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Add lint to check for boolean comparison in assert macro calls
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,127 @@ | ||
| use clippy_utils::diagnostics::span_lint_and_sugg; | ||
| use clippy_utils::source::snippet; | ||
| use rustc_ast::ast::{MacArgs, MacCall}; | ||
| use rustc_ast::token::{Token, TokenKind}; | ||
| use rustc_ast::tokenstream::TokenTree; | ||
| use rustc_errors::Applicability; | ||
| use rustc_lint::{EarlyContext, EarlyLintPass}; | ||
| use rustc_session::{declare_lint_pass, declare_tool_lint}; | ||
| use rustc_span::symbol::kw::{False, True}; | ||
|
|
||
| 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, | ||
| pedantic, | ||
| "Using a boolean as comparison value when there is no need" | ||
| } | ||
|
|
||
| declare_lint_pass!(BoolAssertComparison => [BOOL_ASSERT_COMPARISON]); | ||
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||
| fn is_bool(tt: Option<&TokenTree>) -> bool { | ||
| match tt { | ||
| Some(TokenTree::Token(Token { | ||
| kind: TokenKind::Ident(i, _), | ||
| .. | ||
| })) => *i == True || *i == False, | ||
| _ => false, | ||
| } | ||
| } | ||
|
|
||
| impl EarlyLintPass for BoolAssertComparison { | ||
| fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &MacCall) { | ||
| let macros = ["assert_eq", "debug_assert_eq"]; | ||
| let inverted_macros = ["assert_ne", "debug_assert_ne"]; | ||
|
|
||
| if let MacArgs::Delimited(_, _, ts) = &*mac.args { | ||
| let name; | ||
| if let [seg] = &*mac.path.segments { | ||
| name = seg.ident.name.as_str().to_string(); | ||
| if !macros.contains(&name.as_str()) && !inverted_macros.contains(&name.as_str()) { | ||
| return; | ||
| } | ||
| } else { | ||
| return; | ||
| } | ||
| let mut has_true = false; | ||
| let mut has_false = false; | ||
| let mut bool_span = None; | ||
| let mut spans = Vec::new(); | ||
| let mut nb_comma = 0; | ||
| let mut iter = ts.trees().peekable(); | ||
| while let Some(tt) = iter.next() { | ||
| if let TokenTree::Token(ref token) = tt { | ||
| match token.kind { | ||
| TokenKind::Ident(i, _) => { | ||
| // We only want to check the comparison arguments, nothing else! | ||
| if nb_comma < 2 { | ||
| if i == True { | ||
| has_true = true; | ||
| bool_span = Some(token.span); | ||
| continue; | ||
| } else if i == False { | ||
| has_false = true; | ||
| bool_span = Some(token.span); | ||
| continue; | ||
| } | ||
| } | ||
| }, | ||
| TokenKind::Comma => { | ||
| nb_comma += 1; | ||
| if nb_comma > 1 || !is_bool(iter.peek()) { | ||
| spans.push((token.span, true)); | ||
| } | ||
| continue; | ||
| }, | ||
| _ => {}, | ||
| } | ||
| } | ||
| spans.push((tt.span(), false)); | ||
| } | ||
| #[allow(clippy::if_same_then_else)] // It allows better code reability here. | ||
| if has_false && has_true { | ||
| // Don't know what's going on here, but better leave things as is... | ||
| return; | ||
| } else if !has_true && !has_false { | ||
| // No problem detected! | ||
| return; | ||
| } | ||
| let text = spans | ||
| .into_iter() | ||
| .map(|(s, needs_whitespace)| { | ||
| let mut s = snippet(cx, s, "arg").to_string(); | ||
| if needs_whitespace { | ||
| s.push(' '); | ||
| } | ||
| s | ||
| }) | ||
| .collect::<String>(); | ||
| let is_cond_inverted = inverted_macros.contains(&name.as_str()); | ||
| let extra = (has_true && is_cond_inverted) || has_false; | ||
|
|
||
| span_lint_and_sugg( | ||
| cx, | ||
| BOOL_ASSERT_COMPARISON, | ||
| bool_span.expect("failed to get the bool span"), | ||
| "assert macro with a boolean comparison", | ||
| "replace it with", | ||
| format!("{}!({}{})", &name[..name.len() - 3], if extra { "!" } else { "" }, text), | ||
| Applicability::MachineApplicable, | ||
| ); | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,25 @@ | ||
| #![warn(clippy::bool_assert_comparison)] | ||
|
|
||
| fn main() { | ||
| assert_eq!("a".len(), 1); | ||
| assert_eq!("a".is_empty(), false); | ||
| assert_eq!("".is_empty(), true); | ||
|
|
||
| assert_ne!("a".len(), 1); | ||
| assert_ne!("a".is_empty(), false); | ||
| assert_ne!("".is_empty(), true); | ||
|
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||
| debug_assert_eq!("a".len(), 1); | ||
| debug_assert_eq!("a".is_empty(), false); | ||
| debug_assert_eq!("".is_empty(), true); | ||
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||
| debug_assert_ne!("a".len(), 1); | ||
| debug_assert_ne!("a".is_empty(), false); | ||
| debug_assert_ne!("".is_empty(), true); | ||
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||
| // 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); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,64 @@ | ||
| error: assert macro with a boolean comparison | ||
| --> $DIR/bool_assert_comparison.rs:5:32 | ||
| | | ||
| LL | assert_eq!("a".is_empty(), false); | ||
| | ^^^^^ help: replace it with: `assert!(!"a".is_empty())` | ||
| | | ||
| = note: `-D clippy::bool-assert-comparison` implied by `-D warnings` | ||
|
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||
| error: assert macro with a boolean comparison | ||
| --> $DIR/bool_assert_comparison.rs:6:31 | ||
| | | ||
| LL | assert_eq!("".is_empty(), true); | ||
| | ^^^^ help: replace it with: `assert!("".is_empty())` | ||
|
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||
| error: assert macro with a boolean comparison | ||
| --> $DIR/bool_assert_comparison.rs:9:32 | ||
| | | ||
| LL | assert_ne!("a".is_empty(), false); | ||
| | ^^^^^ help: replace it with: `assert!(!"a".is_empty())` | ||
|
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| error: assert macro with a boolean comparison | ||
| --> $DIR/bool_assert_comparison.rs:10:31 | ||
| | | ||
| LL | assert_ne!("".is_empty(), true); | ||
| | ^^^^ help: replace it with: `assert!(!"".is_empty())` | ||
|
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||
| error: assert macro with a boolean comparison | ||
| --> $DIR/bool_assert_comparison.rs:13:38 | ||
| | | ||
| LL | debug_assert_eq!("a".is_empty(), false); | ||
| | ^^^^^ help: replace it with: `debug_assert!(!"a".is_empty())` | ||
|
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||
| error: assert macro with a boolean comparison | ||
| --> $DIR/bool_assert_comparison.rs:14:37 | ||
| | | ||
| LL | debug_assert_eq!("".is_empty(), true); | ||
| | ^^^^ help: replace it with: `debug_assert!("".is_empty())` | ||
|
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||
| error: assert macro with a boolean comparison | ||
| --> $DIR/bool_assert_comparison.rs:17:38 | ||
| | | ||
| LL | debug_assert_ne!("a".is_empty(), false); | ||
| | ^^^^^ help: replace it with: `debug_assert!(!"a".is_empty())` | ||
|
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||
| error: assert macro with a boolean comparison | ||
| --> $DIR/bool_assert_comparison.rs:18:37 | ||
| | | ||
| LL | debug_assert_ne!("".is_empty(), true); | ||
| | ^^^^ help: replace it with: `debug_assert!(!"".is_empty())` | ||
|
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||
| error: assert macro with a boolean comparison | ||
| --> $DIR/bool_assert_comparison.rs:23:32 | ||
| | | ||
| LL | assert_eq!("a".is_empty(), false, "tadam {}", 1); | ||
| | ^^^^^ help: replace it with: `assert!(!"a".is_empty(), "tadam {}", 1)` | ||
|
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||
| error: assert macro with a boolean comparison | ||
| --> $DIR/bool_assert_comparison.rs:24:32 | ||
| | | ||
| LL | assert_eq!("a".is_empty(), false, "tadam {}", true); | ||
| | ^^^^^ help: replace it with: `assert!(!"a".is_empty(), "tadam {}", true)` | ||
|
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||
| error: aborting due to 10 previous errors | ||
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