Re: [PATCH 2/3] Matching tokens: C parts (v2)

[David Malcolm <dmalcolm at redhat dot com>]

On Thu, 2017-08-03 at 11:34 -0600, Jeff Law wrote:
> On 08/01/2017 02:21 PM, David Malcolm wrote:
> > Changed in v2:
> > 
> > * Renamed template argument to traits_t; eliminated subclasses,
> > just
> >   using traits struct.
> > * Moved enum constants into struct bodies (string constants can't
> > be
> >   without constexpr, which isn't available in C++98).
> > * Fixed typo.
> > 
> > OK for trunk?
> > 
> > gcc/c/ChangeLog:
> > 	* c-parser.c (c_parser_error): Rename to...
> > 	(c_parser_error_richloc): ...this, making static, and adding
> > 	"richloc" parameter, passing it to the c_parse_error call,
> > 	rather than calling c_parser_set_source_position_from_token.
> > 	(c_parser_error): Reintroduce, reimplementing in terms of the
> > 	above, converting return type from void to bool.
> > 	(class token_pair): New class.
> > 	(struct matching_paren_traits): New struct.
> > 	(matching_parens): New typedef.
> > 	(struct matching_brace_traits): New struct.
> > 	(matching_braces): New typedef.
> > 	(get_matching_symbol): New function.
> > 	(c_parser_require): Add param MATCHING_LOCATION, using it to
> > 	highlight matching "opening" tokens for missing "closing"
> > tokens.
> > 	(c_parser_skip_until_found): Likewise.
> > 	(c_parser_static_assert_declaration_no_semi): Convert explicit
> > 	parsing of CPP_OPEN_PAREN and CPP_CLOSE_PAREN to use of
> > 	class matching_parens, so that the pertinent open parenthesis
> > is
> > 	highlighted when there are problems locating the close
> > 	parenthesis.
> > 	(c_parser_struct_or_union_specifier): Likewise.
> > 	(c_parser_typeof_specifier): Likewise.
> > 	(c_parser_alignas_specifier): Likewise.
> > 	(c_parser_simple_asm_expr): Likewise.
> > 	(c_parser_braced_init): Likewise, for matching_braces.
> > 	(c_parser_paren_condition): Likewise, for matching_parens.
> > 	(c_parser_switch_statement): Likewise.
> > 	(c_parser_for_statement): Likewise.
> > 	(c_parser_asm_statement): Likewise.
> > 	(c_parser_asm_operands): Likewise.
> > 	(c_parser_cast_expression): Likewise.
> > 	(c_parser_sizeof_expression): Likewise.
> > 	(c_parser_alignof_expression): Likewise.
> > 	(c_parser_generic_selection): Likewise.
> > 	(c_parser_postfix_expression): Likewise for cases RID_VA_ARG,
> > 	RID_OFFSETOF, RID_TYPES_COMPATIBLE_P, RID_AT_SELECTOR,
> > 	RID_AT_PROTOCOL, RID_AT_ENCODE, reindenting as necessary.
> > 	In case CPP_OPEN_PAREN, pass loc_open_paren to the
> > 	c_parser_skip_until_found call.
> > 	(c_parser_objc_class_definition): Use class matching_parens as
> > 	above.
> > 	(c_parser_objc_method_decl): Likewise.
> > 	(c_parser_objc_try_catch_finally_statement): Likewise.
> > 	(c_parser_objc_synchronized_statement): Likewise.
> > 	(c_parser_objc_at_property_declaration): Likewise.
> > 	(c_parser_oacc_wait_list): Likewise.
> > 	(c_parser_omp_var_list_parens): Likewise.
> > 	(c_parser_omp_clause_collapse): Likewise.
> > 	(c_parser_omp_clause_default): Likewise.
> > 	(c_parser_omp_clause_if): Likewise.
> > 	(c_parser_omp_clause_num_threads): Likewise.
> > 	(c_parser_omp_clause_num_tasks): Likewise.
> > 	(c_parser_omp_clause_grainsize): Likewise.
> > 	(c_parser_omp_clause_priority): Likewise.
> > 	(c_parser_omp_clause_hint): Likewise.
> > 	(c_parser_omp_clause_defaultmap): Likewise.
> > 	(c_parser_oacc_single_int_clause): Likewise.
> > 	(c_parser_omp_clause_ordered): Likewise.
> > 	(c_parser_omp_clause_reduction): Likewise.
> > 	(c_parser_omp_clause_schedule): Likewise.
> > 	(c_parser_omp_clause_num_teams): Likewise.
> > 	(c_parser_omp_clause_thread_limit): Likewise.
> > 	(c_parser_omp_clause_aligned): Likewise.
> > 	(c_parser_omp_clause_linear): Likewise.
> > 	(c_parser_omp_clause_safelen): Likewise.
> > 	(c_parser_omp_clause_simdlen): Likewise.
> > 	(c_parser_omp_clause_depend): Likewise.
> > 	(c_parser_omp_clause_map): Likewise.
> > 	(c_parser_omp_clause_device): Likewise.
> > 	(c_parser_omp_clause_dist_schedule): Likewise.
> > 	(c_parser_omp_clause_proc_bind): Likewise.
> > 	(c_parser_omp_clause_uniform): Likewise.
> > 	(c_parser_omp_for_loop): Likewise.
> > 	(c_parser_cilk_clause_vectorlength): Likewise.
> > 	(c_parser_cilk_clause_linear): Likewise.
> > 	(c_parser_transaction_expression): Likewise.
> > 	* c-parser.h (c_parser_require): Add param matching_location
> > with
> > 	default UNKNOWN_LOCATION.
> > 	(c_parser_error): Convert return type from void to bool.
> > 	(c_parser_skip_until_found): Add param matching_location with
> > 	default UNKNOWN_LOCATION.
> > 
> > gcc/testsuite/ChangeLog:
> > 	* gcc.dg/unclosed-init.c: New test case.
> 
> Phew.  I only spot-checked most of the changes around the new API for
> requiring the open/close paren/brace/bracket or consuming
> parens/braces/brackets.  They were very mechanical :-)

Thanks for looking at this.  Do you have an opinion on Trevor's idea
the the "parser" argument should be moved into the token_pair class (to
avoid manually passing it in everywhere), or should it be kept outside
and passed in as needed? 

I was worried about increasing register pressure in the parsers, since
it's not clear to me that the optimizer can always prove that a field
"token_pair::m_parser" in a local token_pair is equal to the parser
local (see:
https://gcc.gnu.org/ml/gcc-patches/2017-08/msg00114.html )

Dave