Serialization: protect maybeReadGenericParams against errors

Update signature and implementation of `maybeReadGenericParams` to pass
up errors to the caller. Also update all of its callers to pass up any
error.

rdar://126582124

Author: xymus

lib/Serialization/Deserialization.cpp

@@ -1198,7 +1198,8 @@ ModuleFile::getConformanceChecked(ProtocolConformanceID conformanceID) {
   }
 }
 
-GenericParamList *ModuleFile::maybeReadGenericParams(DeclContext *DC) {
+Expected<GenericParamList *>
+ModuleFile::maybeReadGenericParams(DeclContext *DC) {
   using namespace decls_block;
 
   assert(DC && "need a context for the decls in the list");
@@ -1223,7 +1224,10 @@ GenericParamList *ModuleFile::maybeReadGenericParams(DeclContext *DC) {
   ArrayRef<uint64_t> paramIDs;
   GenericParamListLayout::readRecord(scratch, paramIDs);
   for (DeclID nextParamID : paramIDs) {
-    auto genericParam = cast<GenericTypeParamDecl>(getDecl(nextParamID));
+    Decl *nextParam;
+    UNWRAP(getDeclChecked(nextParamID), nextParam);
+
+    auto genericParam = cast<GenericTypeParamDecl>(nextParam);
     params.push_back(genericParam);
   }
 
@@ -3428,7 +3432,8 @@ class DeclDeserializer {
     DeclContext *DC;
     UNWRAP(MF.getDeclContextChecked(contextID), DC);
 
-    auto genericParams = MF.maybeReadGenericParams(DC);
+    GenericParamList *genericParams;
+    UNWRAP(MF.maybeReadGenericParams(DC), genericParams);
     if (declOrOffset.isComplete())
       return declOrOffset;
 
@@ -3587,7 +3592,8 @@ class DeclDeserializer {
     if (declOrOffset.isComplete())
       return declOrOffset;
 
-    auto genericParams = MF.maybeReadGenericParams(DC);
+    GenericParamList *genericParams;
+    UNWRAP(MF.maybeReadGenericParams(DC), genericParams);
     if (declOrOffset.isComplete())
       return declOrOffset;
 
@@ -3701,7 +3707,8 @@ class DeclDeserializer {
     if (declOrOffset.isComplete())
       return declOrOffset;
 
-    auto *genericParams = MF.maybeReadGenericParams(parent);
+    GenericParamList *genericParams;
+    UNWRAP(MF.maybeReadGenericParams(parent), genericParams);
     if (declOrOffset.isComplete())
       return declOrOffset;
 
@@ -4262,7 +4269,8 @@ class DeclDeserializer {
     // Read generic params before reading the type, because the type may
     // reference generic parameters, and we want them to have a dummy
     // DeclContext for now.
-    GenericParamList *genericParams = MF.maybeReadGenericParams(DC);
+    GenericParamList *genericParams;
+    UNWRAP(MF.maybeReadGenericParams(DC), genericParams);
 
     auto staticSpelling = getActualStaticSpellingKind(rawStaticSpelling);
     if (!staticSpelling.has_value())
@@ -4496,7 +4504,8 @@ class DeclDeserializer {
     if (declOrOffset.isComplete())
       return cast<OpaqueTypeDecl>(declOrOffset.get());
 
-    auto genericParams = MF.maybeReadGenericParams(declContext);
+    GenericParamList *genericParams;
+    UNWRAP(MF.maybeReadGenericParams(declContext), genericParams);
 
     // Create the decl.
     auto opaqueDecl = OpaqueTypeDecl::get(
@@ -4697,7 +4706,8 @@ class DeclDeserializer {
     ctx.evaluator.cacheOutput(InheritedProtocolsRequest{proto},
                               ctx.AllocateCopy(inherited));
 
-    auto genericParams = MF.maybeReadGenericParams(DC);
+    GenericParamList *genericParams;
+    UNWRAP(MF.maybeReadGenericParams(DC), genericParams);
     assert(genericParams && "protocol with no generic parameters?");
     ctx.evaluator.cacheOutput(GenericParamListRequest{proto},
                               std::move(genericParams));
@@ -4892,7 +4902,8 @@ class DeclDeserializer {
     if (declOrOffset.isComplete())
       return declOrOffset;
 
-    auto genericParams = MF.maybeReadGenericParams(DC);
+    GenericParamList *genericParams;
+    UNWRAP(MF.maybeReadGenericParams(DC), genericParams);
     if (declOrOffset.isComplete())
       return declOrOffset;
 
@@ -4970,7 +4981,8 @@ class DeclDeserializer {
       return DCOrError.takeError();
     auto DC = DCOrError.get();
 
-    auto genericParams = MF.maybeReadGenericParams(DC);
+    GenericParamList *genericParams;
+    UNWRAP(MF.maybeReadGenericParams(DC), genericParams);
     if (declOrOffset.isComplete())
       return declOrOffset;
 
@@ -5165,7 +5177,8 @@ class DeclDeserializer {
     if (declOrOffset.isComplete())
       return declOrOffset;
 
-    auto *genericParams = MF.maybeReadGenericParams(parent);
+    GenericParamList *genericParams;
+    UNWRAP(MF.maybeReadGenericParams(parent), genericParams);
     if (declOrOffset.isComplete())
       return declOrOffset;
 
@@ -5271,7 +5284,12 @@ class DeclDeserializer {
     // Generic parameter lists are written from outermost to innermost.
     // Keep reading until we run out of generic parameter lists.
     GenericParamList *outerParams = nullptr;
-    while (auto *genericParams = MF.maybeReadGenericParams(DC)) {
+    while (true) {
+      GenericParamList *genericParams;
+      UNWRAP(MF.maybeReadGenericParams(DC), genericParams);
+      if (!genericParams)
+        break;
+
       genericParams->setOuterParameters(outerParams);
 
       // Set up the DeclContexts for the GenericTypeParamDecls in the list.
@@ -5415,7 +5433,8 @@ class DeclDeserializer {
     if (declOrOffset.isComplete())
       return declOrOffset;
 
-    auto *genericParams = MF.maybeReadGenericParams(parent);
+    GenericParamList *genericParams;
+    UNWRAP(MF.maybeReadGenericParams(parent), genericParams);
     if (declOrOffset.isComplete())
       return declOrOffset;
 

lib/Serialization/ModuleFile.h

@@ -507,7 +507,7 @@ class ModuleFile
   ///
   /// If the record at the cursor is not a generic param list, returns null
   /// without moving the cursor.
-  GenericParamList *maybeReadGenericParams(DeclContext *DC);
+  llvm::Expected<GenericParamList *> maybeReadGenericParams(DeclContext *DC);
 
   /// Reads a set of requirements from \c DeclTypeCursor.
   void deserializeGenericRequirements(ArrayRef<uint64_t> scratch,