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Auto merge of #7669 - Labelray:if_then_panic, r=giraffate

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New lint `if_then_panic`

changelog: add the new lint [`if_then_panic`]
fix #7645
This commit is contained in:
bors 2021-09-24 14:43:51 +00:00
commit fb61d04896
14 changed files with 263 additions and 29 deletions
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1
CHANGELOG.md
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@ -2688,6 +2688,7 @@ 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_panic`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_then_panic
[`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

97
clippy_lints/src/if_then_panic.rs Normal file
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@ -0,0 +1,97 @@
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::higher::PanicExpn;
use clippy_utils::is_expn_of;
use clippy_utils::source::snippet_with_applicability;
use rustc_errors::Applicability;
use rustc_hir::{Block, Expr, ExprKind, StmtKind, UnOp};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
/// ### What it does
/// Detects `if`-then-`panic!` that can be replaced with `assert!`.
///
/// ### Why is this bad?
/// `assert!` is simpler than `if`-then-`panic!`.
///
/// ### Example
/// ```rust
/// let sad_people: Vec<&str> = vec![];
/// if !sad_people.is_empty() {
/// panic!("there are sad people: {:?}", sad_people);
/// }
/// ```
/// Use instead:
/// ```rust
/// let sad_people: Vec<&str> = vec![];
/// assert!(sad_people.is_empty(), "there are sad people: {:?}", sad_people);
/// ```
pub IF_THEN_PANIC,
style,
"`panic!` and only a `panic!` in `if`-then statement"
}
declare_lint_pass!(IfThenPanic => [IF_THEN_PANIC]);
impl LateLintPass<'_> for IfThenPanic {
fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
if_chain! {
if let Expr {
kind: ExprKind:: If(cond, Expr {
kind: ExprKind::Block(
Block {
stmts: [stmt],
..
},
_),
..
}, None),
..
} = &expr;
if is_expn_of(stmt.span, "panic").is_some();
if !matches!(cond.kind, ExprKind::Let(_, _, _));
if let StmtKind::Semi(semi) = stmt.kind;
if !cx.tcx.sess.source_map().is_multiline(cond.span);
then {
let span = if let Some(panic_expn) = PanicExpn::parse(semi) {
match *panic_expn.format_args.value_args {
[] => panic_expn.format_args.format_string_span,
[.., last] => panic_expn.format_args.format_string_span.to(last.span),
}
} else {
if_chain! {
if let ExprKind::Block(block, _) = semi.kind;
if let Some(init) = block.expr;
if let ExprKind::Call(_, [format_args]) = init.kind;
then {
format_args.span
} else {
return
}
}
};
let mut applicability = Applicability::MachineApplicable;
let sugg = snippet_with_applicability(cx, span, "..", &mut applicability);
let cond_sugg =
if let ExprKind::DropTemps(Expr{kind: ExprKind::Unary(UnOp::Not, not_expr), ..}) = cond.kind {
snippet_with_applicability(cx, not_expr.span, "..", &mut applicability).to_string()
} else {
format!("!{}", snippet_with_applicability(cx, cond.span, "..", &mut applicability))
};
span_lint_and_sugg(
cx,
IF_THEN_PANIC,
expr.span,
"only a `panic!` in `if`-then statement",
"try",
format!("assert!({}, {});", cond_sugg, sugg),
Applicability::MachineApplicable,
);
}
}
}
}

5
clippy_lints/src/lib.rs
View File

@ -227,6 +227,7 @@ macro_rules! declare_clippy_lint {
mod if_let_mutex;
mod if_let_some_result;
mod if_not_else;
mod if_then_panic;
mod if_then_some_else_none;
mod implicit_hasher;
mod implicit_return;
@ -659,6 +660,7 @@ 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_panic::IF_THEN_PANIC,
if_then_some_else_none::IF_THEN_SOME_ELSE_NONE,
implicit_hasher::IMPLICIT_HASHER,
implicit_return::IMPLICIT_RETURN,
@ -1257,6 +1259,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(identity_op::IDENTITY_OP),
LintId::of(if_let_mutex::IF_LET_MUTEX),
LintId::of(if_let_some_result::IF_LET_SOME_RESULT),
LintId::of(if_then_panic::IF_THEN_PANIC),
LintId::of(indexing_slicing::OUT_OF_BOUNDS_INDEXING),
LintId::of(infinite_iter::INFINITE_ITER),
LintId::of(inherent_to_string::INHERENT_TO_STRING),
@ -1511,6 +1514,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(functions::MUST_USE_UNIT),
LintId::of(functions::RESULT_UNIT_ERR),
LintId::of(if_let_some_result::IF_LET_SOME_RESULT),
LintId::of(if_then_panic::IF_THEN_PANIC),
LintId::of(inherent_to_string::INHERENT_TO_STRING),
LintId::of(len_zero::COMPARISON_TO_EMPTY),
LintId::of(len_zero::LEN_WITHOUT_IS_EMPTY),
@ -2138,6 +2142,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(move || Box::new(self_named_constructors::SelfNamedConstructors));
store.register_late_pass(move || Box::new(feature_name::FeatureName));
store.register_late_pass(move || Box::new(iter_not_returning_iterator::IterNotReturningIterator));
store.register_late_pass(move || Box::new(if_then_panic::IfThenPanic));
}
#[rustfmt::skip]

4
clippy_lints/src/utils/internal_lints.rs
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@ -561,9 +561,7 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
impl EarlyLintPass for ProduceIce {
fn check_fn(&mut self, _: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: Span, _: NodeId) {
if is_trigger_fn(fn_kind) {
panic!("Would you like some help with that?");
}
assert!(!is_trigger_fn(fn_kind), "Would you like some help with that?");
}
}

30
clippy_utils/src/higher.rs
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@ -608,3 +608,33 @@ pub fn is_from_for_desugar(local: &hir::Local<'_>) -> bool {
false
}
/// A parsed `panic!` expansion
pub struct PanicExpn<'tcx> {
/// Span of `panic!(..)`
pub call_site: Span,
/// Inner `format_args!` expansion
pub format_args: FormatArgsExpn<'tcx>,
}
impl PanicExpn<'tcx> {
/// Parses an expanded `panic!` invocation
pub fn parse(expr: &'tcx Expr<'tcx>) -> Option<Self> {
if_chain! {
if let ExprKind::Block(block, _) = expr.kind;
if let Some(init) = block.expr;
if let ExprKind::Call(_, [format_args]) = init.kind;
let expn_data = expr.span.ctxt().outer_expn_data();
if let ExprKind::AddrOf(_, _, format_args) = format_args.kind;
if let Some(format_args) = FormatArgsExpn::parse(format_args);
then {
Some(PanicExpn {
call_site: expn_data.call_site,
format_args,
})
} else {
None
}
}
}
}

8
tests/compile-test.rs
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@ -90,9 +90,11 @@ fn extern_flags() -> String {
.copied()
.filter(|n| !crates.contains_key(n))
.collect();
if !not_found.is_empty() {
panic!("dependencies not found in depinfo: {:?}", not_found);
}
assert!(
not_found.is_empty(),
"dependencies not found in depinfo: {:?}",
not_found
);
crates
.into_iter()
.map(|(name, path)| format!(" --extern {}={}", name, path))

7
tests/integration.rs
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@ -74,8 +74,11 @@ fn integration_test() {
panic!("incompatible crate versions");
} else if stderr.contains("failed to run `rustc` to learn about target-specific information") {
panic!("couldn't find librustc_driver, consider setting `LD_LIBRARY_PATH`");
} else if stderr.contains("toolchain") && stderr.contains("is not installed") {
panic!("missing required toolchain");
} else {
assert!(
!stderr.contains("toolchain") || !stderr.contains("is not installed"),
"missing required toolchain"
);
}
match output.status.code() {

1
tests/ui/fallible_impl_from.rs
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@ -1,4 +1,5 @@
#![deny(clippy::fallible_impl_from)]
#![allow(clippy::if_then_panic)]
// docs example
struct Foo(i32);

16
tests/ui/fallible_impl_from.stderr
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@ -1,5 +1,5 @@
error: consider implementing `TryFrom` instead
--> $DIR/fallible_impl_from.rs:5:1
--> $DIR/fallible_impl_from.rs:6:1
|
LL | / impl From<String> for Foo {
LL | | fn from(s: String) -> Self {
@ -15,13 +15,13 @@ LL | #![deny(clippy::fallible_impl_from)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
= help: `From` is intended for infallible conversions only. Use `TryFrom` if there's a possibility for the conversion to fail
note: potential failure(s)
--> $DIR/fallible_impl_from.rs:7:13
--> $DIR/fallible_impl_from.rs:8:13
|
LL | Foo(s.parse().unwrap())
| ^^^^^^^^^^^^^^^^^^
error: consider implementing `TryFrom` instead
--> $DIR/fallible_impl_from.rs:26:1
--> $DIR/fallible_impl_from.rs:27:1
|
LL | / impl From<usize> for Invalid {
LL | | fn from(i: usize) -> Invalid {
@ -34,14 +34,14 @@ LL | | }
|
= help: `From` is intended for infallible conversions only. Use `TryFrom` if there's a possibility for the conversion to fail
note: potential failure(s)
--> $DIR/fallible_impl_from.rs:29:13
--> $DIR/fallible_impl_from.rs:30:13
|
LL | panic!();
| ^^^^^^^^^
= note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
error: consider implementing `TryFrom` instead
--> $DIR/fallible_impl_from.rs:35:1
--> $DIR/fallible_impl_from.rs:36:1
|
LL | / impl From<Option<String>> for Invalid {
LL | | fn from(s: Option<String>) -> Invalid {
@ -54,7 +54,7 @@ LL | | }
|
= help: `From` is intended for infallible conversions only. Use `TryFrom` if there's a possibility for the conversion to fail
note: potential failure(s)
--> $DIR/fallible_impl_from.rs:37:17
--> $DIR/fallible_impl_from.rs:38:17
|
LL | let s = s.unwrap();
| ^^^^^^^^^^
@ -68,7 +68,7 @@ LL | panic!("{:?}", s);
= note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
error: consider implementing `TryFrom` instead
--> $DIR/fallible_impl_from.rs:53:1
--> $DIR/fallible_impl_from.rs:54:1
|
LL | / impl<'a> From<&'a mut <Box<u32> as ProjStrTrait>::ProjString> for Invalid {
LL | | fn from(s: &'a mut <Box<u32> as ProjStrTrait>::ProjString) -> Invalid {
@ -81,7 +81,7 @@ LL | | }
|
= help: `From` is intended for infallible conversions only. Use `TryFrom` if there's a possibility for the conversion to fail
note: potential failure(s)
--> $DIR/fallible_impl_from.rs:55:12
--> $DIR/fallible_impl_from.rs:56:12
|
LL | if s.parse::<u32>().ok().unwrap() != 42 {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

34
tests/ui/if_then_panic.fixed Normal file
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@ -0,0 +1,34 @@
// run-rustfix
#![warn(clippy::if_then_panic)]
fn main() {
let a = vec![1, 2, 3];
let c = Some(2);
if !a.is_empty()
&& a.len() == 3
&& c != None
&& !a.is_empty()
&& a.len() == 3
&& !a.is_empty()
&& a.len() == 3
&& !a.is_empty()
&& a.len() == 3
{
panic!("qaqaq{:?}", a);
}
assert!(a.is_empty(), "qaqaq{:?}", a);
assert!(a.is_empty(), "qwqwq");
if a.len() == 3 {
println!("qwq");
println!("qwq");
println!("qwq");
}
if let Some(b) = c {
panic!("orz {}", b);
}
if a.len() == 3 {
panic!("qaqaq");
} else {
println!("qwq");
}
}

38
tests/ui/if_then_panic.rs Normal file
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@ -0,0 +1,38 @@
// run-rustfix
#![warn(clippy::if_then_panic)]
fn main() {
let a = vec![1, 2, 3];
let c = Some(2);
if !a.is_empty()
&& a.len() == 3
&& c != None
&& !a.is_empty()
&& a.len() == 3
&& !a.is_empty()
&& a.len() == 3
&& !a.is_empty()
&& a.len() == 3
{
panic!("qaqaq{:?}", a);
}
if !a.is_empty() {
panic!("qaqaq{:?}", a);
}
if !a.is_empty() {
panic!("qwqwq");
}
if a.len() == 3 {
println!("qwq");
println!("qwq");
println!("qwq");
}
if let Some(b) = c {
panic!("orz {}", b);
}
if a.len() == 3 {
panic!("qaqaq");
} else {
println!("qwq");
}
}

20
tests/ui/if_then_panic.stderr Normal file
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@ -0,0 +1,20 @@
error: only a `panic!` in `if`-then statement
--> $DIR/if_then_panic.rs:19:5
|
LL | / if !a.is_empty() {
LL | | panic!("qaqaq{:?}", a);
LL | | }
| |_____^ help: try: `assert!(a.is_empty(), "qaqaq{:?}", a);`
|
= note: `-D clippy::if-then-panic` implied by `-D warnings`
error: only a `panic!` in `if`-then statement
--> $DIR/if_then_panic.rs:22:5
|
LL | / if !a.is_empty() {
LL | | panic!("qwqwq");
LL | | }
| |_____^ help: try: `assert!(a.is_empty(), "qwqwq");`
error: aborting due to 2 previous errors

7
tests/ui/ptr_arg.rs
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@ -1,4 +1,9 @@
#![allow(unused, clippy::redundant_clone)]
#![allow(
unused,
clippy::many_single_char_names,
clippy::redundant_clone,
clippy::if_then_panic
)]
#![warn(clippy::ptr_arg)]
use std::borrow::Cow;

24
tests/ui/ptr_arg.stderr
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@ -1,5 +1,5 @@
error: writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used with non-Vec-based slices
--> $DIR/ptr_arg.rs:7:14
--> $DIR/ptr_arg.rs:12:14
|
LL | fn do_vec(x: &Vec<i64>) {
| ^^^^^^^^^ help: change this to: `&[i64]`
@ -7,25 +7,25 @@ LL | fn do_vec(x: &Vec<i64>) {
= note: `-D clippy::ptr-arg` implied by `-D warnings`
error: writing `&String` instead of `&str` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:16:14
--> $DIR/ptr_arg.rs:21:14
|
LL | fn do_str(x: &String) {
| ^^^^^^^ help: change this to: `&str`
error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:25:15
--> $DIR/ptr_arg.rs:30:15
|
LL | fn do_path(x: &PathBuf) {
| ^^^^^^^^ help: change this to: `&Path`
error: writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used with non-Vec-based slices
--> $DIR/ptr_arg.rs:38:18
--> $DIR/ptr_arg.rs:43:18
|
LL | fn do_vec(x: &Vec<i64>);
| ^^^^^^^^^ help: change this to: `&[i64]`
error: writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used with non-Vec-based slices
--> $DIR/ptr_arg.rs:51:14
--> $DIR/ptr_arg.rs:56:14
|
LL | fn cloned(x: &Vec<u8>) -> Vec<u8> {
| ^^^^^^^^
@ -44,7 +44,7 @@ LL | x.to_owned()
|
error: writing `&String` instead of `&str` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:60:18
--> $DIR/ptr_arg.rs:65:18
|
LL | fn str_cloned(x: &String) -> String {
| ^^^^^^^
@ -67,7 +67,7 @@ LL | x.to_string()
|
error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:68:19
--> $DIR/ptr_arg.rs:73:19
|
LL | fn path_cloned(x: &PathBuf) -> PathBuf {
| ^^^^^^^^
@ -90,7 +90,7 @@ LL | x.to_path_buf()
|
error: writing `&String` instead of `&str` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:76:44
--> $DIR/ptr_arg.rs:81:44
|
LL | fn false_positive_capacity(x: &Vec<u8>, y: &String) {
| ^^^^^^^
@ -109,13 +109,13 @@ LL | let c = y;
| ~
error: using a reference to `Cow` is not recommended
--> $DIR/ptr_arg.rs:90:25
--> $DIR/ptr_arg.rs:95:25
|
LL | fn test_cow_with_ref(c: &Cow<[i32]>) {}
| ^^^^^^^^^^^ help: change this to: `&[i32]`
error: writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used with non-Vec-based slices
--> $DIR/ptr_arg.rs:143:21
--> $DIR/ptr_arg.rs:148:21
|
LL | fn foo_vec(vec: &Vec<u8>) {
| ^^^^^^^^
@ -134,7 +134,7 @@ LL | let _ = vec.to_owned().clone();
| ~~~~~~~~~~~~~~
error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:148:23
--> $DIR/ptr_arg.rs:153:23
|
LL | fn foo_path(path: &PathBuf) {
| ^^^^^^^^
@ -153,7 +153,7 @@ LL | let _ = path.to_path_buf().clone();
| ~~~~~~~~~~~~~~~~~~
error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do
--> $DIR/ptr_arg.rs:153:21
--> $DIR/ptr_arg.rs:158:21
|
LL | fn foo_str(str: &PathBuf) {
| ^^^^^^^^