New type GenericParam represents a generic parameter.

tests/rust/const_generics.rs

@@ -0,0 +1,15 @@
+#[repr(transparent)]
+pub struct CArrayString<const CAP: usize> {
+    pub chars: [i8; CAP],
+}
+
+pub const TITLE_SIZE: usize = 80;
+
+#[repr(C)]
+pub struct Book {
+    pub title: CArrayString<TITLE_SIZE>,
+    pub author: CArrayString<40>,
+}
+
+#[no_mangle]
+pub extern "C" fn root(a: *mut Book) {}

tests/rust/const_generics_arrayvec.rs

@@ -0,0 +1,17 @@
+#[repr(C)]
+pub struct ArrayVec<T, const CAP: usize> {
+    // the `len` first elements of the array are initialized
+    xs: [T; CAP],
+    len: u32,
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn push(v: *mut ArrayVec<*mut u8, 100>, elem: *mut u8) -> i32 {
+    if (*v).len < 100 {
+        (*v).xs[(*v).len] = elem;
+        (*v).len += 1;
+        1
+    } else {
+        0
+    }
+}