gdb/dwarf: pass a file_entry to line_header::file_file_name

In the following patch, there will be some callers of file_file_name
that will already have access to the file_entry object for which they
want the file name.  It would be inefficient to have them pass an index,
only for line_header::file_file_name to re-lookup the same file_entry
object.  Change line_header::file_file_name to accept a file_entry
object reference, instead of an index to look up.

I think this change makes sense in any case.  Callers that have an index
can first obtain a file_entry using line_header::file_name_at or
line_header::file_names.

When passing a file_entry object, we can assume that the file_entry's
index is valid, unlike when passing an index.  So, push the special case
about an invalid index to the sole current caller of file_file_name,
macro_start_file.  I think that error belongs there anyway, since it
specifically talks about "bad file number in macro information".

This requires recording the file index in the file_entry structure, so
add that.

Change-Id: Ic6e44c407539d92b7863d7ba82405ade17f384ad

1 files changed, 15 insertions, 1 deletions

diff --git a/gdb/dwarf2/macro.c b/gdb/dwarf2/macro.c
index 99c3653..38c0fdf 100644
--- a/gdb/dwarf2/macro.c
+++ b/gdb/dwarf2/macro.c
@@ -52,7 +52,21 @@ macro_start_file (buildsym_compunit *builder,
 		  const struct line_header *lh)
 {
   /* File name relative to the compilation directory of this source file.  */
-  std::string file_name = lh->file_file_name (file);
+  const file_entry *fe = lh->file_name_at (file);
+  std::string file_name;
+
+  if (fe != nullptr)
+    file_name = lh->file_file_name (*fe);
+  else
+    {
+      /* The compiler produced a bogus file number.  We can at least
+	 record the macro definitions made in the file, even if we
+	 won't be able to find the file by name.  */
+      complaint (_("bad file number in macro information (%d)"),
+		 file);
+
+      file_name = string_printf ("<bad macro file number %d>", file);
+    }
 
   if (! current_file)
     {