><br></div><div>Generally speaking, how to find in which module some symbol is defined?</div><div><br></div><div>Thanks,</div><div><br></div><div>Jean-Denis</div><div><br></div><div><br></div><div><br></div></div></div>