Commit 7a09482536

@@ -1018,6 +1018,8 @@ TypeTableEntry *get_fn_type(CodeGen *g, FnTypeId *fn_type_id) {
     }
     if (fn_type_id->return_type != nullptr) {
         ensure_complete_type(g, fn_type_id->return_type);
+        if (type_is_invalid(fn_type_id->return_type))
+            return g->builtin_types.entry_invalid;
     } else {
         zig_panic("TODO implement inferred return types https://github.com/ziglang/zig/issues/447");
     }

@@ -1,6 +1,22 @@
 const tests = @import("tests.zig");
 
 pub fn addCases(cases: *tests.CompileErrorContext) void {
+    cases.add(
+        "error when evaluating return type",
+        \\const Foo = struct {
+        \\    map: i32(i32),
+        \\
+        \\    fn init() Foo {
+        \\        return undefined;
+        \\    }
+        \\};
+        \\export fn entry() void {
+        \\    var rule_set = try Foo.init();
+        \\}
+    ,
+        ".tmp_source.zig:2:13: error: invalid cast from type 'type' to 'i32'",
+    );
+
     cases.add(
         "slicing single-item pointer",
         \\export fn entry(ptr: *i32) void {