Merge pull request #28206 from slavapestov/skip-override-check-constrained-extension

Skip override checking for members of constrained extensions

Author: slavapestov

lib/AST/ASTContext.cpp

@@ -4354,42 +4354,28 @@ ASTContext::getOverrideGenericSignature(const ValueDecl *base,
   auto derivedGenericCtx = derived->getAsGenericContext();
   auto &ctx = base->getASTContext();
 
-  if (!baseGenericCtx) {
+  if (!baseGenericCtx || !derivedGenericCtx)
     return nullptr;
-  }
 
   auto baseClass = base->getDeclContext()->getSelfClassDecl();
-
-  if (!baseClass) {
+  if (!baseClass)
     return nullptr;
-  }
 
   auto derivedClass = derived->getDeclContext()->getSelfClassDecl();
-  auto baseClassSig = baseClass->getGenericSignature();
-
-  if (!derivedClass) {
+  if (!derivedClass)
     return nullptr;
-  }
 
-  if (derivedClass->getSuperclass().isNull()) {
+  if (derivedClass->getSuperclass().isNull())
     return nullptr;
-  }
 
-  if (!derivedGenericCtx || !derivedGenericCtx->isGeneric()) {
+  if (baseGenericCtx->getGenericSignature().isNull() ||
+      derivedGenericCtx->getGenericSignature().isNull())
     return nullptr;
-  }
-
-  if (derivedClass->getGenericSignature().isNull() &&
-      !baseGenericCtx->isGeneric()) {
-    return nullptr;
-  }
 
+  auto baseClassSig = baseClass->getGenericSignature();
   auto subMap = derivedClass->getSuperclass()->getContextSubstitutionMap(
       derivedClass->getModuleContext(), baseClass);
 
-  if (baseGenericCtx->getGenericSignature().isNull()) {
-    return nullptr;
-  }
   unsigned derivedDepth = 0;
 
   auto key = OverrideSignatureKey(baseGenericCtx->getGenericSignature(),
@@ -4405,9 +4391,11 @@ ASTContext::getOverrideGenericSignature(const ValueDecl *base,
     derivedDepth = derivedSig->getGenericParams().back()->getDepth() + 1;
 
   SmallVector<GenericTypeParamType *, 2> addedGenericParams;
-  for (auto gp : *derivedGenericCtx->getGenericParams()) {
-    addedGenericParams.push_back(
-        gp->getDeclaredInterfaceType()->castTo<GenericTypeParamType>());
+  if (auto *gpList = derivedGenericCtx->getGenericParams()) {
+    for (auto gp : *gpList) {
+      addedGenericParams.push_back(
+          gp->getDeclaredInterfaceType()->castTo<GenericTypeParamType>());
+    }
   }
 
   unsigned baseDepth = 0;

lib/AST/Decl.cpp

@@ -1221,16 +1221,21 @@ bool ExtensionDecl::hasValidParent() const {
 }
 
 bool ExtensionDecl::isConstrainedExtension() const {
-  // Non-generic extension.
-  if (!getGenericSignature())
+  auto nominal = getExtendedNominal();
+  if (!nominal)
     return false;
 
-  auto nominal = getExtendedNominal();
-  assert(nominal);
+  auto typeSig = nominal->getGenericSignature();
+  if (!typeSig)
+    return false;
+
+  auto extSig = getGenericSignature();
+  if (!extSig)
+    return false;
 
   // If the generic signature differs from that of the nominal type, it's a
   // constrained extension.
-  return !getGenericSignature()->isEqual(nominal->getGenericSignature());
+  return !typeSig->isEqual(extSig);
 }
 
 bool ExtensionDecl::isEquivalentToExtendedContext() const {

lib/Sema/TypeCheckDeclOverride.cpp

@@ -234,6 +234,11 @@ static bool areOverrideCompatibleSimple(ValueDecl *decl,
     return false;
   }
 
+  // Ignore declarations that are defined inside constrained extensions.
+  if (auto *ext = dyn_cast<ExtensionDecl>(parentDecl->getDeclContext()))
+    if (ext->isConstrainedExtension())
+      return false;
+
   // The declarations must be of the same kind.
   if (decl->getKind() != parentDecl->getKind())
     return false;
@@ -1169,6 +1174,11 @@ bool swift::checkOverrides(ValueDecl *decl) {
     // Otherwise, we have more checking to do.
   }
 
+  // Members of constrained extensions are not considered to be overrides.
+  if (auto *ext = dyn_cast<ExtensionDecl>(decl->getDeclContext()))
+    if (ext->isConstrainedExtension())
+      return false;
+
   // Accessor methods get overrides through their storage declaration, and
   // all checking can be performed via that mechanism.
   if (isa<AccessorDecl>(decl)) {

test/attr/attr_override.swift

@@ -626,3 +626,25 @@ class SR_10198_Derived_1: SR_10198_Base_1 {
   init(_ arg1: Int) { super.init(SR_10198_Base_S()) } // okay, doesn't crash
 }
 
+// SR-11740
+
+public class SR_11740_Base<F, A> {}
+
+public class SR_11740_Derived<F, A>
+  : SR_11740_Base<SR_11740_Base<F, A>, A>,
+    SR_11740_Q {}
+
+public protocol SR_11740_P {}
+
+public protocol SR_11740_Q: SR_11740_P {
+    associatedtype A
+}
+
+public extension SR_11740_Base where F: SR_11740_Q {
+    static func foo(_: F.A) {}
+}
+
+extension SR_11740_Derived where F: SR_11740_P {
+    public static func foo(_: A) {}
+}
+