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Fix for issue 6640

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This commit is contained in:
Pierre-Andre Gagnon 2021-02-02 18:39:23 -05:00
parent c5f3f9df3b
commit bfbc083587
3 changed files with 93 additions and 136 deletions
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92
clippy_lints/src/unnecessary_wraps.rs
View file

@ -1,6 +1,6 @@
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;
@ -64,6 +64,7 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryWraps {
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() {
@ -74,6 +75,7 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryWraps {
_ => (),
}
// 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,
@ -83,22 +85,43 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryWraps {
}
}
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()));
@ -110,39 +133,42 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryWraps {
});
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,
);
},
);
}
}
}
}