Re: [PATCH 1/2][PR gdb/20239] Make evaluation and type-printing of all NonZero-optimized enums work

[Manish Goregaokar <manish at mozilla dot com>]

After further fixups, these patches have been pushed as
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=b5a4b3c5e711be9096423f9765623eda449d8f4d
and https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=fccb08f8cd2035b50a2b0a5e09983180b7411685

Thanks!
-Manish


On Tue, Jun 21, 2016 at 3:10 PM, Manish Goregaokar <manish@mozilla.com> wrote:
> Moved over from https://sourceware.org/bugzilla/show_bug.cgi?id=20239.
> Regarding the xstrdup, this is done because strsep edits the string
> itself.
>
> Built and tested on OS X El Capitan. Methods tests fail, but they are
> a preexisting failure due to Rust's debuginfo changing.
>
>
>
> gdb/ChangeLog:
> 2016-06-21  Manish Goregaokar  <manish@mozilla.com>
>
>     PR gdb/20239
>     * rust-lang.c (rust_get_disr_info): Correctly interpret
>     NonZero-optimized enums of arbitrary depth.
>     (rust_print_type): Correctly print NonZero-optimized
>     enums.
> ---
>  gdb/rust-lang.c | 72 +++++++++++++++++++++++++++++++++++++++++++--------------
>  1 file changed, 55 insertions(+), 17 deletions(-)
>
> diff --git a/gdb/rust-lang.c b/gdb/rust-lang.c
> index 5df99ce..baabf76 100644
> --- a/gdb/rust-lang.c
> +++ b/gdb/rust-lang.c
> @@ -120,42 +120,69 @@ rust_get_disr_info (struct type *type, const
> gdb_byte *valaddr,
>    if (strncmp (TYPE_FIELD_NAME (type, 0), RUST_ENUM_PREFIX,
>             strlen (RUST_ENUM_PREFIX)) == 0)
>      {
> -      char *tail;
> +      char *name, *tail, *token;
>        unsigned long fieldno;
>        struct type *member_type;
>        LONGEST value;
>
> +         char *type_name;
> +
>        ret.is_encoded = 1;
>
>        if (TYPE_NFIELDS (type) != 1)
>      error (_("Only expected one field in %s type"), RUST_ENUM_PREFIX);
>
> -      fieldno = strtoul (TYPE_FIELD_NAME (type, 0) + strlen (RUST_ENUM_PREFIX),
> -             &tail, 10);
> -      if (*tail != '$')
> +      /* Optimized enums have only one field */
> +      member_type = TYPE_FIELD_TYPE (type, 0);
> +
> +      name = xstrdup (TYPE_FIELD_NAME (type, 0));
> +      cleanup = make_cleanup (xfree, name);
> +      tail = name + strlen (RUST_ENUM_PREFIX);
> +
> +      /* The location of the value that doubles as a discriminant is
> +         stored in the name of the field, as
> +         RUST$ENCODED$ENUM$<fieldno>$<fieldno>$...$<variantname>
> +         where the fieldnos are the indices of the fields that should be
> +         traversed in order to find the field (which may be several
> fields deep)
> +         and the variantname is the name of the variant of the case when the
> +         field is zero */
> +      while ((token = strsep (&tail, "$")) != NULL)
> +      {
> +         if (sscanf (token, "%lu", &fieldno) != 1)
> +         {
> +            /* We have reached the enum name, which cannot start with
> a digit */
> +            break;
> +         }
> +        if (fieldno >= TYPE_NFIELDS (member_type))
> +    error (_("%s refers to field after end of member type"),
> +           RUST_ENUM_PREFIX);
> +
> +        embedded_offset += TYPE_FIELD_BITPOS (member_type, fieldno) / 8;
> +        member_type = TYPE_FIELD_TYPE (member_type, fieldno);
> +        type_name = TYPE_NAME (member_type);
> +      };
> +
> +      if (token >= name + strlen (TYPE_FIELD_NAME (type, 0)))
>      error (_("Invalid form for %s"), RUST_ENUM_PREFIX);
> +        value = unpack_long (member_type,
> +           valaddr + embedded_offset);
> +
>
> -      member_type = TYPE_FIELD_TYPE (type, 0);
> -      if (fieldno >= TYPE_NFIELDS (member_type))
> -    error (_("%s refers to field after end of member type"),
> -           RUST_ENUM_PREFIX);
>
> -      embedded_offset += TYPE_FIELD_BITPOS (member_type, fieldno) / 8;
> -      value = unpack_long (TYPE_FIELD_TYPE (member_type, fieldno),
> -               valaddr + embedded_offset);
>        if (value == 0)
>      {
>        ret.field_no = RUST_ENCODED_ENUM_HIDDEN;
> -      ret.name = concat (TYPE_NAME (type), "::", tail + 1, (char *) NULL);
> +      ret.name = concat (TYPE_NAME (type), "::", token, (char *) NULL);
>      }
>        else
>      {
>        ret.field_no = RUST_ENCODED_ENUM_REAL;
>        ret.name = concat (TYPE_NAME (type), "::",
> -                 rust_last_path_segment (TYPE_NAME (member_type)),
> +                 rust_last_path_segment (TYPE_NAME (TYPE_FIELD_TYPE
> (type, 0))),
>                   (char *) NULL);
>      }
>
> +      do_cleanups (cleanup);
>        return ret;
>      }
>
> @@ -841,6 +868,7 @@ rust_print_type (struct type *type, const char *varstring,
>        {
>      /* ADT enums */
>      int i, len = 0;
> +  int skip_to = 1; /* Skip the discriminant field */
>
>      fputs_filtered ("enum ", stream);
>      if (TYPE_TAG_NAME (type) != NULL)
> @@ -849,7 +877,17 @@ rust_print_type (struct type *type, const char *varstring,
>          fputs_filtered (" ", stream);
>          len = strlen (TYPE_TAG_NAME (type));
>        }
> -    fputs_filtered ("{\n", stream);
> +    fputs_filtered ("{\n", stream);
> +
> +  if (strncmp (TYPE_FIELD_NAME (type, 0), RUST_ENUM_PREFIX,
> +       strlen (RUST_ENUM_PREFIX)) == 0) {
> +    char *zero_field = strrchr (TYPE_FIELD_NAME (type, 0), '$');
> +    if (zero_field != NULL && strlen (zero_field) > 1) {
> +      fprintfi_filtered (level+2, stream, "%s,\n", zero_field+1);
> +      /* there is no explicit discriminant field, skip nothing */
> +      skip_to = 0;
> +    }
> +  }
>
>      for (i = 0; i < TYPE_NFIELDS (type); ++i)
>        {
> @@ -859,14 +897,14 @@ rust_print_type (struct type *type, const char *varstring,
>
>          fprintfi_filtered (level + 2, stream, "%s", name);
>
> -        if (TYPE_NFIELDS (variant_type) > 1)
> +        if (TYPE_NFIELDS (variant_type) > skip_to)
>            {
> -        int first = 1;
> +    int first = 1;
>          int is_tuple = rust_tuple_variant_type_p (variant_type);
>          int j;
>
>          fputs_filtered (is_tuple ? "(" : "{", stream);
> -        for (j = 1; j < TYPE_NFIELDS (variant_type); j++)
> +        for (j = skip_to; j < TYPE_NFIELDS (variant_type); j++)
>            {
>              if (first)
>                first = 0;
> --
> 2.8.3