Re: [PATCH 6/6] gdb: extend .gdb_index tests to skip all data blocks

[Simon Marchi <simark@simark.ca>]

On 10/18/26 4:50 PM, Andrew Burgess wrote:
> diff --git a/gdb/dwarf2/read-gdb-index.c b/gdb/dwarf2/read-gdb-index.c
> index 5959b0ba6bc..d624ba1779c 100644
> --- a/gdb/dwarf2/read-gdb-index.c
> +++ b/gdb/dwarf2/read-gdb-index.c
> @@ -606,10 +606,12 @@ read_gdb_index_from_buffer (const char *filename,
>  
>    map->constant_pool = buffer.slice (metadata[i]);
>  
> -  if (map->constant_pool.empty () && !map->symbol_table.empty ())
> +  if ((map->constant_pool.empty () || *cu_list_elements == 0)
> +      && !map->symbol_table.empty ())

Is an index with no CUs necessarily invalid?  What if there are some
TUs, or some CUs in the dwz file?

It seems to me like we could let those go through, and if the index is
really invalid in some way, then one of the checks you added in the
previous patches will trigger and reject the index.

>      {
> -      /* An empty constant pool implies that all symbol table entries are
> -	 empty.  Make map->symbol_table.empty () == true.  */
> +      /* An empty constant pool or an empty CU list implies that all symbol
> +	 table entries are empty.  Recreate the symbol table as empty so
> +	 this index will be ignored.  */
>        map->symbol_table
>  	= offset_view (gdb::array_view<const gdb_byte> (symbol_table,
>  							symbol_table));

I wonder why this rejects the index by clearing symbol_table, instead of
just returning false.

Simon