Bugfix: Variables declared in return paramaters can have a storage lo…

…cation (hyperledger-solang#1552)

src/sema/statements.rs

@@ -247,7 +247,7 @@ pub fn resolve_function_body(
                 ns,
                 VariableInitializer::Solidity(None),
                 VariableUsage::ReturnVariable,
-                None,
+                p.1.as_ref().unwrap().storage.clone(),
             ) {
                 ns.check_shadowing(file_no, contract_no, name);
                 symtable.returns.push(pos);
@@ -270,7 +270,7 @@ pub fn resolve_function_body(
                     ns,
                     VariableInitializer::Solidity(None),
                     VariableUsage::AnonymousReturnVariable,
-                    None,
+                    p.1.as_ref().unwrap().storage.clone(),
                 )
                 .unwrap();
 

tests/evm.rs

@@ -249,7 +249,7 @@ fn ethereum_solidity_tests() {
         })
         .sum();
 
-    assert_eq!(errors, 1006);
+    assert_eq!(errors, 1003);
 }
 
 fn set_file_contents(source: &str, path: &Path) -> (FileResolver, Vec<String>) {

tests/polkadot_tests/yul.rs

@@ -3,6 +3,7 @@
 use crate::build_solidity;
 use parity_scale_codec::{Decode, Encode};
 use primitive_types::U256;
+use rand::{thread_rng, Rng};
 
 #[derive(Debug, Encode, Decode)]
 struct Val256(U256);
@@ -257,3 +258,60 @@ contract Testing {
     runtime.function("switch_no_case", Val256(U256::from(3)).encode());
     assert_eq!(runtime.output(), Val256(U256::from(4)).encode());
 }
+
+#[test]
+fn storage_slot_on_return_data() {
+    let mut runtime = build_solidity(
+        r#"
+    library StorageSlot {
+        struct AddressSlot {
+            address value;
+        }
+    
+        function getAddressSlot(
+            bytes32 slot
+        ) internal pure returns (AddressSlot storage r) {
+            assembly {
+                r.slot := slot
+            }
+        }
+    }
+    
+    contract StorageKeys {
+        function set(bytes32 key) public {
+            StorageSlot.AddressSlot storage slot = StorageSlot.getAddressSlot(key);
+            slot.value = msg.sender;
+        }
+    
+        function get(bytes32 key) public returns (address a) {
+            a = StorageSlot.getAddressSlot(key).value;
+        }
+    }"#,
+    );
+
+    let default_address = [0u8; 32];
+
+    // Without setting any key, they all shuld be default
+    let key = [0u8; 32];
+    runtime.function("get", key.to_vec());
+    assert_eq!(runtime.output(), default_address);
+
+    let key = [0xffu8; 32];
+    runtime.function("get", key.to_vec());
+    assert_eq!(runtime.output(), default_address);
+
+    let mut key = [0u8; 32];
+    thread_rng().try_fill(&mut key).unwrap();
+    runtime.function("get", key.to_vec());
+    assert_eq!(runtime.output(), default_address);
+
+    // Setting the key should write to the correct storage slot
+    runtime.function("set", key.to_vec());
+    runtime.function("get", key.to_vec());
+    assert_eq!(runtime.output(), runtime.caller());
+
+    let key = [0u8; 32];
+    runtime.function("set", key.to_vec());
+    runtime.function("get", key.to_vec());
+    assert_eq!(runtime.output(), runtime.caller())
+}