76 lines
2.5 KiB
Rust
76 lines
2.5 KiB
Rust
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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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}
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