[AST] Add a possibility to check whether PackConformance is invalid

(cherry picked from commit 8f4ad8b)

Author: xedin

include/swift/AST/PackConformance.h

@@ -68,6 +68,8 @@ class alignas(1 << DeclAlignInBits) PackConformance final
 
   ArrayRef<ProtocolConformanceRef> getPatternConformances() const;
 
+  bool isInvalid() const;
+
   bool isCanonical() const;
 
   PackConformance *getCanonicalConformance() const;
@@ -103,4 +105,4 @@ void simple_display(llvm::raw_ostream &out, PackConformance *conformance);
 
 } // end namespace swift
 
-#endif  // SWIFT_AST_PACKCONFORMANCE_H
+#endif // SWIFT_AST_PACKCONFORMANCE_H

lib/AST/Module.cpp

@@ -1827,8 +1827,11 @@ static ProtocolConformanceRef getPackTypeConformance(
     patternConformances.push_back(patternConformance);
   }
 
-  return ProtocolConformanceRef(
-      PackConformance::get(type, protocol, patternConformances));
+  auto *conformance = PackConformance::get(type, protocol, patternConformances);
+  if (conformance->isInvalid())
+    return ProtocolConformanceRef::forInvalid();
+
+  return ProtocolConformanceRef(conformance);
 }
 
 ProtocolConformanceRef

lib/AST/PackConformance.cpp

@@ -55,6 +55,11 @@ size_t PackConformance::numTrailingObjects(
   return ConformingType->getNumElements();
 }
 
+bool PackConformance::isInvalid() const {
+  return llvm::any_of(getPatternConformances(),
+                      [&](const auto ref) { return ref.isInvalid(); });
+}
+
 ArrayRef<ProtocolConformanceRef>
 PackConformance::getPatternConformances() const {
   return {getTrailingObjects<ProtocolConformanceRef>(),
@@ -244,6 +249,9 @@ PackConformance::subst(InFlightSubstitution &IFS) const {
 
   auto substConformance = PackConformance::get(substConformingType, Protocol,
                                                expander.substConformances);
+  if (substConformance->isInvalid())
+    return ProtocolConformanceRef::forInvalid();
+
   return ProtocolConformanceRef(substConformance);
 }
 

lib/AST/Type.cpp

@@ -4547,8 +4547,13 @@ operator()(CanType dependentType, Type conformingReplacementType,
         (*this)(dependentType, conformingPackElt, conformedProtocol);
       conformances.push_back(conformance);
     }
-    return ProtocolConformanceRef(
-        PackConformance::get(conformingPack, conformedProtocol, conformances));
+
+    auto *conformance =
+        PackConformance::get(conformingPack, conformedProtocol, conformances);
+    if (conformance->isInvalid())
+      return ProtocolConformanceRef::forInvalid();
+
+    return ProtocolConformanceRef(conformance);
   }
 
   assert((conformingReplacementType->is<ErrorType>() ||