Fixes error while using From trait that returns a tuple.

Instead of `Trait "MyFrom<u256>" is not implemented for type "U".`
We now get `Trait "MyFrom<u256>" is not implemented for type "(_, _, _, _)".`

The error is followed by:
`Cannot infer type for type parameter "_". Insufficient type information provided. Try annotating its type.`

While Rust compiler is able to inference the type in this situation
it is non trivial to do it properly hence we should probably keep asking
for the type to be annotated.

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.