[v2] abidw: add --ignore-enumerator-names flag

  Bug 28319 - abidw - regression in treatment of anonymous enums in structs

This commit reinstates the abidw behaviour of comparing enumerator
names during duplicate enum type resolution which was lost by default
as of commit 1cfbff1b3037d1049bdff7e86de27c3a86af23b3.

That commit addressed an issue with a certain library that contained
duplicate enum type definitions with variations in the enumerator
names but with the same enumerator values.

Many projects will be able to avoid this issue by always compiling
from fresh and consistent sources.  This commit avoids the risk of
conflating unrelated anonymous enum types.

The previous behaviour can be requested with --ignore-enumerator-names
and this flag is now used for that specific library test case.

Note that code that uses libabigail library facilities directly will
still continue to ignore enumerator names by default. This means that
all other tests are also unaffected by this code change.

	* doc/manuals/abidw.rst: Document --ignore-enumerator-names.
	* include/abg-dwarf-reader.h (get_ignore_enumerator_names):
	New function.
	(set_ignore_enumerator_names): Likewise.
	* src/abg-dwarf-reader.cc (read_context): Fix documentation
	typos. Add ignore_enumerator_names_ member variable.
	(read_context::initialize): Set ignore_enumerator_names_ to
	false.
	(read_context::ignore_enumerator_names): New getter and
	setter methods.
	(compare_before_canonicalisation): Set environment flag
	use_enum_binary_only_equality according to the value of
	ignore_enumerator_names_.
	(get_ignore_enumerator_names): New function.
	(set_ignore_enumerator_names): Likewise.
	* src/abg-ir-priv.h (environment::priv::priv): Add comment to
	default use_enum_binary_only_equality value.
	* tests/test-alt-dwarf-file.cc: Add --ignore-enumerator-names
	to rhbz1951526 test.
	* tools/abidw.cc (options): Add ignore_enumerator_names_
	option, defaulted to false.
	(parse_command_line): Parse --ignore-enumerator-names flag.
	(load_corpus_and_write_abixml): Set ignore_enumerator_names
	flag in DWARF reader context.

Reviewed-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Giuliano Procida <gprocida@google.com>
---

This is really just for-the-record. This is the commit we are going to
land in AOSP. I've kept the impact on tests minimal to ease rebase,
revert etc.

If you cannot find a better way forward on Bug 28319, then perhaps
take this commit, flip the default in src/abg-ir-priv.h and refresh
the few tests affected?

That still leaves whoever cares about oddly-compiled libraries having
to pass a flag manually though. Could something be done with abidiff
suppressions instead?

Regards,
Giuliano.

 doc/manuals/abidw.rst        | 12 +++++++++
 include/abg-dwarf-reader.h   |  7 ++++++
 src/abg-dwarf-reader.cc      | 47 ++++++++++++++++++++++++++++++++++--
 src/abg-ir-priv.h            |  2 +-
 tests/test-alt-dwarf-file.cc |  2 +-
 tools/abidw.cc               |  7 ++++++
 6 files changed, 73 insertions(+), 4 deletions(-)
  

This doesn't actually fix the problem - the environment default
matters. I will follow up on Bug 28319.

Giuliano.

On Wed, 12 Jan 2022 at 10:40, Giuliano Procida <gprocida@google.com> wrote:
>
> Bug 28319 - abidw - regression in treatment of anonymous enums in structs
>
> This commit reinstates the abidw behaviour of comparing enumerator
> names during duplicate enum type resolution which was lost by default
> as of commit 1cfbff1b3037d1049bdff7e86de27c3a86af23b3.
>
> That commit addressed an issue with a certain library that contained
> duplicate enum type definitions with variations in the enumerator
> names but with the same enumerator values.
>
> Many projects will be able to avoid this issue by always compiling
> from fresh and consistent sources.  This commit avoids the risk of
> conflating unrelated anonymous enum types.
>
> The previous behaviour can be requested with --ignore-enumerator-names
> and this flag is now used for that specific library test case.
>
> Note that code that uses libabigail library facilities directly will
> still continue to ignore enumerator names by default. This means that
> all other tests are also unaffected by this code change.
>
>         * doc/manuals/abidw.rst: Document --ignore-enumerator-names.
>         * include/abg-dwarf-reader.h (get_ignore_enumerator_names):
>         New function.
>         (set_ignore_enumerator_names): Likewise.
>         * src/abg-dwarf-reader.cc (read_context): Fix documentation
>         typos. Add ignore_enumerator_names_ member variable.
>         (read_context::initialize): Set ignore_enumerator_names_ to
>         false.
>         (read_context::ignore_enumerator_names): New getter and
>         setter methods.
>         (compare_before_canonicalisation): Set environment flag
>         use_enum_binary_only_equality according to the value of
>         ignore_enumerator_names_.
>         (get_ignore_enumerator_names): New function.
>         (set_ignore_enumerator_names): Likewise.
>         * src/abg-ir-priv.h (environment::priv::priv): Add comment to
>         default use_enum_binary_only_equality value.
>         * tests/test-alt-dwarf-file.cc: Add --ignore-enumerator-names
>         to rhbz1951526 test.
>         * tools/abidw.cc (options): Add ignore_enumerator_names_
>         option, defaulted to false.
>         (parse_command_line): Parse --ignore-enumerator-names flag.
>         (load_corpus_and_write_abixml): Set ignore_enumerator_names
>         flag in DWARF reader context.
>
> Reviewed-by: Matthias Maennich <maennich@google.com>
> Signed-off-by: Giuliano Procida <gprocida@google.com>
> ---
>
> This is really just for-the-record. This is the commit we are going to
> land in AOSP. I've kept the impact on tests minimal to ease rebase,
> revert etc.
>
> If you cannot find a better way forward on Bug 28319, then perhaps
> take this commit, flip the default in src/abg-ir-priv.h and refresh
> the few tests affected?
>
> That still leaves whoever cares about oddly-compiled libraries having
> to pass a flag manually though. Could something be done with abidiff
> suppressions instead?
>
> Regards,
> Giuliano.
>
>  doc/manuals/abidw.rst        | 12 +++++++++
>  include/abg-dwarf-reader.h   |  7 ++++++
>  src/abg-dwarf-reader.cc      | 47 ++++++++++++++++++++++++++++++++++--
>  src/abg-ir-priv.h            |  2 +-
>  tests/test-alt-dwarf-file.cc |  2 +-
>  tools/abidw.cc               |  7 ++++++
>  6 files changed, 73 insertions(+), 4 deletions(-)
>
> diff --git a/doc/manuals/abidw.rst b/doc/manuals/abidw.rst
> index bdd6204d..53a0a18f 100644
> --- a/doc/manuals/abidw.rst
> +++ b/doc/manuals/abidw.rst
> @@ -182,6 +182,18 @@ Options
>      ELF binary.  It thus considers functions and variables which are
>      defined and exported in the ELF sense.
>
> +  * ``--ignore-enumerator-names``
> +
> +    During resolution of duplicate enum types, abidw can consider both
> +    enumerator names and values, or just enumerator values.
> +
> +    The default is to consider enums, including anonymous enums, to be
> +    distinct if there any differences in their enumerators' names or
> +    values.
> +
> +    This option causes abidw to only check for differences between
> +    sets of enumerator values.
> +
>    * ``--check-alternate-debug-info`` <*elf-path*>
>
>      If the debug info for the file *elf-path* contains a reference to
> diff --git a/include/abg-dwarf-reader.h b/include/abg-dwarf-reader.h
> index 4c2de779..1ecc7ac4 100644
> --- a/include/abg-dwarf-reader.h
> +++ b/include/abg-dwarf-reader.h
> @@ -142,6 +142,13 @@ void
>  set_drop_undefined_syms(read_context& ctxt,
>                         bool f);
>
> +bool
> +get_ignore_enumerator_names(read_context& ctxt);
> +
> +void
> +set_ignore_enumerator_names(read_context& ctxt,
> +                           bool f);
> +
>  void
>  set_do_log(read_context& ctxt, bool f);
>
> diff --git a/src/abg-dwarf-reader.cc b/src/abg-dwarf-reader.cc
> index 3f716944..f34bc3ee 100644
> --- a/src/abg-dwarf-reader.cc
> +++ b/src/abg-dwarf-reader.cc
> @@ -1897,7 +1897,7 @@ struct dwarf_expr_eval_context
>  /// get some important data from it.
>  ///
>  /// When a new data member is added to this context, it must be
> -/// initiliazed by the read_context::initiliaze() function.  So please
> +/// initialized by the read_context::initialize() function.  So please
>  /// do not forget.
>  class read_context
>  {
> @@ -2116,6 +2116,7 @@ public:
>    corpus::exported_decls_builder* exported_decls_builder_;
>    options_type                 options_;
>    bool                         drop_undefined_syms_;
> +  bool                         ignore_enumerator_names_;
>    read_context();
>
>  private:
> @@ -2259,6 +2260,7 @@ public:
>      options_.load_in_linux_kernel_mode = linux_kernel_mode;
>      options_.load_all_types = load_all_types;
>      drop_undefined_syms_ = false;
> +    ignore_enumerator_names_ = false;
>      load_in_linux_kernel_mode(linux_kernel_mode);
>    }
>
> @@ -2346,6 +2348,23 @@ public:
>    drop_undefined_syms(bool f)
>    {drop_undefined_syms_ = f;}
>
> +  /// Getter for the flag that tells if we should ignore enumerator
> +  /// names during duplicate enum type resolution.
> +  ///
> +  /// @return true iff we should ignore enumerator names during
> +  /// duplicate enum type resolution.
> +  bool
> +  ignore_enumerator_names() const
> +  {return ignore_enumerator_names_;}
> +
> +  /// Setter for the flag that tells if we should ignore enumerator
> +  /// names during duplicate enum type resolution.
> +  ///
> +  /// @param f the new value of the flag.
> +  void
> +  ignore_enumerator_names(bool f)
> +  {ignore_enumerator_names_ = f;}
> +
>    /// Getter of the suppression specifications to be used during
>    /// ELF/DWARF parsing.
>    ///
> @@ -4151,7 +4170,7 @@ public:
>      bool s0 = e->decl_only_class_equals_definition();
>      bool s1 = e->use_enum_binary_only_equality();
>      e->decl_only_class_equals_definition(true);
> -    e->use_enum_binary_only_equality(true);
> +    e->use_enum_binary_only_equality(ignore_enumerator_names_);
>      bool equal = l == r;
>      e->decl_only_class_equals_definition(s0);
>      e->use_enum_binary_only_equality(s1);
> @@ -6221,6 +6240,30 @@ void
>  set_drop_undefined_syms(read_context& ctxt, bool f)
>  {ctxt.drop_undefined_syms(f);}
>
> +/// Getter of the "ignore_enumerator_names" flag.
> +///
> +/// This flag tells if we should ignore enumerator names during
> +/// duplicate enum type resolution.
> +///
> +/// @param ctx the read context to consider for this flag.
> +///
> +/// @return the value of the flag.
> +bool
> +get_ignore_enumerator_names(read_context& ctxt)
> +{return ctxt.ignore_enumerator_names();}
> +
> +/// Setter of the "ignore_enumerator_names" flag.
> +///
> +/// This flag tells if we should ignore enumerator names during
> +/// duplicate enum type resolution.
> +///
> +/// @param ctxt the read context to consider for this flag.
> +///
> +/// @param f the value of the flag.
> +void
> +set_ignore_enumerator_names(read_context& ctxt, bool f)
> +{ctxt.ignore_enumerator_names(f);}
> +
>  /// Setter of the "do_log" flag.
>  ///
>  /// This flag tells if we should emit verbose logs for various
> diff --git a/src/abg-ir-priv.h b/src/abg-ir-priv.h
> index a01a1b2c..79b5e2dd 100644
> --- a/src/abg-ir-priv.h
> +++ b/src/abg-ir-priv.h
> @@ -409,7 +409,7 @@ struct environment::priv
>      : canonicalization_is_done_(),
>        do_on_the_fly_canonicalization_(true),
>        decl_only_class_equals_definition_(false),
> -      use_enum_binary_only_equality_(true)
> +      use_enum_binary_only_equality_(true)  // NOTE: != abidw default
>  #ifdef WITH_DEBUG_SELF_COMPARISON
>      ,
>        self_comparison_debug_on_(false)
> diff --git a/tests/test-alt-dwarf-file.cc b/tests/test-alt-dwarf-file.cc
> index 315296ab..13ccb961 100644
> --- a/tests/test-alt-dwarf-file.cc
> +++ b/tests/test-alt-dwarf-file.cc
> @@ -56,7 +56,7 @@ InOutSpec in_out_specs[] =
>    {
>      "data/test-alt-dwarf-file/rhbz1951526/usr/bin/gimp-2.10",
>      "data/test-alt-dwarf-file/rhbz1951526/usr/lib/debug",
> -    "--abidiff",
> +    "--abidiff --ignore-enumerator-names",
>      "data/test-alt-dwarf-file/rhbz1951526/rhbz1951526-report-0.txt",
>      "output/test-alt-dwarf-file/rhbz1951526/rhbz1951526-report-0.txt"
>    },
> diff --git a/tools/abidw.cc b/tools/abidw.cc
> index f7a8937d..ea2a4ad5 100644
> --- a/tools/abidw.cc
> +++ b/tools/abidw.cc
> @@ -95,6 +95,7 @@ struct options
>    bool                 default_sizes;
>    bool                 load_all_types;
>    bool                 linux_kernel_mode;
> +  bool                 ignore_enumerator_names;
>    bool                 corpus_group_for_linux;
>    bool                 show_stats;
>    bool                 noout;
> @@ -132,6 +133,7 @@ struct options
>        default_sizes(true),
>        load_all_types(),
>        linux_kernel_mode(true),
> +      ignore_enumerator_names(false),
>        corpus_group_for_linux(false),
>        show_stats(),
>        noout(),
> @@ -206,6 +208,8 @@ display_usage(const string& prog_name, ostream& out)
>      "vmlinux and its modules\n"
>      << "  --vmlinux <path>  the path to the vmlinux binary to consider to emit "
>         "the ABI of the union of vmlinux and its modules\n"
> +    << "  --ignore-enumerator-names  only consider enumerator value sets when "
> +       "deciding whether identically-named or anonymous enums are the same\n"
>      << "  --abidiff  compare the loaded ABI against itself\n"
>  #ifdef WITH_DEBUG_SELF_COMPARISON
>      << "  --debug-abidiff  debug the process of comparing the loaded ABI against itself\n"
> @@ -367,6 +371,8 @@ parse_command_line(int argc, char* argv[], options& opts)
>         opts.drop_undefined_syms = true;
>        else if (!strcmp(argv[i], "--no-linux-kernel-mode"))
>         opts.linux_kernel_mode = false;
> +      else if (!strcmp(argv[i], "--ignore-enumerator-names"))
> +       opts.ignore_enumerator_names = true;
>        else if (!strcmp(argv[i], "--abidiff"))
>         opts.abidiff = true;
>  #ifdef WITH_DEBUG_SELF_COMPARISON
> @@ -562,6 +568,7 @@ load_corpus_and_write_abixml(char* argv[],
>                                                       opts.linux_kernel_mode);
>        dwarf_reader::read_context& ctxt = *c;
>        set_drop_undefined_syms(ctxt, opts.drop_undefined_syms);
> +      set_ignore_enumerator_names(ctxt, opts.ignore_enumerator_names);
>        set_show_stats(ctxt, opts.show_stats);
>        set_suppressions(ctxt, opts);
>        abigail::dwarf_reader::set_do_log(ctxt, opts.do_log);
> --
> 2.34.1.575.g55b058a8bb-goog
>