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Auto merge of rust-lang#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
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‎CHANGELOG.md‎

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@@ -2124,6 +2124,7 @@ Released 2018-09-13
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[`blacklisted_name`]: https://rust-lang.github.io/rust-clippy/master/index.html#blacklisted_name
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[`blanket_clippy_restriction_lints`]: https://rust-lang.github.io/rust-clippy/master/index.html#blanket_clippy_restriction_lints
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[`blocks_in_if_conditions`]: https://rust-lang.github.io/rust-clippy/master/index.html#blocks_in_if_conditions
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[`bool_assert_comparison`]: https://rust-lang.github.io/rust-clippy/master/index.html#bool_assert_comparison
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[`bool_comparison`]: https://rust-lang.github.io/rust-clippy/master/index.html#bool_comparison
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[`borrow_interior_mutable_const`]: https://rust-lang.github.io/rust-clippy/master/index.html#borrow_interior_mutable_const
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[`borrowed_box`]: https://rust-lang.github.io/rust-clippy/master/index.html#borrowed_box

‎clippy_lints/src/bool_assert_comparison.rs‎

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

‎clippy_lints/src/lib.rs‎

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

‎clippy_utils/src/ast_utils.rs‎

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@@ -5,6 +5,7 @@
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#![allow(clippy::similar_names, clippy::wildcard_imports, clippy::enum_glob_use)]
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use crate::{both, over};
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use if_chain::if_chain;
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use rustc_ast::ptr::P;
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use rustc_ast::{self as ast, *};
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use rustc_span::symbol::Ident;
@@ -571,3 +572,34 @@ pub fn eq_mac_args(l: &MacArgs, r: &MacArgs) -> bool {
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_ => false,
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}
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}
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/// Extract args from an assert-like macro.
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///
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/// Currently working with:
579+
/// - `assert_eq!` and `assert_ne!`
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/// - `debug_assert_eq!` and `debug_assert_ne!`
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///
582+
/// For example:
583+
///
584+
/// `debug_assert_eq!(a, b)` will return Some([a, b])
585+
pub fn extract_assert_macro_args(mut expr: &Expr) -> Option<[&Expr; 2]> {
586+
if_chain! {
587+
if let ExprKind::If(_, ref block, _) = expr.kind;
588+
if let StmtKind::Semi(ref e) = block.stmts.get(0)?.kind;
589+
then {
590+
expr = e;
591+
}
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}
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if_chain! {
594+
if let ExprKind::Block(ref block, _) = expr.kind;
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if let StmtKind::Expr(ref expr) = block.stmts.get(0)?.kind;
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if let ExprKind::Match(ref match_expr, _) = expr.kind;
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if let ExprKind::Tup(ref tup) = match_expr.kind;
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if let [a, b, ..] = tup.as_slice();
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if let (&ExprKind::AddrOf(_, _, ref a), &ExprKind::AddrOf(_, _, ref b)) = (&a.kind, &b.kind);
600+
then {
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return Some([&*a, &*b]);
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}
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}
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None
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}

‎tests/ui/bool_assert_comparison.rs‎

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#![warn(clippy::bool_assert_comparison)]
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macro_rules! a {
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() => {
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true
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};
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}
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macro_rules! b {
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() => {
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true
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};
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}
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fn main() {
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assert_eq!("a".len(), 1);
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assert_eq!("a".is_empty(), false);
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assert_eq!("".is_empty(), true);
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assert_eq!(true, "".is_empty());
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assert_eq!(a!(), b!());
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assert_eq!(a!(), "".is_empty());
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assert_eq!("".is_empty(), b!());
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assert_ne!("a".len(), 1);
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assert_ne!("a".is_empty(), false);
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assert_ne!("".is_empty(), true);
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assert_ne!(true, "".is_empty());
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assert_ne!(a!(), b!());
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assert_ne!(a!(), "".is_empty());
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assert_ne!("".is_empty(), b!());
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debug_assert_eq!("a".len(), 1);
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debug_assert_eq!("a".is_empty(), false);
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debug_assert_eq!("".is_empty(), true);
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debug_assert_eq!(true, "".is_empty());
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debug_assert_eq!(a!(), b!());
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debug_assert_eq!(a!(), "".is_empty());
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debug_assert_eq!("".is_empty(), b!());
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debug_assert_ne!("a".len(), 1);
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debug_assert_ne!("a".is_empty(), false);
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debug_assert_ne!("".is_empty(), true);
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debug_assert_ne!(true, "".is_empty());
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debug_assert_ne!(a!(), b!());
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debug_assert_ne!(a!(), "".is_empty());
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debug_assert_ne!("".is_empty(), b!());
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// assert with error messages
48+
assert_eq!("a".len(), 1, "tadam {}", 1);
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assert_eq!("a".len(), 1, "tadam {}", true);
50+
assert_eq!("a".is_empty(), false, "tadam {}", 1);
51+
assert_eq!("a".is_empty(), false, "tadam {}", true);
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assert_eq!(false, "a".is_empty(), "tadam {}", true);
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debug_assert_eq!("a".len(), 1, "tadam {}", 1);
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debug_assert_eq!("a".len(), 1, "tadam {}", true);
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debug_assert_eq!("a".is_empty(), false, "tadam {}", 1);
57+
debug_assert_eq!("a".is_empty(), false, "tadam {}", true);
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debug_assert_eq!(false, "a".is_empty(), "tadam {}", true);
59+
}

‎tests/ui/bool_assert_comparison.stderr‎

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error: used `assert_eq!` with a literal bool
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--> $DIR/bool_assert_comparison.rs:16:5
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|
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LL | assert_eq!("a".is_empty(), false);
5+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
6+
|
7+
= note: `-D clippy::bool-assert-comparison` implied by `-D warnings`
8+
9+
error: used `assert_eq!` with a literal bool
10+
--> $DIR/bool_assert_comparison.rs:17:5
11+
|
12+
LL | assert_eq!("".is_empty(), true);
13+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
14+
15+
error: used `assert_eq!` with a literal bool
16+
--> $DIR/bool_assert_comparison.rs:18:5
17+
|
18+
LL | assert_eq!(true, "".is_empty());
19+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
20+
21+
error: used `assert_ne!` with a literal bool
22+
--> $DIR/bool_assert_comparison.rs:24:5
23+
|
24+
LL | assert_ne!("a".is_empty(), false);
25+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
26+
27+
error: used `assert_ne!` with a literal bool
28+
--> $DIR/bool_assert_comparison.rs:25:5
29+
|
30+
LL | assert_ne!("".is_empty(), true);
31+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
32+
33+
error: used `assert_ne!` with a literal bool
34+
--> $DIR/bool_assert_comparison.rs:26:5
35+
|
36+
LL | assert_ne!(true, "".is_empty());
37+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
38+
39+
error: used `debug_assert_eq!` with a literal bool
40+
--> $DIR/bool_assert_comparison.rs:32:5
41+
|
42+
LL | debug_assert_eq!("a".is_empty(), false);
43+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
44+
45+
error: used `debug_assert_eq!` with a literal bool
46+
--> $DIR/bool_assert_comparison.rs:33:5
47+
|
48+
LL | debug_assert_eq!("".is_empty(), true);
49+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
50+
51+
error: used `debug_assert_eq!` with a literal bool
52+
--> $DIR/bool_assert_comparison.rs:34:5
53+
|
54+
LL | debug_assert_eq!(true, "".is_empty());
55+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
56+
57+
error: used `debug_assert_ne!` with a literal bool
58+
--> $DIR/bool_assert_comparison.rs:40:5
59+
|
60+
LL | debug_assert_ne!("a".is_empty(), false);
61+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
62+
63+
error: used `debug_assert_ne!` with a literal bool
64+
--> $DIR/bool_assert_comparison.rs:41:5
65+
|
66+
LL | debug_assert_ne!("".is_empty(), true);
67+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
68+
69+
error: used `debug_assert_ne!` with a literal bool
70+
--> $DIR/bool_assert_comparison.rs:42:5
71+
|
72+
LL | debug_assert_ne!(true, "".is_empty());
73+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
74+
75+
error: used `assert_eq!` with a literal bool
76+
--> $DIR/bool_assert_comparison.rs:50:5
77+
|
78+
LL | assert_eq!("a".is_empty(), false, "tadam {}", 1);
79+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
80+
81+
error: used `assert_eq!` with a literal bool
82+
--> $DIR/bool_assert_comparison.rs:51:5
83+
|
84+
LL | assert_eq!("a".is_empty(), false, "tadam {}", true);
85+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
86+
87+
error: used `assert_eq!` with a literal bool
88+
--> $DIR/bool_assert_comparison.rs:52:5
89+
|
90+
LL | assert_eq!(false, "a".is_empty(), "tadam {}", true);
91+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `assert!(..)`
92+
93+
error: used `debug_assert_eq!` with a literal bool
94+
--> $DIR/bool_assert_comparison.rs:56:5
95+
|
96+
LL | debug_assert_eq!("a".is_empty(), false, "tadam {}", 1);
97+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
98+
99+
error: used `debug_assert_eq!` with a literal bool
100+
--> $DIR/bool_assert_comparison.rs:57:5
101+
|
102+
LL | debug_assert_eq!("a".is_empty(), false, "tadam {}", true);
103+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
104+
105+
error: used `debug_assert_eq!` with a literal bool
106+
--> $DIR/bool_assert_comparison.rs:58:5
107+
|
108+
LL | debug_assert_eq!(false, "a".is_empty(), "tadam {}", true);
109+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `debug_assert!(..)`
110+
111+
error: aborting due to 18 previous errors
112+

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