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cmd/gc: do simple bounds checking of constant indices/slices in typecheck.

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This should make the compiler emit errors specific to the bounds checking instead of overflow errors on the underlying types.

Updates #4232.

R=rsc
CC=golang-dev
https://golang.org/cl/6783054
This commit is contained in:
Daniel Morsing 2012-11-01 18:45:19 +01:00
parent 1e8e14c901
commit 85d60a727c
1 changed files with 15 additions and 2 deletions
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17
src/cmd/gc/typecheck.c
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@ -817,9 +817,18 @@ reswitch:
case TARRAY:
defaultlit(&n->right, T);
if(n->right->type != T && !isint[n->right->type->etype])
yyerror("non-integer array index %N", n->right);
n->type = t->type;
if(n->right->type != T && !isint[n->right->type->etype]) {
yyerror("non-integer array index %N", n->right);
break;
}
if(n->right->op == OLITERAL) {
if(mpgetfix(n->right->val.u.xval) < 0) {
why = isfixedarray(t) ? "array" : "slice";
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)
yyerror("invalid array index %N (out of bounds for %d-element array)", n->right, t->bound);
}
break;
case TMAP:
@ -912,6 +921,8 @@ reswitch:
yyerror("invalid slice index %N (type %T)", n->right->left, t);
goto error;
}
if(n->right->left->op == OLITERAL && mpgetfix(n->right->left->val.u.xval) < 0)
yyerror("invalid slice index %N (index must be non-negative)", n->right->left);
}
if(n->right->right != N) {
if((t = n->right->right->type) == T)
@ -920,6 +931,8 @@ reswitch:
yyerror("invalid slice index %N (type %T)", n->right->right, t);
goto error;
}
if(n->right->right->op == OLITERAL && mpgetfix(n->right->right->val.u.xval) < 0)
yyerror("invalid slice index %N (index must be non-negative)", n->right->right);
}
l = n->left;
if((t = l->type) == T)