[PATCH v3 6/7] gdb/dwarf: add more context to complaints in mapped_debug_names_reader::scan_one_entry

[Simon Marchi <simon.marchi@efficios.com>]

From: Simon Marchi <simon.marchi@polymtl.ca>

I realize that complaints are not often enabled and shown, but if we
emit them, I think they should include enough context to help a user who
wishes to dig in the problem to pinpoint where the problem happened
exactly.  For this reason, change the complaints in
mapped_debug_names_reader::scan_one_entry to include precisions
regarding which index entry is problematic exactly.

I am not attached to the particular format.  I thought that because this
is extra contextual information, I would put it in the square brackets
at the end (which only shows the module name currently).  However, it
would be nice to converge towards a format that we could replicate
elsewhere in the DWARF reader, so feel free to chime in.

I factored out the formatting to a separate function, because I will be
adding more of these in a subsequent patch, and it's easier to have the
formatting centralized.

I have not touched the "Unsupported .debug_names form" warning.  If that
comes up, we probably don't care about the specific index entry, we just
need to implement support for that form.

Change-Id: Id68a0ae406a3ca620408576b81f893f05c7e3df2
Approved-By: Tom Tromey <tom@tromey.com>
---
 gdb/dwarf2/read-debug-names.c | 43 ++++++++++++++++++++++++++---------
 1 file changed, 32 insertions(+), 11 deletions(-)

diff --git a/gdb/dwarf2/read-debug-names.c b/gdb/dwarf2/read-debug-names.c
index 6ac65d101b16..487e2ea87edb 100644
--- a/gdb/dwarf2/read-debug-names.c
+++ b/gdb/dwarf2/read-debug-names.c
@@ -155,6 +155,25 @@ struct mapped_debug_names_reader
   std::vector<std::vector<cooked_index_entry *>> all_entries;
 };
 
+/* Emit a complaint about a specific index entry.  */
+
+static void ATTRIBUTE_PRINTF (4, 5)
+complain_about_index_entry (bfd *abfd, const char *name,
+			    ptrdiff_t offset_in_entry_pool, const char *fmt,
+			    ...)
+{
+  va_list ap;
+  va_start (ap, fmt);
+  std::string msg = string_vprintf (fmt, ap);
+  va_end (ap);
+
+  msg += string_printf (_(" [in module %s, index entry for name %s,"
+			   " entry pool offset 0x%tx]"),
+			bfd_get_filename (abfd), name, offset_in_entry_pool);
+
+  complaint ("%s", msg.c_str ());
+}
+
 /* Scan a single entry from the entries table.  Set *RESULT and PARENT
    (if needed) and return the updated pointer on success, or return
    nullptr on error, or at the end of the table.  */
@@ -180,9 +199,11 @@ mapped_debug_names_reader::scan_one_entry (const char *name,
   const auto indexval_it = abbrev_map.find (abbrev);
   if (indexval_it == abbrev_map.cend ())
     {
-      complaint (_("Wrong .debug_names undefined abbrev code %s "
-		   "[in module %s]"),
-		 pulongest (abbrev), bfd_get_filename (abfd));
+      complain_about_index_entry (abfd, name, offset_in_entry_pool,
+				  _("Wrong .debug_names abbrev code %s"),
+				  pulongest (abbrev));
+      /* We can't go past this entry because we don't know its size, stop
+	 reading this entry chain.  */
       return nullptr;
     }
 
@@ -264,10 +285,10 @@ mapped_debug_names_reader::scan_one_entry (const char *name,
 	    /* Don't crash on bad data.  */
 	    if (ull >= this->comp_units.size ())
 	      {
-		complaint (_(".debug_names entry has bad CU index %s"
-			     " [in module %s]"),
-			   pulongest (ull),
-			   bfd_get_filename (abfd));
+		complain_about_index_entry
+		  (abfd, name, offset_in_entry_pool,
+		   _(".debug_names entry has bad CU index %s"),
+		   pulongest (ull));
 		continue;
 	      }
 
@@ -279,10 +300,10 @@ mapped_debug_names_reader::scan_one_entry (const char *name,
 	    /* Don't crash on bad data.  */
 	    if (ull >= this->type_units.size ())
 	      {
-		complaint (_(".debug_names entry has bad TU index %s"
-			     " [in module %s]"),
-			   pulongest (ull),
-			   bfd_get_filename (abfd));
+		complain_about_index_entry
+		  (abfd, name, offset_in_entry_pool,
+		   _(".debug_names entry has bad TU index %s"),
+		   pulongest (ull));
 		continue;
 	      }
 
-- 
2.54.0