[Symbol] Use llvm::Expected when getting TypeSystems

Summary:
This commit achieves the following:
- Functions used to return a `TypeSystem *` return an
  `llvm::Expected<TypeSystem *>` now. This means that the result of a call
  is always checked, forcing clients to move more carefully.
- `TypeSystemMap::GetTypeSystemForLanguage` will either return an Error or a
  non-null pointer to a TypeSystem.

Reviewers: JDevlieghere, davide, compnerd

Subscribers: jdoerfert, lldb-commits

Differential Revision: https://reviews.llvm.org/D65122

llvm-svn: 367360

1 files changed, 19 insertions, 9 deletions

diff --git a/lldb/source/API/SBModule.cpp b/lldb/source/API/SBModule.cpp
index 4bd32bce1c5..e3c48cfcecc 100644
--- a/lldb/source/API/SBModule.cpp
+++ b/lldb/source/API/SBModule.cpp
@@ -468,10 +468,13 @@ lldb::SBType SBModule::FindFirstType(const char *name_cstr) {
     sb_type = SBType(module_sp->FindFirstType(sc, name, exact_match));
 
     if (!sb_type.IsValid()) {
-      TypeSystem *type_system =
+      auto type_system_or_err =
           module_sp->GetTypeSystemForLanguage(eLanguageTypeC);
-      if (type_system)
-        sb_type = SBType(type_system->GetBuiltinTypeByName(name));
+      if (auto err = type_system_or_err.takeError()) {
+        llvm::consumeError(std::move(err));
+        return LLDB_RECORD_RESULT(SBType());
+      }
+      sb_type = SBType(type_system_or_err->GetBuiltinTypeByName(name));
     }
   }
   return LLDB_RECORD_RESULT(sb_type);
@@ -483,10 +486,14 @@ lldb::SBType SBModule::GetBasicType(lldb::BasicType type) {
 
   ModuleSP module_sp(GetSP());
   if (module_sp) {
-    TypeSystem *type_system =
+    auto type_system_or_err =
         module_sp->GetTypeSystemForLanguage(eLanguageTypeC);
-    if (type_system)
-      return LLDB_RECORD_RESULT(SBType(type_system->GetBasicTypeFromAST(type)));
+    if (auto err = type_system_or_err.takeError()) {
+      llvm::consumeError(std::move(err));
+    } else {
+      return LLDB_RECORD_RESULT(
+          SBType(type_system_or_err->GetBasicTypeFromAST(type)));
+    }
   }
   return LLDB_RECORD_RESULT(SBType());
 }
@@ -513,10 +520,13 @@ lldb::SBTypeList SBModule::FindTypes(const char *type) {
           retval.Append(SBType(type_sp));
       }
     } else {
-      TypeSystem *type_system =
+      auto type_system_or_err =
           module_sp->GetTypeSystemForLanguage(eLanguageTypeC);
-      if (type_system) {
-        CompilerType compiler_type = type_system->GetBuiltinTypeByName(name);
+      if (auto err = type_system_or_err.takeError()) {
+        llvm::consumeError(std::move(err));
+      } else {
+        CompilerType compiler_type =
+            type_system_or_err->GetBuiltinTypeByName(name);
         if (compiler_type)
           retval.Append(SBType(compiler_type));
       }