Re: [FYI] Handle TYPE_CODE_PTR when printing Rust types

Sergio Durigan Junior
2018-11-16T23:21:28Z

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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