Sema: Stop calling getAllConformances() on protocols

Author: slavapestov

lib/Sema/CSSimplify.cpp

@@ -8093,16 +8093,12 @@ allFromConditionalConformances(DeclContext *DC, Type baseTy,
     }
 
     if (auto *protocol = candidateDC->getSelfProtocolDecl()) {
-      SmallVector<ProtocolConformance *, 4> conformances;
-      if (!NTD->lookupConformance(protocol, conformances))
+      auto conformance = DC->getParentModule()->lookupConformance(
+          baseTy, protocol);
+      if (!conformance.isConcrete())
         return false;
 
-      // This is opportunistic, there should be a way to narrow the
-      // list down to a particular declaration member comes from.
-      return llvm::any_of(
-          conformances, [](const ProtocolConformance *conformance) {
-            return !conformance->getConditionalRequirements().empty();
-          });
+      return !conformance.getConcrete()->getConditionalRequirements().empty();
     }
 
     return false;

lib/Sema/ConstraintSystem.cpp

@@ -6947,15 +6947,10 @@ bool TypeVarBindingProducer::requiresOptionalAdjustment(
     // produce an optional of that type as a potential binding. We
     // overwrite the binding in place because the non-optional type
     // will fail to type-check against the nil-literal conformance.
-    bool conformsToExprByNilLiteral = false;
-    if (auto *nominalBindingDecl = type->getAnyNominal()) {
-      SmallVector<ProtocolConformance *, 2> conformances;
-      conformsToExprByNilLiteral = nominalBindingDecl->lookupConformance(
-          CS.getASTContext().getProtocol(
-              KnownProtocolKind::ExpressibleByNilLiteral),
-          conformances);
-    }
-    return !conformsToExprByNilLiteral;
+    auto *proto = CS.getASTContext().getProtocol(
+         KnownProtocolKind::ExpressibleByNilLiteral);
+
+    return !proto->getParentModule()->lookupConformance(type, proto);
   } else if (binding.isDefaultableBinding() && binding.BindingType->isAny()) {
     return true;
   }

lib/Sema/TypeCheckAttr.cpp

@@ -3306,14 +3306,22 @@ void AttributeChecker::visitImplementsAttr(ImplementsAttr *attr) {
     // Check that the decl we're decorating is a member of a type that actually
     // conforms to the specified protocol.
     NominalTypeDecl *NTD = DC->getSelfNominalTypeDecl();
-    SmallVector<ProtocolConformance *, 2> conformances;
-    if (!NTD->lookupConformance(PD, conformances)) {
-      diagnose(attr->getLocation(),
-               diag::implements_attr_protocol_not_conformed_to,
-               NTD->getName(), PD->getName())
-        .highlight(attr->getProtocolTypeRepr()->getSourceRange());
+    if (auto *OtherPD = dyn_cast<ProtocolDecl>(NTD)) {
+      if (!OtherPD->inheritsFrom(PD)) {
+        diagnose(attr->getLocation(),
+                 diag::implements_attr_protocol_not_conformed_to,
+                 NTD->getName(), PD->getName())
+          .highlight(attr->getProtocolTypeRepr()->getSourceRange());
+      }
+    } else {
+      SmallVector<ProtocolConformance *, 2> conformances;
+      if (!NTD->lookupConformance(PD, conformances)) {
+        diagnose(attr->getLocation(),
+                 diag::implements_attr_protocol_not_conformed_to,
+                 NTD->getName(), PD->getName())
+          .highlight(attr->getProtocolTypeRepr()->getSourceRange());
+      }
     }
-
   } else {
     diagnose(attr->getLocation(), diag::implements_attr_non_protocol_type)
       .highlight(attr->getProtocolTypeRepr()->getSourceRange());

lib/Sema/TypeCheckProtocol.cpp

@@ -6762,7 +6762,9 @@ swift::findWitnessedObjCRequirements(const ValueDecl *witness,
 
   auto dc = witness->getDeclContext();
   auto nominal = dc->getSelfNominalTypeDecl();
+
   if (!nominal) return result;
+  if (isa<ProtocolDecl>(nominal)) return result;
 
   DeclName name = witness->getName();
   Optional<AccessorKind> accessorKind;

lib/Sema/TypeCheckStmt.cpp

@@ -229,8 +229,7 @@ static void tryDiagnoseUnnecessaryCastOverOptionSet(ASTContext &Ctx,
   auto optionSetType = dyn_cast_or_null<ProtocolDecl>(Ctx.getOptionSetDecl());
   if (!optionSetType)
     return;
-  SmallVector<ProtocolConformance *, 4> conformances;
-  if (!(optionSetType && NTD->lookupConformance(optionSetType, conformances)))
+  if (!module->lookupConformance(ResultType, optionSetType))
     return;
 
   auto *CE = dyn_cast<CallExpr>(E);