Silence some standard library warnings

Author: Azoy

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -2032,6 +2032,17 @@ static void checkProtocolRefinementRequirements(ProtocolDecl *proto) {
       // TODO(kavon): emit tailored error diagnostic to remove the ~Copyable
     }
 
+    // SIMDScalar in the standard library currently emits this warning for:
+    // 'Hashable', 'Encodable', and 'Decodable'. This is unfortunate, but we
+    // cannot fix it as it would alter the ABI of the protocol. Silence these
+    // warnings specifically for those cases.
+    if (proto->isSpecificProtocol(KnownProtocolKind::SIMDScalar) &&
+        (otherProto->isSpecificProtocol(KnownProtocolKind::Hashable) ||
+        otherProto->isSpecificProtocol(KnownProtocolKind::Encodable) ||
+        otherProto->isSpecificProtocol(KnownProtocolKind::Decodable))) {
+      continue;
+    }
+
     // GenericSignature::getRequiredProtocols() canonicalizes the protocol
     // list by dropping protocols that are inherited by other protocols in
     // the list. Any protocols that remain in the list other than 'proto'

stdlib/public/core/Macros.swift

@@ -25,6 +25,8 @@
 public macro externalMacro<T>(module: String, type: String) -> T =
   Builtin.ExternalMacro
 
+#if false
+
 // File and path-related information
 
 /// Produces a unique identifier for the given source file, comprised of
@@ -71,4 +73,6 @@ public macro warning(_ message: String) = Builtin.WarningMacro
 @freestanding(declaration)
 public macro error(_ message: String) = Builtin.ErrorMacro
 
-#endif
+#endif // false
+
+#endif // $Macros && hasAttribute(attached)