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Auto merge of #6190 - montrivo:manual_result_unwrap_or, r=ebroto

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manual_unwrap_or / support Result::unwrap_or

Implements partially #5923.

changelog: support Result::unwrap_or in manual_unwrap_or
This commit is contained in:
bors 2020-10-24 23:09:14 +00:00
commit 29979ad043
5 changed files with 311 additions and 37 deletions
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80
clippy_lints/src/manual_unwrap_or.rs
View File

@ -1,8 +1,9 @@
use crate::consts::constant_simple;
use crate::utils;
use crate::utils::sugg;
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::{def, Arm, Expr, ExprKind, PatKind, QPath};
use rustc_hir::{def, Arm, Expr, ExprKind, Pat, PatKind, QPath};
use rustc_lint::LintContext;
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::lint::in_external_macro;
@ -10,7 +11,7 @@ use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
/// **What it does:**
/// Finds patterns that reimplement `Option::unwrap_or`.
/// Finds patterns that reimplement `Option::unwrap_or` or `Result::unwrap_or`.
///
/// **Why is this bad?**
/// Concise code helps focusing on behavior instead of boilerplate.
@ -33,7 +34,7 @@ declare_clippy_lint! {
/// ```
pub MANUAL_UNWRAP_OR,
complexity,
"finds patterns that can be encoded more concisely with `Option::unwrap_or`"
"finds patterns that can be encoded more concisely with `Option::unwrap_or` or `Result::unwrap_or`"
}
declare_lint_pass!(ManualUnwrapOr => [MANUAL_UNWRAP_OR]);
@ -43,32 +44,50 @@ impl LateLintPass<'_> for ManualUnwrapOr {
if in_external_macro(cx.sess(), expr.span) {
return;
}
lint_option_unwrap_or_case(cx, expr);
lint_manual_unwrap_or(cx, expr);
}
}
fn lint_option_unwrap_or_case<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
fn applicable_none_arm<'a>(arms: &'a [Arm<'a>]) -> Option<&'a Arm<'a>> {
#[derive(Copy, Clone)]
enum Case {
Option,
Result,
}
impl Case {
fn unwrap_fn_path(&self) -> &str {
match self {
Case::Option => "Option::unwrap_or",
Case::Result => "Result::unwrap_or",
}
}
}
fn lint_manual_unwrap_or<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
fn applicable_or_arm<'a>(arms: &'a [Arm<'a>]) -> Option<&'a Arm<'a>> {
if_chain! {
if arms.len() == 2;
if arms.iter().all(|arm| arm.guard.is_none());
if let Some((idx, none_arm)) = arms.iter().enumerate().find(|(_, arm)|
if let PatKind::Path(ref qpath) = arm.pat.kind {
utils::match_qpath(qpath, &utils::paths::OPTION_NONE)
} else {
false
if let Some((idx, or_arm)) = arms.iter().enumerate().find(|(_, arm)|
match arm.pat.kind {
PatKind::Path(ref some_qpath) =>
utils::match_qpath(some_qpath, &utils::paths::OPTION_NONE),
PatKind::TupleStruct(ref err_qpath, &[Pat { kind: PatKind::Wild, .. }], _) =>
utils::match_qpath(err_qpath, &utils::paths::RESULT_ERR),
_ => false,
}
);
let some_arm = &arms[1 - idx];
if let PatKind::TupleStruct(ref some_qpath, &[some_binding], _) = some_arm.pat.kind;
if utils::match_qpath(some_qpath, &utils::paths::OPTION_SOME);
if let PatKind::Binding(_, binding_hir_id, ..) = some_binding.kind;
if let ExprKind::Path(QPath::Resolved(_, body_path)) = some_arm.body.kind;
let unwrap_arm = &arms[1 - idx];
if let PatKind::TupleStruct(ref unwrap_qpath, &[unwrap_pat], _) = unwrap_arm.pat.kind;
if utils::match_qpath(unwrap_qpath, &utils::paths::OPTION_SOME)
|| utils::match_qpath(unwrap_qpath, &utils::paths::RESULT_OK);
if let PatKind::Binding(_, binding_hir_id, ..) = unwrap_pat.kind;
if let ExprKind::Path(QPath::Resolved(_, body_path)) = unwrap_arm.body.kind;
if let def::Res::Local(body_path_hir_id) = body_path.res;
if body_path_hir_id == binding_hir_id;
if !utils::usage::contains_return_break_continue_macro(none_arm.body);
if !utils::usage::contains_return_break_continue_macro(or_arm.body);
then {
Some(none_arm)
Some(or_arm)
} else {
None
}
@ -78,24 +97,29 @@ fn lint_option_unwrap_or_case<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tc
if_chain! {
if let ExprKind::Match(scrutinee, match_arms, _) = expr.kind;
let ty = cx.typeck_results().expr_ty(scrutinee);
if utils::is_type_diagnostic_item(cx, ty, sym!(option_type));
if let Some(none_arm) = applicable_none_arm(match_arms);
if let Some(scrutinee_snippet) = utils::snippet_opt(cx, scrutinee.span);
if let Some(none_body_snippet) = utils::snippet_opt(cx, none_arm.body.span);
if let Some(case) = if utils::is_type_diagnostic_item(cx, ty, sym!(option_type)) {
Some(Case::Option)
} else if utils::is_type_diagnostic_item(cx, ty, sym!(result_type)) {
Some(Case::Result)
} else {
None
};
if let Some(or_arm) = applicable_or_arm(match_arms);
if let Some(or_body_snippet) = utils::snippet_opt(cx, or_arm.body.span);
if let Some(indent) = utils::indent_of(cx, expr.span);
if constant_simple(cx, cx.typeck_results(), none_arm.body).is_some();
if constant_simple(cx, cx.typeck_results(), or_arm.body).is_some();
then {
let reindented_none_body =
utils::reindent_multiline(none_body_snippet.into(), true, Some(indent));
let reindented_or_body =
utils::reindent_multiline(or_body_snippet.into(), true, Some(indent));
utils::span_lint_and_sugg(
cx,
MANUAL_UNWRAP_OR, expr.span,
"this pattern reimplements `Option::unwrap_or`",
&format!("this pattern reimplements `{}`", case.unwrap_fn_path()),
"replace with",
format!(
"{}.unwrap_or({})",
scrutinee_snippet,
reindented_none_body,
sugg::Sugg::hir(cx, scrutinee, "..").maybe_par(),
reindented_or_body,
),
Applicability::MachineApplicable,
);

2
src/lintlist/mod.rs
View File

@ -1190,7 +1190,7 @@ vec![
Lint {
name: "manual_unwrap_or",
group: "complexity",
desc: "finds patterns that can be encoded more concisely with `Option::unwrap_or`",
desc: "finds patterns that can be encoded more concisely with `Option::unwrap_or` or `Result::unwrap_or`",
deprecation: None,
module: "manual_unwrap_or",
},

73
tests/ui/manual_unwrap_or.fixed
View File

@ -1,7 +1,8 @@
// run-rustfix
#![allow(dead_code)]
#![allow(unused_variables)]
fn unwrap_or() {
fn option_unwrap_or() {
// int case
Some(1).unwrap_or(42);
@ -65,4 +66,74 @@ fn unwrap_or() {
};
}
fn result_unwrap_or() {
// int case
Ok::<i32, &str>(1).unwrap_or(42);
// int case, scrutinee is a binding
let a = Ok::<i32, &str>(1);
a.unwrap_or(42);
// int case, suggestion must surround Result expr with parenthesis
(Ok(1) as Result<i32, &str>).unwrap_or(42);
// method call case, suggestion must not surround Result expr `s.method()` with parenthesis
struct S {}
impl S {
fn method(self) -> Option<i32> {
Some(42)
}
}
let s = S {};
s.method().unwrap_or(42);
// int case reversed
Ok::<i32, &str>(1).unwrap_or(42);
// richer none expr
Ok::<i32, &str>(1).unwrap_or(1 + 42);
// multiline case
#[rustfmt::skip]
Ok::<i32, &str>(1).unwrap_or({
42 + 42
+ 42 + 42 + 42
+ 42 + 42 + 42
});
// string case
Ok::<&str, &str>("Bob").unwrap_or("Alice");
// don't lint
match Ok::<i32, &str>(1) {
Ok(i) => i + 2,
Err(_) => 42,
};
match Ok::<i32, &str>(1) {
Ok(i) => i,
Err(_) => return,
};
for j in 0..4 {
match Ok::<i32, &str>(j) {
Ok(i) => i,
Err(_) => continue,
};
match Ok::<i32, &str>(j) {
Ok(i) => i,
Err(_) => break,
};
}
// don't lint, Err value is used
match Ok::<&str, &str>("Alice") {
Ok(s) => s,
Err(s) => s,
};
// could lint, but unused_variables takes care of it
match Ok::<&str, &str>("Alice") {
Ok(s) => s,
Err(s) => "Bob",
};
}
fn main() {}

97
tests/ui/manual_unwrap_or.rs
View File

@ -1,7 +1,8 @@
// run-rustfix
#![allow(dead_code)]
#![allow(unused_variables)]
fn unwrap_or() {
fn option_unwrap_or() {
// int case
match Some(1) {
Some(i) => i,
@ -80,4 +81,98 @@ fn unwrap_or() {
};
}
fn result_unwrap_or() {
// int case
match Ok::<i32, &str>(1) {
Ok(i) => i,
Err(_) => 42,
};
// int case, scrutinee is a binding
let a = Ok::<i32, &str>(1);
match a {
Ok(i) => i,
Err(_) => 42,
};
// int case, suggestion must surround Result expr with parenthesis
match Ok(1) as Result<i32, &str> {
Ok(i) => i,
Err(_) => 42,
};
// method call case, suggestion must not surround Result expr `s.method()` with parenthesis
struct S {}
impl S {
fn method(self) -> Option<i32> {
Some(42)
}
}
let s = S {};
match s.method() {
Some(i) => i,
None => 42,
};
// int case reversed
match Ok::<i32, &str>(1) {
Err(_) => 42,
Ok(i) => i,
};
// richer none expr
match Ok::<i32, &str>(1) {
Ok(i) => i,
Err(_) => 1 + 42,
};
// multiline case
#[rustfmt::skip]
match Ok::<i32, &str>(1) {
Ok(i) => i,
Err(_) => {
42 + 42
+ 42 + 42 + 42
+ 42 + 42 + 42
}
};
// string case
match Ok::<&str, &str>("Bob") {
Ok(i) => i,
Err(_) => "Alice",
};
// don't lint
match Ok::<i32, &str>(1) {
Ok(i) => i + 2,
Err(_) => 42,
};
match Ok::<i32, &str>(1) {
Ok(i) => i,
Err(_) => return,
};
for j in 0..4 {
match Ok::<i32, &str>(j) {
Ok(i) => i,
Err(_) => continue,
};
match Ok::<i32, &str>(j) {
Ok(i) => i,
Err(_) => break,
};
}
// don't lint, Err value is used
match Ok::<&str, &str>("Alice") {
Ok(s) => s,
Err(s) => s,
};
// could lint, but unused_variables takes care of it
match Ok::<&str, &str>("Alice") {
Ok(s) => s,
Err(s) => "Bob",
};
}
fn main() {}

96
tests/ui/manual_unwrap_or.stderr
View File

@ -1,5 +1,5 @@
error: this pattern reimplements `Option::unwrap_or`
--> $DIR/manual_unwrap_or.rs:6:5
--> $DIR/manual_unwrap_or.rs:7:5
|
LL | / match Some(1) {
LL | | Some(i) => i,
@ -10,7 +10,7 @@ LL | | };
= note: `-D clippy::manual-unwrap-or` implied by `-D warnings`
error: this pattern reimplements `Option::unwrap_or`
--> $DIR/manual_unwrap_or.rs:12:5
--> $DIR/manual_unwrap_or.rs:13:5
|
LL | / match Some(1) {
LL | | None => 42,
@ -19,7 +19,7 @@ LL | | };
| |_____^ help: replace with: `Some(1).unwrap_or(42)`
error: this pattern reimplements `Option::unwrap_or`
--> $DIR/manual_unwrap_or.rs:18:5
--> $DIR/manual_unwrap_or.rs:19:5
|
LL | / match Some(1) {
LL | | Some(i) => i,
@ -28,7 +28,7 @@ LL | | };
| |_____^ help: replace with: `Some(1).unwrap_or(1 + 42)`
error: this pattern reimplements `Option::unwrap_or`
--> $DIR/manual_unwrap_or.rs:25:5
--> $DIR/manual_unwrap_or.rs:26:5
|
LL | / match Some(1) {
LL | | Some(i) => i,
@ -49,7 +49,7 @@ LL | });
|
error: this pattern reimplements `Option::unwrap_or`
--> $DIR/manual_unwrap_or.rs:35:5
--> $DIR/manual_unwrap_or.rs:36:5
|
LL | / match Some("Bob") {
LL | | Some(i) => i,
@ -57,5 +57,89 @@ LL | | None => "Alice",
LL | | };
| |_____^ help: replace with: `Some("Bob").unwrap_or("Alice")`
error: aborting due to 5 previous errors
error: this pattern reimplements `Result::unwrap_or`
--> $DIR/manual_unwrap_or.rs:86:5
|
LL | / match Ok::<i32, &str>(1) {
LL | | Ok(i) => i,
LL | | Err(_) => 42,
LL | | };
| |_____^ help: replace with: `Ok::<i32, &str>(1).unwrap_or(42)`
error: this pattern reimplements `Result::unwrap_or`
--> $DIR/manual_unwrap_or.rs:93:5
|
LL | / match a {
LL | | Ok(i) => i,
LL | | Err(_) => 42,
LL | | };
| |_____^ help: replace with: `a.unwrap_or(42)`
error: this pattern reimplements `Result::unwrap_or`
--> $DIR/manual_unwrap_or.rs:99:5
|
LL | / match Ok(1) as Result<i32, &str> {
LL | | Ok(i) => i,
LL | | Err(_) => 42,
LL | | };
| |_____^ help: replace with: `(Ok(1) as Result<i32, &str>).unwrap_or(42)`
error: this pattern reimplements `Option::unwrap_or`
--> $DIR/manual_unwrap_or.rs:112:5
|
LL | / match s.method() {
LL | | Some(i) => i,
LL | | None => 42,
LL | | };
| |_____^ help: replace with: `s.method().unwrap_or(42)`
error: this pattern reimplements `Result::unwrap_or`
--> $DIR/manual_unwrap_or.rs:118:5
|
LL | / match Ok::<i32, &str>(1) {
LL | | Err(_) => 42,
LL | | Ok(i) => i,
LL | | };
| |_____^ help: replace with: `Ok::<i32, &str>(1).unwrap_or(42)`
error: this pattern reimplements `Result::unwrap_or`
--> $DIR/manual_unwrap_or.rs:124:5
|
LL | / match Ok::<i32, &str>(1) {
LL | | Ok(i) => i,
LL | | Err(_) => 1 + 42,
LL | | };
| |_____^ help: replace with: `Ok::<i32, &str>(1).unwrap_or(1 + 42)`
error: this pattern reimplements `Result::unwrap_or`
--> $DIR/manual_unwrap_or.rs:131:5
|
LL | / match Ok::<i32, &str>(1) {
LL | | Ok(i) => i,
LL | | Err(_) => {
LL | | 42 + 42
... |
LL | | }
LL | | };
| |_____^
|
help: replace with
|
LL | Ok::<i32, &str>(1).unwrap_or({
LL | 42 + 42
LL | + 42 + 42 + 42
LL | + 42 + 42 + 42
LL | });
|
error: this pattern reimplements `Result::unwrap_or`
--> $DIR/manual_unwrap_or.rs:141:5
|
LL | / match Ok::<&str, &str>("Bob") {
LL | | Ok(i) => i,
LL | | Err(_) => "Alice",
LL | | };
| |_____^ help: replace with: `Ok::<&str, &str>("Bob").unwrap_or("Alice")`
error: aborting due to 13 previous errors