From cff509f33ba44fd1d0d9b579791dad527d50068e Mon Sep 17 00:00:00 2001
From: Pavel Labath <pavel@labath.sk>
Date: Thu, 30 Jun 2022 16:30:51 +0200
Subject: [PATCH] [lldb] Fix libc++ string formatter for the "unstable" layout

D128285 only changed the stable (v1) layout, so the matching change in
D128694 broke the formatting of the unstable strings. This fixes that,
and ensures compatibility with all older layouts as well.
---
 lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp | 43 +++++++++++++----------
 1 file changed, 24 insertions(+), 19 deletions(-)

diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
index 18bca3b..eaaa164 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
@@ -587,14 +587,19 @@ ExtractLibcxxStringInfo(ValueObject &valobj) {
   if (!short_sp)
     return {};
 
-  // After D128285, we need to access the `__is_long_` and `__size_` fields from
-  // a packed anonymous struct
-  ValueObjectSP packed_fields_sp = short_sp->GetChildAtIndex(0, true);
-  if (!packed_fields_sp)
-    return {};
+  ValueObjectSP short_fields_sp;
+  ValueObjectSP is_long =
+      short_sp->GetChildMemberWithName(ConstString("__is_long_"), true);
+  if (is_long) {
+    short_fields_sp = short_sp;
+  } else {
+    // After D128285, we need to access the `__is_long_` and `__size_` fields
+    // from a packed anonymous struct
+    short_fields_sp = short_sp->GetChildAtIndex(0, true);
+    is_long = short_sp->GetChildMemberWithName(ConstString("__is_long_"), true);
+  }
 
-  if (ValueObjectSP is_long = packed_fields_sp->GetChildMemberWithName(
-          ConstString("__is_long_"), true)) {
+  if (is_long) {
     using_bitmasks = false;
     short_mode = !is_long->GetValueAsUnsigned(/*fail_value=*/0);
     if (ValueObjectSP size_member =
@@ -631,11 +636,8 @@ ExtractLibcxxStringInfo(ValueObject &valobj) {
   }
 
   if (short_mode) {
-    ValueObjectSP location_sp = packed_fields_sp->GetChildAtIndex(
-        (layout == eLibcxxStringLayoutModeDSC) ? 0 : 1, true);
-    // After D125496, there is a flat layout.
-    if (location_sp->GetName() == g_size_name)
-      location_sp = short_sp->GetChildMemberWithName(g_data_name, true);
+    ValueObjectSP location_sp =
+        short_sp->GetChildMemberWithName(g_data_name, true);
     if (using_bitmasks)
       size = (layout == eLibcxxStringLayoutModeDSC)
                  ? size_mode_value
@@ -658,18 +660,21 @@ ExtractLibcxxStringInfo(ValueObject &valobj) {
   if (!l)
     return {};
 
-  // After D128285, we need to access the `__cap_` field from a packed anonymous
-  // struct
-  packed_fields_sp = l->GetChildAtIndex(0, true);
-  if (!packed_fields_sp)
-    return {};
   // we can use the layout_decider object as the data pointer
   ValueObjectSP location_sp =
       l->GetChildMemberWithName(ConstString("__data_"), /*can_create=*/true);
   ValueObjectSP size_vo =
       l->GetChildMemberWithName(ConstString("__size_"), /*can_create=*/true);
-  ValueObjectSP capacity_vo = packed_fields_sp->GetChildMemberWithName(
-      ConstString("__cap_"), /*can_create=*/true);
+  ValueObjectSP capacity_vo =
+      l->GetChildMemberWithName(ConstString("__cap_"), /*can_create=*/true);
+  if (!capacity_vo) {
+    // After D128285, we need to access the `__cap_` field from a packed
+    // anonymous struct
+    if (ValueObjectSP packed_fields_sp = l->GetChildAtIndex(0, true)) {
+      ValueObjectSP capacity_vo = packed_fields_sp->GetChildMemberWithName(
+          ConstString("__cap_"), /*can_create=*/true);
+    }
+  }
   if (!size_vo || !location_sp || !capacity_vo)
     return {};
   size = size_vo->GetValueAsUnsigned(LLDB_INVALID_OFFSET);
-- 
2.7.4