[LLDB] Fix assertion failure by removing CopyType in `std::coroutin…

…e_handle` pretty printer

The pretty printer for `std::coroutine_handle` was running into
> Assertion failed: (target_ctx != source_ctx && "Can't import into itself")
from ClangASTImporter.h, line 270.

This commit fixes the issue by removing the `CopyType` call from the
pretty printer. While this call was necessary in the past, it seems to
be no longer required, at least all test cases are still passing. Maybe
something changed in the meantime around the handling of `TypesystemClang`
instances. I don't quite understand why `CopyType` was necessary earlier.

I am not sure how to add a regression test for this, though. It seems
the issue is already triggered by the exising `TestCoroutineHandle.py`,
but API tests seem to ignore all violations of `lldbassert` and still
report the test as "passed", even if assertions were triggered

Differential Revision: https://reviews.llvm.org/D143127

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

@@ -8,7 +8,6 @@
 
 #include "Coroutines.h"
 
-#include "Plugins/ExpressionParser/Clang/ClangASTImporter.h"
 #include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
 #include "lldb/Symbol/Function.h"
 #include "lldb/Symbol/VariableList.h"
@@ -97,8 +96,7 @@ bool lldb_private::formatters::StdlibCoroutineHandleSummaryProvider(
 
 lldb_private::formatters::StdlibCoroutineHandleSyntheticFrontEnd::
     StdlibCoroutineHandleSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
-    : SyntheticChildrenFrontEnd(*valobj_sp),
-      m_ast_importer(std::make_unique<ClangASTImporter>()) {
+    : SyntheticChildrenFrontEnd(*valobj_sp) {
   if (valobj_sp)
     Update();
 }
@@ -174,8 +172,7 @@ bool lldb_private::formatters::StdlibCoroutineHandleSyntheticFrontEnd::
     if (Function *destroy_func =
             ExtractDestroyFunction(target_sp, frame_ptr_addr)) {
       if (CompilerType inferred_type = InferPromiseType(*destroy_func)) {
-        // Copy the type over to the correct `TypeSystemClang` instance
-        promise_type = m_ast_importer->CopyType(*ast_ctx, inferred_type);
+        promise_type = inferred_type;
       }
     }
   }

lldb/source/Plugins/Language/CPlusPlus/Coroutines.h

@@ -16,8 +16,6 @@
 
 namespace lldb_private {
 
-class ClangASTImporter;
-
 namespace formatters {
 
 /// Summary provider for `std::coroutine_handle<T>` from  libc++, libstdc++ and
@@ -50,7 +48,6 @@ class StdlibCoroutineHandleSyntheticFrontEnd
   lldb::ValueObjectSP m_resume_ptr_sp;
   lldb::ValueObjectSP m_destroy_ptr_sp;
   lldb::ValueObjectSP m_promise_ptr_sp;
-  std::unique_ptr<lldb_private::ClangASTImporter> m_ast_importer;
 };
 
 SyntheticChildrenFrontEnd *