[gdb/symtab] Fix .debug_aranges duplicate offset warning

The function read_addrmap_from_aranges contains code to issue a warning:
...
      if (!insertpair.second)
       {
         warning (_("Section .debug_aranges in %s has duplicate "
                    "debug_info_offset %s, ignoring .debug_aranges."),
                  objfile_name (objfile), sect_offset_str (per_cu->sect_off));
         return false;
       }
...
but the warning is in fact activated when all_comp_units has duplicate
entries, which is very misleading.

Fix this by:
- adding a test-case that should trigger the warning,
- replacing the current implementation of the warning with an
  assert that all_comp_units should not contain duplicates, and
- properly re-implementing the warning, such that it is triggered
  by the test-case.

Tested on x86_64-linux.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29381

1 files changed, 15 insertions, 7 deletions

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index ae0b5d7..8c66cb8 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -2347,15 +2347,13 @@ read_addrmap_from_aranges (dwarf2_per_objfile *per_objfile,
       const auto insertpair
 	= debug_info_offset_to_per_cu.emplace (per_cu->sect_off,
 					       per_cu.get ());
-      if (!insertpair.second)
-	{
-	  warning (_("Section .debug_aranges in %s has duplicate "
-		     "debug_info_offset %s, ignoring .debug_aranges."),
-		   objfile_name (objfile), sect_offset_str (per_cu->sect_off));
-	  return false;
-	}
+
+      /* Assume no duplicate offsets in all_comp_units.  */
+      gdb_assert (insertpair.second);
     }
 
+  std::set<sect_offset> debug_info_offset_seen;
+
   section->read (objfile);
 
   const bfd_endian dwarf5_byte_order = gdbarch_byte_order (gdbarch);
@@ -2413,6 +2411,16 @@ read_addrmap_from_aranges (dwarf2_per_objfile *per_objfile,
 		   pulongest (debug_info_offset));
 	  return false;
 	}
+      const auto insertpair
+	= debug_info_offset_seen.insert (sect_offset (debug_info_offset));
+      if (!insertpair.second)
+	{
+	  warning (_("Section .debug_aranges in %s has duplicate "
+		     "debug_info_offset %s, ignoring .debug_aranges."),
+		   objfile_name (objfile),
+		   sect_offset_str (sect_offset (debug_info_offset)));
+	  return false;
+	}
       dwarf2_per_cu_data *const per_cu = per_cu_it->second;
 
       const uint8_t address_size = *addr++;