Correctly handle forward DIE references in scanner

The cooked index scanner has special code to handle forward DIE
references.  However, a bug report lead to the discovery that this
code does not work -- the "deferred_entry::spec_offset" field is
written to but never used, i.e., the lookup is done using the wrong
key.

This patch fixes the bug and adds a regression test.

The test in the bug itself used a thread_local variable, which
provoked a failure at runtime.  This test instead uses "maint print
objfiles" and then inspects to ensure that the entry in question has a
parent.  This lets us avoid a clang dependency in the test.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30271

1 files changed, 2 insertions, 3 deletions

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index b99c5cd3a2c..4828409222c 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -16641,9 +16641,8 @@ cooked_indexer::make_index (cutu_reader *reader)
 
   for (const auto &entry : m_deferred_entries)
     {
-      CORE_ADDR key = form_addr (entry.die_offset, m_per_cu->is_dwz);
-      void *obj = m_die_range_map.find (key);
-      cooked_index_entry *parent = static_cast <cooked_index_entry *> (obj);
+      void *obj = m_die_range_map.find (entry.spec_offset);
+      cooked_index_entry *parent = static_cast<cooked_index_entry *> (obj);
       m_index_storage->add (entry.die_offset, entry.tag, entry.flags,
 			    entry.name, parent, m_per_cu);
     }