[lldb][NFCI] Change return type of REPL::GetSourceFileBasename

These don't really need to be in the ConstString StringPool. I've
changed the return type to StringRef because on llvm.org and downstream
in the swift fork, this returns a constant value. We could change it to
return a std::string or something else if it needs to be able to change
between calls.

Differential Revision: https://reviews.llvm.org/D151962

Author: bulbazord

lldb/include/lldb/Expression/REPL.h

@@ -131,7 +131,7 @@ class REPL : public IOHandlerDelegate,
 
   virtual Status DoInitialization() = 0;
 
-  virtual ConstString GetSourceFileBasename() = 0;
+  virtual llvm::StringRef GetSourceFileBasename() = 0;
 
   virtual const char *GetAutoIndentCharacters() = 0;
 

lldb/source/Expression/REPL.cpp

@@ -57,14 +57,14 @@ lldb::REPLSP REPL::Create(Status &err, lldb::LanguageType language,
 }
 
 std::string REPL::GetSourcePath() {
-  ConstString file_basename = GetSourceFileBasename();
+  llvm::StringRef file_basename = GetSourceFileBasename();
   FileSpec tmpdir_file_spec = HostInfo::GetProcessTempDir();
   if (tmpdir_file_spec) {
     tmpdir_file_spec.SetFilename(file_basename);
     m_repl_source_path = tmpdir_file_spec.GetPath();
   } else {
     tmpdir_file_spec = FileSpec("/tmp");
-    tmpdir_file_spec.AppendPathComponent(file_basename.GetStringRef());
+    tmpdir_file_spec.AppendPathComponent(file_basename);
   }
 
   return tmpdir_file_spec.GetPath();

lldb/source/Plugins/REPL/Clang/ClangREPL.cpp

@@ -62,8 +62,9 @@ lldb::REPLSP ClangREPL::CreateInstance(Status &error,
 
 Status ClangREPL::DoInitialization() { return Status(); }
 
-ConstString ClangREPL::GetSourceFileBasename() {
-  return ConstString("repl.c");
+llvm::StringRef ClangREPL::GetSourceFileBasename() {
+  static constexpr llvm::StringLiteral g_repl("repl.c");
+  return g_repl;
 }
 
 const char *ClangREPL::GetAutoIndentCharacters() { return "  "; }

lldb/source/Plugins/REPL/Clang/ClangREPL.h

@@ -36,7 +36,7 @@ class ClangREPL : public llvm::RTTIExtends<ClangREPL, REPL> {
 protected:
   Status DoInitialization() override;
 
-  ConstString GetSourceFileBasename() override;
+  llvm::StringRef GetSourceFileBasename() override;
 
   const char *GetAutoIndentCharacters() override;