From 4c1ee51d5cd75123568f1f9eb96f0aff68d5e9d7 Mon Sep 17 00:00:00 2001
From: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Date: Mon, 20 Feb 2023 15:09:04 +0100
Subject: [PATCH 1/2] Add defensive_assert macro

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
---
 frame/support/src/traits/misc.rs | 48 ++++++++++++++++++++++++++++++--
 1 file changed, 46 insertions(+), 2 deletions(-)

diff --git a/frame/support/src/traits/misc.rs b/frame/support/src/traits/misc.rs
index 734b84ebd9d85..08338ebacd5af 100644
--- a/frame/support/src/traits/misc.rs
+++ b/frame/support/src/traits/misc.rs
@@ -49,7 +49,7 @@ macro_rules! defensive {
 		);
 		debug_assert!(false, "{}", $crate::traits::DEFENSIVE_OP_INTERNAL_ERROR);
 	};
-	($error:tt) => {
+	($error:expr $(,)?) => {
 		frame_support::log::error!(
 			target: "runtime",
 			"{}: {:?}",
@@ -58,7 +58,7 @@ macro_rules! defensive {
 		);
 		debug_assert!(false, "{}: {:?}", $crate::traits::DEFENSIVE_OP_INTERNAL_ERROR, $error);
 	};
-	($error:tt, $proof:tt) => {
+	($error:expr, $proof:expr $(,)?) => {
 		frame_support::log::error!(
 			target: "runtime",
 			"{}: {:?}: {:?}",
@@ -70,6 +70,29 @@ macro_rules! defensive {
 	}
 }
 
+/// Trigger a defensive failure if a condition is not met.
+///
+/// Similar to [`assert!`] but will print an error without `debug_assertions` instead of silently
+/// ignoring it. Only accepts one instead of variable formatting arguments.
+///
+/// # Example
+///
+/// ```
+/// use frame_support::defensive_assert;
+///
+/// std::panic::catch_unwind(|| {
+/// 	defensive_assert!(1 == 0, "Must fail")
+/// }).unwrap_err();
+/// ```
+#[macro_export]
+macro_rules! defensive_assert {
+	($cond:expr $(, $proof:expr )? $(,)?) => {
+		if !($cond) {
+			$crate::defensive!(::core::stringify!($cond) $(, $proof )?);
+		}
+	};
+}
+
 /// Prelude module for all defensive traits to be imported at once.
 pub mod defensive_prelude {
 	pub use super::{Defensive, DefensiveOption, DefensiveResult};
@@ -1141,6 +1164,27 @@ mod test {
 	use sp_core::bounded::{BoundedSlice, BoundedVec};
 	use sp_std::marker::PhantomData;
 
+	#[test]
+	fn defensive_assert_works() {
+		defensive_assert!(true);
+		defensive_assert!(true,);
+		defensive_assert!(true, "must work");
+		defensive_assert!(true, "must work",);
+	}
+
+	#[test]
+	#[cfg(debug_assertions)]
+	#[should_panic(expected = "Defensive failure has been triggered!: \"1 == 0\": \"Must fail\"")]
+	fn defensive_assert_panics() {
+		defensive_assert!(1 == 0, "Must fail");
+	}
+
+	#[test]
+	#[cfg(not(debug_assertions))]
+	fn defensive_assert_does_not_panic() {
+		defensive_assert!(1 == 0, "Must fail");
+	}
+
 	#[test]
 	#[cfg(not(debug_assertions))]
 	fn defensive_saturating_accrue_works() {

From c352596b22abe7bdc7f9de901fce219fb8720bfa Mon Sep 17 00:00:00 2001
From: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Date: Tue, 21 Feb 2023 13:33:41 +0100
Subject: [PATCH 2/2] Apply review suggestions
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Bastian Köcher <git@kchr.de>

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
---
 frame/support/src/traits/misc.rs | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/frame/support/src/traits/misc.rs b/frame/support/src/traits/misc.rs
index 08338ebacd5af..5a13fc4ab6509 100644
--- a/frame/support/src/traits/misc.rs
+++ b/frame/support/src/traits/misc.rs
@@ -77,12 +77,8 @@ macro_rules! defensive {
 ///
 /// # Example
 ///
-/// ```
-/// use frame_support::defensive_assert;
-///
-/// std::panic::catch_unwind(|| {
-/// 	defensive_assert!(1 == 0, "Must fail")
-/// }).unwrap_err();
+/// ```should_panic
+/// frame_support::defensive_assert!(1 == 0, "Must fail")
 /// ```
 #[macro_export]
 macro_rules! defensive_assert {