harec

commit 4f3f7801a2e5fdce901e6a8c1ff445d288772599
parent bddf034db646a1d7f9e934527b4d35354fbe69cd
Author: Bor Grošelj Simić <bor.groseljsimic@telemach.net>
Date:   Sun, 25 Apr 2021 04:16:15 +0200

forbid tagged unions with a single member

Signed-off-by: Bor Grošelj Simić <bor.groseljsimic@telemach.net>

Diffstat:
M
src/type_store.c
 | 
9
+++++++--
M
tests/13-tagged.ha
 | 
6
++++++

2 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/src/type_store.c b/src/type_store.c
@@ -358,7 +358,7 @@ tagged_cmp(const void *ptr_a, const void *ptr_b)
 		: (*a)->type->id > (*b)->type->id ? 1 : 0;
 }
 
-static void
+static size_t
 tagged_init(struct type *type, struct type_tagged_union **tu, size_t nmemb)
 {
 	// Prune duplicates
@@ -412,6 +412,8 @@ tagged_init(struct type *type, struct type_tagged_union **tu, size_t nmemb)
 	if (type->align < builtin_type_uint.align) {
 		type->align = builtin_type_uint.align;
 	}
+
+	return nmemb;
 }
 
 static void
@@ -423,7 +425,10 @@ tagged_init_from_atype(struct type_store *store,
 		xcalloc(nmemb, sizeof(struct type_tagged_union *));
 	size_t i = 0;
 	collect_atagged_memb(store, tu, &atype->tagged_union, &i);
-	tagged_init(type, tu, nmemb);
+	nmemb = tagged_init(type, tu, nmemb);
+
+	expect(&atype->loc, nmemb > 1,
+			"Cannot create tagged union with a single member");
 }
 
 static void
diff --git a/tests/13-tagged.ha b/tests/13-tagged.ha
@@ -57,6 +57,12 @@ fn reduction() void = {
 	const c: (i8 | i16 | i32) = a;
 	const d: (i8 | i16 | i8 | i16) = a;
 	assert(rt::compile(
+		// Cannot reduce to a single member
+		"fn test() void = {
+			let a: (u8 | u8) = 42u8;
+		};"
+	) != 0);
+	assert(rt::compile(
 		// Cannot assign from more general type
 		"fn test() void = {
 			let a: (i8 | i16 | i32) = 42i8;