[LLDB] Fixes summary formatter for libc++ map allowing modification of contained value

Reviewed By: clayborg

Differential Revision: https://reviews.llvm.org/D140624

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

@@ -397,18 +397,9 @@ lldb_private::formatters::LibcxxStdMapSyntheticFrontEnd::GetChildAtIndex(
   // at this point we have a valid
   // we need to copy current_sp into a new object otherwise we will end up with
   // all items named __value_
-  DataExtractor data;
-  Status error;
-  iterated_sp->GetData(data, error);
-  if (error.Fail()) {
-    m_tree = nullptr;
-    return lldb::ValueObjectSP();
-  }
   StreamString name;
   name.Printf("[%" PRIu64 "]", (uint64_t)idx);
-  auto potential_child_sp = CreateValueObjectFromData(
-      name.GetString(), data, m_backend.GetExecutionContextRef(),
-      m_element_type);
+  auto potential_child_sp = iterated_sp->Clone(ConstString(name.GetString()));
   if (potential_child_sp) {
     switch (potential_child_sp->GetNumChildren()) {
     case 1: {

lldb/test/API/python_api/value/change_values/libcxx/map/Makefile

@@ -0,0 +1,6 @@
+CXX_SOURCES := main.cpp
+
+USE_LIBCPP := 1
+
+CXXFLAGS_EXTRAS := -O0
+include Makefile.rules

lldb/test/API/python_api/value/change_values/libcxx/map/TestChangeValue.py

@@ -0,0 +1,51 @@
+"""
+Test change libc++ map values.
+"""
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+class LibcxxChangeValueTestCase(TestBase):
+
+    def setUp(self):
+        # Call super's setUp().
+        TestBase.setUp(self)
+
+    @add_test_categories(["libc++"])
+    @expectedFailureAll(oslist=["windows"], bugnumber="llvm.org/pr24772")
+    def test(self):
+        """Test that we can change values of libc++ map."""
+        self.build()
+        self.runCmd("file " + self.getBuildArtifact("a.out"), CURRENT_EXECUTABLE_SET)
+
+        bkpt = self.target().FindBreakpointByID(
+            lldbutil.run_break_set_by_source_regexp(
+                self, "Set break point at this line."))
+
+        self.runCmd("run", RUN_SUCCEEDED)
+
+        # Get Frame #0.
+        target = self.dbg.GetSelectedTarget()
+        process = target.GetProcess()
+        self.assertState(process.GetState(), lldb.eStateStopped)
+        thread = lldbutil.get_stopped_thread(
+            process, lldb.eStopReasonBreakpoint)
+        self.assertTrue(
+            thread.IsValid(),
+            "There should be a thread stopped due to breakpoint condition")
+        frame0 = thread.GetFrameAtIndex(0)
+        self.assertTrue(frame0.IsValid(), "Got a valid frame.")
+
+        val_value = frame0.FindVariable("M")
+        self.assertTrue(val_value.IsValid(), "Got the SBValue for val")
+        pair0 = val_value.GetChildMemberWithName("[0]")
+        self.assertTrue(pair0.IsValid(), "Got the SBValue for [0]")
+        self.assertTrue(pair0.GetNumChildren() == 2, "Got 2 children")
+        pair0_second = pair0.GetChildMemberWithName("second")
+        self.assertTrue(pair0_second.IsValid(), "Got the SBValue for [0].second")
+        result = pair0_second.SetValueFromCString("12345")
+        self.assertTrue(result, "Setting val returned True.")
+        result = pair0_second.GetValueAsUnsigned()
+        self.assertTrue(result == 12345, "Got correct value (12345)")

lldb/test/API/python_api/value/change_values/libcxx/map/main.cpp

@@ -0,0 +1,7 @@
+#include <map>
+
+int main()
+{
+    std::map<int, int> M = {{1,1},{2,2}};
+    return M[1]; // Set break point at this line.
+}