kconfig: warn of unhandled characters in Kconfig commands

In Kconfig, definitions of options take the following form:
"<COMMAND> <PARAM> <PARAM> ...". COMMANDs and PARAMs are treated
slightly different by the underlying parser.

While commit 2e0d737fc76f ("kconfig: don't silently ignore unhandled
characters") introduced a warning for unsupported characters around
PARAMs, it does not cover situations where a COMMAND has additional
characters before it.

This change makes Kconfig emit a warning if superfluous characters
are found before COMMANDs. As the 'help' statement sometimes is
written as '---help---', the '-' character would now also be regarded
as unhandled and generate a warning. To avoid that, '-' is added to
the list of allowed characters, and the token '---help---' is included
in the zconf.gperf file.

Reported-by: Valentin Rothberg <valentinrothberg@gmail.com>
Signed-off-by: Andreas Ruprecht <andreas.ruprecht@fau.de>
Reviewed-by: Ulf Magnusson <ulfalizer@gmail.com>
Tested-by: Ulf Magnusson <ulfalizer@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.com>

scripts/kconfig/zconf.gperf

@@ -22,6 +22,7 @@ comment,	T_COMMENT,	TF_COMMAND
 config,		T_CONFIG,	TF_COMMAND
 menuconfig,	T_MENUCONFIG,	TF_COMMAND
 help,		T_HELP,		TF_COMMAND
+---help---,	T_HELP,		TF_COMMAND
 if,		T_IF,		TF_COMMAND|TF_PARAM
 endif,		T_ENDIF,	TF_COMMAND
 depends,	T_DEPENDS,	TF_COMMAND

scripts/kconfig/zconf.l

@@ -66,9 +66,16 @@ static void alloc_string(const char *str, int size)
 	memcpy(text, str, size);
 	text[size] = 0;
 }
+
+static void warn_ignored_character(char chr)
+{
+	fprintf(stderr,
+	        "%s:%d:warning: ignoring unsupported character '%c'\n",
+	        zconf_curname(), zconf_lineno(), chr);
+}
 %}
 
-n	[A-Za-z0-9_]
+n	[A-Za-z0-9_-]
 
 %%
 	int str = 0;
@@ -106,7 +113,7 @@ n	[A-Za-z0-9_]
 		zconflval.string = text;
 		return T_WORD;
 	}
-	.
+	.	warn_ignored_character(*yytext);
 	\n	{
 		BEGIN(INITIAL);
 		current_file->lineno++;
@@ -132,8 +139,7 @@ n	[A-Za-z0-9_]
 		BEGIN(STRING);
 	}
 	\n	BEGIN(INITIAL); current_file->lineno++; return T_EOL;
-	---	/* ignore */
-	({n}|[-/.])+	{
+	({n}|[/.])+	{
 		const struct kconf_id *id = kconf_id_lookup(yytext, yyleng);
 		if (id && id->flags & TF_PARAM) {
 			zconflval.id = id;
@@ -146,11 +152,7 @@ n	[A-Za-z0-9_]
 	#.*	/* comment */
 	\\\n	current_file->lineno++;
 	[[:blank:]]+
-	.	{
-		fprintf(stderr,
-		        "%s:%d:warning: ignoring unsupported character '%c'\n",
-		        zconf_curname(), zconf_lineno(), *yytext);
-	}
+	.	warn_ignored_character(*yytext);
 	<<EOF>> {
 		BEGIN(INITIAL);
 	}