IDE: Fix my own lazyness in SynthesizedExtensionAnalyzer::Implementation::isApplicable()

Fixes #76561

Author: slavapestov

lib/IDE/IDETypeChecking.cpp

@@ -333,10 +333,6 @@ struct SynthesizedExtensionAnalyzer::Implementation {
       ProtocolDecl *BaseProto = OwningExt->getInnermostDeclContext()
         ->getSelfProtocolDecl();
       for (auto Req : Reqs) {
-        // FIXME: Don't skip layout requirements.
-        if (Req.getKind() == RequirementKind::Layout)
-          continue;
-
         // Skip protocol's Self : <Protocol> requirement.
         if (BaseProto &&
             Req.getKind() == RequirementKind::Conformance &&
@@ -357,40 +353,33 @@ struct SynthesizedExtensionAnalyzer::Implementation {
         }
 
         assert(!Req.getFirstType()->hasArchetype());
-        assert(!Req.getSecondType()->hasArchetype());
-
-        auto SubstReq = Req.subst(
-          [&](Type type) -> Type {
-            if (type->isTypeParameter())
-              return Target->mapTypeIntoContext(type);
-
-            return type;
-          },
-          LookUpConformanceInModule());
+        if (Req.getKind() != RequirementKind::Layout)
+          assert(!Req.getSecondType()->hasArchetype());
 
         SmallVector<Requirement, 2> subReqs;
-        switch (SubstReq.checkRequirement(subReqs)) {
-        case CheckRequirementResult::Success:
-          break;
-
-        case CheckRequirementResult::ConditionalConformance:
-          // FIXME: Need to handle conditional requirements here!
-          break;
-
-        case CheckRequirementResult::PackRequirement:
-          // FIXME
-          assert(false && "Refactor this");
-          return true;
-
-        case CheckRequirementResult::SubstitutionFailure:
-          return true;
-
-        case CheckRequirementResult::RequirementFailure:
-          if (!SubstReq.canBeSatisfied())
+        subReqs.push_back(
+          Req.subst(
+            QueryInterfaceTypeSubstitutions(Target->getGenericEnvironment()),
+            LookUpConformanceInModule()));
+
+        while (!subReqs.empty()) {
+          auto req = subReqs.pop_back_val();
+          switch (req.checkRequirement(subReqs)) {
+          case CheckRequirementResult::Success:
+          case CheckRequirementResult::PackRequirement:
+          case CheckRequirementResult::ConditionalConformance:
+            break;
+
+          case CheckRequirementResult::SubstitutionFailure:
             return true;
 
-          MergeInfo.addRequirement(Req);
-          break;
+          case CheckRequirementResult::RequirementFailure:
+            if (!req.canBeSatisfied())
+              return true;
+
+            MergeInfo.addRequirement(Req);
+            break;
+          }
         }
       }
       return false;