kconfig: remove grammatically ambiguous "unexpected option" diagnostic

This commit decreases 15 shift/reduce conflicts.

The location of this error recovery is ambiguous.

For example, there are two ways to interpret the following code:

  1 config FOO
  2         bool "foo"

 [A] Both lines are reduced together into a config_stmt.

 [B] The only line 1 is reduced into a config_stmt, and the line 2
     matches to "option_name error T_EOL"

Of course, we expect [A], but [B] could be grammatically possible.

Kconfig has no terminator for a config block. So, we cannot detect its
end until we see a non-property keyword. People often insert a blank
line between two config blocks, but it is just a coding convention.
Blank lines are actually allowed anywhere in Kconfig files.

The real error is when a property keyword appears right after "endif",
"endchoice", "endmenu",  "source", "comment", or variable assignment.

Instead of fixing the grammatical ambiguity, I chose to simply remove
this error recovery.

The difference is

  unexpected option "bool"

... is turned into a more generic message:

  invalid statement

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
This commit is contained in:
Masahiro Yamada 2018-12-11 20:00:52 +09:00
parent 723679339d
commit 6900ae9eee
1 changed files with 1 additions and 10 deletions

View File

@ -31,7 +31,7 @@ struct symbol *symbol_hash[SYMBOL_HASHSIZE];
static struct menu *current_menu, *current_entry;
%}
%expect 21
%expect 6
%union
{
@ -94,7 +94,6 @@ static struct menu *current_menu, *current_entry;
%type <expr> expr
%type <expr> if_expr
%type <id> end
%type <id> option_name
%type <menu> if_entry menu_entry choice_entry
%type <string> symbol_option_arg word_opt assign_val
@ -127,17 +126,9 @@ stmt_list:
| stmt_list menu_stmt
| stmt_list end { zconf_error("unexpected end statement"); }
| stmt_list T_WORD error T_EOL { zconf_error("unknown statement \"%s\"", $2); }
| stmt_list option_name error T_EOL
{
zconf_error("unexpected option \"%s\"", $2->name);
}
| stmt_list error T_EOL { zconf_error("invalid statement"); }
;
option_name:
T_DEPENDS | T_PROMPT | T_TYPE | T_SELECT | T_IMPLY | T_OPTIONAL | T_RANGE | T_DEFAULT | T_VISIBLE
;
common_stmt:
if_stmt
| comment_stmt