cmd/gc: clean up string index errors
Unify with array/slice errors, which were already good.
Fixes #4232.
R=ken2
CC=golang-dev
https://golang.org/cl/7271046
diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c
index 1bfa0cc..d029b8b 100644
--- a/src/cmd/gc/typecheck.c
+++ b/src/cmd/gc/typecheck.c
@@ -832,23 +832,34 @@
yyerror("invalid operation: %N (index of type %T)", n, t);
goto error;
+
+ case TSTRING:
case TARRAY:
defaultlit(&n->right, T);
- n->type = t->type;
+ if(t->etype == TSTRING)
+ n->type = types[TUINT8];
+ else
+ n->type = t->type;
+ why = "string";
+ if(t->etype == TARRAY) {
+ if(isfixedarray(t))
+ why = "array";
+ else
+ why = "slice";
+ }
if(n->right->type != T && !isint[n->right->type->etype]) {
- yyerror("non-integer array index %N", n->right);
+ yyerror("non-integer %s index %N", why, n->right);
break;
}
if(n->right->op == OLITERAL) {
- if(mpgetfix(n->right->val.u.xval) < 0) {
- why = isfixedarray(t) ? "array" : "slice";
+ if(mpgetfix(n->right->val.u.xval) < 0)
yyerror("invalid %s index %N (index must be non-negative)", why, n->right);
- } else if(isfixedarray(t) && t->bound > 0 && mpgetfix(n->right->val.u.xval) >= t->bound)
+ else if(isfixedarray(t) && t->bound > 0 && mpgetfix(n->right->val.u.xval) >= t->bound)
yyerror("invalid array index %N (out of bounds for %d-element array)", n->right, t->bound);
- else if(mpcmpfixfix(n->right->val.u.xval, maxintval[TINT]) > 0) {
- why = isfixedarray(t) ? "array" : "slice";
+ else if(isconst(n->left, CTSTR) && mpgetfix(n->right->val.u.xval) >= n->left->val.u.sval->len)
+ yyerror("invalid string index %N (out of bounds for %d-byte string)", n->right, n->left->val.u.sval->len);
+ else if(mpcmpfixfix(n->right->val.u.xval, maxintval[TINT]) > 0)
yyerror("invalid %s index %N (index too large)", why, n->right);
- }
}
break;
@@ -860,13 +871,6 @@
n->type = t->type;
n->op = OINDEXMAP;
break;
-
- case TSTRING:
- defaultlit(&n->right, types[TUINT]);
- if(n->right->type != T && !isint[n->right->type->etype])
- yyerror("non-integer string index %N", n->right);
- n->type = types[TUINT8];
- break;
}
goto ret;
