[CSDiagnostics] Adjacent diagnostics for the new rules of static member lookup in generic context

Author: xedin

include/swift/AST/DiagnosticsSema.def

@@ -1902,9 +1902,8 @@ ERROR(type_does_not_conform_owner,none,
 ERROR(type_does_not_conform_in_decl_ref,none,
       "referencing %0 %1 on %2 requires that %3 conform to %4",
       (DescriptiveDeclKind, DeclName, Type, Type, Type))
-ERROR(type_does_not_conform_in_member_ref_on_protocol_type,none,
-      "cannot reference %0 %1 on %2 with non-conforming result type %3",
-      (DescriptiveDeclKind, DeclName, Type, Type))
+NOTE(missing_sametype_requirement_on_self,none,
+      "missing same-type requirement on 'Self'", ())
 ERROR(type_does_not_conform_anyobject_in_decl_ref,none,
       "referencing %0 %1 on %2 requires that %3 be a class type",
       (DescriptiveDeclKind, DeclName, Type, Type, Type))

lib/Sema/CSDiagnostics.cpp

@@ -7199,25 +7199,29 @@ bool InvalidMemberRefOnProtocolMetatype::diagnoseAsError() {
   if (!overload)
     return false;
 
-  auto resultTy = resolveType(overload->openedType);
-  if (auto *fnType = resultTy->getAs<FunctionType>())
-    resultTy = fnType->getResult();
-
   auto *member = overload->choice.getDeclOrNull();
   assert(member);
 
-  auto *DC = member->getDeclContext()->getSelfProtocolDecl();
-  auto protocolTy = DC->getDeclaredInterfaceType();
+  emitDiagnostic(diag::cannot_infer_base_of_unresolved_member,
+                 DeclNameRef(member->getName()));
+
+  auto *extension = dyn_cast<ExtensionDecl>(member->getDeclContext());
+
+  // If this was a protocol requirement we can't suggest a fix-it.
+  if (!extension)
+    return true;
 
-  emitDiagnostic(diag::type_does_not_conform_in_member_ref_on_protocol_type,
-                 member->getDescriptiveKind(), member->getName(),
-                 MetatypeType::get(protocolTy), resultTy);
+  auto note =
+      emitDiagnosticAt(extension, diag::missing_sametype_requirement_on_self);
 
-  if (resultTy->is<FunctionType>() || resultTy->is<TupleType>() ||
-      resultTy->isExistentialType() || resultTy->is<AnyMetatypeType>())
-    emitDiagnostic(diag::only_concrete_types_conform_to_protocols);
+  if (auto *whereClause = extension->getTrailingWhereClause()) {
+    auto sourceRange = whereClause->getSourceRange();
+    note.fixItInsertAfter(sourceRange.End, ", Self == <#Type#> ");
+  } else {
+    auto nameRepr = extension->getExtendedTypeRepr();
+    note.fixItInsertAfter(nameRepr->getEndLoc(), " where Self == <#Type#>");
+  }
 
-  emitDiagnosticAt(member, diag::decl_declared_here, member->getName());
   return true;
 }
 

lib/Sema/CSSimplify.cpp

@@ -5972,6 +5972,10 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
         // If this is a `Self` conformance requirement from a static member
         // reference on a protocol metatype, let's produce a tailored diagnostic.
         if (memberRef->isStatic()) {
+          if (hasFixFor(memberLoc,
+                        FixKind::AllowInvalidStaticMemberRefOnProtocolMetatype))
+            return SolutionKind::Solved;
+
           if (auto *protocolDecl =
                   memberRef->getDeclContext()->getSelfProtocolDecl()) {
             auto selfTy = protocolDecl->getProtocolSelfType();
@@ -6869,8 +6873,9 @@ performMemberLookup(ConstraintKind constraintKind, DeclNameRef memberName,
       if (getConcreteReplacementForProtocolSelfType(decl)) {
         result.addViable(candidate);
       } else {
-        result.addUnviable(candidate,
-                           MemberLookupResult::UR_TypeMemberOnInstance);
+        result.addUnviable(
+            candidate,
+            MemberLookupResult::UR_InvalidStaticMemberOnProtocolMetatype);
       }
 
       return;