From 63a5032ca06cd9f9bfaea6b0ea077d49a3034654 Mon Sep 17 00:00:00 2001 From: Bruce Hill Date: Sun, 27 Oct 2024 20:25:16 -0400 Subject: Disallow mutation of read-only views --- compile.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) (limited to 'compile.c') diff --git a/compile.c b/compile.c index a0069b34..775c17df 100644 --- a/compile.c +++ b/compile.c @@ -278,9 +278,20 @@ CORD compile_type(type_t *t) static CORD compile_lvalue(env_t *env, ast_t *ast) { if (!can_be_mutated(env, ast)) { - if (ast->tag == Index || ast->tag == FieldAccess) { - ast_t *subject = ast->tag == Index ? Match(ast, Index)->indexed : Match(ast, FieldAccess)->fielded; - code_err(subject, "This is an immutable value, you can't assign to it"); + if (ast->tag == Index) { + ast_t *subject = Match(ast, Index)->indexed; + type_t *t = get_type(env, subject); + if (t->tag == PointerType && Match(t, PointerType)->is_view) + code_err(ast, "This is a read-only view and you can't mutate its contents"); + else + code_err(subject, "This is an immutable value, you can't mutate its contents"); + } else if (ast->tag == FieldAccess) { + ast_t *subject = Match(ast, FieldAccess)->fielded; + type_t *t = get_type(env, subject); + if (t->tag == PointerType && Match(t, PointerType)->is_view) + code_err(subject, "This is a read-only view and you can't mutate its fields"); + else + code_err(subject, "This is an immutable value, you can't assign to its fields"); } else { code_err(ast, "This is a value of type %T and can't be used as an assignment target", get_type(env, ast)); } -- cgit v1.2.3