AST: Use QueryOverrideSubs/LookUpConformanceInOverrideSubs in getOverrideGenericSignature()

Author: slavapestov

lib/AST/ASTContext.cpp

@@ -5321,40 +5321,12 @@ ASTContext::getOverrideGenericSignature(const NominalTypeDecl *baseNominal,
 
   SmallVector<Requirement, 2> addedRequirements;
 
-  unsigned derivedDepth = 0;
-  unsigned baseDepth = 0;
-  if (derivedNominalSig)
-    derivedDepth = derivedNominalSig.getGenericParams().back()->getDepth() + 1;
-  if (const auto baseNominalSig = baseNominal->getGenericSignature())
-    baseDepth = baseNominalSig.getGenericParams().back()->getDepth() + 1;
-
-  const auto subMap = derivedNominal->getDeclaredInterfaceType()
-      ->getContextSubstitutionMap(derivedNominal->getModuleContext(),
-                                  baseNominal);
-
-  auto substFn = [&](SubstitutableType *type) -> Type {
-    auto *gp = cast<GenericTypeParamType>(type);
-
-    if (gp->getDepth() < baseDepth) {
-      return Type(gp).subst(subMap);
-    }
-
-    return CanGenericTypeParamType::get(
-        gp->isTypeSequence(), gp->getDepth() - baseDepth + derivedDepth,
-        gp->getIndex(), *this);
-  };
-
-  auto lookupConformanceFn =
-      [&](CanType depTy, Type substTy,
-          ProtocolDecl *proto) -> ProtocolConformanceRef {
-    if (auto conf = subMap.lookupConformance(depTy, proto))
-      return conf;
-
-    return ProtocolConformanceRef(proto);
-  };
+  OverrideSubsInfo info(baseNominal, derivedNominal,
+                        baseGenericSig, derivedParams);
 
   for (auto reqt : baseGenericSig.getRequirements()) {
-    if (auto substReqt = reqt.subst(substFn, lookupConformanceFn)) {
+    if (auto substReqt = reqt.subst(QueryOverrideSubs(info),
+                                    LookUpConformanceInOverrideSubs(info))) {
       addedRequirements.push_back(*substReqt);
     }
   }