From d3eff6ddbc1f1718e662d65c756889621288fc50 Mon Sep 17 00:00:00 2001
From: Iulian Barbu <14218860+iulianbarbu@users.noreply.github.com>
Date: Fri, 11 Apr 2025 20:06:48 +0300
Subject: [PATCH] Use `TryFrom` impls instead of `as` operator in
 `polkadot-runtime-parachains` (#8118)
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# Description

- changed conversions based on `as` operator to `usize::try_from` in
`polkadot-runtime-parachains`

## Integration

N/A

## Review Notes

N/A

---------

Signed-off-by: Iulian Barbu <iulian.barbu@parity.io>
Co-authored-by: cmd[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Bastian Köcher <info@kchr.de>
Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: teor <teor@riseup.net>
Co-authored-by: Guillaume Thiolliere <guillaume.thiolliere@parity.io>
(cherry picked from commit fc0fcbaecab7dc7e0c3a0ff380c8a81af8b7c48b)
---
 polkadot/runtime/parachains/src/inclusion/mod.rs | 14 +++++++++-----
 prdoc/pr_8118.prdoc                              |  8 ++++++++
 2 files changed, 17 insertions(+), 5 deletions(-)
 create mode 100644 prdoc/pr_8118.prdoc

diff --git a/polkadot/runtime/parachains/src/inclusion/mod.rs b/polkadot/runtime/parachains/src/inclusion/mod.rs
index 8ad9711a0f388..387a55831550c 100644
--- a/polkadot/runtime/parachains/src/inclusion/mod.rs
+++ b/polkadot/runtime/parachains/src/inclusion/mod.rs
@@ -1306,19 +1306,23 @@ impl<T: Config> CandidateCheckContext<T> {
 		hrmp_watermark: BlockNumberFor<T>,
 		horizontal_messages: &[polkadot_primitives::OutboundHrmpMessage<ParaId>],
 	) -> Result<(), AcceptanceCheckErr> {
-		ensure!(
-			head_data.0.len() <= self.config.max_head_data_size as _,
-			AcceptanceCheckErr::HeadDataTooLarge,
-		);
+		// Safe convertions when `self.config.max_head_data_size` is in bounds of `usize` type.
+		let max_head_data_size = usize::try_from(self.config.max_head_data_size)
+			.map_err(|_| AcceptanceCheckErr::HeadDataTooLarge)?;
+		ensure!(head_data.0.len() <= max_head_data_size, AcceptanceCheckErr::HeadDataTooLarge);
 
 		// if any, the code upgrade attempt is allowed.
 		if let Some(new_validation_code) = new_validation_code {
+			// Safe convertions when `self.config.max_code_size` is in bounds of `usize` type.
+			let max_code_size = usize::try_from(self.config.max_code_size)
+				.map_err(|_| AcceptanceCheckErr::NewCodeTooLarge)?;
+
 			ensure!(
 				paras::Pallet::<T>::can_upgrade_validation_code(para_id),
 				AcceptanceCheckErr::PrematureCodeUpgrade,
 			);
 			ensure!(
-				new_validation_code.0.len() <= self.config.max_code_size as _,
+				new_validation_code.0.len() <= max_code_size,
 				AcceptanceCheckErr::NewCodeTooLarge,
 			);
 		}
diff --git a/prdoc/pr_8118.prdoc b/prdoc/pr_8118.prdoc
new file mode 100644
index 0000000000000..ae997635d7da1
--- /dev/null
+++ b/prdoc/pr_8118.prdoc
@@ -0,0 +1,8 @@
+title: Safer conversions in polkadot-runtime-parachains
+doc:
+- audience: Runtime Dev
+  description: |-
+    Use TryFrom impls instead of `as` operator for conversions.
+crates:
+- name: polkadot-runtime-parachains
+  bump: patch