Support cast expressions in array lengths

Happens typically to cast to a usize, let's just make it work.

Closes rust-lang#15

Author: alexcrichton

ctest/src/lib.rs

@@ -873,7 +873,6 @@ impl<'a> Generator<'a> {
             }
 
             let cfield = self.rust2cfield(ty, &name);
-            let rust_fieldty = self.ty2name(&field.node.ty, true);
 
             t!(writeln!(self.c, r#"
                 uint64_t __test_offset_{ty}_{rust_field}(void) {{
@@ -915,15 +914,15 @@ impl<'a> Generator<'a> {
             t!(writeln!(self.rust, r#"
                 extern {{
                     fn __test_field_type_{ty}_{field}(a: *mut {ty})
-                                                      -> *mut {field_ty};
+                                                      -> *mut u8;
                 }}
                 unsafe {{
                     let foo = 0 as *mut {ty};
                     same(&(*foo).{field} as *const _ as *mut _,
                          __test_field_type_{ty}_{field}(foo),
                          "field type {field} of {ty}");
                 }}
-            "#, ty = ty, field = name, field_ty = rust_fieldty));
+            "#, ty = ty, field = name));
         }
         t!(writeln!(self.rust, r#"
             }}
@@ -1194,6 +1193,7 @@ impl<'a> Generator<'a> {
             ast::ExprPath(_, ref path) => {
                 path.segments.last().unwrap().identifier.to_string()
             }
+            ast::ExprCast(ref e, _) => self.expr2str(e),
             _ => panic!("unknown expr: {:?}", e),
         }
     }

ctest/testcrate/src/t1.h

@@ -2,11 +2,14 @@
 
 typedef int32_t T1Foo;
 
+#define T1N 5
+
 struct T1Bar {
   int32_t a;
   uint32_t b;
   T1Foo c;
   uint8_t d;
+  int64_t e[T1N];
 };
 
 struct T1Baz {
@@ -22,3 +25,4 @@ void T1e(unsigned, const struct T1Bar*);
 void T1f(void);
 
 #define T1C 4
+

ctest/testcrate/src/t1.rs

@@ -4,12 +4,15 @@ use libc::*;
 
 pub type T1Foo = i32;
 
+pub const T1N: i32 = 5;
+
 #[repr(C)]
 pub struct T1Bar {
     pub a: i32,
     pub b: u32,
     pub c: T1Foo,
     pub d: u8,
+    pub e: [i64; T1N as usize],
 }
 
 #[repr(C)]