Kill validateExtension

include/swift/AST/Decl.h

@@ -1536,6 +1536,7 @@ class GenericContext : private _GenericContext, public DeclContext {
   /// \endcode
   bool isGeneric() const { return getGenericParams() != nullptr; }
   bool hasComputedGenericSignature() const;
+  bool isComputingGenericSignature() const;
 
   /// Retrieve the trailing where clause for this extension, if any.
   TrailingWhereClause *getTrailingWhereClause() const {

lib/AST/Decl.cpp

@@ -859,6 +859,11 @@ GenericParamList *GenericContext::getGenericParams() const {
 bool GenericContext::hasComputedGenericSignature() const {
   return GenericSigAndBit.getInt();
 }
+
+bool GenericContext::isComputingGenericSignature() const {
+  return getASTContext().evaluator.hasActiveRequest(
+                 GenericSignatureRequest{const_cast<GenericContext*>(this)});
+}
 
 GenericSignature *GenericContext::getGenericSignature() const {
   return evaluateOrDefault(

lib/AST/NameLookup.cpp

@@ -470,7 +470,7 @@ static void recordShadowedDecls(ArrayRef<ValueDecl *> decls,
       // If the decl is currently being validated, this is likely a recursive
       // reference and we'll want to skip ahead so as to avoid having its type
       // attempt to desugar itself.
-      if (!decl->hasValidSignature())
+      if (!decl->hasInterfaceType())
         continue;
 
       // FIXME: the canonical type makes a poor signature, because we don't

lib/AST/ProtocolConformance.cpp

@@ -531,7 +531,7 @@ void NormalProtocolConformance::differenceAndStoreConditionalRequirements()
     assert(CRState == ConditionalRequirementsState::Computing);
     CRState = ConditionalRequirementsState::Uncomputed;
   };
-
+  
   auto &ctxt = getProtocol()->getASTContext();
   auto DC = getDeclContext();
   // A non-extension conformance won't have conditional requirements.
@@ -550,30 +550,24 @@ void NormalProtocolConformance::differenceAndStoreConditionalRequirements()
     return;
   }
 
-  // The type is generic, but the extension doesn't have a signature yet, so
-  // we might be in a recursive validation situation.
-  if (!ext->hasComputedGenericSignature()) {
-    // If the extension is invalid, it won't ever get a signature, so we
-    // "succeed" with an empty result instead.
-    if (ext->isInvalid()) {
-      success({});
-      return;
-    }
+  // If the extension is invalid, it won't ever get a signature, so we
+  // "succeed" with an empty result instead.
+  if (ext->isInvalid()) {
+    success({});
+    return;
+  }
 
-    // Otherwise we'll try again later.
+  // Recursively validating the signature comes up frequently as expanding
+  // conformance requirements might re-enter this method.  We can at least catch
+  // this and come back to these requirements later.
+  //
+  // FIXME: In the long run, break this cycle in a more principled way.
+  if (ext->isComputingGenericSignature()) {
     failure();
     return;
   }
-
-  // FIXME: All of this will be removed when validateExtension goes away.
-  auto extensionSig = ext->getGenericSignature();
-  if (!extensionSig) {
-    if (auto lazyResolver = ctxt.getLazyResolver()) {
-      lazyResolver->resolveExtension(ext);
-      extensionSig = ext->getGenericSignature();
-    }
-  }
 
+  auto extensionSig = ext->getGenericSignature();
   auto canExtensionSig = extensionSig->getCanonicalSignature();
   auto canTypeSig = typeSig->getCanonicalSignature();
   if (canTypeSig == canExtensionSig) {

lib/Sema/ConstraintSystem.cpp

@@ -498,16 +498,6 @@ Type ConstraintSystem::openUnboundGenericType(UnboundGenericType *unbound,
                                               ConstraintLocatorBuilder locator,
                                               OpenedTypeMap &replacements) {
   auto unboundDecl = unbound->getDecl();
-
-  // If the unbound decl hasn't been validated yet, we have a circular
-  // dependency that isn't being diagnosed properly.
-  //
-  // FIXME: Delete this condition.  He's dead Jim.
-  if (!unboundDecl->hasComputedGenericSignature()) {
-    TC.diagnose(unboundDecl, diag::circular_reference);
-    return Type();
-  }
-
   auto parentTy = unbound->getParent();
   if (parentTy) {
     parentTy = openUnboundGenericType(parentTy, locator);