[LLDB] Do not dereference promise pointer in `coroutine_handle` pretty printer

So far, the pretty printer for `std::coroutine_handle` internally
dereferenced the contained frame pointer displayed the `promise`
as a sub-value. As noticed in https://reviews.llvm.org/D132624
by @labath, this can lead to an endless loop in lldb during printing
if the coroutine frame pointers form a cycle.

This commit breaks the cycle by exposing the `promise` as a pointer
type instead of a value type. The depth to which the `frame variable`
and the `expression` commands dereference those pointers can be
controlled using the `--ptr-depth` argument.

Differential Revision: https://reviews.llvm.org/D132815

1 files changed, 7 insertions, 1 deletions

diff --git a/lldb/packages/Python/lldbsuite/test/lldbtest.py b/lldb/packages/Python/lldbsuite/test/lldbtest.py
index 63bad9d0241d..f579a0160b2b 100644
--- a/lldb/packages/Python/lldbsuite/test/lldbtest.py
+++ b/lldb/packages/Python/lldbsuite/test/lldbtest.py
@@ -246,7 +246,7 @@ def which(program):
 
 class ValueCheck:
     def __init__(self, name=None, value=None, type=None, summary=None,
-                 children=None):
+                 children=None, dereference=None):
         """
         :param name: The name that the SBValue should have. None if the summary
                      should not be checked.
@@ -261,12 +261,15 @@ class ValueCheck:
                          The order of checks is the order of the checks in the
                          list. The number of checks has to match the number of
                          children.
+        :param dereference: A ValueCheck for the SBValue returned by the
+                            `Dereference` function.
         """
         self.expect_name = name
         self.expect_value = value
         self.expect_type = type
         self.expect_summary = summary
         self.children = children
+        self.dereference = dereference
 
     def check_value(self, test_base, val, error_msg=None):
         """
@@ -308,6 +311,9 @@ class ValueCheck:
         if self.children is not None:
             self.check_value_children(test_base, val, error_msg)
 
+        if self.dereference is not None:
+            self.dereference.check_value(test_base, val.Dereference(), error_msg)
+
     def check_value_children(self, test_base, val, error_msg=None):
         """
         Checks that the children of a SBValue match a certain structure and