shithub: scc

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Warn when a local symbol is defined but not used

--- a/cc1/cc1.h

+++ b/cc1/cc1.h

@@ -34,7 +34,7 @@

 	unsigned char ctx;

 	unsigned char ns;

 	unsigned char token;

-	char flags;

+	short flags;

 	union {

 		int i;

 		char *s;

@@ -111,14 +111,15 @@

 /* symbol flags */

 enum {

-	ISGLOBAL   =  1,

-	ISSTATIC   =  2,

-	ISAUTO     =  4,

-	ISREGISTER =  8,

-	ISDEFINED  = 16,

-	ISFIELD    = 32,

-	ISPARAM    = 64,

-	ISEXTERN   =128

+	ISGLOBAL   =       1,

+	ISSTATIC   =       2,

+	ISAUTO     =       4,

+	ISREGISTER =       8,

+	ISDEFINED  =      16,

+	ISFIELD    =      32,

+	ISPARAM    =      64,

+	ISEXTERN   =     128,

+	ISUSED     =     256

 };

--- a/cc1/expr.c

+++ b/cc1/expr.c

@@ -473,6 +473,7 @@

 			yylval.sym->flags |= ISDEFINED;

 			error("'%s' undeclared", yytext);

 		}

+		yylval.sym->flags |= ISUSED;

 		np = varnode(yylval.sym);

 		next();

 		break;

--- a/cc1/stmt.c

+++ b/cc1/stmt.c

@@ -201,6 +201,7 @@

 	next();

 	if (yytoken != IDEN)

 		unexpected();

+	yylval.sym->flags |= ISUSED;

 	emit(OJUMP, yylval.sym);

 	next();

 	expect(';');

--- a/cc1/symbol.c

+++ b/cc1/symbol.c

@@ -71,7 +71,6 @@

 				goto save_symbol;

 			if (sym->flags & ISDEFINED)

 				break;

-			/* TODO: check if the label was used */

 			printerr("label '%s' is not defined", sym->name);

 			break;

 		case NS_CPP:

@@ -87,8 +86,11 @@

 			sym->type->defined = 0;

 			break;

 		}

-		if (sym->name)

+		if (sym->name) {

 			htab[hash(sym->name)] = sym->hash;

+			if ((sym->flags & (ISUSED|ISGLOBAL)) == 0)

+				warn("'%s' defined but not used", sym->name);

+		}

 		free(sym->name);

 		free(sym);

 	}