Commit 6900ae9e authored Dec 11, 2018 by Masahiro Yamada

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>

parent 72367933

scripts/kconfig/zconf.y

+1 −10

Original line number	Diff line number	Diff line
		@@ -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

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