[lldb][TypeSystemClang] Desugar an elaborated type before checking if it's a typedef or getting a typedefed type

Summary:
Sometimes a result variable of some expression can be presented as an elaborated
type. In this case the methods `IsTypedefType()` and `GetTypedefedType()` of
`SBType` didn't work. This patch fixes that.

I didn't find the test for these API methods, so I added a basic test for this
too.

Reviewers: aprantl, teemperor, labath, leonid.mashinskiy

Reviewed By: teemperor

Subscribers: labath, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D78697

lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp

@@ -3541,7 +3541,8 @@ bool TypeSystemClang::IsScalarType(lldb::opaque_compiler_type_t type) {
 bool TypeSystemClang::IsTypedefType(lldb::opaque_compiler_type_t type) {
   if (!type)
     return false;
-  return GetQualType(type)->getTypeClass() == clang::Type::Typedef;
+  return RemoveWrappingTypes(GetQualType(type), {clang::Type::Typedef})
+             ->getTypeClass() == clang::Type::Typedef;
 }
 
 bool TypeSystemClang::IsVoidType(lldb::opaque_compiler_type_t type) {
@@ -4525,8 +4526,8 @@ CompilerType TypeSystemClang::CreateTypedef(
 CompilerType
 TypeSystemClang::GetTypedefedType(lldb::opaque_compiler_type_t type) {
   if (type) {
-    const clang::TypedefType *typedef_type =
-        llvm::dyn_cast<clang::TypedefType>(GetQualType(type));
+    const clang::TypedefType *typedef_type = llvm::dyn_cast<clang::TypedefType>(
+        RemoveWrappingTypes(GetQualType(type), {clang::Type::Typedef}));
     if (typedef_type)
       return GetType(typedef_type->getDecl()->getUnderlyingType());
   }

lldb/test/API/lang/cpp/typedef/Makefile

@@ -0,0 +1,2 @@
+CXX_SOURCES := main.cpp
+include Makefile.rules

lldb/test/API/lang/cpp/typedef/TestCppTypedef.py

@@ -0,0 +1,55 @@
+"""
+Test that we can retrieve typedefed types correctly
+"""
+
+
+
+import lldb
+import lldbsuite.test.lldbutil as lldbutil
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import decorators
+
+class TestCppTypedef(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    def test_typedef(self):
+        """
+            Test that we retrieve typedefed types correctly
+        """
+
+        # Build and run until the breakpoint
+        self.build()
+        self.main_source_file = lldb.SBFileSpec("main.cpp")
+        (target, process, thread, bkpt) = lldbutil.run_to_source_breakpoint(
+            self, "Set a breakpoint here", self.main_source_file)
+
+        # Get the current frame
+        frame = thread.GetSelectedFrame()
+
+        # First of all, check that we can get a typedefed type correctly in a simple case
+
+        expr_result = frame.EvaluateExpression("(SF)s")
+        self.assertTrue(expr_result.IsValid(), "Expression failed with: " + str(expr_result.GetError()))
+
+        typedef_type = expr_result.GetType();
+        self.assertTrue(typedef_type.IsValid(), "Can't get `SF` type of evaluated expression")
+        self.assertTrue(typedef_type.IsTypedefType(), "Type `SF` should be a typedef")
+
+        typedefed_type = typedef_type.GetTypedefedType()
+        self.assertTrue(typedefed_type.IsValid(), "Can't get `SF` typedefed type")
+        self.assertEqual(typedefed_type.GetName(), "S<float>", "Got invalid `SF` typedefed type")
+
+        # Check that we can get a typedefed type correctly in the case
+        # when an elaborated type is created during the parsing
+
+        expr_result = frame.EvaluateExpression("(SF::V)s.value")
+        self.assertTrue(expr_result.IsValid(), "Expression failed with: " + str(expr_result.GetError()))
+
+        typedef_type = expr_result.GetType();
+        self.assertTrue(typedef_type.IsValid(), "Can't get `SF::V` type of evaluated expression")
+        self.assertTrue(typedef_type.IsTypedefType(), "Type `SF::V` should be a typedef")
+
+        typedefed_type = typedef_type.GetTypedefedType()
+        self.assertTrue(typedefed_type.IsValid(), "Can't get `SF::V` typedefed type")
+        self.assertEqual(typedefed_type.GetName(), "float", "Got invalid `SF::V` typedefed type")

lldb/test/API/lang/cpp/typedef/main.cpp

@@ -0,0 +1,13 @@
+template<typename T>
+struct S {
+  typedef T V;
+
+  V value;
+};
+
+typedef S<float> SF;
+
+int main (int argc, char const *argv[]) {
+  SF s{ .5 };
+  return 0; // Set a breakpoint here
+}