Auto merge of #6665 - pag4k:unnecessary_wraps_bug_6640, r=camsteffen
Fix for issue 6640 *Please write a short comment explaining your change (or "none" for internal only changes)* changelog: unnecessary_wraps will now suggest to remove unnecessary wrapped return unit type, like Option<()> fixes #6640
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0f70e88137
@ -1,5 +1,5 @@
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use crate::utils::{
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contains_return, in_macro, is_type_diagnostic_item, match_qpath, paths, return_ty, snippet, span_lint_and_then,
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contains_return, in_macro, match_qpath, paths, return_ty, snippet, span_lint_and_then,
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visitors::find_all_ret_expressions,
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};
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use if_chain::if_chain;
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@ -7,7 +7,7 @@ use rustc_errors::Applicability;
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use rustc_hir::intravisit::FnKind;
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use rustc_hir::{Body, ExprKind, FnDecl, HirId, Impl, ItemKind, Node};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::ty::subst::GenericArgKind;
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use rustc_middle::ty;
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::symbol::sym;
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use rustc_span::Span;
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@ -64,6 +64,7 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryWraps {
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span: Span,
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hir_id: HirId,
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) {
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// Abort if public function/method or closure.
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match fn_kind {
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FnKind::ItemFn(.., visibility, _) | FnKind::Method(.., Some(visibility), _) => {
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if visibility.node.is_pub() {
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@ -74,6 +75,7 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryWraps {
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_ => (),
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}
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// Abort if the method is implementing a trait or of it a trait method.
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if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
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if matches!(
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item.kind,
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@ -83,25 +85,44 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryWraps {
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}
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}
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let (return_type, path) = if is_type_diagnostic_item(cx, return_ty(cx, hir_id), sym::option_type) {
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("Option", &paths::OPTION_SOME)
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} else if is_type_diagnostic_item(cx, return_ty(cx, hir_id), sym::result_type) {
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("Result", &paths::RESULT_OK)
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// Get the wrapper and inner types, if can't, abort.
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let (return_type_label, path, inner_type) = if let ty::Adt(adt_def, subst) = return_ty(cx, hir_id).kind() {
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if cx.tcx.is_diagnostic_item(sym::option_type, adt_def.did) {
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("Option", &paths::OPTION_SOME, subst.type_at(0))
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} else if cx.tcx.is_diagnostic_item(sym::result_type, adt_def.did) {
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("Result", &paths::RESULT_OK, subst.type_at(0))
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} else {
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return;
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}
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} else {
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return;
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};
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// Check if all return expression respect the following condition and collect them.
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let mut suggs = Vec::new();
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let can_sugg = find_all_ret_expressions(cx, &body.value, |ret_expr| {
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if_chain! {
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if !in_macro(ret_expr.span);
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// Check if a function call.
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if let ExprKind::Call(ref func, ref args) = ret_expr.kind;
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// Get the Path of the function call.
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if let ExprKind::Path(ref qpath) = func.kind;
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// Check if OPTION_SOME or RESULT_OK, depending on return type.
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if match_qpath(qpath, path);
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if args.len() == 1;
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// Make sure the function argument does not contain a return expression.
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if !contains_return(&args[0]);
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then {
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suggs.push((ret_expr.span, snippet(cx, args[0].span.source_callsite(), "..").to_string()));
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suggs.push(
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(
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ret_expr.span,
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if inner_type.is_unit() {
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"".to_string()
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} else {
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snippet(cx, args[0].span.source_callsite(), "..").to_string()
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}
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)
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);
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true
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} else {
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false
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@ -110,39 +131,34 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryWraps {
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});
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if can_sugg && !suggs.is_empty() {
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span_lint_and_then(
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cx,
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UNNECESSARY_WRAPS,
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span,
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format!(
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"this function's return value is unnecessarily wrapped by `{}`",
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return_type
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let (lint_msg, return_type_sugg_msg, return_type_sugg, body_sugg_msg) = if inner_type.is_unit() {
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(
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"this function's return value is unnecessary".to_string(),
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"remove the return type...".to_string(),
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snippet(cx, fn_decl.output.span(), "..").to_string(),
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"...and then remove returned values",
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)
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.as_str(),
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|diag| {
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let inner_ty = return_ty(cx, hir_id)
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.walk()
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.skip(1) // skip `std::option::Option` or `std::result::Result`
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.take(1) // take the first outermost inner type
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.filter_map(|inner| match inner.unpack() {
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GenericArgKind::Type(inner_ty) => Some(inner_ty.to_string()),
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_ => None,
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});
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inner_ty.for_each(|inner_ty| {
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diag.span_suggestion(
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fn_decl.output.span(),
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format!("remove `{}` from the return type...", return_type).as_str(),
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inner_ty,
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Applicability::MaybeIncorrect,
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);
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});
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diag.multipart_suggestion(
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"...and change the returning expressions",
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suggs,
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Applicability::MaybeIncorrect,
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);
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},
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);
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} else {
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(
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format!(
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"this function's return value is unnecessarily wrapped by `{}`",
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return_type_label
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),
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format!("remove `{}` from the return type...", return_type_label),
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inner_type.to_string(),
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"...and then change returning expressions",
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)
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};
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span_lint_and_then(cx, UNNECESSARY_WRAPS, span, lint_msg.as_str(), |diag| {
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diag.span_suggestion(
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fn_decl.output.span(),
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return_type_sugg_msg.as_str(),
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return_type_sugg,
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Applicability::MaybeIncorrect,
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);
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diag.multipart_suggestion(body_sugg_msg, suggs, Applicability::MaybeIncorrect);
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});
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}
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}
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}
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@ -116,8 +116,53 @@ fn issue_6384(s: &str) -> Option<&str> {
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})
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}
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// should be linted
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fn issue_6640_1(a: bool, b: bool) -> Option<()> {
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if a && b {
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return Some(());
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}
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if a {
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Some(());
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Some(())
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} else {
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return Some(());
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}
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}
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// should be linted
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fn issue_6640_2(a: bool, b: bool) -> Result<(), i32> {
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if a && b {
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return Ok(());
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}
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if a {
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Ok(())
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} else {
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return Ok(());
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}
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}
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// should not be linted
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fn issue_6640_3() -> Option<()> {
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if true {
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Some(())
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} else {
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None
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}
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}
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// should not be linted
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fn issue_6640_4() -> Result<(), ()> {
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if true {
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Ok(())
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} else {
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Err(())
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}
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}
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fn main() {
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// method calls are not linted
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func1(true, true);
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func2(true, true);
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issue_6640_1(true, true);
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issue_6640_2(true, true);
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}
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@ -15,7 +15,7 @@ help: remove `Option` from the return type...
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LL | fn func1(a: bool, b: bool) -> i32 {
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| ^^^
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help: ...and change the returning expressions
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help: ...and then change returning expressions
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LL | return 42;
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LL | }
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@ -41,7 +41,7 @@ help: remove `Option` from the return type...
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LL | fn func2(a: bool, b: bool) -> i32 {
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| ^^^
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help: ...and change the returning expressions
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help: ...and then change returning expressions
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LL | return 10;
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LL | }
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@ -63,7 +63,7 @@ help: remove `Option` from the return type...
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LL | fn func5() -> i32 {
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| ^^^
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help: ...and change the returning expressions
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help: ...and then change returning expressions
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LL | 1
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@ -80,7 +80,7 @@ help: remove `Result` from the return type...
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LL | fn func7() -> i32 {
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| ^^^
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help: ...and change the returning expressions
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help: ...and then change returning expressions
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LL | 1
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@ -97,10 +97,62 @@ help: remove `Option` from the return type...
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LL | fn func12() -> i32 {
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| ^^^
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help: ...and change the returning expressions
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help: ...and then change returning expressions
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LL | 1
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error: aborting due to 5 previous errors
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error: this function's return value is unnecessary
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--> $DIR/unnecessary_wraps.rs:120:1
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LL | / fn issue_6640_1(a: bool, b: bool) -> Option<()> {
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LL | | if a && b {
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LL | | return Some(());
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LL | | }
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... |
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LL | | }
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LL | | }
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| |_^
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help: remove the return type...
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LL | fn issue_6640_1(a: bool, b: bool) -> Option<()> {
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| ^^^^^^^^^^
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help: ...and then remove returned values
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LL | return ;
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LL | }
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LL | if a {
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LL | Some(());
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LL |
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LL | } else {
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...
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error: this function's return value is unnecessary
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--> $DIR/unnecessary_wraps.rs:133:1
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LL | / fn issue_6640_2(a: bool, b: bool) -> Result<(), i32> {
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LL | | if a && b {
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LL | | return Ok(());
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LL | | }
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... |
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LL | | }
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LL | | }
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| |_^
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help: remove the return type...
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LL | fn issue_6640_2(a: bool, b: bool) -> Result<(), i32> {
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| ^^^^^^^^^^^^^^^
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help: ...and then remove returned values
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LL | return ;
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LL | }
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LL | if a {
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LL |
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LL | } else {
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LL | return ;
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error: aborting due to 7 previous errors
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