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Auto merge of #7083 - GuillaumeGomez:bool-assert-eq, r=camsteffen 

Add lint to check for boolean comparison in assert macro calls

This PR adds a lint to check if an assert macro is using a boolean as "comparison value". For example:

```rust
assert_eq!("a".is_empty(), false);
```

Could be rewritten as:

```rust
assert!(!"a".is_empty());
```

PS: The dev guidelines are amazing. Thanks a lot for writing them!

changelog: Add `bool_assert_comparison` lint
This commit is contained in:
bors 2021-04-21 13:58:53 +00:00
parent 926286acfe e2e104b993
commit bbc22e2ef3
6 changed files with 284 additions and 0 deletions
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1
CHANGELOG.md
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@ -2124,6 +2124,7 @@ Released 2018-09-13
[`blacklisted_name`]: https://rust-lang.github.io/rust-clippy/master/index.html#blacklisted_name
[`blanket_clippy_restriction_lints`]: https://rust-lang.github.io/rust-clippy/master/index.html#blanket_clippy_restriction_lints
[`blocks_in_if_conditions`]: https://rust-lang.github.io/rust-clippy/master/index.html#blocks_in_if_conditions
[`bool_assert_comparison`]: https://rust-lang.github.io/rust-clippy/master/index.html#bool_assert_comparison
[`bool_comparison`]: https://rust-lang.github.io/rust-clippy/master/index.html#bool_comparison
[`borrow_interior_mutable_const`]: https://rust-lang.github.io/rust-clippy/master/index.html#borrow_interior_mutable_const
[`borrowed_box`]: https://rust-lang.github.io/rust-clippy/master/index.html#borrowed_box

75
clippy_lints/src/bool_assert_comparison.rs Normal file
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@ -0,0 +1,75 @@
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::{ast_utils, is_direct_expn_of};
use rustc_ast::ast::{Expr, ExprKind, Lit, LitKind};
use rustc_errors::Applicability;
use rustc_lint::{EarlyContext, EarlyLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
/// **What it does:** This lint warns about boolean comparisons in assert-like macros.
///
/// **Why is this bad?** It is shorter to use the equivalent.
///
/// **Known problems:** None.
///
/// **Example:**
///
/// ```rust
/// // Bad
/// assert_eq!("a".is_empty(), false);
/// assert_ne!("a".is_empty(), true);
///
/// // Good
/// assert!(!"a".is_empty());
/// ```
pub BOOL_ASSERT_COMPARISON,
style,
"Using a boolean as comparison value in an assert_* macro when there is no need"
}
declare_lint_pass!(BoolAssertComparison => [BOOL_ASSERT_COMPARISON]);
fn is_bool_lit(e: &Expr) -> bool {
matches!(
e.kind,
ExprKind::Lit(Lit {
kind: LitKind::Bool(_),
..
})
) && !e.span.from_expansion()
}
impl EarlyLintPass for BoolAssertComparison {
fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &Expr) {
let macros = ["assert_eq", "debug_assert_eq"];
let inverted_macros = ["assert_ne", "debug_assert_ne"];
for mac in macros.iter().chain(inverted_macros.iter()) {
if let Some(span) = is_direct_expn_of(e.span, mac) {
if let Some([a, b]) = ast_utils::extract_assert_macro_args(e) {
let nb_bool_args = is_bool_lit(a) as usize + is_bool_lit(b) as usize;
if nb_bool_args != 1 {
// If there are two boolean arguments, we definitely don't understand
// what's going on, so better leave things as is...
//
// Or there is simply no boolean and then we can leave things as is!
return;
}
let non_eq_mac = &mac[..mac.len() - 3];
span_lint_and_sugg(
cx,
BOOL_ASSERT_COMPARISON,
span,
&format!("used `{}!` with a literal bool", mac),
"replace it with",
format!("{}!(..)", non_eq_mac),
Applicability::MaybeIncorrect,
);
return;
}
}
}
}
}

5
clippy_lints/src/lib.rs
View File

@ -178,6 +178,7 @@ mod await_holding_invalid;
mod bit_mask;
mod blacklisted_name;
mod blocks_in_if_conditions;
mod bool_assert_comparison;
mod booleans;
mod bytecount;
mod cargo_common_metadata;
@ -568,6 +569,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
bit_mask::VERBOSE_BIT_MASK,
blacklisted_name::BLACKLISTED_NAME,
blocks_in_if_conditions::BLOCKS_IN_IF_CONDITIONS,
bool_assert_comparison::BOOL_ASSERT_COMPARISON,
booleans::LOGIC_BUG,
booleans::NONMINIMAL_BOOL,
bytecount::NAIVE_BYTECOUNT,
@ -1273,6 +1275,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| box from_str_radix_10::FromStrRadix10);
store.register_late_pass(|| box manual_map::ManualMap);
store.register_late_pass(move || box if_then_some_else_none::IfThenSomeElseNone::new(msrv));
store.register_early_pass(|| box bool_assert_comparison::BoolAssertComparison);
store.register_group(true, "clippy::restriction", Some("clippy_restriction"), vec![
LintId::of(arithmetic::FLOAT_ARITHMETIC),
@ -1453,6 +1456,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(bit_mask::INEFFECTIVE_BIT_MASK),
LintId::of(blacklisted_name::BLACKLISTED_NAME),
LintId::of(blocks_in_if_conditions::BLOCKS_IN_IF_CONDITIONS),
LintId::of(bool_assert_comparison::BOOL_ASSERT_COMPARISON),
LintId::of(booleans::LOGIC_BUG),
LintId::of(booleans::NONMINIMAL_BOOL),
LintId::of(casts::CAST_REF_TO_MUT),
@ -1739,6 +1743,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(attrs::BLANKET_CLIPPY_RESTRICTION_LINTS),
LintId::of(blacklisted_name::BLACKLISTED_NAME),
LintId::of(blocks_in_if_conditions::BLOCKS_IN_IF_CONDITIONS),
LintId::of(bool_assert_comparison::BOOL_ASSERT_COMPARISON),
LintId::of(casts::FN_TO_NUMERIC_CAST),
LintId::of(casts::FN_TO_NUMERIC_CAST_WITH_TRUNCATION),
LintId::of(collapsible_if::COLLAPSIBLE_ELSE_IF),

32
clippy_utils/src/ast_utils.rs
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@ -5,6 +5,7 @@
#![allow(clippy::similar_names, clippy::wildcard_imports, clippy::enum_glob_use)]
use crate::{both, over};
use if_chain::if_chain;
use rustc_ast::ptr::P;
use rustc_ast::{self as ast, *};
use rustc_span::symbol::Ident;
@ -571,3 +572,34 @@ pub fn eq_mac_args(l: &MacArgs, r: &MacArgs) -> bool {
_ => false,
}
}
/// Extract args from an assert-like macro.
///
/// Currently working with:
/// - `assert_eq!` and `assert_ne!`
/// - `debug_assert_eq!` and `debug_assert_ne!`
///
/// For example:
///
/// `debug_assert_eq!(a, b)` will return Some([a, b])
pub fn extract_assert_macro_args(mut expr: &Expr) -> Option<[&Expr; 2]> {
if_chain! {
if let ExprKind::If(_, ref block, _) = expr.kind;
if let StmtKind::Semi(ref e) = block.stmts.get(0)?.kind;
then {
expr = e;
}
}
if_chain! {
if let ExprKind::Block(ref block, _) = expr.kind;
if let StmtKind::Expr(ref expr) = block.stmts.get(0)?.kind;
if let ExprKind::Match(ref match_expr, _) = expr.kind;
if let ExprKind::Tup(ref tup) = match_expr.kind;
if let [a, b, ..] = tup.as_slice();
if let (&ExprKind::AddrOf(_, _, ref a), &ExprKind::AddrOf(_, _, ref b)) = (&a.kind, &b.kind);
then {
return Some([&*a, &*b]);
}
}
None
}

59
tests/ui/bool_assert_comparison.rs Normal file
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@ -0,0 +1,59 @@
#![warn(clippy::bool_assert_comparison)]
macro_rules! a {
() => {
true
};
}
macro_rules! b {
() => {
true
};
}
fn main() {
assert_eq!("a".len(), 1);
assert_eq!("a".is_empty(), false);
assert_eq!("".is_empty(), true);
assert_eq!(true, "".is_empty());
assert_eq!(a!(), b!());
assert_eq!(a!(), "".is_empty());
assert_eq!("".is_empty(), b!());
assert_ne!("a".len(), 1);
assert_ne!("a".is_empty(), false);
assert_ne!("".is_empty(), true);
assert_ne!(true, "".is_empty());
assert_ne!(a!(), b!());
assert_ne!(a!(), "".is_empty());
assert_ne!("".is_empty(), b!());
debug_assert_eq!("a".len(), 1);
debug_assert_eq!("a".is_empty(), false);
debug_assert_eq!("".is_empty(), true);
debug_assert_eq!(true, "".is_empty());
debug_assert_eq!(a!(), b!());
debug_assert_eq!(a!(), "".is_empty());
debug_assert_eq!("".is_empty(), b!());
debug_assert_ne!("a".len(), 1);
debug_assert_ne!("a".is_empty(), false);
debug_assert_ne!("".is_empty(), true);
debug_assert_ne!(true, "".is_empty());
debug_assert_ne!(a!(), b!());
debug_assert_ne!(a!(), "".is_empty());
debug_assert_ne!("".is_empty(), b!());
// assert with error messages
assert_eq!("a".len(), 1, "tadam {}", 1);
assert_eq!("a".len(), 1, "tadam {}", true);
assert_eq!("a".is_empty(), false, "tadam {}", 1);
assert_eq!("a".is_empty(), false, "tadam {}", true);
assert_eq!(false, "a".is_empty(), "tadam {}", true);
debug_assert_eq!("a".len(), 1, "tadam {}", 1);
debug_assert_eq!("a".len(), 1, "tadam {}", true);
debug_assert_eq!("a".is_empty(), false, "tadam {}", 1);
debug_assert_eq!("a".is_empty(), false, "tadam {}", true);
debug_assert_eq!(false, "a".is_empty(), "tadam {}", true);
}

112
tests/ui/bool_assert_comparison.stderr Normal file
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@ -0,0 +1,112 @@
error: used `assert_eq!` with a literal bool
--> $DIR/bool_assert_comparison.rs:16:5
|
LL | assert_eq!("a".is_empty(), false);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
|
= note: `-D clippy::bool-assert-comparison` implied by `-D warnings`
error: used `assert_eq!` with a literal bool
--> $DIR/bool_assert_comparison.rs:17:5
|
LL | assert_eq!("".is_empty(), true);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
error: used `assert_eq!` with a literal bool
--> $DIR/bool_assert_comparison.rs:18:5
|
LL | assert_eq!(true, "".is_empty());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
error: used `assert_ne!` with a literal bool
--> $DIR/bool_assert_comparison.rs:24:5
|
LL | assert_ne!("a".is_empty(), false);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
error: used `assert_ne!` with a literal bool
--> $DIR/bool_assert_comparison.rs:25:5
|
LL | assert_ne!("".is_empty(), true);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
error: used `assert_ne!` with a literal bool
--> $DIR/bool_assert_comparison.rs:26:5
|
LL | assert_ne!(true, "".is_empty());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
error: used `debug_assert_eq!` with a literal bool
--> $DIR/bool_assert_comparison.rs:32:5
|
LL | debug_assert_eq!("a".is_empty(), false);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
error: used `debug_assert_eq!` with a literal bool
--> $DIR/bool_assert_comparison.rs:33:5
|
LL | debug_assert_eq!("".is_empty(), true);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
error: used `debug_assert_eq!` with a literal bool
--> $DIR/bool_assert_comparison.rs:34:5
|
LL | debug_assert_eq!(true, "".is_empty());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
error: used `debug_assert_ne!` with a literal bool
--> $DIR/bool_assert_comparison.rs:40:5
|
LL | debug_assert_ne!("a".is_empty(), false);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
error: used `debug_assert_ne!` with a literal bool
--> $DIR/bool_assert_comparison.rs:41:5
|
LL | debug_assert_ne!("".is_empty(), true);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
error: used `debug_assert_ne!` with a literal bool
--> $DIR/bool_assert_comparison.rs:42:5
|
LL | debug_assert_ne!(true, "".is_empty());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
error: used `assert_eq!` with a literal bool
--> $DIR/bool_assert_comparison.rs:50:5
|
LL | assert_eq!("a".is_empty(), false, "tadam {}", 1);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
error: used `assert_eq!` with a literal bool
--> $DIR/bool_assert_comparison.rs:51:5
|
LL | assert_eq!("a".is_empty(), false, "tadam {}", true);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
error: used `assert_eq!` with a literal bool
--> $DIR/bool_assert_comparison.rs:52:5
|
LL | assert_eq!(false, "a".is_empty(), "tadam {}", true);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
error: used `debug_assert_eq!` with a literal bool
--> $DIR/bool_assert_comparison.rs:56:5
|
LL | debug_assert_eq!("a".is_empty(), false, "tadam {}", 1);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
error: used `debug_assert_eq!` with a literal bool
--> $DIR/bool_assert_comparison.rs:57:5
|
LL | debug_assert_eq!("a".is_empty(), false, "tadam {}", true);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
error: used `debug_assert_eq!` with a literal bool
--> $DIR/bool_assert_comparison.rs:58:5
|
LL | debug_assert_eq!(false, "a".is_empty(), "tadam {}", true);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
error: aborting due to 18 previous errors