Fix libcxx formatters for changes in r300140.

Summary:
LLVM r300140 changed the layout and field names of __compressed_pair, which
broke LLDB's std::vector, std::map and std::unsorted_map formatters.

This patch attempts to fix these formatters by having them interogate the
__compressed_pair values to determine whether they're pre- or post-r300140
variants, then access them accordingly.

Reviewers: jingham, EricWF

Reviewed By: jingham

Differential Revision: https://reviews.llvm.org/D32554

llvm-svn: 301493

1 files changed, 18 insertions, 1 deletions

diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp
index 2843201e2ed..96d7e51deba 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp
@@ -127,8 +127,25 @@ bool lldb_private::formatters::LibcxxStdVectorSyntheticFrontEnd::Update() {
       m_backend.GetChildMemberWithName(ConstString("__end_cap_"), true));
   if (!data_type_finder_sp)
     return false;
-  data_type_finder_sp = data_type_finder_sp->GetChildMemberWithName(
+
+  switch (data_type_finder_sp->GetCompilerType().GetNumDirectBaseClasses()) {
+  case 1:
+    // Assume a pre llvm r300140 __compressed_pair implementation:
+    data_type_finder_sp = data_type_finder_sp->GetChildMemberWithName(
       ConstString("__first_"), true);
+    break;
+  case 2: {
+    // Assume a post llvm r300140 __compressed_pair implementation:
+    ValueObjectSP first_elem_parent_sp =
+      data_type_finder_sp->GetChildAtIndex(0, true);
+    data_type_finder_sp = first_elem_parent_sp->GetChildMemberWithName(
+      ConstString("__value_"), true);
+    break;
+  }
+  default:
+    return false;
+  }
+
   if (!data_type_finder_sp)
     return false;
   m_element_type = data_type_finder_sp->GetCompilerType().GetPointeeType();