Fixes error while using From trait that returns a tuple.

sway-core/src/transform/to_parsed_lang/convert_parse_tree.rs

@@ -3483,36 +3483,6 @@ fn statement_let_to_ast_nodes(
 
                 let tuple_name = Ident::new_with_override(tuple_name, span.clone());
 
-                // Parse the type ascription and the type ascription span.
-                // In the event that the user did not provide a type ascription,
-                // it is set to TypeInfo::Unknown and the span to None.
-                let type_ascription = match &ty_opt {
-                    Some(ty) => ty_to_type_argument(context, handler, engines, ty.clone())?,
-                    None => {
-                        let type_id = engines.te().insert(engines, TypeInfo::Unknown, None);
-                        TypeArgument {
-                            type_id,
-                            initial_type_id: type_id,
-                            span: tuple_name.span(),
-                            call_path_tree: None,
-                        }
-                    }
-                };
-
-                // Save the tuple to the new name as a new variable declaration.
-                let save_body_first = VariableDeclaration {
-                    name: tuple_name.clone(),
-                    type_ascription,
-                    body: expression,
-                    is_mutable: false,
-                };
-                ast_nodes.push(AstNode {
-                    content: AstNodeContent::Declaration(Declaration::VariableDeclaration(
-                        save_body_first,
-                    )),
-                    span: span.clone(),
-                });
-
                 // Acript a second declaration to a tuple of placeholders to check that the tuple
                 // is properly sized to the pattern
                 let placeholders_type_ascription = {
@@ -3561,6 +3531,28 @@ fn statement_let_to_ast_nodes(
                     }
                 };
 
+                // Parse the type ascription and the type ascription span.
+                // In the event that the user did not provide a type ascription,
+                // it is set to TypeInfo::Unknown and the span to None.
+                let type_ascription = match &ty_opt {
+                    Some(ty) => ty_to_type_argument(context, handler, engines, ty.clone())?,
+                    None => placeholders_type_ascription.clone(),
+                };
+
+                // Save the tuple to the new name as a new variable declaration.
+                let save_body_first = VariableDeclaration {
+                    name: tuple_name.clone(),
+                    type_ascription,
+                    body: expression,
+                    is_mutable: false,
+                };
+                ast_nodes.push(AstNode {
+                    content: AstNodeContent::Declaration(Declaration::VariableDeclaration(
+                        save_body_first,
+                    )),
+                    span: span.clone(),
+                });
+
                 // create a variable expression that points to the new tuple name that we just created
                 let new_expr = Expression {
                     kind: ExpressionKind::Variable(tuple_name.clone()),

test/src/e2e_vm_tests/test_programs/should_fail/generic_trait_tuple_without_type_ascription/Forc.lock

@@ -0,0 +1,13 @@
+[[package]]
+name = "core"
+source = "path+from-root-B089E2A459F9A9B9"
+
+[[package]]
+name = "generic_trait_tuple_without_type_ascription"
+source = "member"
+dependencies = ["std"]
+
+[[package]]
+name = "std"
+source = "path+from-root-B089E2A459F9A9B9"
+dependencies = ["core"]

test/src/e2e_vm_tests/test_programs/should_fail/generic_trait_tuple_without_type_ascription/Forc.toml

@@ -0,0 +1,8 @@
+[project]
+authors = ["Fuel Labs <[email protected]>"]
+entry = "main.sw"
+license = "Apache-2.0"
+name = "generic_trait_tuple_without_type_ascription"
+
+[dependencies]
+std = { path = "../../../../../../sway-lib-std" }

test/src/e2e_vm_tests/test_programs/should_fail/generic_trait_tuple_without_type_ascription/src/main.sw

@@ -0,0 +1,32 @@
+script;
+
+pub trait MyFrom<T> {
+    fn from(b: T) -> Self;
+}
+
+
+pub trait MyInto<T> {
+    fn into(self) -> T;
+}
+
+
+impl<T, U> MyInto<U> for T
+where
+    U: MyFrom<T>,
+{
+    fn into(self) -> U {
+        U::from(self)
+    }
+}
+
+impl MyFrom<u256> for (u64, u64, u64, u64) {
+    fn from(_val: u256) -> (u64, u64, u64, u64) {
+        (42, 0, 0, 0)
+    }
+}
+
+fn main() -> bool {
+    let (_a, _b, _c, _d) = u256::min().into();
+
+    true
+}

test/src/e2e_vm_tests/test_programs/should_fail/generic_trait_tuple_without_type_ascription/test.toml

@@ -0,0 +1,7 @@
+category = "fail"
+
+# check: $()let (_a, _b, _c, _d) = u256::min().into();
+# nextln: $()Trait "MyFrom<u256>" is not implemented for type "(_, _, _, _)".
+
+# check: $()let (_a, _b, _c, _d) = u256::min().into();
+# nextln: $()Cannot infer type for type parameter "_". Insufficient type information provided. Try annotating its type.