[PATCH] Print type name when printing Rust slice

[Simon Marchi]

On 3/11/24 11:14, Tom Tromey wrote:
> The recent change to how unsized Rust values are printed included a
> small regression from past behavior.  Previously, a slice's type would
> be printed, like:
> 
>     (gdb) print slice
>     $80 = &[i32] [3]
> 
> The patch changed this to just
> 
>     (gdb) print slice
>     $80 = [3]
> 
> This patch restores the previous behavior.
> ---
>  gdb/rust-lang.c                    | 11 +++++++++++
>  gdb/testsuite/gdb.rust/simple.exp  |  2 +-
>  gdb/testsuite/gdb.rust/unsized.exp |  2 +-
>  3 files changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/gdb/rust-lang.c b/gdb/rust-lang.c
> index ab537cc9752..d7265f72770 100644
> --- a/gdb/rust-lang.c
> +++ b/gdb/rust-lang.c
> @@ -476,6 +476,17 @@ rust_language::val_print_slice
>  	}
>      }
>  
> +  /* Print the slice type here.  This was gdb's historical behavior
> +     (from before unsized types were generically handled) and helps
> +     make it clear that the user is seeing a slice, not an array.
> +     Only arrays must be handled as the other cases are handled by
> +     value_print_inner.  */
> +  if (type->code () == TYPE_CODE_ARRAY)
> +    {
> +      type_print (orig_type, "", stream, -1);
> +      gdb_printf (stream, " ");
> +    }

Just for me education, how are slices represented in the GDB type
system, as opposed to arrays?  What are the value types that
rust_language::val_print_slice expects to receive, other than
TYPE_CODE_ARRAY?

You can add my:

Reviewed-By: Simon Marchi <simon.marchi@efficios.com>

... although it's not worth much because I don't know this area.

Simon