IDE: Refactor IsDeclApplicableRequest to use Requirement::isSatisfied()

Author: slavapestov

lib/Sema/CSGen.cpp

@@ -4135,31 +4135,6 @@ void ConstraintSystem::optimizeConstraints(Expr *e) {
   e->walk(optimizer);
 }
 
-bool swift::areGenericRequirementsSatisfied(
-    const DeclContext *DC, GenericSignature sig,
-    SubstitutionMap Substitutions, bool isExtension) {
-
-  ConstraintSystemOptions Options;
-  ConstraintSystem CS(const_cast<DeclContext *>(DC), Options);
-  auto Loc = CS.getConstraintLocator({});
-
-  // For every requirement, add a constraint.
-  for (auto Req : sig->getRequirements()) {
-    if (auto resolved = Req.subst(
-          QuerySubstitutionMap{Substitutions},
-          LookUpConformanceInModule(DC->getParentModule()))) {
-      CS.addConstraint(*resolved, Loc);
-    } else if (isExtension) {
-      return false;
-    }
-    // Unresolved requirements are requirements of the function itself. This
-    // does not prevent it from being applied. E.g. func foo<T: Sequence>(x: T).
-  }
-
-  // Having a solution implies the requirements have been fulfilled.
-  return CS.solveSingle().hasValue();
-}
-
 struct ResolvedMemberResult::Implementation {
   llvm::SmallVector<ValueDecl*, 4> AllDecls;
   unsigned ViableStartIdx;

lib/Sema/IDETypeCheckingRequests.cpp

@@ -116,6 +116,36 @@ class ContainsSpecializableArchetype : public TypeWalker {
   }
 };
 
+static bool areGenericRequirementsSatisfied(GenericSignature sig,
+                                            SubstitutionMap substMap,
+                                            bool isExtension) {
+  SmallVector<Requirement, 4> worklist;
+
+  for (auto req : sig->getRequirements()) {
+    if (auto resolved = req.subst(
+          QuerySubstitutionMap{substMap},
+          LookUpConformanceInSignature(sig.getPointer()))) {
+      worklist.push_back(*resolved);
+    } else if (isExtension) {
+      return false;
+    }
+    // Unresolved requirements are requirements of the function itself. This
+    // does not prevent it from being applied. E.g. func foo<T: Sequence>(x: T).
+  }
+
+  while (!worklist.empty()) {
+    auto req = worklist.pop_back_val();
+    ArrayRef<Requirement> conditionalRequirements;
+    if (req.isSatisfied(conditionalRequirements) != Requirement::Satisfied)
+      return false;
+
+    worklist.append(conditionalRequirements.begin(),
+                    conditionalRequirements.end());
+  }
+
+  return true;
+}
+
 static bool isExtensionAppliedInternal(const DeclContext *DC, Type BaseTy,
                                        const ExtensionDecl *ED) {
   // We can't do anything if the base type has unbound generic parameters.
@@ -133,7 +163,7 @@ static bool isExtensionAppliedInternal(const DeclContext *DC, Type BaseTy,
   GenericSignature genericSig = ED->getGenericSignature();
   SubstitutionMap substMap = BaseTy->getContextSubstitutionMap(
       DC->getParentModule(), ED->getExtendedNominal());
-  return areGenericRequirementsSatisfied(DC, genericSig, substMap,
+  return areGenericRequirementsSatisfied(genericSig, substMap,
                                          /*isExtension=*/true);
 }
 
@@ -157,7 +187,7 @@ static bool isMemberDeclAppliedInternal(const DeclContext *DC, Type BaseTy,
 
   SubstitutionMap substMap = BaseTy->getContextSubstitutionMap(
       DC->getParentModule(), VD->getDeclContext());
-  return areGenericRequirementsSatisfied(DC, genericSig, substMap,
+  return areGenericRequirementsSatisfied(genericSig, substMap,
                                          /*isExtension=*/false);
 }
 

lib/Sema/TypeChecker.h

@@ -1285,11 +1285,6 @@ bool diagnoseObjCUnsatisfiedOptReqConflicts(SourceFile &sf);
 std::pair<unsigned, DeclName> getObjCMethodDiagInfo(
                                 AbstractFunctionDecl *method);
 
-bool areGenericRequirementsSatisfied(const DeclContext *DC,
-                                     GenericSignature sig,
-                                     SubstitutionMap Substitutions,
-                                     bool isExtension);
-
 /// Check for restrictions on the use of the @unknown attribute on a
 /// case statement.
 void checkUnknownAttrRestrictions(