harec

commit a62c0875e2f3d5f42fa1d67936242ef8a9a5aee2
parent db9663f9b9e7868ab31614bbe27fb7d0a7de8198
Author: Drew DeVault <sir@cmpwn.com>
Date:   Tue,  2 Feb 2021 14:36:05 -0500

check: lower switch branches to type hint

Diffstat:
M
src/check.c
 | 
17
+++++++++++++----
M
tests/18-match.ha
 | 
2
+-

2 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/src/check.c b/src/check.c
@@ -1331,7 +1331,7 @@ check_expr_switch(struct context *ctx,
 
 	struct expression *value = xcalloc(1, sizeof(struct expression));
 	check_expression(ctx, aexpr->_switch.value, value, NULL);
-	const struct type *type = value->result;
+	const struct type *type = type_dealias(value->result);
 	expr->_switch.value = value;
 
 	struct type_tagged_union result_type = {0};
@@ -1357,7 +1357,7 @@ check_expr_switch(struct context *ctx,
 			check_expression(ctx, aopt->value, value, type);
 			// XXX: Should this be assignable instead?
 			expect(&aopt->value->loc,
-				type == value->result,
+				type == type_dealias(value->result),
 				"Invalid type for switch case");
 
 			enum eval_result r = eval_expr(ctx, value, evaled);
@@ -1392,14 +1392,23 @@ check_expr_switch(struct context *ctx,
 	}
 
 	if (result_type.next) {
-		expr->result = type_store_lookup_tagged(
-			ctx->store, &result_type);
+		if (hint) {
+			expr->result = hint;
+		} else {
+			expr->result = type_store_lookup_tagged(
+				ctx->store, &result_type);
+		}
 
 		struct switch_case *_case = expr->_switch.cases;
+		struct ast_switch_case *acase = aexpr->_switch.cases;
 		while (_case) {
+			expect(&acase->value->loc,
+				type_is_assignable(expr->result, _case->value->result),
+				"Switch case is not assignable to result type");
 			_case->value = lower_implicit_cast(
 				expr->result, _case->value);
 			_case = _case->next;
+			acase = acase->next;
 		}
 
 		struct type_tagged_union *tu = result_type.next;
diff --git a/tests/18-match.ha b/tests/18-match.ha
@@ -86,7 +86,7 @@ fn implicit_cast() void = {
 	let x: foobar = foo;
 	let y: nullable *int = null;
 	let a: (int | foobar) = match (y) {
-		null => foo: foobar,
+		null => foo,
 		z: *int => *z,
 	};
 	assert(a is foobar);