Fix assertion in ClangASTContext

Summary:
llvm::APSInt(0) asserts because it creates an int with bit-width 0 and
not (as I thought) a value 0.

Theoretically it should be sufficient to change this to APSInt(1), as
the intention there was that the value of the first argument should be
ignored if the type is invalid, but that would look dodgy.

Instead, I use llvm::Optional to denote an invalid value and use a
special struct instead of a std::pair, to reduce typing and increase
clarity.

Reviewers: clayborg

Subscribers: lldb-commits

Differential Revision: https://reviews.llvm.org/D40615

llvm-svn: 319414

lldb/include/lldb/Symbol/ClangASTContext.h

@@ -787,7 +787,7 @@ public:
                           size_t idx) override;
   CompilerType GetTypeTemplateArgument(lldb::opaque_compiler_type_t type,
                                        size_t idx) override;
-  std::pair<llvm::APSInt, CompilerType>
+  llvm::Optional<CompilerType::IntegralTemplateArgument>
   GetIntegralTemplateArgument(lldb::opaque_compiler_type_t type,
                               size_t idx) override;
 

lldb/include/lldb/Symbol/CompilerType.h

@@ -20,6 +20,7 @@
 // Project includes
 #include "lldb/Core/ClangForward.h"
 #include "lldb/lldb-private.h"
+#include "llvm/ADT/APSInt.h"
 
 namespace lldb_private {
 
@@ -290,6 +291,8 @@ public:
   // Exploring the type
   //----------------------------------------------------------------------
 
+  struct IntegralTemplateArgument;
+
   uint64_t GetByteSize(ExecutionContextScope *exe_scope) const;
 
   uint64_t GetBitSize(ExecutionContextScope *exe_scope) const;
@@ -368,9 +371,9 @@ public:
   lldb::TemplateArgumentKind GetTemplateArgumentKind(size_t idx) const;
   CompilerType GetTypeTemplateArgument(size_t idx) const;
 
-  // Returns the value of the template argument and its type. In case the
-  // argument is not found, returns an invalid CompilerType.
-  std::pair<llvm::APSInt, CompilerType> GetIntegralTemplateArgument(size_t idx) const;
+  // Returns the value of the template argument and its type.
+  llvm::Optional<IntegralTemplateArgument>
+  GetIntegralTemplateArgument(size_t idx) const;
 
   CompilerType GetTypeForFormatters() const;
 
@@ -433,6 +436,11 @@ private:
 bool operator==(const CompilerType &lhs, const CompilerType &rhs);
 bool operator!=(const CompilerType &lhs, const CompilerType &rhs);
 
+struct CompilerType::IntegralTemplateArgument {
+  llvm::APSInt value;
+  CompilerType type;
+};
+
 } // namespace lldb_private
 
 #endif // liblldb_CompilerType_h_

lldb/include/lldb/Symbol/TypeSystem.h

@@ -355,9 +355,8 @@ public:
   GetTemplateArgumentKind(lldb::opaque_compiler_type_t type, size_t idx);
   virtual CompilerType GetTypeTemplateArgument(lldb::opaque_compiler_type_t type,
                                            size_t idx);
-  virtual std::pair<llvm::APSInt, CompilerType>
-  GetIntegralTemplateArgument(lldb::opaque_compiler_type_t type,
-                              size_t idx);
+  virtual llvm::Optional<CompilerType::IntegralTemplateArgument>
+  GetIntegralTemplateArgument(lldb::opaque_compiler_type_t type, size_t idx);
 
   //----------------------------------------------------------------------
   // Dumping types

lldb/source/API/SBType.cpp

@@ -426,7 +426,7 @@ lldb::SBType SBType::GetTemplateArgumentType(uint32_t idx) {
     case eTemplateArgumentKindIntegral:
       type = m_opaque_sp->GetCompilerType(false)
                  .GetIntegralTemplateArgument(idx)
-                 .second;
+                 ->type;
       break;
     default:
       break;

lldb/source/Plugins/Language/CPlusPlus/LibCxxBitset.cpp

@@ -59,10 +59,8 @@ bool BitsetFrontEnd::Update() {
   size_t capping_size = target_sp->GetMaximumNumberOfChildrenToDisplay();
 
   size_t size = 0;
-  auto value_and_type =
-      m_backend.GetCompilerType().GetIntegralTemplateArgument(0);
-  if (value_and_type.second)
-    size = value_and_type.first.getLimitedValue(capping_size);
+  if (auto arg = m_backend.GetCompilerType().GetIntegralTemplateArgument(0))
+    size = arg->value.getLimitedValue(capping_size);
 
   m_elements.assign(size, ValueObjectSP());
 

lldb/source/Symbol/ClangASTContext.cpp

@@ -7650,21 +7650,21 @@ ClangASTContext::GetTypeTemplateArgument(lldb::opaque_compiler_type_t type,
   return CompilerType(getASTContext(), template_arg.getAsType());
 }
 
-std::pair<llvm::APSInt, CompilerType>
+llvm::Optional<CompilerType::IntegralTemplateArgument>
 ClangASTContext::GetIntegralTemplateArgument(lldb::opaque_compiler_type_t type,
                                              size_t idx) {
   const clang::ClassTemplateSpecializationDecl *template_decl =
       GetAsTemplateSpecialization(type);
   if (! template_decl || idx >= template_decl->getTemplateArgs().size())
-    return {llvm::APSInt(0), CompilerType()};
+    return llvm::None;
 
   const clang::TemplateArgument &template_arg =
       template_decl->getTemplateArgs()[idx];
   if (template_arg.getKind() != clang::TemplateArgument::Integral)
-    return {llvm::APSInt(0), CompilerType()};
+    return llvm::None;
 
-  return {template_arg.getAsIntegral(),
-          CompilerType(getASTContext(), template_arg.getIntegralType())};
+  return {{template_arg.getAsIntegral(),
+           CompilerType(getASTContext(), template_arg.getIntegralType())}};
 }
 
 CompilerType ClangASTContext::GetTypeForFormatters(void *type) {

lldb/source/Symbol/CompilerType.cpp

@@ -703,12 +703,11 @@ CompilerType CompilerType::GetTypeTemplateArgument(size_t idx) const {
   return CompilerType();
 }
 
-std::pair<llvm::APSInt, CompilerType>
-CompilerType::GetIntegralTemplateArgument(size_t idx) const
-{
+llvm::Optional<CompilerType::IntegralTemplateArgument>
+CompilerType::GetIntegralTemplateArgument(size_t idx) const {
   if (IsValid())
     return m_type_system->GetIntegralTemplateArgument(m_type, idx);
-  return {llvm::APSInt(0), CompilerType()};
+  return llvm::None;
 }
 
 CompilerType CompilerType::GetTypeForFormatters() const {

lldb/source/Symbol/TypeSystem.cpp

@@ -111,10 +111,10 @@ CompilerType TypeSystem::GetTypeTemplateArgument(opaque_compiler_type_t type,
   return CompilerType();
 }
 
-std::pair<llvm::APSInt, CompilerType>
+llvm::Optional<CompilerType::IntegralTemplateArgument>
 TypeSystem::GetIntegralTemplateArgument(opaque_compiler_type_t type,
-                            size_t idx) {
-  return {llvm::APSInt(0), CompilerType()};
+                                        size_t idx) {
+  return llvm::None;
 }
 
 LazyBool TypeSystem::ShouldPrintAsOneLiner(void *type, ValueObject *valobj) {

lldb/unittests/Symbol/TestClangASTContext.cpp

@@ -382,8 +382,8 @@ TEST_F(TestClangASTContext, TemplateArguments) {
   infos.names.push_back("T");
   infos.args.push_back(TemplateArgument(m_ast->getASTContext()->IntTy));
   infos.names.push_back("I");
-  infos.args.push_back(TemplateArgument(*m_ast->getASTContext(),
-                                        llvm::APSInt(47),
+  llvm::APSInt arg(llvm::APInt(8, 47));
+  infos.args.push_back(TemplateArgument(*m_ast->getASTContext(), arg,
                                         m_ast->getASTContext()->IntTy));
 
   // template<typename T, int I> struct foo;
@@ -419,15 +419,16 @@ TEST_F(TestClangASTContext, TemplateArguments) {
               eTemplateArgumentKindType);
     EXPECT_EQ(m_ast->GetTypeTemplateArgument(t.GetOpaqueQualType(), 0),
               int_type);
-    auto p = m_ast->GetIntegralTemplateArgument(t.GetOpaqueQualType(), 0);
-    EXPECT_EQ(p.second, CompilerType());
+    EXPECT_EQ(llvm::None,
+              m_ast->GetIntegralTemplateArgument(t.GetOpaqueQualType(), 0));
 
     EXPECT_EQ(m_ast->GetTemplateArgumentKind(t.GetOpaqueQualType(), 1),
               eTemplateArgumentKindIntegral);
     EXPECT_EQ(m_ast->GetTypeTemplateArgument(t.GetOpaqueQualType(), 1),
               CompilerType());
-    p = m_ast->GetIntegralTemplateArgument(t.GetOpaqueQualType(), 1);
-    EXPECT_EQ(p.first, llvm::APSInt(47));
-    EXPECT_EQ(p.second, int_type);
+    auto result = m_ast->GetIntegralTemplateArgument(t.GetOpaqueQualType(), 1);
+    ASSERT_NE(llvm::None, result);
+    EXPECT_EQ(arg, result->value);
+    EXPECT_EQ(int_type, result->type);
   }
 }