transpile: Allow limited cast translation in patterns

Author: Rua

c2rust-transpile/src/translator/mod.rs

@@ -2967,7 +2967,11 @@ impl<'c> Translation<'c> {
         if ctx.is_pattern
             && !matches!(
                 expr_kind,
-                CExprKind::Paren(..) | CExprKind::ConstantExpr(..) | CExprKind::Literal(..)
+                CExprKind::Paren(..)
+                    | CExprKind::ConstantExpr(..)
+                    | CExprKind::Literal(..)
+                    | CExprKind::ImplicitCast(..)
+                    | CExprKind::ExplicitCast(..)
             )
         {
             return Err(TranslationError::generic(
@@ -3698,6 +3702,12 @@ impl<'c> Translation<'c> {
             return Ok(val);
         }
 
+        if ctx.is_pattern && !matches!(kind, CastKind::ToVoid | CastKind::ConstCast) {
+            return Err(TranslationError::generic(
+                "cast kind is not supported in patterns",
+            ));
+        }
+
         match kind {
             CastKind::BitCast | CastKind::NoOp => {
                 self.convert_pointer_to_pointer_cast(source_cty.ctype, target_cty.ctype, val)