Add a few deserialization recovery paths.

This avoids cross-reference modularization error crashes in
lldb/lldb-dap on Windows, seen with our internal app, reported at
#69374.

Author: hjyamauchi

lib/Serialization/Deserialization.cpp

@@ -585,7 +585,10 @@ Expected<Pattern *> ModuleFile::readPattern(DeclContext *owningDC) {
 
     auto var = cast<VarDecl>(deserialized.get());
     auto result = NamedPattern::createImplicit(getContext(), var);
-    recordPatternType(result, getType(typeID));
+    auto typeOrErr = getTypeChecked(typeID);
+    if (!typeOrErr)
+      return typeOrErr.takeError();
+    recordPatternType(result, typeOrErr.get());
     restoreOffset.reset();
     return result;
   }
@@ -3021,7 +3024,14 @@ void ModuleFile::configureStorage(AbstractStorageDecl *decl,
 
   SmallVector<AccessorDecl*, 8> accessors;
   for (DeclID id : rawIDs.IDs) {
-    auto accessor = dyn_cast_or_null<AccessorDecl>(getDecl(id));
+    auto accessorOrErr = getDeclChecked(id);
+    if (!accessorOrErr) {
+      if (!getContext().LangOpts.EnableDeserializationRecovery)
+        fatal(accessorOrErr.takeError());
+      diagnoseAndConsumeError(accessorOrErr.takeError());
+      continue;
+    }
+    auto accessor = dyn_cast_or_null<AccessorDecl>(accessorOrErr.get());
     if (!accessor) return;
     accessors.push_back(accessor);
   }
@@ -3241,9 +3251,11 @@ class DeclDeserializer {
     auto genericSig = MF.getGenericSignature(genericSigID);
     alias->setGenericSignature(genericSig);
 
-    auto underlying = MF.getType(underlyingTypeID);
-    alias->setUnderlyingType(underlying);
-    
+    auto underlyingOrErr = MF.getTypeChecked(underlyingTypeID);
+    if (!underlyingOrErr)
+      return underlyingOrErr.takeError();
+    alias->setUnderlyingType(underlyingOrErr.get());
+
     if (auto accessLevel = getActualAccessLevel(rawAccessLevel))
       alias->setAccess(*accessLevel);
     else
@@ -4174,7 +4186,9 @@ class DeclDeserializer {
                                               rawAccessLevel);
 
     auto declContext = MF.getDeclContext(contextID);
-    auto interfaceSig = MF.getGenericSignature(interfaceSigID);
+    auto interfaceSigOrErr = MF.getGenericSignatureChecked(interfaceSigID);
+    if (!interfaceSigOrErr)
+      return interfaceSigOrErr.takeError();
 
     // Check for reentrancy.
     if (declOrOffset.isComplete())
@@ -4185,7 +4199,7 @@ class DeclDeserializer {
     // Create the decl.
     auto opaqueDecl = OpaqueTypeDecl::get(
         /*NamingDecl=*/ nullptr, genericParams, declContext,
-        interfaceSig, /*OpaqueReturnTypeReprs*/ { });
+        interfaceSigOrErr.get(), /*OpaqueReturnTypeReprs*/ { });
     declOrOffset = opaqueDecl;
 
     auto namingDecl = cast<ValueDecl>(MF.getDecl(namingDeclID));

lib/Serialization/ModuleFile.cpp

@@ -440,7 +440,14 @@ TypeDecl *ModuleFile::lookupNestedType(Identifier name,
         Decl *decl = declOrOffset;
         if (decl != parent)
           continue;
-        return cast<TypeDecl>(getDecl(entry.second));
+        Expected<Decl *> typeOrErr = getDeclChecked(entry.second);
+        if (!typeOrErr) {
+          if (!getContext().LangOpts.EnableDeserializationRecovery)
+            fatal(typeOrErr.takeError());
+          diagnoseAndConsumeError(typeOrErr.takeError());
+          continue;
+        }
+        return cast<TypeDecl>(typeOrErr.get());
       }
     }
   }