Use an artifical namespace so that member vars do not hide local vars.

Summary:
While evaluating expressions when stopped in a class method, there was a
problem of member variables hiding local variables. This was happening
because, in the context of a method, clang already knew about member
variables with their name and assumed that they were the only variables
with those names in scope. Consequently, clang never checks with LLDB
about the possibility of local variables with the same name and goes
wrong. This change addresses the problem by using an artificial
namespace "$__lldb_local_vars". All local variables in scope are
declared in the "$__lldb_expr" method as follows:

    using $__lldb_local_vars::<local var 1>;
    using $__lldb_local_vars::<local var 2>;
    ...

This hides the member variables with the same name and forces clang to
enquire about the variables which it thinks are declared in
$__lldb_local_vars. When LLDB notices that clang is enquiring about
variables in $__lldb_local_vars, it looks up local vars and conveys
their information if found. This way, member variables do not hide local
variables, leading to correct evaluation of expressions.

A point to keep in mind is that the above solution does not solve the
problem for one specific case:

    namespace N
    {
        int a;
    }

    class A
    {
    public:
        void Method();
        int a;
    };

    void
    A::Method()
    {
        using N::a;
        ...

        // Since the above solution only touches locals, it does not
        // force clang to enquire about "a" coming from namespace N.
    }

Reviewers: clayborg, spyffe

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D16746

llvm-svn: 259810

3 files changed, 275 insertions, 0 deletions

diff --git a/lldb/packages/Python/lldbsuite/test/lang/cpp/member-and-local-vars-with-same-name/Makefile b/lldb/packages/Python/lldbsuite/test/lang/cpp/member-and-local-vars-with-same-name/Makefile
new file mode 100644
index 00000000000..35eb63f922f
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/lang/cpp/member-and-local-vars-with-same-name/Makefile
@@ -0,0 +1,5 @@
+LEVEL = ../../../make
+
+CXX_SOURCES = main.cpp
+
+include $(LEVEL)/Makefile.rules
diff --git a/lldb/packages/Python/lldbsuite/test/lang/cpp/member-and-local-vars-with-same-name/TestMembersAndLocalsWithSameName.py b/lldb/packages/Python/lldbsuite/test/lang/cpp/member-and-local-vars-with-same-name/TestMembersAndLocalsWithSameName.py
new file mode 100644
index 00000000000..12fc4c23637
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/lang/cpp/member-and-local-vars-with-same-name/TestMembersAndLocalsWithSameName.py
@@ -0,0 +1,197 @@
+import lldb
+from lldbsuite.test.lldbtest import *
+import lldbsuite.test.lldbutil as lldbutil
+
+class TestMembersAndLocalsWithSameName(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    def test_when_stopped_in_method(self):
+        self._load_exe()
+
+        # Set breakpoints
+        bp1 = self.target.BreakpointCreateBySourceRegex("Break 1", self.src_file_spec)
+        self.assertTrue(bp1.IsValid() and bp1.GetNumLocations() >= 1, VALID_BREAKPOINT)
+        bp2 = self.target.BreakpointCreateBySourceRegex("Break 2", self.src_file_spec)
+        self.assertTrue(bp2.IsValid() and bp2.GetNumLocations() >= 1, VALID_BREAKPOINT)
+        bp3 = self.target.BreakpointCreateBySourceRegex("Break 3", self.src_file_spec)
+        self.assertTrue(bp3.IsValid() and bp3.GetNumLocations() >= 1, VALID_BREAKPOINT)
+        bp4 = self.target.BreakpointCreateBySourceRegex("Break 4", self.src_file_spec)
+        self.assertTrue(bp4.IsValid() and bp4.GetNumLocations() >= 1, VALID_BREAKPOINT)
+
+        # Launch the process
+        self.process = self.target.LaunchSimple(None, None, self.get_process_working_directory())
+        self.assertTrue(self.process.IsValid(), PROCESS_IS_VALID)
+
+        self.assertTrue(self.process.GetState() == lldb.eStateStopped, PROCESS_STOPPED)
+
+        self._test_globals()
+
+        self.process.Continue()
+        self.assertTrue(self.process.GetState() == lldb.eStateStopped, PROCESS_STOPPED)
+        thread = lldbutil.get_stopped_thread(self.process, lldb.eStopReasonBreakpoint)
+        self.assertTrue(thread.IsValid())
+        frame = thread.GetSelectedFrame()
+        self.assertTrue(frame.IsValid())
+
+        val = frame.EvaluateExpression("a");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 12345)
+
+        val = frame.EvaluateExpression("b");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 54321)
+
+        val = frame.EvaluateExpression("c");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 34567)
+
+        self.process.Continue()
+        self.assertTrue(self.process.GetState() == lldb.eStateStopped, PROCESS_STOPPED)
+        thread = lldbutil.get_stopped_thread(self.process, lldb.eStopReasonBreakpoint)
+        self.assertTrue(thread.IsValid())
+        frame = thread.GetSelectedFrame()
+        self.assertTrue(frame.IsValid())
+
+        val = frame.EvaluateExpression("a");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 10001)
+
+        val = frame.EvaluateExpression("b");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 10002)
+
+        val = frame.EvaluateExpression("c");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 10003)
+
+        self.process.Continue()
+        self.assertTrue(self.process.GetState() == lldb.eStateStopped, PROCESS_STOPPED)
+        thread = lldbutil.get_stopped_thread(self.process, lldb.eStopReasonBreakpoint)
+        self.assertTrue(thread.IsValid())
+        frame = thread.GetSelectedFrame()
+        self.assertTrue(frame.IsValid())
+
+        val = frame.EvaluateExpression("a");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 1)
+
+        val = frame.EvaluateExpression("b");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 2)
+
+        val = frame.EvaluateExpression("c");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 778899)
+
+    def test_when_stopped_in_function(self):
+        self._load_exe()
+
+        # Set breakpoints
+        bp1 = self.target.BreakpointCreateBySourceRegex("Break 1", self.src_file_spec)
+        self.assertTrue(bp1.IsValid() and bp1.GetNumLocations() >= 1, VALID_BREAKPOINT)
+        bp5 = self.target.BreakpointCreateBySourceRegex("Break 5", self.src_file_spec)
+        self.assertTrue(bp5.IsValid() and bp5.GetNumLocations() >= 1, VALID_BREAKPOINT)
+        bp6 = self.target.BreakpointCreateBySourceRegex("Break 6", self.src_file_spec)
+        self.assertTrue(bp6.IsValid() and bp6.GetNumLocations() >= 1, VALID_BREAKPOINT)
+        bp7 = self.target.BreakpointCreateBySourceRegex("Break 7", self.src_file_spec)
+        self.assertTrue(bp7.IsValid() and bp7.GetNumLocations() >= 1, VALID_BREAKPOINT)
+
+        # Launch the process
+        self.process = self.target.LaunchSimple(None, None, self.get_process_working_directory())
+        self.assertTrue(self.process.IsValid(), PROCESS_IS_VALID)
+
+        self.assertTrue(self.process.GetState() == lldb.eStateStopped, PROCESS_STOPPED)
+
+        self._test_globals()
+
+        self.process.Continue()
+        self.assertTrue(self.process.GetState() == lldb.eStateStopped, PROCESS_STOPPED)
+        thread = lldbutil.get_stopped_thread(self.process, lldb.eStopReasonBreakpoint)
+        self.assertTrue(thread.IsValid())
+        frame = thread.GetSelectedFrame()
+        self.assertTrue(frame.IsValid())
+
+        val = frame.EvaluateExpression("a");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 12345)
+
+        val = frame.EvaluateExpression("b");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 54321)
+
+        val = frame.EvaluateExpression("c");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 34567)
+
+        self.process.Continue()
+        self.assertTrue(self.process.GetState() == lldb.eStateStopped, PROCESS_STOPPED)
+        thread = lldbutil.get_stopped_thread(self.process, lldb.eStopReasonBreakpoint)
+        self.assertTrue(thread.IsValid())
+        frame = thread.GetSelectedFrame()
+        self.assertTrue(frame.IsValid())
+
+        val = frame.EvaluateExpression("a");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 10001)
+
+        val = frame.EvaluateExpression("b");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 10002)
+
+        val = frame.EvaluateExpression("c");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 10003)
+
+        self.process.Continue()
+        self.assertTrue(self.process.GetState() == lldb.eStateStopped, PROCESS_STOPPED)
+        thread = lldbutil.get_stopped_thread(self.process, lldb.eStopReasonBreakpoint)
+        self.assertTrue(thread.IsValid())
+        frame = thread.GetSelectedFrame()
+        self.assertTrue(frame.IsValid())
+
+        val = frame.EvaluateExpression("a");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 1)
+
+        val = frame.EvaluateExpression("b");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 2)
+
+        val = frame.EvaluateExpression("c");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 778899)
+
+    def _load_exe(self):
+        self.build()
+
+        cwd = os.getcwd()
+
+        src_file = os.path.join(cwd, "main.cpp")
+        self.src_file_spec = lldb.SBFileSpec(src_file)
+        self.assertTrue(self.src_file_spec.IsValid(), "breakpoint file")
+
+        # Get the path of the executable
+        exe_path  = os.path.join(cwd, 'a.out')
+
+        # Load the executable
+        self.target = self.dbg.CreateTarget(exe_path)
+        self.assertTrue(self.target.IsValid(), VALID_TARGET)
+
+    def _test_globals(self):
+        thread = lldbutil.get_stopped_thread(self.process, lldb.eStopReasonBreakpoint)
+        self.assertTrue(thread.IsValid())
+        frame = thread.GetSelectedFrame()
+        self.assertTrue(frame.IsValid())
+
+        val = frame.EvaluateExpression("a");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 112233)
+
+        val = frame.EvaluateExpression("b");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 445566)
+
+        val = frame.EvaluateExpression("c");
+        self.assertTrue(val.IsValid())
+        self.assertEqual(val.GetValueAsUnsigned(), 778899)
diff --git a/lldb/packages/Python/lldbsuite/test/lang/cpp/member-and-local-vars-with-same-name/main.cpp b/lldb/packages/Python/lldbsuite/test/lang/cpp/member-and-local-vars-with-same-name/main.cpp
new file mode 100644
index 00000000000..baf08f6a983
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/lang/cpp/member-and-local-vars-with-same-name/main.cpp
@@ -0,0 +1,73 @@
+namespace NN
+{
+  int a = 778899;
+  int b = 665544;
+  int c = 445566;
+}
+
+class A
+{
+public:
+  A();
+  int Method(int a, int b);
+
+private:
+  int a, b;
+};
+
+A::A() : a(10), b(100) { }
+
+int a = 112233;
+int b = 445566;
+int c = 778899;
+
+int
+A::Method(int a, int b)
+{
+    {
+        int a = 12345;
+        int b = 54321;
+        int c = 34567;
+        this->a = a + b + this->b; // Break 2
+    }
+
+    {
+        using namespace NN;
+        int a = 10001;
+        int b = 10002;
+        int c = 10003;
+        this->a = a + b + this->b; // Break 3
+    }
+
+    return this->a + this->b + a + b; // Break 4
+}
+
+int
+Function(int a, int b)
+{
+    int A;
+
+    {
+        int a = 12345;
+        int b = 54321;
+        int c = 34567;
+        A = a + b + c; // Break 5
+    }
+
+    {
+        using namespace NN;
+        int a = 10001;
+        int b = 10002;
+        int c = 10003;
+        A = a + b + c; // Break 6
+    }
+
+    return A + a + b; // Break 7
+}
+
+int
+main()
+{
+    A obj;
+    return obj.Method(1, 2) + Function(1, 2); // Break 1
+}