From c7b723dbada77d7f6472a686611a05c0aac8ac12 Mon Sep 17 00:00:00 2001
From: Neil Conway <neil.conway@gmail.com>
Date: Tue, 29 Sep 2026 09:42:23 -0400
Subject: [PATCH] chore: gate Parquet opener encryption on `parquet_encryption`

Without the `parquet_encryption` feature, clippy fails on a dead stub in
`opener/encryption.rs` (`clippy::unused_async_trait_impl`). For example:

    cargo clippy -p datafusion-datasource-parquet --all-targets -- -D warnings

Every use of the module is already gated on the feature, so gate the
module itself and remove the stubs. CI doesn't catch this because its
`--workspace` build enables the feature.
---
 .../src/opener/encryption.rs                  | 34 ++-----------------
 .../datasource-parquet/src/opener/mod.rs      |  1 +
 2 files changed, 4 insertions(+), 31 deletions(-)

diff --git a/datafusion/datasource-parquet/src/opener/encryption.rs b/datafusion/datasource-parquet/src/opener/encryption.rs
index 498fe8acf7530..232c356b9b572 100644
--- a/datafusion/datasource-parquet/src/opener/encryption.rs
+++ b/datafusion/datasource-parquet/src/opener/encryption.rs
@@ -17,31 +17,24 @@
 
 //! Encryption context used during Parquet file open.
 //!
-//! Isolated here so the `#[cfg(feature = "parquet_encryption")]` gating does
-//! not pollute the rest of the opener module.
+//! This module is only compiled with the `parquet_encryption` feature. It is
+//! isolated here so the feature gating does not pollute the rest of the
+//! opener module.
 
-#[cfg(feature = "parquet_encryption")]
 use std::sync::Arc;
 
 use datafusion_common::Result;
-#[cfg(feature = "parquet_encryption")]
 use datafusion_common::config::EncryptionFactoryOptions;
-#[cfg(feature = "parquet_encryption")]
 use datafusion_common::encryption::FileDecryptionProperties;
-#[cfg(feature = "parquet_encryption")]
 use datafusion_execution::parquet_encryption::EncryptionFactory;
 
 use super::ParquetMorselizer;
 
-#[derive(Default)]
 pub(super) struct EncryptionContext {
-    #[cfg(feature = "parquet_encryption")]
     file_decryption_properties: Option<Arc<FileDecryptionProperties>>,
-    #[cfg(feature = "parquet_encryption")]
     encryption_factory: Option<(Arc<dyn EncryptionFactory>, EncryptionFactoryOptions)>,
 }
 
-#[cfg(feature = "parquet_encryption")]
 impl EncryptionContext {
     fn new(
         file_decryption_properties: Option<Arc<FileDecryptionProperties>>,
@@ -74,32 +67,11 @@ impl EncryptionContext {
     }
 }
 
-#[cfg(not(feature = "parquet_encryption"))]
-#[expect(dead_code)]
-#[expect(clippy::unused_async)]
-impl EncryptionContext {
-    pub(super) async fn get_file_decryption_properties(
-        &self,
-        _file_location: &object_store::path::Path,
-    ) -> Result<
-        Option<std::sync::Arc<datafusion_common::encryption::FileDecryptionProperties>>,
-    > {
-        Ok(None)
-    }
-}
-
 impl ParquetMorselizer {
-    #[cfg(feature = "parquet_encryption")]
     pub(super) fn get_encryption_context(&self) -> EncryptionContext {
         EncryptionContext::new(
             self.file_decryption_properties.clone(),
             self.encryption_factory.clone(),
         )
     }
-
-    #[cfg(not(feature = "parquet_encryption"))]
-    #[expect(dead_code)]
-    pub(super) fn get_encryption_context(&self) -> EncryptionContext {
-        EncryptionContext::default()
-    }
 }
diff --git a/datafusion/datasource-parquet/src/opener/mod.rs b/datafusion/datasource-parquet/src/opener/mod.rs
index eb329fb3037c0..6b2e47e134949 100644
--- a/datafusion/datasource-parquet/src/opener/mod.rs
+++ b/datafusion/datasource-parquet/src/opener/mod.rs
@@ -18,6 +18,7 @@
 //! [`ParquetMorselizer`] state machines for opening Parquet files
 
 mod early_stop;
+#[cfg(feature = "parquet_encryption")]
 mod encryption;
 
 use self::early_stop::EarlyStoppingStream;