Support casts in constants

src/bindgen/ir/constant.rs

@@ -37,6 +37,10 @@ pub enum Literal {
         export_name: String,
         fields: HashMap<String, Literal>,
     },
+    Cast {
+        ty: Type,
+        value: Box<Literal>,
+    },
 }
 
 impl Literal {
@@ -45,7 +49,8 @@ impl Literal {
             Literal::PostfixUnaryOp { .. }
             | Literal::BinOp { .. }
             | Literal::Expr(..)
-            | Literal::Path(..) => {}
+            | Literal::Path(..)
+            | Literal::Cast { .. } => {}
             Literal::Struct {
                 ref mut path,
                 ref mut export_name,
@@ -72,6 +77,7 @@ impl Literal {
                 ..
             } => left.is_valid(bindings) && right.is_valid(bindings),
             Literal::Struct { ref path, .. } => bindings.struct_exists(path),
+            Literal::Cast { ref value, .. } => value.is_valid(bindings),
         }
     }
 }
@@ -104,6 +110,9 @@ impl Literal {
                 right.rename_for_config(config);
             }
             Literal::Expr(_) => {}
+            Literal::Cast { ref mut value, .. } => {
+                value.rename_for_config(config);
+            }
         }
     }
 
@@ -229,6 +238,19 @@ impl Literal {
 
             syn::Expr::Paren(syn::ExprParen { ref expr, .. }) => Self::load(expr),
 
+            syn::Expr::Cast(syn::ExprCast {
+                ref expr, ref ty, ..
+            }) => {
+                let val = Self::load(expr)?;
+                match Type::load(ty)? {
+                    Some(ty) => Ok(Literal::Cast {
+                        ty,
+                        value: Box::new(val),
+                    }),
+                    None => Err("Cannot cast to zero sized type.".to_owned()),
+                }
+            }
+
             _ => Err(format!("Unsupported expression. {:?}", *expr)),
         }
     }
@@ -252,6 +274,12 @@ impl Literal {
                 right.write(config, out);
                 write!(out, ")");
             }
+            Literal::Cast { ref ty, ref value } => {
+                write!(out, "(");
+                ty.write(config, out);
+                write!(out, ")");
+                value.write(config, out);
+            }
             Literal::Struct {
                 export_name,
                 fields,

tests/expectations/both/constant.c

@@ -3,8 +3,12 @@
 #include <stdint.h>
 #include <stdlib.h>
 
+#define CAST (uint8_t)'A'
+
 #define DELIMITER ':'
 
+#define DOUBLE_CAST (uint32_t)(float)1
+
 #define EQUID L'\U00010083'
 
 #define FOO 10

tests/expectations/both/constant.compat.c

@@ -3,8 +3,12 @@
 #include <stdint.h>
 #include <stdlib.h>
 
+#define CAST (uint8_t)'A'
+
 #define DELIMITER ':'
 
+#define DOUBLE_CAST (uint32_t)(float)1
+
 #define EQUID L'\U00010083'
 
 #define FOO 10

tests/expectations/constant.c

@@ -3,8 +3,12 @@
 #include <stdint.h>
 #include <stdlib.h>
 
+#define CAST (uint8_t)'A'
+
 #define DELIMITER ':'
 
+#define DOUBLE_CAST (uint32_t)(float)1
+
 #define EQUID L'\U00010083'
 
 #define FOO 10

tests/expectations/constant.compat.c

@@ -3,8 +3,12 @@
 #include <stdint.h>
 #include <stdlib.h>
 
+#define CAST (uint8_t)'A'
+
 #define DELIMITER ':'
 
+#define DOUBLE_CAST (uint32_t)(float)1
+
 #define EQUID L'\U00010083'
 
 #define FOO 10

tests/expectations/constant.cpp

@@ -3,8 +3,12 @@
 #include <cstdlib>
 #include <new>
 
+static const uint8_t CAST = (uint8_t)'A';
+
 static const uint32_t DELIMITER = ':';
 
+static const uint32_t DOUBLE_CAST = (uint32_t)(float)1;
+
 static const uint32_t EQUID = L'\U00010083';
 
 static const int32_t FOO = 10;

tests/expectations/tag/constant.c

@@ -3,8 +3,12 @@
 #include <stdint.h>
 #include <stdlib.h>
 
+#define CAST (uint8_t)'A'
+
 #define DELIMITER ':'
 
+#define DOUBLE_CAST (uint32_t)(float)1
+
 #define EQUID L'\U00010083'
 
 #define FOO 10

tests/expectations/tag/constant.compat.c

@@ -3,8 +3,12 @@
 #include <stdint.h>
 #include <stdlib.h>
 
+#define CAST (uint8_t)'A'
+
 #define DELIMITER ':'
 
+#define DOUBLE_CAST (uint32_t)(float)1
+
 #define EQUID L'\U00010083'
 
 #define FOO 10

tests/rust/constant.rs

@@ -26,6 +26,9 @@ pub const XBOOL: i64 = 1;
 pub const XFALSE: i64 = (0 << SHIFT) | XBOOL;
 pub const XTRUE: i64 = 1 << (SHIFT | XBOOL);
 
+pub const CAST: u8 = 'A' as u8;
+pub const DOUBLE_CAST: u32 = 1 as f32 as u32;
+
 #[repr(C)]
 struct Foo {
     x: [i32; FOO],