var: Constant arrays of const elements should not generate static muts.

Fixes #1727

Author: emilio

src/ir/var.rs

@@ -232,8 +232,12 @@ impl ClangSubItemParser for Var {
 
                 let ty = cursor.cur_type();
 
-                // XXX this is redundant, remove!
-                let is_const = ty.is_const();
+                // TODO(emilio): do we have to special-case constant arrays in
+                // some other places?
+                let is_const = ty.is_const() ||
+                    (ty.kind() == CXType_ConstantArray &&
+                        ty.elem_type()
+                            .map_or(false, |element| element.is_const()));
 
                 let ty = match Item::from_ty(&ty, cursor, None, ctx) {
                     Ok(ty) => ty,

tests/expectations/tests/const_array.rs

@@ -0,0 +1,15 @@
+/* automatically generated by rust-bindgen */
+
+#![allow(
+    dead_code,
+    non_snake_case,
+    non_camel_case_types,
+    non_upper_case_globals
+)]
+
+extern "C" {
+    pub static foo: [::std::os::raw::c_int; 1usize];
+}
+extern "C" {
+    pub static mut bar: [::std::os::raw::c_int; 1usize];
+}

tests/headers/const_array.h

@@ -0,0 +1,2 @@
+extern const int foo[1];
+extern int bar[1];

tests/tests.rs

@@ -353,10 +353,10 @@ fn test_clang_env_args() {
         "/* automatically generated by rust-bindgen */
 
 extern \"C\" {
-    pub static mut x: [::std::os::raw::c_int; 1usize];
+    pub static x: [::std::os::raw::c_int; 1usize];
 }
 extern \"C\" {
-    pub static mut y: [::std::os::raw::c_int; 1usize];
+    pub static y: [::std::os::raw::c_int; 1usize];
 }
 "
         .to_string(),