Fix pointer-casting

reid/lib/std.reid

@@ -1,13 +1,13 @@
 
 extern fn puts(message: *str) -> i32;
+extern fn malloc(size: u64) -> *u8;
+extern fn div(numerator: i32, denominator: i32) -> div_t;
 
 struct div_t {
     quotient: i32,
     remainder: i32,
 }
 
-extern fn div(numerator: i32, denominator: i32) -> div_t;
-
 pub fn print(message: *str) {
     puts(message);
 }
@@ -16,6 +16,10 @@ pub fn int_div(numerator: i32, denominator: i32) -> div_t {
     return div(numerator, denominator);
 }
 
+pub fn allocate(size: u64) -> *u8 {
+    malloc(size)
+}
+
 fn main() -> u16 {
     return 0;
 }

reid/src/codegen.rs

@@ -1030,18 +1030,22 @@ impl mir::Expression {
             }
             mir::ExprKind::CastTo(expression, type_kind) => {
                 let val = expression.codegen(scope, state)?;
-                let cast_instr = val
-                    .1
-                    .get_type(scope.type_values, scope.types)
-                    .cast_instruction(
-                        val.instr(),
-                        &type_kind.get_type(scope.type_values, scope.types),
-                    )
-                    .unwrap();
-                Some(StackValue(
-                    val.0.derive(scope.block.build(cast_instr).unwrap()),
-                    type_kind.clone(),
-                ))
+                let instr =
+                    if let (TypeKind::UserPtr(_), TypeKind::UserPtr(_)) = (&val.1, type_kind) {
+                        val.0.instr()
+                    } else {
+                        let cast_instr = val
+                            .1
+                            .get_type(scope.type_values, scope.types)
+                            .cast_instruction(
+                                val.instr(),
+                                &type_kind.get_type(scope.type_values, scope.types),
+                            )
+                            .unwrap();
+                        scope.block.build(cast_instr).unwrap()
+                    };
+
+                Some(StackValue(val.0.derive(instr), type_kind.clone()))
             }
         };
         if let Some(value) = &value {

reid_src/cast.reid

@@ -1,5 +1,7 @@
 // Arithmetic, function calls and imports!
 
+import std::allocate;
+
 fn other() -> i16 {
   return 6;
 }
@@ -7,5 +9,7 @@ fn other() -> i16 {
 fn main() -> u32 {
   let value = other() as u32;
 
-  return value;
+  let v = (allocate(4) as *u32);
+
+  return v[0];
 }

reid_src/ptr.reid

@@ -1,8 +1,6 @@
 // Arithmetic, function calls and imports!
 
 
-extern fn malloc(size: u64) -> *u8;
-
 fn main() -> u8 {
     let mut ptr = malloc(4);