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Auto merge of #4137 - euclio:let-return, r=oli-obk

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tweak `let_and_return` diagnostic

changelog: `let_and_return`: label the unnecessary let binding and convert the note to a structured
suggestion
This commit is contained in:
bors 2019-05-27 13:04:14 +00:00
commit 7b501f0f6a
3 changed files with 43 additions and 23 deletions
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27
clippy_lints/src/returns.rs
View file

@ -7,7 +7,7 @@ use syntax::source_map::Span;
use syntax::visit::FnKind; use syntax::visit::FnKind;
use syntax_pos::BytePos; use syntax_pos::BytePos;
use crate::utils::{in_macro_or_desugar, match_path_ast, snippet_opt, span_lint_and_then, span_note_and_lint}; use crate::utils::{in_macro_or_desugar, match_path_ast, snippet_opt, span_lint_and_then};
declare_clippy_lint! { declare_clippy_lint! {
/// **What it does:** Checks for return statements at the end of a block. /// **What it does:** Checks for return statements at the end of a block.
@ -164,13 +164,28 @@ impl Return {
if match_path_ast(path, &[&*ident.name.as_str()]); if match_path_ast(path, &[&*ident.name.as_str()]);
if !in_external_macro(cx.sess(), initexpr.span); if !in_external_macro(cx.sess(), initexpr.span);
then { then {
span_note_and_lint(cx, span_lint_and_then(
cx,
LET_AND_RETURN, LET_AND_RETURN,
retexpr.span, retexpr.span,
"returning the result of a let binding from a block. \ "returning the result of a let binding from a block",
Consider returning the expression directly.", |err| {
initexpr.span, err.span_label(local.span, "unnecessary let binding");
"this expression can be directly returned");
if let Some(snippet) = snippet_opt(cx, initexpr.span) {
err.multipart_suggestion(
"return the expression directly",
vec![
(local.span, String::new()),
(retexpr.span, snippet),
],
Applicability::MachineApplicable,
);
} else {
err.span_help(initexpr.span, "this expression can be directly returned");
}
},
);
} }
} }
} }

12
tests/ui/author/matches.stderr
View file

@ -1,15 +1,17 @@
error: returning the result of a let binding from a block. Consider returning the expression directly. error: returning the result of a let binding from a block
--> $DIR/matches.rs:9:13 --> $DIR/matches.rs:9:13
| |
LL | let x = 3;
| ---------- unnecessary let binding
LL | x LL | x
| ^ | ^
| |
= note: `-D clippy::let-and-return` implied by `-D warnings` = note: `-D clippy::let-and-return` implied by `-D warnings`
note: this expression can be directly returned help: return the expression directly
--> $DIR/matches.rs:8:21 |
LL |
LL | 3
| |
LL | let x = 3;
| ^
error: aborting due to previous error error: aborting due to previous error

23
tests/ui/let_return.stderr
View file

@ -1,27 +1,30 @@
error: returning the result of a let binding from a block. Consider returning the expression directly. error: returning the result of a let binding from a block
--> $DIR/let_return.rs:7:5 --> $DIR/let_return.rs:7:5
| |
LL | let x = 5;
| ---------- unnecessary let binding
LL | x LL | x
| ^ | ^
| |
= note: `-D clippy::let-and-return` implied by `-D warnings` = note: `-D clippy::let-and-return` implied by `-D warnings`
note: this expression can be directly returned help: return the expression directly
--> $DIR/let_return.rs:6:13 |
LL |
LL | 5
| |
LL | let x = 5;
| ^
error: returning the result of a let binding from a block. Consider returning the expression directly. error: returning the result of a let binding from a block
--> $DIR/let_return.rs:13:9 --> $DIR/let_return.rs:13:9
| |
LL | let x = 5;
| ---------- unnecessary let binding
LL | x LL | x
| ^ | ^
help: return the expression directly
| |
note: this expression can be directly returned LL |
--> $DIR/let_return.rs:12:17 LL | 5
| |
LL | let x = 5;
| ^
error: aborting due to 2 previous errors error: aborting due to 2 previous errors