Add ConstString::IsNull() to tell between null vs. empty strings and fix usage in Mangled::GetDemangledName()

Summary: `IsEmpty()` and `operator bool() == false` have equal semantics. Usage in Mangled::GetDemangledName() was incorrect. What it actually wants is a check for null-string. Split this off of D50071 and added a test to clarify usage.

Reviewers: labath, jingham

Subscribers: erik.pilkington, lldb-commits

Differential Revision: https://reviews.llvm.org/D50327

llvm-svn: 339014

1 files changed, 2 insertions, 2 deletions

diff --git a/lldb/source/Core/Mangled.cpp b/lldb/source/Core/Mangled.cpp
index 043afe735fd..a6a5f8d3660 100644
--- a/lldb/source/Core/Mangled.cpp
+++ b/lldb/source/Core/Mangled.cpp
@@ -242,7 +242,7 @@ const ConstString &
 Mangled::GetDemangledName(lldb::LanguageType language) const {
   // Check to make sure we have a valid mangled name and that we haven't
   // already decoded our mangled name.
-  if (m_mangled && !m_demangled) {
+  if (m_mangled && m_demangled.IsNull()) {
     // We need to generate and cache the demangled name.
     static Timer::Category func_cat(LLVM_PRETTY_FUNCTION);
     Timer scoped_timer(func_cat, "Mangled::GetDemangledName (m_mangled = %s)",
@@ -312,7 +312,7 @@ Mangled::GetDemangledName(lldb::LanguageType language) const {
         free(demangled_name);
       }
     }
-    if (!m_demangled) {
+    if (m_demangled.IsNull()) {
       // Set the demangled string to the empty string to indicate we tried to
       // parse it once and failed.
       m_demangled.SetCString("");