Merge pull request #72286 from tshortli/silgen-lazy-typecheck-conformance-errors

SILGen: Avoid crashing for invalid conformances

Author: tshortli

include/swift/AST/ProtocolConformance.h

@@ -747,6 +747,9 @@ class NormalProtocolConformance : public RootProtocolConformance,
   /// Override the witness for a given requirement.
   void overrideWitness(ValueDecl *requirement, Witness newWitness);
 
+  /// Triggers a request that resolves all of the conformance's value witnesses.
+  void resolveValueWitnesses() const;
+
   /// Determine whether the witness for the given type requirement
   /// is the default definition.
   bool usesDefaultDefinition(AssociatedTypeDecl *requirement) const {

lib/AST/ProtocolConformance.cpp

@@ -706,6 +706,13 @@ void NormalProtocolConformance::overrideWitness(ValueDecl *requirement,
   Mapping[requirement] = witness;
 }
 
+void NormalProtocolConformance::resolveValueWitnesses() const {
+  auto mutableThis = const_cast<NormalProtocolConformance *>(this);
+  evaluateOrDefault(getProtocol()->getASTContext().evaluator,
+                    ResolveValueWitnessesRequest{mutableThis},
+                    evaluator::SideEffect());
+}
+
 SpecializedProtocolConformance::SpecializedProtocolConformance(
     Type conformingType,
     NormalProtocolConformance *genericConformance,

lib/SILGen/SILGen.cpp

@@ -2106,7 +2106,7 @@ class SILGenModuleRAII {
         SGM.pendingForcedFunctions.pop_front();
       }
       while (!SGM.pendingConformances.empty()) {
-        SGM.getWitnessTable(SGM.pendingConformances.front());
+        (void)SGM.getWitnessTable(SGM.pendingConformances.front());
         SGM.pendingConformances.pop_front();
       }
     }

lib/SILGen/SILGenType.cpp

@@ -23,9 +23,9 @@
 #include "Scope.h"
 #include "swift/AST/ASTMangler.h"
 #include "swift/AST/GenericEnvironment.h"
-#include "swift/AST/ProtocolConformance.h"
 #include "swift/AST/PrettyStackTrace.h"
 #include "swift/AST/PropertyWrappers.h"
+#include "swift/AST/ProtocolConformance.h"
 #include "swift/AST/SourceFile.h"
 #include "swift/AST/SubstitutionMap.h"
 #include "swift/AST/TypeMemberVisitor.h"
@@ -260,6 +260,8 @@ class SILGenVTable : public SILVTableVisitor<SILGenVTable> {
   }
 
   void emitVTable() {
+    PrettyStackTraceDecl("silgen emitVTable", theClass);
+
     // Imported types don't have vtables right now.
     if (theClass->hasClangNode())
       return;
@@ -529,6 +531,11 @@ class SILGenConformance : public SILGenWitnessTable<SILGenConformance> {
     PrettyStackTraceConformance trace("generating SIL witness table",
                                       Conformance);
 
+    // Check whether the conformance is valid first.
+    Conformance->resolveValueWitnesses();
+    if (Conformance->isInvalid())
+      return nullptr;
+
     auto *proto = Conformance->getProtocol();
     visitProtocolDecl(proto);
 
@@ -1113,6 +1120,8 @@ class SILGenType : public TypeMemberVisitor<SILGenType> {
 
   /// Emit SIL functions for all the members of the type.
   void emitType() {
+    PrettyStackTraceDecl("silgen emitType", theType);
+
     SGM.emitLazyConformancesForType(theType);
 
     for (Decl *member : theType->getABIMembers()) {
@@ -1150,7 +1159,7 @@ class SILGenType : public TypeMemberVisitor<SILGenType> {
     for (auto *conformance : theType->getLocalConformances(
                                ConformanceLookupKind::NonInherited)) {
       if (auto *normal = dyn_cast<NormalProtocolConformance>(conformance))
-        SGM.getWitnessTable(normal);
+        (void)SGM.getWitnessTable(normal);
     }
   }
 
@@ -1287,6 +1296,8 @@ class SILGenExtension : public TypeMemberVisitor<SILGenExtension> {
 
   /// Emit SIL functions for all the members of the extension.
   void emitExtension(ExtensionDecl *e) {
+    PrettyStackTraceDecl("silgen emitExtension", e);
+
     // Arguably, we should divert to SILGenType::emitType() here if it's an
     // @_objcImplementation extension, but we don't actually need to do any of
     // the stuff that it currently does.
@@ -1309,7 +1320,7 @@ class SILGenExtension : public TypeMemberVisitor<SILGenExtension> {
       for (auto *conformance : e->getLocalConformances(
                                  ConformanceLookupKind::All)) {
         if (auto *normal =dyn_cast<NormalProtocolConformance>(conformance))
-          SGM.getWitnessTable(normal);
+          (void)SGM.getWitnessTable(normal);
       }
     }
   }

lib/Sema/CSDiagnostics.cpp

@@ -3473,9 +3473,7 @@ bool ContextualFailure::tryProtocolConformanceFixIt(
       evaluateOrDefault(getASTContext().evaluator,
                         ResolveTypeWitnessesRequest{conformance},
                         evaluator::SideEffect());
-      evaluateOrDefault(getASTContext().evaluator,
-                        ResolveValueWitnessesRequest{conformance},
-                        evaluator::SideEffect());
+      conformance->resolveValueWitnesses();
 
       fakeConformances.push_back(conformance);
     }

lib/Sema/CodeSynthesis.cpp

@@ -1401,9 +1401,7 @@ ResolveImplicitMemberRequest::evaluate(Evaluator &evaluator,
       // FIXME: This should be more fine-grained to avoid having to check
       // for a cycle here.
       if (!evaluator.hasActiveRequest(ResolveValueWitnessesRequest{conformance})) {
-        evaluateOrDefault(evaluator,
-                          ResolveValueWitnessesRequest{conformance},
-                          evaluator::SideEffect());
+        conformance->resolveValueWitnesses();
       }
     }
 

lib/Sema/TypeCheckDecl.cpp

@@ -2870,9 +2870,7 @@ static ArrayRef<Decl *> evaluateMembersRequest(
     }
 
     if (isDerivable) {
-      evaluateOrDefault(ctx.evaluator,
-                        ResolveValueWitnessesRequest{normal},
-                        evaluator::SideEffect());
+      normal->resolveValueWitnesses();
     }
   }
 

lib/Sema/TypeCheckProtocol.cpp

@@ -2472,9 +2472,7 @@ checkIndividualConformance(NormalProtocolConformance *conformance) {
   ensureRequirementsAreSatisfied(Context, conformance);
 
   // Check non-type requirements.
-  evaluateOrDefault(Context.evaluator,
-                    ResolveValueWitnessesRequest{conformance},
-                    evaluator::SideEffect());
+  conformance->resolveValueWitnesses();
 }
 
 /// Add the next associated type deduction to the string representation

lib/Sema/TypeCheckStorage.cpp

@@ -169,9 +169,7 @@ static void computeLoweredProperties(NominalTypeDecl *decl,
             evaluateOrDefault(ctx.evaluator,
                               ResolveTypeWitnessesRequest{normal},
                               evaluator::SideEffect());
-            evaluateOrDefault(ctx.evaluator,
-                              ResolveValueWitnessesRequest{normal},
-                              evaluator::SideEffect());
+            normal->resolveValueWitnesses();
           }
         }
       };

test/SILGen/lazy_typecheck_errors.swift

@@ -0,0 +1,55 @@
+// RUN: %target-swift-frontend -emit-silgen %s -parse-as-library -enable-library-evolution -module-name Test -experimental-lazy-typecheck -verify
+// RUN: %target-swift-frontend -emit-silgen %s -parse-as-library -enable-library-evolution -module-name Test -experimental-lazy-typecheck -experimental-skip-non-inlinable-function-bodies -verify
+// RUN: %target-swift-frontend -emit-silgen %s -parse-as-library -enable-library-evolution -module-name Test -experimental-lazy-typecheck -experimental-skip-non-inlinable-function-bodies -experimental-skip-non-exportable-decls -verify
+
+
+public protocol Proto {
+  func req()
+}
+
+public struct ConformsToProtoMissingRequirement: Proto {
+  // expected-error@-1 {{type 'ConformsToProtoMissingRequirement' does not conform to protocol 'Proto'}}
+}
+
+public struct ConformsToProtoNearMiss: Proto {
+  // expected-error@-1 {{type 'ConformsToProtoNearMiss' does not conform to protocol 'Proto'}}
+
+  public func req(x: Int) {}
+}
+
+public protocol ProtoWithAssociatedType {
+  associatedtype A
+}
+
+public struct ConformsToProtoProtoWithAssociatedType: ProtoWithAssociatedType {
+  // expected-error@-1 {{type 'ConformsToProtoProtoWithAssociatedType' does not conform to protocol 'ProtoWithAssociatedType'}}
+}
+
+public struct GenericStruct<T> {
+  public var t: T
+}
+
+public struct GenericStructWithInvalidParameterConstraint<T: NonExistent> {
+  // expected-error@-1 {{cannot find type 'NonExistent' in scope}}
+}
+
+extension GenericStruct where T == NonExistent {
+  // expected-error@-1 {{cannot find type 'NonExistent' in scope}}
+  public func methodInExtensionWithInvalidWhereClause() {}
+}
+
+public class ValidClass {
+  public func methodReturningNonExistentType() -> NonExistent {}
+  // expected-error@-1 {{cannot find type 'NonExistent' in scope}}
+}
+
+public class DerivedFromValidClass: ValidClass {
+  override public func methodReturningNonExistentType() -> NonExistent {}
+  // expected-error@-1 {{cannot find type 'NonExistent' in scope}}
+}
+
+public class DerivedFromNonExistent: NonExistent {
+  // expected-error@-1 {{cannot find type 'NonExistent' in scope}}
+
+  public func method() {}
+}