Allow storage access in fallback only contracts

Contract that do not implement any ABI (and therefore have no methods)
do not always properly set the storage annotations of the entry function
because the fallback function's storage annotations are not taken into
account. This changes makes sure that the storage function's storage
permissions are also considered.

sway-core/src/semantic_analysis/ast_node/declaration/auto_impl.rs

@@ -628,27 +628,19 @@ where
             let method_name = decl.name.as_str();
 
             if args_types == "()" {
-                code.push_str(&format!("if method_name == \"{method_name}\" {{
+                code.push_str(&format!("if _method_name == \"{method_name}\" {{
                     let result_{method_name}: raw_slice = encode::<{return_type}>(__contract_entry_{method_name}());
                     __contract_ret(result_{method_name}.ptr(), result_{method_name}.len::<u8>());
                 }}\n"));
             } else {
-                code.push_str(&format!("if method_name == \"{method_name}\" {{
+                code.push_str(&format!("if _method_name == \"{method_name}\" {{
                     let args: {args_types} = decode_second_param::<{args_types}>();
                     let result_{method_name}: raw_slice = encode::<{return_type}>(__contract_entry_{method_name}({expanded_args}));
                     __contract_ret(result_{method_name}.ptr(), result_{method_name}.len::<u8>());
                 }}\n"));
             }
         }
 
-        let att: String = match (reads, writes) {
-            (true, true) => "#[storage(read, write)]",
-            (true, false) => "#[storage(read)]",
-            (false, true) => "#[storage(write)]",
-            (false, false) => "",
-        }
-        .into();
-
         let fallback = if let Some(fallback_fn) = fallback_fn {
             let fallback_fn = engines.de().get(&fallback_fn);
             let Some(return_type) = Self::generate_type(engines, fallback_fn.return_type.type_id)
@@ -659,16 +651,32 @@ where
                 return Err(err);
             };
             let method_name = fallback_fn.name.as_str();
-
+            match fallback_fn.purity {
+                Purity::Pure => {}
+                Purity::Reads => reads = true,
+                Purity::Writes => writes = true,
+                Purity::ReadsWrites => {
+                    reads = true;
+                    writes = true;
+                }
+            }
             format!("let result: raw_slice = encode::<{return_type}>({method_name}()); __contract_ret(result.ptr(), result.len::<u8>());")
         } else {
             // as the old encoding does
             format!("__revert({});", MISMATCHED_SELECTOR_REVERT_CODE)
         };
 
+        let att: String = match (reads, writes) {
+            (true, true) => "#[storage(read, write)]",
+            (true, false) => "#[storage(read)]",
+            (false, true) => "#[storage(write)]",
+            (false, false) => "",
+        }
+        .into();
+
         let code = format!(
             "{att} pub fn __entry() {{
-            let method_name = decode_first_param::<str>();
+            let _method_name = decode_first_param::<str>();
             {code}
             {fallback}
         }}"

test/src/e2e_vm_tests/test_programs/should_pass/language/fallback_only/Forc.lock

@@ -0,0 +1,16 @@
+[[package]]
+name = "core"
+source = "path+from-root-542D0E8F1D1E5950"
+
+[[package]]
+name = "fallback_only"
+source = "member"
+dependencies = [
+    "core",
+    "std",
+]
+
+[[package]]
+name = "std"
+source = "path+from-root-542D0E8F1D1E5950"
+dependencies = ["core"]

test/src/e2e_vm_tests/test_programs/should_pass/language/fallback_only/Forc.toml

@@ -0,0 +1,10 @@
+[project]
+authors = ["Fuel Labs <[email protected]>"]
+entry = "main.sw"
+license = "Apache-2.0"
+name = "fallback_only"
+implicit-std = false
+
+[dependencies]
+core = { path = "../../../../../../../sway-lib-core" }
+std = { path = "../../../../../../../sway-lib-std" }

test/src/e2e_vm_tests/test_programs/should_pass/language/fallback_only/json_abi_oracle.json

@@ -0,0 +1,8 @@
+{
+  "configurables": [],
+  "encoding": "1",
+  "functions": [],
+  "loggedTypes": [],
+  "messagesTypes": [],
+  "types": []
+}

test/src/e2e_vm_tests/test_programs/should_pass/language/fallback_only/json_abi_oracle_new_encoding.json

@@ -0,0 +1,8 @@
+{
+  "configurables": [],
+  "encoding": "1",
+  "functions": [],
+  "loggedTypes": [],
+  "messagesTypes": [],
+  "types": []
+}

test/src/e2e_vm_tests/test_programs/should_pass/language/fallback_only/src/main.sw

@@ -0,0 +1,15 @@
+contract;
+
+use std::execution::run_external;
+use std::constants::ZERO_B256;
+
+#[namespace(SRC1822)]
+storage {
+    target: ContractId = ContractId::from(ZERO_B256),
+}
+
+#[fallback]
+#[storage(read)]
+fn fallback() {
+    run_external(storage.target.read())
+}

test/src/e2e_vm_tests/test_programs/should_pass/language/fallback_only/test.toml

@@ -0,0 +1,3 @@
+category = "compile"
+validate_abi = true
+expected_warnings = 0

test/src/e2e_vm_tests/test_programs/should_pass/unit_tests/workspace_test/contract_multi_test/src/main.sw

@@ -17,15 +17,15 @@ fn test_foo() {
 
 #[test(should_revert)]
 fn test_fail() {
-    let contract_id = 0x535d1bbf19a6c7e5e2e2906d09b8c959bd211391e7a3c7602c5dab0455f78305;
+    let contract_id = 0xed94087f1dea86a4590624880f80e97522daedb48a2398a37f6aa039599715ef;
     let caller = abi(MyContract, contract_id);
     let result = caller.test_function {}();
     assert(result == false)
 }
 
 #[test]
 fn test_success() {
-    let contract_id = 0x535d1bbf19a6c7e5e2e2906d09b8c959bd211391e7a3c7602c5dab0455f78305;
+    let contract_id = 0xed94087f1dea86a4590624880f80e97522daedb48a2398a37f6aa039599715ef;
     let caller = abi(MyContract, contract_id);
     let result = caller.test_function {}();
     assert(result == true)