use crate::utils::{
- contains_return, in_macro, is_type_diagnostic_item, match_qpath, paths, return_ty, snippet, span_lint_and_then,
- visitors::find_all_ret_expressions,
+ contains_return, in_macro, is_type_diagnostic_item, match_qpath, paths, return_ty, snippet, span_lint_and_sugg,
+ span_lint_and_then, visitors::find_all_ret_expressions,
};
use if_chain::if_chain;
use rustc_errors::Applicability;
span: Span,
hir_id: HirId,
) {
+ // Abort if public function/method or closure.
match fn_kind {
FnKind::ItemFn(.., visibility, _) | FnKind::Method(.., Some(visibility), _) => {
if visibility.node.is_pub() {
_ => (),
}
+ // Abort if the method is implementing a trait or of it a trait method.
if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
if matches!(
item.kind,
}
}
- let (return_type, path) = if is_type_diagnostic_item(cx, return_ty(cx, hir_id), sym::option_type) {
+ // Check if return type is Option or Result. If neither, abort.
+ let return_ty = return_ty(cx, hir_id);
+ let (return_type_label, path) = if is_type_diagnostic_item(cx, return_ty, sym::option_type) {
("Option", &paths::OPTION_SOME)
- } else if is_type_diagnostic_item(cx, return_ty(cx, hir_id), sym::result_type) {
+ } else if is_type_diagnostic_item(cx, return_ty, sym::result_type) {
("Result", &paths::RESULT_OK)
} else {
return;
};
+ // Take the first inner type of the Option or Result. If can't, abort.
+ let inner_ty = if_chain! {
+ // Skip Option or Result and take the first outermost inner type.
+ if let Some(inner_ty) = return_ty.walk().nth(1);
+ if let GenericArgKind::Type(inner_ty) = inner_ty.unpack();
+ then {
+ inner_ty
+ } else {
+ return;
+ }
+ };
+
+ // Check if all return expression respect the following condition and collect them.
let mut suggs = Vec::new();
let can_sugg = find_all_ret_expressions(cx, &body.value, |ret_expr| {
if_chain! {
+ // Abort if in macro.
if !in_macro(ret_expr.span);
+ // Check if a function call.
if let ExprKind::Call(ref func, ref args) = ret_expr.kind;
+ // Get the Path of the function call.
if let ExprKind::Path(ref qpath) = func.kind;
+ // Check if OPTION_SOME or RESULT_OK, depending on return type.
if match_qpath(qpath, path);
+ // Make sure the function call has only one argument.
if args.len() == 1;
+ // Make sure the function argument does not contain a return expression.
if !contains_return(&args[0]);
then {
suggs.push((ret_expr.span, snippet(cx, args[0].span.source_callsite(), "..").to_string()));
});
if can_sugg && !suggs.is_empty() {
- span_lint_and_then(
- cx,
- UNNECESSARY_WRAPS,
- span,
- format!(
- "this function's return value is unnecessarily wrapped by `{}`",
- return_type
- )
- .as_str(),
- |diag| {
- let inner_ty = return_ty(cx, hir_id)
- .walk()
- .skip(1) // skip `std::option::Option` or `std::result::Result`
- .take(1) // take the first outermost inner type
- .filter_map(|inner| match inner.unpack() {
- GenericArgKind::Type(inner_ty) => Some(inner_ty.to_string()),
- _ => None,
- });
- inner_ty.for_each(|inner_ty| {
+ // Issue 6640: If the inner type is Unit, emit lint similar to clippy::unused_unit.
+ if inner_ty.is_unit() {
+ span_lint_and_sugg(
+ cx,
+ UNNECESSARY_WRAPS,
+ fn_decl.output.span(),
+ "unneeded wrapped unit return type",
+ format!("remove the `-> {}<()>`", return_type_label).as_str(),
+ String::new(),
+ Applicability::MaybeIncorrect,
+ );
+ } else {
+ span_lint_and_then(
+ cx,
+ UNNECESSARY_WRAPS,
+ span,
+ format!(
+ "this function's return value is unnecessarily wrapped by `{}`",
+ return_type_label
+ )
+ .as_str(),
+ |diag| {
diag.span_suggestion(
fn_decl.output.span(),
- format!("remove `{}` from the return type...", return_type).as_str(),
- inner_ty,
+ format!("remove `{}` from the return type...", return_type_label).as_str(),
+ inner_ty.to_string(),
Applicability::MaybeIncorrect,
);
- });
- diag.multipart_suggestion(
- "...and change the returning expressions",
- suggs,
- Applicability::MaybeIncorrect,
- );
- },
- );
+ diag.multipart_suggestion(
+ "...and change the returning expressions",
+ suggs,
+ Applicability::MaybeIncorrect,
+ );
+ },
+ );
+ }
}
}
}
-error: this function's return value is unnecessarily wrapped by `Option`
- --> $DIR/unnecessary_wraps.rs:8:1
- |
-LL | / fn func1(a: bool, b: bool) -> Option<i32> {
-LL | | if a && b {
-LL | | return Some(42);
-LL | | }
-... |
-LL | | }
-LL | | }
- | |_^
- |
- = note: `-D clippy::unnecessary-wraps` implied by `-D warnings`
-help: remove `Option` from the return type...
- |
-LL | fn func1(a: bool, b: bool) -> i32 {
- | ^^^
-help: ...and change the returning expressions
- |
-LL | return 42;
-LL | }
-LL | if a {
-LL | Some(-1);
-LL | 2
-LL | } else {
- ...
-
-error: this function's return value is unnecessarily wrapped by `Option`
- --> $DIR/unnecessary_wraps.rs:21:1
- |
-LL | / fn func2(a: bool, b: bool) -> Option<i32> {
-LL | | if a && b {
-LL | | return Some(10);
-LL | | }
-... |
-LL | | }
-LL | | }
- | |_^
- |
-help: remove `Option` from the return type...
- |
-LL | fn func2(a: bool, b: bool) -> i32 {
- | ^^^
-help: ...and change the returning expressions
- |
-LL | return 10;
-LL | }
-LL | if a {
-LL | 20
-LL | } else {
-LL | 30
- |
-
-error: this function's return value is unnecessarily wrapped by `Option`
- --> $DIR/unnecessary_wraps.rs:51:1
- |
-LL | / fn func5() -> Option<i32> {
-LL | | Some(1)
-LL | | }
- | |_^
- |
-help: remove `Option` from the return type...
- |
-LL | fn func5() -> i32 {
- | ^^^
-help: ...and change the returning expressions
- |
-LL | 1
- |
-
-error: this function's return value is unnecessarily wrapped by `Result`
- --> $DIR/unnecessary_wraps.rs:61:1
- |
-LL | / fn func7() -> Result<i32, ()> {
-LL | | Ok(1)
-LL | | }
- | |_^
- |
-help: remove `Result` from the return type...
- |
-LL | fn func7() -> i32 {
- | ^^^
-help: ...and change the returning expressions
- |
-LL | 1
- |
-
-error: this function's return value is unnecessarily wrapped by `Option`
- --> $DIR/unnecessary_wraps.rs:93:5
- |
-LL | / fn func12() -> Option<i32> {
-LL | | Some(1)
-LL | | }
- | |_____^
- |
-help: remove `Option` from the return type...
- |
-LL | fn func12() -> i32 {
- | ^^^
-help: ...and change the returning expressions
- |
-LL | 1
+error[E0282]: type annotations needed
+ --> $DIR/unnecessary_wraps.rs:138:9
|
+LL | Ok(());
+ | ^^ cannot infer type for type parameter `E` declared on the enum `Result`
-error: aborting due to 5 previous errors
+error: aborting due to previous error
+For more information about this error, try `rustc --explain E0282`.