[lldb] Add SBFunction::GetBaseName() & SBSymbol::GetBaseName() (#155939)

When you are trying for instance to set a breakpoint on a function by
name, but the SBFunction or SBSymbol are returning demangled names with
argument lists, that match can be tedious to do. Internally, the base
name of a symbol is something we handle all the time, so it's reasonable
that there should be a way to get that info from the API as well.

rdar://159318791

lldb/include/lldb/API/SBFunction.h

@@ -36,6 +36,8 @@ public:
 
   const char *GetMangledName() const;
 
+  const char *GetBaseName() const;
+
   lldb::SBInstructionList GetInstructions(lldb::SBTarget target);
 
   lldb::SBInstructionList GetInstructions(lldb::SBTarget target,

lldb/include/lldb/API/SBSymbol.h

@@ -36,6 +36,8 @@ public:
 
   const char *GetMangledName() const;
 
+  const char *GetBaseName() const;
+
   lldb::SBInstructionList GetInstructions(lldb::SBTarget target);
 
   lldb::SBInstructionList GetInstructions(lldb::SBTarget target,

lldb/include/lldb/Core/Mangled.h

@@ -287,6 +287,17 @@ public:
   /// Retrieve \c DemangledNameInfo of the demangled name held by this object.
   const std::optional<DemangledNameInfo> &GetDemangledInfo() const;
 
+  /// Compute the base name (without namespace/class qualifiers) from the
+  /// demangled name.
+  ///
+  /// For a demangled name like "ns::MyClass<int>::templateFunc", this returns
+  /// just "templateFunc".
+  ///
+  /// \return
+  ///     A ConstString containing the basename, or nullptr if computation
+  ///     fails.
+  ConstString GetBaseName() const;
+
 private:
   /// If \c force is \c false, this function will re-use the previously
   /// demangled name (if any). If \c force is \c true (or the mangled name

lldb/source/API/SBFunction.cpp

@@ -79,6 +79,15 @@ const char *SBFunction::GetMangledName() const {
   return nullptr;
 }
 
+const char *SBFunction::GetBaseName() const {
+  LLDB_INSTRUMENT_VA(this);
+
+  if (!m_opaque_ptr)
+    return nullptr;
+
+  return m_opaque_ptr->GetMangled().GetBaseName().AsCString();
+}
+
 bool SBFunction::operator==(const SBFunction &rhs) const {
   LLDB_INSTRUMENT_VA(this, rhs);
 

lldb/source/API/SBSymbol.cpp

@@ -79,6 +79,15 @@ const char *SBSymbol::GetMangledName() const {
   return name;
 }
 
+const char *SBSymbol::GetBaseName() const {
+  LLDB_INSTRUMENT_VA(this);
+
+  if (!m_opaque_ptr)
+    return nullptr;
+
+  return m_opaque_ptr->GetMangled().GetBaseName().AsCString();
+}
+
 bool SBSymbol::operator==(const SBSymbol &rhs) const {
   LLDB_INSTRUMENT_VA(this, rhs);
 

lldb/source/Core/Mangled.cpp

@@ -556,3 +556,18 @@ void Mangled::Encode(DataEncoder &file, ConstStringTable &strtab) const {
       break;
   }
 }
+
+ConstString Mangled::GetBaseName() const {
+  const auto &demangled_info = GetDemangledInfo();
+  if (!demangled_info.has_value())
+    return {};
+
+  ConstString demangled_name = GetDemangledName();
+  if (!demangled_name)
+    return {};
+
+  const char *name_str = demangled_name.AsCString();
+  const auto &range = demangled_info->BasenameRange;
+  return ConstString(
+      llvm::StringRef(name_str + range.first, range.second - range.first));
+}

lldb/test/API/python_api/basename/Makefile

@@ -0,0 +1,3 @@
+CXX_SOURCES := main.cpp
+
+include Makefile.rules

lldb/test/API/python_api/basename/TestGetBaseName.py

@@ -0,0 +1,36 @@
+"""
+Test SBFunction::GetBaseName() and SBSymbol::GetBaseName() APIs.
+"""
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class GetBaseNameTestCase(TestBase):
+    NO_DEBUG_INFO_TESTCASE = True
+
+    def setUp(self):
+        TestBase.setUp(self)
+        self.main_source_file = lldb.SBFileSpec("main.cpp")
+
+    def test(self):
+        """Test SBFunction.GetBaseName() and SBSymbol.GetBaseName()"""
+        self.build()
+        _, _, thread, _ = lldbutil.run_to_source_breakpoint(
+            self, "Set a breakpoint here", self.main_source_file
+        )
+
+        frame0 = thread.GetFrameAtIndex(0)
+
+        # Get both function and symbol
+        function = frame0.GetFunction()
+        symbol = frame0.GetSymbol()
+
+        # Test consistency between function and symbol basename
+        function_basename = function.GetBaseName()
+        symbol_basename = symbol.GetBaseName()
+
+        self.assertEqual(function_basename, "templateFunc")
+        self.assertEqual(symbol_basename, "templateFunc")

lldb/test/API/python_api/basename/main.cpp

@@ -0,0 +1,16 @@
+#include <iostream>
+
+namespace ns {
+template <typename T> class MyClass {
+public:
+  void templateFunc() {
+    std::cout << "In templateFunc" << std::endl; // Set a breakpoint here
+  }
+};
+} // namespace ns
+
+int main() {
+  ns::MyClass<int> obj;
+  obj.templateFunc();
+  return 0;
+}