shithub: scc

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Check against assigns to const variables

It is implementation defined what happens in that cases, and
I choose report an error.

--- a/expr.c

+++ b/expr.c

@@ -511,9 +511,10 @@

 static Node *

 assign(void)

 {

-	register Node *np1 = ternary(), *np2;

+	register Node *np1, *np2;

 	char *err;

+	np1 = ternary();

 	for (;;) {

 		register char op;

@@ -535,6 +536,8 @@

 		np2 = assign();

 		if (!np1->b.lvalue)

 			goto nolvalue;

+		if (isconst(np1->type->op))

+			goto const_mod;

 		/* TODO: if it necessary a 0 comparision? */

 		if ((np2 = convert(np2, np1->type)) == NULL)

 			goto incompatibles;

@@ -543,6 +546,9 @@

 return_np:

 	return np1;

+const_mod:

+	err = "const value modified";

+	goto error;

 nolvalue:

 	err = "lvalue required as left operand of assignment";

 	goto error;

--- a/types.c

+++ b/types.c

@@ -144,7 +144,7 @@

 	case ARY:    letter = 'V'; break;

 	case ENUM:   letter = 'E'; break;

 	case STRUCT: letter = 'S'; break;

-	default:     abort();

+	default: letter = tp->letter;

 	}

 	bp = xmalloc(sizeof(*bp));

 	bp->next = *tbl;