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Added detailled suggs for new case
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@pag4k
pag4k committed Feb 17, 2021
1 parent e0e51e4 commit 6165ccc
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Showing 2 changed files with 97 additions and 65 deletions.
100 changes: 46 additions & 54 deletions clippy_lints/src/unnecessary_wraps.rs
View file
@@ -1,13 +1,13 @@
use crate::utils::{
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,
contains_return, in_macro, match_qpath, paths, return_ty, snippet, span_lint_and_then,
visitors::find_all_ret_expressions,
};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::intravisit::FnKind;
use rustc_hir::{Body, ExprKind, FnDecl, HirId, Impl, ItemKind, Node};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty::subst::GenericArgKind;
use rustc_middle::ty;
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::symbol::sym;
use rustc_span::Span;
Expand Down Expand Up @@ -85,46 +85,44 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryWraps {
}
}

// 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, 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
// Get the wrapper and inner types, if can't, abort.
let (return_type_label, path, inner_type) = if let ty::Adt(adt_def, subst) = return_ty(cx, hir_id).kind() {
if cx.tcx.is_diagnostic_item(sym::option_type, adt_def.did) {
("Option", &paths::OPTION_SOME, subst.type_at(0))
} else if cx.tcx.is_diagnostic_item(sym::result_type, adt_def.did) {
("Result", &paths::RESULT_OK, subst.type_at(0))
} else {
return;
}
} 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()));
suggs.push(
(
ret_expr.span,
if inner_type.is_unit() {
"".to_string()
} else {
snippet(cx, args[0].span.source_callsite(), "..").to_string()
}
)
);
true
} else {
false
Expand All @@ -133,42 +131,36 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryWraps {
});

if can_sugg && !suggs.is_empty() {
// 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,
);
let (lint_msg, return_type_suggestion_msg, return_type_suggestion) = if inner_type.is_unit() {
(
"this function's return value is unnecessary".to_string(),
"remove the return type...".to_string(),
snippet(cx, fn_decl.output.span(), "..").to_string(),
)
} 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_label).as_str(),
inner_ty.to_string(),
Applicability::MaybeIncorrect,
);
diag.multipart_suggestion(
"...and change the returning expressions",
suggs,
Applicability::MaybeIncorrect,
);
},
),
format!("remove `{}` from the return type...", return_type_label),
inner_type.to_string(),
)
};

span_lint_and_then(cx, UNNECESSARY_WRAPS, span, lint_msg.as_str(), |diag| {
diag.span_suggestion(
fn_decl.output.span(),
return_type_suggestion_msg.as_str(),
return_type_suggestion,
Applicability::MaybeIncorrect,
);
}
diag.multipart_suggestion(
"...and then change the returning expressions",
suggs,
Applicability::MaybeIncorrect,
);
});
}
}
}
62 changes: 51 additions & 11 deletions tests/ui/unnecessary_wraps.stderr
View file
Expand Up @@ -15,7 +15,7 @@ help: remove `Option` from the return type...
|
LL | fn func1(a: bool, b: bool) -> i32 {
| ^^^
help: ...and change the returning expressions
help: ...and then change the returning expressions
|
LL | return 42;
LL | }
Expand All @@ -41,7 +41,7 @@ help: remove `Option` from the return type...
|
LL | fn func2(a: bool, b: bool) -> i32 {
| ^^^
help: ...and change the returning expressions
help: ...and then change the returning expressions
|
LL | return 10;
LL | }
Expand All @@ -63,7 +63,7 @@ help: remove `Option` from the return type...
|
LL | fn func5() -> i32 {
| ^^^
help: ...and change the returning expressions
help: ...and then change the returning expressions
|
LL | 1
|
Expand All @@ -80,7 +80,7 @@ help: remove `Result` from the return type...
|
LL | fn func7() -> i32 {
| ^^^
help: ...and change the returning expressions
help: ...and then change the returning expressions
|
LL | 1
|
Expand All @@ -97,22 +97,62 @@ help: remove `Option` from the return type...
|
LL | fn func12() -> i32 {
| ^^^
help: ...and change the returning expressions
help: ...and then change the returning expressions
|
LL | 1
|

error: unneeded wrapped unit return type
--> $DIR/unnecessary_wraps.rs:120:38
error: this function's return value is unnecessary
--> $DIR/unnecessary_wraps.rs:120:1
|
LL | / fn issue_6640_1(a: bool, b: bool) -> Option<()> {
LL | | if a && b {
LL | | return Some(());
LL | | }
... |
LL | | }
LL | | }
| |_^
|
help: remove the return type...
|
LL | fn issue_6640_1(a: bool, b: bool) -> Option<()> {
| ^^^^^^^^^^ help: remove the `-> Option<[...]>`
| ^^^^^^^^^^
help: ...and then change the returning expressions
|
LL | return ;
LL | }
LL | if a {
LL | Some(());
LL |
LL | } else {
...

error: unneeded wrapped unit return type
--> $DIR/unnecessary_wraps.rs:133:38
error: this function's return value is unnecessary
--> $DIR/unnecessary_wraps.rs:133:1
|
LL | / fn issue_6640_2(a: bool, b: bool) -> Result<(), i32> {
LL | | if a && b {
LL | | return Ok(());
LL | | }
... |
LL | | }
LL | | }
| |_^
|
help: remove the return type...
|
LL | fn issue_6640_2(a: bool, b: bool) -> Result<(), i32> {
| ^^^^^^^^^^^^^^^ help: remove the `-> Result<[...]>`
| ^^^^^^^^^^^^^^^
help: ...and then change the returning expressions
|
LL | return ;
LL | }
LL | if a {
LL |
LL | } else {
LL | return ;
|

error: aborting due to 7 previous errors

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