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Auto merge of #7840 - dswij:question-mark-result, r=llogiq

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Cover `Result` for `question_mark`

closes #7135

changelog: [`question_mark`] now covers `Result`
This commit is contained in:
bors 2021-10-20 07:27:13 +00:00
commit ee8c155527
4 changed files with 104 additions and 22 deletions
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74
clippy_lints/src/question_mark.rs
View File

@ -4,10 +4,10 @@
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::sugg::Sugg;
use clippy_utils::ty::is_type_diagnostic_item;
use clippy_utils::{eq_expr_value, path_to_local_id};
use clippy_utils::{eq_expr_value, path_to_local, path_to_local_id};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::LangItem::{OptionNone, OptionSome};
use rustc_hir::LangItem::{OptionNone, OptionSome, ResultOk};
use rustc_hir::{BindingAnnotation, Block, Expr, ExprKind, PatKind, StmtKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
@ -48,16 +48,20 @@ impl QuestionMark {
/// }
/// ```
///
/// ```ignore
/// if result.is_err() {
/// return result;
/// }
/// ```
///
/// If it matches, it will suggest to use the question mark operator instead
fn check_is_none_and_early_return_none(cx: &LateContext<'_>, expr: &Expr<'_>) {
fn check_is_none_or_err_and_early_return(cx: &LateContext<'_>, expr: &Expr<'_>) {
if_chain! {
if let Some(higher::If { cond, then, r#else }) = higher::If::hir(expr);
if let ExprKind::MethodCall(segment, _, args, _) = &cond.kind;
if segment.ident.name == sym!(is_none);
if Self::expression_returns_none(cx, then);
if let Some(subject) = args.get(0);
if Self::is_option(cx, subject);
if (Self::option_check_and_early_return(cx, subject, then) && segment.ident.name == sym!(is_none)) ||
(Self::result_check_and_early_return(cx, subject, then) && segment.ident.name == sym!(is_err));
then {
let mut applicability = Applicability::MachineApplicable;
let receiver_str = &Sugg::hir_with_applicability(cx, subject, "..", &mut applicability);
@ -95,31 +99,24 @@ fn check_is_none_and_early_return_none(cx: &LateContext<'_>, expr: &Expr<'_>) {
}
}
fn check_if_let_some_and_early_return_none(cx: &LateContext<'_>, expr: &Expr<'_>) {
fn check_if_let_some_or_err_and_early_return(cx: &LateContext<'_>, expr: &Expr<'_>) {
if_chain! {
if let Some(higher::IfLet { let_pat, let_expr, if_then, if_else: Some(if_else) })
= higher::IfLet::hir(cx, expr);
if Self::is_option(cx, let_expr);
if let PatKind::TupleStruct(ref path1, fields, None) = let_pat.kind;
if is_lang_ctor(cx, path1, OptionSome);
if (Self::option_check_and_early_return(cx, let_expr, if_else) && is_lang_ctor(cx, path1, OptionSome)) ||
(Self::result_check_and_early_return(cx, let_expr, if_else) && is_lang_ctor(cx, path1, ResultOk));
if let PatKind::Binding(annot, bind_id, _, _) = fields[0].kind;
let by_ref = matches!(annot, BindingAnnotation::Ref | BindingAnnotation::RefMut);
if let ExprKind::Block(block, None) = if_then.kind;
if block.stmts.is_empty();
if let Some(trailing_expr) = &block.expr;
if path_to_local_id(trailing_expr, bind_id);
if Self::expression_returns_none(cx, if_else);
then {
let mut applicability = Applicability::MachineApplicable;
let receiver_str = snippet_with_applicability(cx, let_expr.span, "..", &mut applicability);
let replacement = format!(
"{}{}?",
receiver_str,
if by_ref { ".as_ref()" } else { "" },
);
let replacement = format!("{}{}?", receiver_str, if by_ref { ".as_ref()" } else { "" },);
span_lint_and_sugg(
cx,
@ -134,6 +131,14 @@ fn check_if_let_some_and_early_return_none(cx: &LateContext<'_>, expr: &Expr<'_>
}
}
fn result_check_and_early_return(cx: &LateContext<'_>, expr: &Expr<'_>, nested_expr: &Expr<'_>) -> bool {
Self::is_result(cx, expr) && Self::expression_returns_unmodified_err(cx, nested_expr, expr)
}
fn option_check_and_early_return(cx: &LateContext<'_>, expr: &Expr<'_>, nested_expr: &Expr<'_>) -> bool {
Self::is_option(cx, expr) && Self::expression_returns_none(cx, nested_expr)
}
fn moves_by_default(cx: &LateContext<'_>, expression: &Expr<'_>) -> bool {
let expr_ty = cx.typeck_results().expr_ty(expression);
@ -146,6 +151,12 @@ fn is_option(cx: &LateContext<'_>, expression: &Expr<'_>) -> bool {
is_type_diagnostic_item(cx, expr_ty, sym::Option)
}
fn is_result(cx: &LateContext<'_>, expression: &Expr<'_>) -> bool {
let expr_ty = cx.typeck_results().expr_ty(expression);
is_type_diagnostic_item(cx, expr_ty, sym::Result)
}
fn expression_returns_none(cx: &LateContext<'_>, expression: &Expr<'_>) -> bool {
match expression.kind {
ExprKind::Block(block, _) => {
@ -161,6 +172,27 @@ fn expression_returns_none(cx: &LateContext<'_>, expression: &Expr<'_>) -> bool
}
}
fn expression_returns_unmodified_err(
cx: &LateContext<'_>,
expression: &Expr<'_>,
origin_hir_id: &Expr<'_>,
) -> bool {
match expression.kind {
ExprKind::Block(block, _) => {
if let Some(return_expression) = Self::return_expression(block) {
return Self::expression_returns_unmodified_err(cx, return_expression, origin_hir_id);
}
false
},
ExprKind::Ret(Some(expr)) | ExprKind::Call(expr, _) => {
Self::expression_returns_unmodified_err(cx, expr, origin_hir_id)
},
ExprKind::Path(_) => path_to_local(expression) == path_to_local(origin_hir_id),
_ => false,
}
}
fn return_expression<'tcx>(block: &Block<'tcx>) -> Option<&'tcx Expr<'tcx>> {
// Check if last expression is a return statement. Then, return the expression
if_chain! {
@ -189,7 +221,7 @@ fn return_expression<'tcx>(block: &Block<'tcx>) -> Option<&'tcx Expr<'tcx>> {
impl<'tcx> LateLintPass<'tcx> for QuestionMark {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
Self::check_is_none_and_early_return_none(cx, expr);
Self::check_if_let_some_and_early_return_none(cx, expr);
Self::check_is_none_or_err_and_early_return(cx, expr);
Self::check_if_let_some_or_err_and_early_return(cx, expr);
}
}

17
tests/ui/question_mark.fixed
View File

@ -104,6 +104,21 @@ fn func() -> Option<i32> {
Some(0)
}
fn result_func(x: Result<i32, &str>) -> Result<i32, &str> {
let _ = x?;
x?;
// No warning
let y = if let Ok(x) = x {
x
} else {
return Err("some error");
};
Ok(y)
}
fn main() {
some_func(Some(42));
some_func(None);
@ -123,4 +138,6 @@ fn main() {
returns_something_similar_to_option(so);
func();
let _ = result_func(Ok(42));
}

19
tests/ui/question_mark.rs
View File

@ -134,6 +134,23 @@ fn f() -> Option<String> {
Some(0)
}
fn result_func(x: Result<i32, &str>) -> Result<i32, &str> {
let _ = if let Ok(x) = x { x } else { return x };
if x.is_err() {
return x;
}
// No warning
let y = if let Ok(x) = x {
x
} else {
return Err("some error");
};
Ok(y)
}
fn main() {
some_func(Some(42));
some_func(None);
@ -153,4 +170,6 @@ fn main() {
returns_something_similar_to_option(so);
func();
let _ = result_func(Ok(42));
}

16
tests/ui/question_mark.stderr
View File

@ -100,5 +100,19 @@ LL | | return None;
LL | | }
| |_____^ help: replace it with: `f()?;`
error: aborting due to 11 previous errors
error: this if-let-else may be rewritten with the `?` operator
--> $DIR/question_mark.rs:138:13
|
LL | let _ = if let Ok(x) = x { x } else { return x };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `x?`
error: this block may be rewritten with the `?` operator
--> $DIR/question_mark.rs:140:5
|
LL | / if x.is_err() {
LL | | return x;
LL | | }
| |_____^ help: replace it with: `x?;`
error: aborting due to 13 previous errors