Correctly handle Input::Message when calling msg_sender() (#6231)

## Description

When the input type was of `Input::Message` and the `msg_sender()`
function was called, it would revert. It now properly handle
`Input::Message`.

## Checklist

- [x] I have linked to any relevant issues.
- [x] I have commented my code, particularly in hard-to-understand
areas.
- [x] I have updated the documentation where relevant (API docs, the
reference, and the Sway book).
- [ ] If my change requires substantial documentation changes, I have
[requested support from the DevRel
team](https://github.com/FuelLabs/devrel-requests/issues/new/choose)
- [x] I have added tests that prove my fix is effective or that my
feature works.
- [x] I have added (or requested a maintainer to add) the necessary
`Breaking*` or `New Feature` labels where relevant.
- [x] I have done my best to ensure that my PR adheres to [the Fuel Labs
Code Review
Standards](https://github.com/FuelLabs/rfcs/blob/master/text/code-standards/external-contributors.md).
- [x] I have requested a review from the relevant team or maintainers.

---------

Co-authored-by: Kaya Gökalp <kaya.gokalp@fuel.sh>
Co-authored-by: SwayStar123 <46050679+SwayStar123@users.noreply.github.com>

sway-lib-std/src/auth.sw

@@ -6,7 +6,14 @@ use ::contract_id::ContractId;
 use ::identity::Identity;
 use ::option::Option::{self, *};
 use ::result::Result::{self, *};
-use ::inputs::{Input, input_coin_owner, input_count, input_message_recipient, input_type};
+use ::inputs::{
+    Input,
+    input_coin_owner,
+    input_count,
+    input_message_recipient,
+    input_message_sender,
+    input_type,
+};
 use ::revert::revert;
 
 /// The error type used when an `Identity` cannot be determined.
@@ -151,7 +158,20 @@ pub fn caller_address() -> Result<Address, AuthError> {
         }
 
         // type == InputCoin or InputMessage.
-        let owner_of_input = input_coin_owner(i.as_u64());
+        let owner_of_input = match type_of_input {
+            Input::Coin => {
+                input_coin_owner(i.as_u64())
+            },
+            Input::Message => {
+                Some(input_message_sender(i.as_u64()))
+            },
+            _ => {
+                // type != InputCoin or InputMessage, continue looping.
+                i += 1u16;
+                continue;
+            }
+        };
+
         if candidate.is_none() {
             // This is the first input seen of the correct type.
             candidate = owner_of_input;

test/src/sdk-harness/test_artifacts/auth_testing_contract/src/main.sw

@@ -26,16 +26,16 @@ impl AuthTesting for Contract {
         ret
     }
 
-    fn returns_msg_sender_address(_expected_id: Address) -> bool {
+    fn returns_msg_sender_address(expected_id: Address) -> bool {
         let result: Result<Identity, AuthError> = msg_sender();
         let mut ret = false;
         if result.is_err() {
             ret = false;
         }
         let unwrapped = result.unwrap();
         match unwrapped {
-            Identity::Address(_) => {
-                ret = true
+            Identity::Address(address) => {
+                ret = expected_id == address
             },
             _ => {
                 ret = false

test/src/sdk-harness/test_projects/auth/mod.rs

@@ -9,6 +9,8 @@ use fuels::{
         coin::{Coin, CoinStatus},
         message::{Message, MessageStatus},
         Bytes32, ContractId,
+        coin_type::CoinType,
+        input::Input,
     },
 };
 use std::str::FromStr;
@@ -69,6 +71,66 @@ async fn msg_sender_from_contract() {
     assert!(result.value);
 }
 
+#[tokio::test]
+async fn input_message_msg_sender_from_contract() {
+    // Wallet
+    let mut wallet = WalletUnlocked::new_random(None);
+
+    // Setup coins and messages
+    let coins = setup_single_asset_coins(wallet.address(), AssetId::BASE, 100, 1000);
+    let msg = setup_single_message(
+        &Bech32Address {
+            hrp: "".to_string(),
+            hash: Default::default(),
+        },
+        wallet.address(),
+        DEFAULT_COIN_AMOUNT,
+        10.into(),
+        vec![],
+    );
+
+    let provider = setup_test_provider(coins.clone(), vec![msg.clone()], None, None)
+        .await
+        .unwrap();
+    wallet.set_provider(provider.clone());
+
+    // Setup contract
+    let id = Contract::load_from(
+        "test_artifacts/auth_testing_contract/out/release/auth_testing_contract.bin",
+        LoadConfiguration::default(),
+    )
+    .unwrap()
+    .deploy(&wallet, TxPolicies::default())
+    .await
+    .unwrap();
+    let instance = AuthContract::new(id.clone(), wallet.clone());
+
+    // Start building transactions
+    let call_handler = instance.methods().returns_msg_sender_address(Address::from(*msg.sender.hash()));
+    let mut tb = call_handler.transaction_builder().await.unwrap();
+
+    // Inputs
+    tb.inputs_mut().push(Input::ResourceSigned {
+        resource: CoinType::Message(wallet
+            .get_messages()
+            .await
+            .unwrap()
+            .first()
+            .unwrap()
+            .clone()),
+    });
+
+    // Build transaction
+    tb.add_signer(wallet.clone()).unwrap();
+    let tx = tb.build(provider.clone()).await.unwrap();
+
+    // Send and verify
+    let tx_id = provider.send_transaction(tx).await.unwrap();
+    let tx_status = provider.tx_status(&tx_id).await.unwrap();
+    let response = call_handler.get_response_from(tx_status).unwrap();
+    assert!(response.value);
+}
+
 async fn get_contracts() -> (
     AuthContract<WalletUnlocked>,
     ContractId,