Re: [PATCH] rust/25535 Apply embedded offset to enum variant calculation

["Doug Evans via gdb-patches" <gdb-patches at sourceware dot org>]

Nit: Yeah, I forgot to edit out the ChangeLog diffs.

On Tue, Feb 11, 2020 at 5:01 PM Doug Evans <dje@google.com> wrote:
>
> Hopefully straightforward (and I didn't miss anything ...).
>
> gdb/ChangeLog
>         PR rust/25535
>         * rust-lang.c (rust_print_enum): Apply embedded_offset to
>         rust_enum_variant calculation.
>
> gdb/testsuite/ChangeLog
>         PR rust/25535
>         * gdb.rust/simple.exp: Add test.
>         * gdb.rust/simple.rs: Add test.
>
> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
> index 91d7cec98af..1d8af99d8d6 100644
> --- a/gdb/ChangeLog
> +++ b/gdb/ChangeLog
> @@ -1,3 +1,9 @@
> +2020-02-11  Doug Evans  <dje@google.com>
> +
> +       PR rust/25535
> +       * rust-lang.c (rust_print_enum): Apply embedded_offset to
> +       rust_enum_variant calculation.
> +
>  2020-02-11  Christian Biesinger  <cbiesinger@google.com>
>
>         * cris-tdep.c (cris_supply_gregset): Change signature to match
> diff --git a/gdb/rust-lang.c b/gdb/rust-lang.c
> index 9123bf2146d..18dc6a56471 100644
> --- a/gdb/rust-lang.c
> +++ b/gdb/rust-lang.c
> @@ -481,7 +481,8 @@ rust_print_enum (struct type *type, int embedded_offset,
>      }
>
>    const gdb_byte *valaddr = value_contents_for_printing (val);
> -  struct field *variant_field = rust_enum_variant (type, valaddr);
> +  struct field *variant_field = rust_enum_variant (type,
> +                                                  valaddr + embedded_offset);
>    embedded_offset += FIELD_BITPOS (*variant_field) / 8;
>    struct type *variant_type = FIELD_TYPE (*variant_field);
>
> diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
> index 06826746d5f..a613c1e6565 100644
> --- a/gdb/testsuite/ChangeLog
> +++ b/gdb/testsuite/ChangeLog
> @@ -1,3 +1,9 @@
> +2020-02-11  Doug Evans  <dje@google.com>
> +
> +       PR rust/25535
> +       * gdb.rust/simple.exp: Add test.
> +       * gdb.rust/simple.rs: Add test.
> +
>  2020-02-11  Sergio Durigan Junior  <sergiodj@redhat.com>
>
>         PR tui/25126
> diff --git a/gdb/testsuite/gdb.rust/simple.exp b/gdb/testsuite/gdb.rust/simple.exp
> index aa64e6b08f1..b4fcf274261 100644
> --- a/gdb/testsuite/gdb.rust/simple.exp
> +++ b/gdb/testsuite/gdb.rust/simple.exp
> @@ -357,6 +357,8 @@ gdb_test_sequence "ptype/o SimpleLayout" "" {
>
>  gdb_test "print u2" " = simple::Union2 {name: \\\[1\\\]}"
>
> +gdb_test "print nonzero_offset" " = simple::EnumWithNonzeroOffset {a: core::option::Option<u8>::Some\\(1\\), b: core::option::Option<u8>::None}"
> +
>  # PR rust/23626 - this used to crash.  Note that the results are
>  # fairly lax because most existing versions of Rust (those before the
>  # DW_TAG_variant patches) do not emit what gdb wants here; and there
> diff --git a/gdb/testsuite/gdb.rust/simple.rs b/gdb/testsuite/gdb.rust/simple.rs
> index 1280e04449b..36448ec45c6 100644
> --- a/gdb/testsuite/gdb.rust/simple.rs
> +++ b/gdb/testsuite/gdb.rust/simple.rs
> @@ -104,6 +104,12 @@ struct SimpleLayout {
>
>  enum EmptyEnum {}
>
> +#[derive(Debug)]
> +struct EnumWithNonzeroOffset {
> +    a: Option<u8>,
> +    b: Option<u8>,
> +}
> +
>  fn main () {
>      let a = ();
>      let b : [i32; 0] = [];
> @@ -186,6 +192,8 @@ fn main () {
>
>      let u2 = Union2 { name: [1] };
>
> +    let nonzero_offset = EnumWithNonzeroOffset { a: Some(1), b: None };
> +
>      println!("{}, {}", x.0, x.1);        // set breakpoint here
>      println!("{}", diff2(92, 45));
>      empty();