Handle unsigned integer constants greater than u32::MAX in codegen

We were not checking signed-ness and emitting the appropriate types.

Fixes #1040

Author: fitzgen

src/codegen/mod.rs

@@ -478,7 +478,19 @@ impl CodeGenerator for Var {
                     });
                 }
                 VarType::Int(val) => {
-                    let val = helpers::ast_ty::int_expr(val);
+                    let int_kind = self.ty()
+                        .into_resolver()
+                        .through_type_aliases()
+                        .through_type_refs()
+                        .resolve(ctx)
+                        .expect_type()
+                        .as_integer()
+                        .unwrap();
+                    let val = if int_kind.is_signed() {
+                        helpers::ast_ty::int_expr(val)
+                    } else {
+                        helpers::ast_ty::uint_expr(val as _)
+                    };
                     result.push(quote! {
                         pub const #canonical_ident : #ty = #val ;
                     });

src/ir/ty.rs

@@ -194,6 +194,15 @@ impl Type {
         }
     }
 
+    /// Cast this type to an integer kind, or `None` if it is not an integer
+    /// type.
+    pub fn as_integer(&self) -> Option<IntKind> {
+        match self.kind {
+            TypeKind::Int(int_kind) => Some(int_kind),
+            _ => None,
+        }
+    }
+
     /// Is this a `const` qualified type?
     pub fn is_const(&self) -> bool {
         self.is_const

tests/expectations/tests/error-E0600-cannot-apply-unary-negation-to-u32.rs

@@ -0,0 +1,7 @@
+/* automatically generated by rust-bindgen */
+
+
+#![allow(dead_code, non_snake_case, non_camel_case_types, non_upper_case_globals)]
+
+
+pub const a: u32 = 18446744073709551611;

tests/expectations/tests/issue-1040.rs

@@ -0,0 +1,7 @@
+/* automatically generated by rust-bindgen */
+
+
+#![allow(dead_code, non_snake_case, non_camel_case_types, non_upper_case_globals)]
+
+
+pub const g_107: ::std::os::raw::c_ulonglong = 18446744073709551615;

tests/headers/error-E0600-cannot-apply-unary-negation-to-u32.h

@@ -0,0 +1,3 @@
+typedef unsigned int uint32_t;
+
+uint32_t a = 18446744073709551611;

tests/headers/issue-1040.h

@@ -0,0 +1 @@
+unsigned long long g_107 = 18446744073709551615UL;