Mutable static proof.

core/sr-api-macros/tests/runtime_calls.rs

@@ -106,3 +106,12 @@ fn calling_with_native_else_wasm_and_fail_on_native_should_work() {
 	let block_id = BlockId::Number(client.info().unwrap().chain.best_number);
 	assert_eq!(runtime_api.fail_on_native(&block_id).unwrap(), 1);
 }
+
+#[test]
+fn returns_mutable_static() {
+	let client = test_client::new_with_execution_strategy(ExecutionStrategy::AlwaysWasm);
+	let runtime_api = client.runtime_api();
+	let block_id = BlockId::Number(client.info().unwrap().chain.best_number);
+	assert_eq!(runtime_api.returns_mutable_static(&block_id).unwrap(), 33);
+	assert_eq!(runtime_api.returns_mutable_static(&block_id).unwrap(), 33);
+}

core/test-runtime/src/lib.rs

@@ -232,6 +232,7 @@ cfg_if! {
 				fn fail_on_wasm() -> u64;
 				fn benchmark_indirect_call() -> u64;
 				fn benchmark_direct_call() -> u64;
+				fn returns_mutable_static() -> u64;
 			}
 		}
 	} else {
@@ -254,6 +255,7 @@ cfg_if! {
 				fn fail_on_wasm() -> u64;
 				fn benchmark_indirect_call() -> u64;
 				fn benchmark_direct_call() -> u64;
+				fn returns_mutable_static() -> u64;
 			}
 		}
 	}
@@ -279,6 +281,10 @@ fn benchmark_add_one(i: u64) -> u64 {
 #[cfg(not(feature = "std"))]
 static BENCHMARK_ADD_ONE: runtime_io::ExchangeableFunction<fn(u64) -> u64> = runtime_io::ExchangeableFunction::new(benchmark_add_one);
 
+/// Mutable static variables should be always observed to have
+/// the initialized value at the start of a runtime call.
+static mut MUTABLE_STATIC: u64 = 32;
+
 cfg_if! {
 	if #[cfg(feature = "std")] {
 		impl_runtime_apis! {
@@ -372,6 +378,12 @@ cfg_if! {
 				fn benchmark_direct_call() -> u64 {
 					(0..1000).fold(0, |p, i| p + benchmark_add_one(i))
 				}
+				fn returns_mutable_static() -> u64 {
+					unsafe {
+						MUTABLE_STATIC += 1;
+						MUTABLE_STATIC
+					}
+				}
 			}
 
 			impl consensus_aura::AuraApi<Block> for Runtime {
@@ -475,11 +487,17 @@ cfg_if! {
 				fn benchmark_direct_call() -> u64 {
 					(0..10000).fold(0, |p, i| p + benchmark_add_one(i))
 				}
+				fn returns_mutable_static() -> u64 {
+					unsafe {
+						MUTABLE_STATIC += 1;
+						MUTABLE_STATIC
+					}
+				}
 			}
 
 			impl consensus_aura::AuraApi<Block> for Runtime {
 				fn slot_duration() -> u64 { 1 }
 			}
 		}
 	}
-}
+}