Re: [FYI] Handle TYPE_CODE_PTR when printing Rust types

[Sergio Durigan Junior <sergiodj@redhat.com>]

On Friday, November 16 2018, Tom Tromey wrote:

> This changes the Rust type printers to handle TYPE_CODE_PTR.  The
> current approach is not ideal, because currently the code can't
> distinguish between mut and const, or between pointers and references.
> (These are debuginfo deficiencies, for which there are rustc bugs on
> file.)
>
> Meanwhile, this at least clears up the case seen in PR rust/23625.
>
> Tested on x86-64 Fedora 28 using the current Rust stable compiler.
>
> gdb/ChangeLog
> 2018-11-16  Tom Tromey  <tom@tromey.com>
>
> 	PR rust/23625:
> 	* rust-lang.c (rust_internal_print_type): Handle TYPE_CODE_PTR.
>
> gdb/testsuite/ChangeLog
> 2018-11-16  Tom Tromey  <tom@tromey.com>
>
> 	PR rust/23625:
> 	* gdb.rust/simple.exp: Add ptype test.
> ---
>  gdb/ChangeLog                     |  5 +++++
>  gdb/rust-lang.c                   | 14 ++++++++++++++
>  gdb/testsuite/ChangeLog           |  5 +++++
>  gdb/testsuite/gdb.rust/simple.exp |  1 +
>  4 files changed, 25 insertions(+)
>
> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
> index 4995d551979..ed5123d6b22 100644
> --- a/gdb/ChangeLog
> +++ b/gdb/ChangeLog
> @@ -1,3 +1,8 @@
> +2018-11-16  Tom Tromey  <tom@tromey.com>
> +
> +	PR rust/23625:
> +	* rust-lang.c (rust_internal_print_type): Handle TYPE_CODE_PTR.
> +
>  2018-11-16  Alan Hayward  <alan.hayward@arm.com>
>  
>  	PR gdb/22736:
> diff --git a/gdb/rust-lang.c b/gdb/rust-lang.c
> index 152413a612f..12a9c0b4895 100644
> --- a/gdb/rust-lang.c
> +++ b/gdb/rust-lang.c
> @@ -918,6 +918,20 @@ rust_internal_print_type (struct type *type, const char *varstring,
>        }
>        break;
>  
> +    case TYPE_CODE_PTR:
> +      {
> +	if (TYPE_NAME (type) != nullptr)
> +	  fputs_filtered (TYPE_NAME (type), stream);
> +	else
> +	  {
> +	    /* We currently can distinguish between pointers and
> +	       references.  */

I understand you'll send a new version of the patch soon, but this
caught my attention.  I think you meant to say "... can't
distinguish...", right?  At least that's what I understand from the code
below.

Thanks.

> +	    fputs_filtered ("*mut ", stream);
> +	    type_print (TYPE_TARGET_TYPE (type), "", stream, 0);
> +	  }
> +      }
> +      break;
> +
>      default:
>      c_printer:
>        c_print_type (type, varstring, stream, show, level, flags);
> diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
> index c0de6f2d6cd..4aa9bceb545 100644
> --- a/gdb/testsuite/ChangeLog
> +++ b/gdb/testsuite/ChangeLog
> @@ -1,3 +1,8 @@
> +2018-11-16  Tom Tromey  <tom@tromey.com>
> +
> +	PR rust/23625:
> +	* gdb.rust/simple.exp: Add ptype test.
> +
>  2018-11-16  Alan Hayward  <alan.hayward@arm.com>
>  
>  	PR gdb/22736:
> diff --git a/gdb/testsuite/gdb.rust/simple.exp b/gdb/testsuite/gdb.rust/simple.exp
> index 956a6ca6fee..e26435abb29 100644
> --- a/gdb/testsuite/gdb.rust/simple.exp
> +++ b/gdb/testsuite/gdb.rust/simple.exp
> @@ -54,6 +54,7 @@ gdb_test "print *&c" " = 0"
>  gdb_test "print *(&c as &i32)" " = 0"
>  gdb_test "print *(&c as *const i32)" " = 0"
>  gdb_test "print *(&c as *mut i32)" " = 0"
> +gdb_test "ptype &c as *mut i32" "\\*mut i32"
>  
>  gdb_test "print/c f\[0\]" " = 104 'h'"
>  
> -- 
> 2.17.2

-- 
Sergio
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