Merge pull request swiftlang#27340 from CodaFi/party-crashers

Extensions Do Not Have Parent Signatures

Author: CodaFi

include/swift/AST/TypeCheckRequests.h

@@ -1094,7 +1094,7 @@ class InferredGenericSignatureRequest :
     public SimpleRequest<InferredGenericSignatureRequest,
                          GenericSignature *(ModuleDecl *,
                                             GenericSignature *,
-                                            SmallVector<GenericParamList *, 2>,
+                                            GenericParamList *,
                                             SmallVector<Requirement, 2>,
                                             SmallVector<TypeLoc, 2>,
                                             bool),
@@ -1110,7 +1110,7 @@ class InferredGenericSignatureRequest :
   evaluate(Evaluator &evaluator,
            ModuleDecl *module,
            GenericSignature *baseSignature,
-           SmallVector<GenericParamList *, 2> addedParameters,
+           GenericParamList *gpl,
            SmallVector<Requirement, 2> addedRequirements,
            SmallVector<TypeLoc, 2> inferenceSources,
            bool allowConcreteGenericParams) const;

include/swift/AST/TypeCheckerTypeIDZone.def

@@ -54,7 +54,7 @@ SWIFT_REQUEST(NameLookup, GenericSignatureRequest,
               SeparatelyCached, NoLocationInfo)
 SWIFT_REQUEST(TypeChecker, InferredGenericSignatureRequest,
               GenericSignature *(ModuleDecl *, GenericSignature *,
-                                 SmallVector<GenericParamList *, 2>,
+                                 GenericParamList *,
                                  SmallVector<Requirement, 2>,
                                  SmallVector<TypeLoc, 2>, bool),
               Cached, NoLocationInfo)

lib/AST/GenericSignatureBuilder.cpp

@@ -7690,7 +7690,7 @@ llvm::Expected<GenericSignature *>
 InferredGenericSignatureRequest::evaluate(
         Evaluator &evaluator, ModuleDecl *parentModule,
         GenericSignature *parentSig,
-        SmallVector<GenericParamList *, 2> gpLists,
+        GenericParamList *gpl,
         SmallVector<Requirement, 2> addedRequirements,
         SmallVector<TypeLoc, 2> inferenceSources,
         bool allowConcreteGenericParams) const {
@@ -7701,6 +7701,19 @@ InferredGenericSignatureRequest::evaluate(
   // from that context.
   builder.addGenericSignature(parentSig);
 
+  // Type check the generic parameters, treating all generic type
+  // parameters as dependent, unresolved.
+  SmallVector<GenericParamList *, 2> gpLists;
+  if (gpl->getOuterParameters() && !parentSig) {
+    for (auto *outerParams = gpl;
+         outerParams != nullptr;
+         outerParams = outerParams->getOuterParameters()) {
+      gpLists.push_back(outerParams);
+    }
+  } else {
+    gpLists.push_back(gpl);
+  }
+
   // The generic parameter lists MUST appear from innermost to outermost.
   // We walk them backwards to order outer requirements before
   // inner requirements.

lib/Sema/TypeCheckDecl.cpp

@@ -3088,10 +3088,7 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
 
     // Validate the nominal type declaration being extended.
     (void)nominal->getInterfaceType();
-    // Don't bother computing the generic signature if the extended nominal
-    // type didn't pass validation so we don't crash.
-    if (!nominal->isInvalid())
-      (void)ED->getGenericSignature();
+    (void)ED->getGenericSignature();
     ED->setValidationToChecked();
 
     if (extType && !extType->hasError()) {
@@ -3772,8 +3769,7 @@ void TypeChecker::validateDecl(ValueDecl *D) {
         (void)nominal->getInterfaceType();
 
         // Eagerly validate the generic signature of the extension.
-        if (!nominal->isInvalid())
-          (void)ext->getGenericSignature();
+        (void)ext->getGenericSignature();
       }
     }
     if (ext->getValidationState() == Decl::ValidationState::Checking)

lib/Sema/TypeCheckGeneric.cpp

@@ -448,26 +448,16 @@ void TypeChecker::checkReferencedGenericParams(GenericContext *dc) {
 ///
 
 GenericSignature *TypeChecker::checkGenericSignature(
-                      GenericParamList *genericParams,
+                      GenericParamList *genericParamList,
                       DeclContext *dc,
                       GenericSignature *parentSig,
                       bool allowConcreteGenericParams,
                       SmallVector<Requirement, 2> additionalRequirements,
                       SmallVector<TypeLoc, 2> inferenceSources) {
-  assert(genericParams && "Missing generic parameters?");
-
-  // Type check the generic parameters, treating all generic type
-  // parameters as dependent, unresolved.
-  SmallVector<GenericParamList *, 2> gpLists;
-  for (auto *outerParams = genericParams;
-       outerParams != nullptr;
-       outerParams = outerParams->getOuterParameters()) {
-    gpLists.push_back(outerParams);
-  }
+  assert(genericParamList && "Missing generic parameters?");
 
   auto request = InferredGenericSignatureRequest{
-    dc->getParentModule(), parentSig,
-    gpLists,
+    dc->getParentModule(), parentSig, genericParamList,
     additionalRequirements, inferenceSources,
     allowConcreteGenericParams};
   auto *sig = evaluateOrDefault(dc->getASTContext().evaluator,
@@ -636,6 +626,7 @@ GenericSignatureRequest::evaluate(Evaluator &evaluator,
     return cast<SubscriptDecl>(accessor->getStorage())->getGenericSignature();
   }
 
+  auto *parentSig = GC->getParent()->getGenericSignatureOfContext();
   bool allowConcreteGenericParams = false;
   SmallVector<TypeLoc, 2> inferenceSources;
   SmallVector<Requirement, 2> sameTypeReqs;
@@ -716,13 +707,15 @@ GenericSignatureRequest::evaluate(Evaluator &evaluator,
 
     // Allow parameters to be equated with concrete types.
     allowConcreteGenericParams = true;
+    // Extensions must occur at the top level, they have no
+    // (valid) parent signature.
+    parentSig = nullptr;
     inferenceSources.emplace_back(nullptr, extInterfaceType);
   }
 
   // EGREGIOUS HACK: The GSB cannot handle the addition of parent signatures
   // from malformed decls in many cases.  Check the invalid bit and null out the
   // parent signature.
-  auto *parentSig = GC->getParent()->getGenericSignatureOfContext();
   if (auto *DD = GC->getParent()->getAsDecl()) {
     parentSig = DD->isInvalid() ? nullptr : parentSig;
   }

validation-test/compiler_crashers_2_fixed/0207-rdar55502661.swift

@@ -0,0 +1,4 @@
+// RUN: not %target-swift-frontend %s -typecheck -o /dev/null
+
+extension Result {
+  extension Result where Result.Undefined == Int {