harec

commit 43c2ab14fd8ee84072f850936118795ab46342b6
parent 84fc04c060cf92d0eace6533ed8ef4ebec9cd571
Author: Sebastian <sebastian@sebsite.pw>
Date:   Thu,  5 Jan 2023 18:00:40 -0500

check: add compile-time bounds check for array index

If the index is a constant expression and the length of the array is
defined, a bounds check is performed at compile-time.

Signed-off-by: Sebastian <sebastian@sebsite.pw>

Diffstat:
M
src/check.c
 | 
29
++++++++++++++++++++++++-----
M
src/eval.c
 | 
1
-
M
tests/01-arrays.ha
 | 
7
+++++++

3 files changed, 31 insertions(+), 6 deletions(-)
diff --git a/src/check.c b/src/check.c
@@ -228,6 +228,23 @@ check_expr_access(struct context *ctx,
 			&builtin_type_size, expr->access.index);
 		expr->result = type_store_lookup_with_flags(ctx->store,
 			atype->array.members, atype->flags | atype->array.members->flags);
+
+		// Compile-time bounds check
+		if (atype->storage == STORAGE_ARRAY
+				&& atype->array.length != SIZE_UNDEFINED) {
+			struct expression *evaled = xcalloc(1, sizeof(struct expression));
+			enum eval_result r = eval_expr(ctx, expr->access.index, evaled);
+			if (r == EVAL_OK) {
+				if (evaled->constant.uval >= atype->array.length) {
+					error(ctx, aexpr->loc, expr,
+						"Index must not be greater than array length");
+					free(evaled);
+					return;
+				}
+			}
+			free(evaled);
+		}
+
 		break;
 	case ACCESS_FIELD:
 		expr->access._struct = xcalloc(1, sizeof(struct expression));
@@ -2447,8 +2464,8 @@ slice_bounds_check(struct context *ctx, struct expression *expr)
 			return;
 		}
 
-		if (dtype->storage == STORAGE_ARRAY) {
-			assert(dtype->array.length != SIZE_UNDEFINED);
+		if (dtype->storage == STORAGE_ARRAY
+				&& dtype->array.length != SIZE_UNDEFINED) {
 			if (end->constant.uval > dtype->array.length) {
 				error(ctx, expr->loc, expr,
 					"End index must not be greater than array length");
@@ -2456,9 +2473,11 @@ slice_bounds_check(struct context *ctx, struct expression *expr)
 				return;
 			}
 		}
-	} else if (dtype->storage != STORAGE_ARRAY
-			|| dtype->array.length == SIZE_UNDEFINED) {
-		return;
+	} else {
+		if (dtype->storage != STORAGE_ARRAY) {
+			return;
+		}
+		assert(dtype->array.length != SIZE_UNDEFINED);
 	}
 
 	if (expr->slice.start == NULL) {
diff --git a/src/eval.c b/src/eval.c
@@ -988,7 +988,6 @@ eval_expr(struct context *ctx, struct expression *in, struct expression *out)
 	case EXPR_VAEND:
 	case EXPR_VASTART:
 	case EXPR_YIELD:
-		error(ctx, in->loc, "unavailable at translation time");
 		return EVAL_INVALID;
 	}
 	assert(0); // Unreachable
diff --git a/tests/01-arrays.ha b/tests/01-arrays.ha
@@ -17,6 +17,13 @@ fn indexing() void = {
 	let q = &x[0];
 	*q = 1337;
 	assert(x[0] == 1337 && y[0] == 1337);
+
+	assert(compile("
+		export fn main() void = {
+			let a = [1, 2, 3];
+			a[3];
+		};
+	") as exited != EXIT_SUCCESS);
 };
 
 fn measurements() void = {