mirror of
https://github.com/rust-lang/rust.git
synced 2024-11-23 15:23:46 +00:00
Implement new lint: if_then_some_else_none
This commit is contained in:
parent
0153679a4e
commit
a672d335a2
@ -2103,6 +2103,7 @@ Released 2018-09-13
|
||||
[`if_let_some_result`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_let_some_result
|
||||
[`if_not_else`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_not_else
|
||||
[`if_same_then_else`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_same_then_else
|
||||
[`if_then_some_else_none`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_then_some_else_none
|
||||
[`ifs_same_cond`]: https://rust-lang.github.io/rust-clippy/master/index.html#ifs_same_cond
|
||||
[`implicit_clone`]: https://rust-lang.github.io/rust-clippy/master/index.html#implicit_clone
|
||||
[`implicit_hasher`]: https://rust-lang.github.io/rust-clippy/master/index.html#implicit_hasher
|
||||
|
88
clippy_lints/src/if_then_some_else_none.rs
Normal file
88
clippy_lints/src/if_then_some_else_none.rs
Normal file
@ -0,0 +1,88 @@
|
||||
use crate::utils;
|
||||
use if_chain::if_chain;
|
||||
use rustc_errors::Applicability;
|
||||
use rustc_hir::{Expr, ExprKind};
|
||||
use rustc_lint::{LateContext, LateLintPass, LintContext};
|
||||
use rustc_middle::lint::in_external_macro;
|
||||
use rustc_session::{declare_lint_pass, declare_tool_lint};
|
||||
|
||||
declare_clippy_lint! {
|
||||
/// **What it does:** Checks for if-else that could be written to `bool::then`.
|
||||
///
|
||||
/// **Why is this bad?** Looks a little redundant. Using `bool::then` helps it have less lines of code.
|
||||
///
|
||||
/// **Known problems:** None.
|
||||
///
|
||||
/// **Example:**
|
||||
///
|
||||
/// ```rust
|
||||
/// # let v = vec![0];
|
||||
/// let a = if v.is_empty() {
|
||||
/// println!("true!");
|
||||
/// Some(42)
|
||||
/// } else {
|
||||
/// None
|
||||
/// };
|
||||
/// ```
|
||||
///
|
||||
/// Could be written:
|
||||
///
|
||||
/// ```rust
|
||||
/// # let v = vec![0];
|
||||
/// let a = v.is_empty().then(|| {
|
||||
/// println!("true!");
|
||||
/// 42
|
||||
/// });
|
||||
/// ```
|
||||
pub IF_THEN_SOME_ELSE_NONE,
|
||||
restriction,
|
||||
"Finds if-else that could be written using `bool::then`"
|
||||
}
|
||||
|
||||
declare_lint_pass!(IfThenSomeElseNone => [IF_THEN_SOME_ELSE_NONE]);
|
||||
|
||||
impl LateLintPass<'_> for IfThenSomeElseNone {
|
||||
fn check_expr(&mut self, cx: &LateContext<'_>, expr: &'tcx Expr<'_>) {
|
||||
if in_external_macro(cx.sess(), expr.span) {
|
||||
return;
|
||||
}
|
||||
|
||||
// We only care about the top-most `if` in the chain
|
||||
if utils::parent_node_is_if_expr(expr, cx) {
|
||||
return;
|
||||
}
|
||||
|
||||
if_chain! {
|
||||
if let ExprKind::If(ref cond, ref then, Some(ref els)) = expr.kind;
|
||||
if let ExprKind::Block(ref then_block, _) = then.kind;
|
||||
if let Some(ref then_expr) = then_block.expr;
|
||||
if let ExprKind::Call(ref then_call, [then_arg]) = then_expr.kind;
|
||||
if let ExprKind::Path(ref then_call_qpath) = then_call.kind;
|
||||
if utils::match_qpath(then_call_qpath, &utils::paths::OPTION_SOME);
|
||||
if let ExprKind::Block(ref els_block, _) = els.kind;
|
||||
if els_block.stmts.is_empty();
|
||||
if let Some(ref els_expr) = els_block.expr;
|
||||
if let ExprKind::Path(ref els_call_qpath) = els_expr.kind;
|
||||
if utils::match_qpath(els_call_qpath, &utils::paths::OPTION_NONE);
|
||||
then {
|
||||
let mut applicability = Applicability::MachineApplicable;
|
||||
let cond_snip = utils::snippet_with_applicability(cx, cond.span, "[condition]", &mut applicability);
|
||||
let arg_snip = utils::snippet_with_applicability(cx, then_arg.span, "", &mut applicability);
|
||||
let sugg = format!(
|
||||
"{}.then(|| {{ /* snippet */ {} }})",
|
||||
cond_snip,
|
||||
arg_snip,
|
||||
);
|
||||
utils::span_lint_and_sugg(
|
||||
cx,
|
||||
IF_THEN_SOME_ELSE_NONE,
|
||||
expr.span,
|
||||
"this could be simplified with `bool::then`",
|
||||
"try this",
|
||||
sugg,
|
||||
applicability,
|
||||
);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
@ -230,6 +230,7 @@ mod identity_op;
|
||||
mod if_let_mutex;
|
||||
mod if_let_some_result;
|
||||
mod if_not_else;
|
||||
mod if_then_some_else_none;
|
||||
mod implicit_return;
|
||||
mod implicit_saturating_sub;
|
||||
mod inconsistent_struct_constructor;
|
||||
@ -667,6 +668,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
|
||||
&if_let_mutex::IF_LET_MUTEX,
|
||||
&if_let_some_result::IF_LET_SOME_RESULT,
|
||||
&if_not_else::IF_NOT_ELSE,
|
||||
&if_then_some_else_none::IF_THEN_SOME_ELSE_NONE,
|
||||
&implicit_return::IMPLICIT_RETURN,
|
||||
&implicit_saturating_sub::IMPLICIT_SATURATING_SUB,
|
||||
&inconsistent_struct_constructor::INCONSISTENT_STRUCT_CONSTRUCTOR,
|
||||
@ -1282,6 +1284,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
|
||||
store.register_late_pass(|| box redundant_slicing::RedundantSlicing);
|
||||
store.register_late_pass(|| box from_str_radix_10::FromStrRadix10);
|
||||
store.register_late_pass(|| box manual_map::ManualMap);
|
||||
store.register_late_pass(|| box if_then_some_else_none::IfThenSomeElseNone);
|
||||
|
||||
store.register_group(true, "clippy::restriction", Some("clippy_restriction"), vec![
|
||||
LintId::of(&arithmetic::FLOAT_ARITHMETIC),
|
||||
@ -1297,6 +1300,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
|
||||
LintId::of(&exhaustive_items::EXHAUSTIVE_STRUCTS),
|
||||
LintId::of(&exit::EXIT),
|
||||
LintId::of(&float_literal::LOSSY_FLOAT_LITERAL),
|
||||
LintId::of(&if_then_some_else_none::IF_THEN_SOME_ELSE_NONE),
|
||||
LintId::of(&implicit_return::IMPLICIT_RETURN),
|
||||
LintId::of(&indexing_slicing::INDEXING_SLICING),
|
||||
LintId::of(&inherent_impl::MULTIPLE_INHERENT_IMPL),
|
||||
|
66
tests/ui/if_then_some_else_none.rs
Normal file
66
tests/ui/if_then_some_else_none.rs
Normal file
@ -0,0 +1,66 @@
|
||||
#![warn(clippy::if_then_some_else_none)]
|
||||
|
||||
fn main() {
|
||||
// Should issue an error.
|
||||
let _ = if foo() {
|
||||
println!("true!");
|
||||
Some("foo")
|
||||
} else {
|
||||
None
|
||||
};
|
||||
|
||||
// Should not issue an error since the `else` block has a statement besides `None`.
|
||||
let _ = if foo() {
|
||||
println!("true!");
|
||||
Some("foo")
|
||||
} else {
|
||||
eprintln!("false...");
|
||||
None
|
||||
};
|
||||
|
||||
// Should not issue an error since there are more than 2 blocks in the if-else chain.
|
||||
let _ = if foo() {
|
||||
println!("foo true!");
|
||||
Some("foo")
|
||||
} else if bar() {
|
||||
println!("bar true!");
|
||||
Some("bar")
|
||||
} else {
|
||||
None
|
||||
};
|
||||
|
||||
let _ = if foo() {
|
||||
println!("foo true!");
|
||||
Some("foo")
|
||||
} else {
|
||||
bar().then(|| {
|
||||
println!("bar true!");
|
||||
"bar"
|
||||
})
|
||||
};
|
||||
|
||||
// Should not issue an error since the `then` block has `None`, not `Some`.
|
||||
let _ = if foo() { None } else { Some("foo is false") };
|
||||
|
||||
// Should not issue an error since the `else` block doesn't use `None` directly.
|
||||
let _ = if foo() { Some("foo is true") } else { into_none() };
|
||||
|
||||
// Should not issue an error since the `then` block doesn't use `Some` directly.
|
||||
let _ = if foo() { into_some("foo") } else { None };
|
||||
}
|
||||
|
||||
fn foo() -> bool {
|
||||
unimplemented!()
|
||||
}
|
||||
|
||||
fn bar() -> bool {
|
||||
unimplemented!()
|
||||
}
|
||||
|
||||
fn into_some<T>(v: T) -> Option<T> {
|
||||
Some(v)
|
||||
}
|
||||
|
||||
fn into_none<T>() -> Option<T> {
|
||||
None
|
||||
}
|
16
tests/ui/if_then_some_else_none.stderr
Normal file
16
tests/ui/if_then_some_else_none.stderr
Normal file
@ -0,0 +1,16 @@
|
||||
error: this could be simplified with `bool::then`
|
||||
--> $DIR/if_then_some_else_none.rs:5:13
|
||||
|
|
||||
LL | let _ = if foo() {
|
||||
| _____________^
|
||||
LL | | println!("true!");
|
||||
LL | | Some("foo")
|
||||
LL | | } else {
|
||||
LL | | None
|
||||
LL | | };
|
||||
| |_____^ help: try this: `foo().then(|| { /* snippet */ "foo" })`
|
||||
|
|
||||
= note: `-D clippy::if-then-some-else-none` implied by `-D warnings`
|
||||
|
||||
error: aborting due to previous error
|
||||
|
Loading…
Reference in New Issue
Block a user