Add tests for packed unions

Author: chrysn

tests/unions/src/test_unions.rs

@@ -9,12 +9,12 @@ extern "C" {
     fn entry(_: c_uint, _: *mut c_int);
 }
 
-const BUFFER_SIZE: usize = 18;
+const BUFFER_SIZE: usize = 19;
 
 pub fn test_buffer() {
     let mut buffer = [0; BUFFER_SIZE];
     let mut rust_buffer = [0; BUFFER_SIZE];
-    let expected_buffer = [12, 12, 0, 1, 2, 3, 4, 0, 5, 6, 7, 8, 0, 8, 9, 10, 12, 17];
+    let expected_buffer = [12, 12, 0, 5, 1, 2, 3, 4, 0, 5, 6, 7, 8, 0, 8, 9, 10, 12, 18];
 
     unsafe {
         entry(BUFFER_SIZE as u32, buffer.as_mut_ptr());

tests/unions/src/unions.c

@@ -17,6 +17,11 @@ union union_with_anon_struct {
     };
 };
 
+union __attribute__((packed)) packed_union {
+    int as_int;
+    char as_chars[5];
+};
+
 void entry(const unsigned int buffer_size, int buffer[const])
 {
     int i = 0;
@@ -35,6 +40,7 @@ void entry(const unsigned int buffer_size, int buffer[const])
     buffer[i++] = sizeof(union my_union);
     buffer[i++] = sizeof(union my_union_flipped);
     buffer[i++] = sizeof(union empty_union);
+    buffer[i++] = sizeof(union packed_union);
     buffer[i++] = u1.as_int;
     buffer[i++] = u2.as_int;
     buffer[i++] = u3.as_chars[0];