- Empty struct after @if processing was not detected, causing a crash instead of an error.

- Comparing an uint and int[<4>] was incorrectly assumed to be uint compared to int, causing a crash instead of an error.
- When an `int[*][6]` was given too few values, the compiler would assert instead of giving an error.

releasenotes.md

@@ -84,6 +84,7 @@
 - Empty struct after `@if` processing was not detected, causing a crash instead of an error. #2771
 - Comparing an uint and int[<4>] was incorrectly assumed to be uint compared to int, causing a crash instead of an error. #2771
 - When an `int[*][6]` was given too few values, the compiler would assert instead of giving an error. #2771
+- Inferring length from a slice was accidentally not an error.
 
 ### Stdlib changes
 - Add `ThreadPool` join function to wait for all threads to finish in the pool without destroying the threads.

src/compiler/sema_casts.c

@@ -1193,6 +1193,10 @@ static bool rule_slice_to_infer(CastContext *cc, bool is_explicit, bool is_silen
 static bool rule_vecarr_to_infer(CastContext *cc, bool is_explicit, bool is_silent)
 {
 	Type *new_type = type_infer_len_from_actual_type(cc->to, cc->from);
+	if (type_is_inferred(new_type))
+	{
+		return sema_cast_error(cc, false, is_silent);
+	}
 	cast_context_set_to(cc, new_type);
 	return cast_is_allowed(cc, is_explicit, is_silent);
 }

test/test_suite/arrays/inferred_array_slice_fail.c3

@@ -0,0 +1,11 @@
+import std;
+macro  test(int[*][1] a) {
+	var b = a;
+}
+
+fn int main()
+{
+	int[][1] b;
+	test(b); // #error:  It is not possible to cast 'int[][1]' to 'int[*][1]'
+	return 12;
+}