diff options
| -rw-r--r-- | CHANGELOG.md | 1 | ||||
| -rw-r--r-- | clippy_lints/src/lib.register_all.rs | 1 | ||||
| -rw-r--r-- | clippy_lints/src/lib.register_lints.rs | 1 | ||||
| -rw-r--r-- | clippy_lints/src/lib.register_suspicious.rs | 1 | ||||
| -rw-r--r-- | clippy_lints/src/methods/mod.rs | 23 | ||||
| -rw-r--r-- | clippy_lints/src/methods/no_effect_replace.rs | 47 | ||||
| -rw-r--r-- | tests/ui/no_effect_replace.rs | 51 | ||||
| -rw-r--r-- | tests/ui/no_effect_replace.stderr | 52 |
8 files changed, 177 insertions, 0 deletions
diff --git a/CHANGELOG.md b/CHANGELOG.md index 47aaae9c198..4b62ccbf8bc 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -3594,6 +3594,7 @@ Released 2018-09-13 [`new_ret_no_self`]: https://rust-lang.github.io/rust-clippy/master/index.html#new_ret_no_self [`new_without_default`]: https://rust-lang.github.io/rust-clippy/master/index.html#new_without_default [`no_effect`]: https://rust-lang.github.io/rust-clippy/master/index.html#no_effect +[`no_effect_replace`]: https://rust-lang.github.io/rust-clippy/master/index.html#no_effect_replace [`no_effect_underscore_binding`]: https://rust-lang.github.io/rust-clippy/master/index.html#no_effect_underscore_binding [`non_ascii_literal`]: https://rust-lang.github.io/rust-clippy/master/index.html#non_ascii_literal [`non_octal_unix_permissions`]: https://rust-lang.github.io/rust-clippy/master/index.html#non_octal_unix_permissions diff --git a/clippy_lints/src/lib.register_all.rs b/clippy_lints/src/lib.register_all.rs index fca5e109509..2d0dca87b10 100644 --- a/clippy_lints/src/lib.register_all.rs +++ b/clippy_lints/src/lib.register_all.rs @@ -190,6 +190,7 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![ LintId::of(methods::NEEDLESS_OPTION_TAKE), LintId::of(methods::NEEDLESS_SPLITN), LintId::of(methods::NEW_RET_NO_SELF), + LintId::of(methods::NO_EFFECT_REPLACE), LintId::of(methods::OK_EXPECT), LintId::of(methods::OPTION_AS_REF_DEREF), LintId::of(methods::OPTION_FILTER_MAP), diff --git a/clippy_lints/src/lib.register_lints.rs b/clippy_lints/src/lib.register_lints.rs index 7489f53fd3c..5d6360838ec 100644 --- a/clippy_lints/src/lib.register_lints.rs +++ b/clippy_lints/src/lib.register_lints.rs @@ -331,6 +331,7 @@ store.register_lints(&[ methods::NEEDLESS_OPTION_TAKE, methods::NEEDLESS_SPLITN, methods::NEW_RET_NO_SELF, + methods::NO_EFFECT_REPLACE, methods::OK_EXPECT, methods::OPTION_AS_REF_DEREF, methods::OPTION_FILTER_MAP, diff --git a/clippy_lints/src/lib.register_suspicious.rs b/clippy_lints/src/lib.register_suspicious.rs index 940bf7ace5e..7e1ba5336c6 100644 --- a/clippy_lints/src/lib.register_suspicious.rs +++ b/clippy_lints/src/lib.register_suspicious.rs @@ -23,6 +23,7 @@ store.register_group(true, "clippy::suspicious", Some("clippy_suspicious"), vec! LintId::of(loops::EMPTY_LOOP), LintId::of(loops::FOR_LOOPS_OVER_FALLIBLES), LintId::of(loops::MUT_RANGE_BOUND), + LintId::of(methods::NO_EFFECT_REPLACE), LintId::of(methods::SUSPICIOUS_MAP), LintId::of(mut_key::MUTABLE_KEY_TYPE), LintId::of(octal_escapes::OCTAL_ESCAPES), diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs index cfeee4d0c70..5102fa17a67 100644 --- a/clippy_lints/src/methods/mod.rs +++ b/clippy_lints/src/methods/mod.rs @@ -44,6 +44,7 @@ mod map_identity; mod map_unwrap_or; mod needless_option_as_deref; mod needless_option_take; +mod no_effect_replace; mod ok_expect; mod option_as_ref_deref; mod option_map_or_none; @@ -2197,6 +2198,24 @@ declare_clippy_lint! { "using `.as_ref().take()` on a temporary value" } +declare_clippy_lint! { + /// ### What it does + /// Checks for `replace` statements which have no effect. + /// + /// ### Why is this bad? + /// It's either a mistake or confusing. + /// + /// ### Example + /// ```rust + /// "1234".replace("12", "12"); + /// "1234".replacen("12", "12", 1); + /// ``` + #[clippy::version = "1.62.0"] + pub NO_EFFECT_REPLACE, + suspicious, + "replace with no effect" +} + pub struct Methods { avoid_breaking_exported_api: bool, msrv: Option<RustcVersion>, @@ -2296,6 +2315,7 @@ impl_lint_pass!(Methods => [ NEEDLESS_OPTION_AS_DEREF, IS_DIGIT_ASCII_RADIX, NEEDLESS_OPTION_TAKE, + NO_EFFECT_REPLACE, ]); /// Extracts a method call name, args, and `Span` of the method name. @@ -2707,6 +2727,9 @@ impl Methods { unnecessary_lazy_eval::check(cx, expr, recv, u_arg, "unwrap_or"); }, }, + ("replace" | "replacen", [arg1, arg2] | [arg1, arg2, _]) => { + no_effect_replace::check(cx, expr, arg1, arg2); + }, _ => {}, } } diff --git a/clippy_lints/src/methods/no_effect_replace.rs b/clippy_lints/src/methods/no_effect_replace.rs new file mode 100644 index 00000000000..a76341855b6 --- /dev/null +++ b/clippy_lints/src/methods/no_effect_replace.rs @@ -0,0 +1,47 @@ +use clippy_utils::diagnostics::span_lint; +use clippy_utils::ty::is_type_diagnostic_item; +use clippy_utils::SpanlessEq; +use if_chain::if_chain; +use rustc_ast::LitKind; +use rustc_hir::ExprKind; +use rustc_lint::LateContext; +use rustc_span::sym; + +use super::NO_EFFECT_REPLACE; + +pub(super) fn check<'tcx>( + cx: &LateContext<'tcx>, + expr: &'tcx rustc_hir::Expr<'_>, + arg1: &'tcx rustc_hir::Expr<'_>, + arg2: &'tcx rustc_hir::Expr<'_>, +) { + let ty = cx.typeck_results().expr_ty(expr).peel_refs(); + if !(ty.is_str() || is_type_diagnostic_item(cx, ty, sym::String)) { + return; + } + + if_chain! { + if let ExprKind::Lit(spanned) = &arg1.kind; + if let Some(param1) = lit_string_value(&spanned.node); + + if let ExprKind::Lit(spanned) = &arg2.kind; + if let LitKind::Str(param2, _) = &spanned.node; + if param1 == param2.as_str(); + + then { + span_lint(cx, NO_EFFECT_REPLACE, expr.span, "replacing text with itself"); + } + } + + if SpanlessEq::new(cx).eq_expr(arg1, arg2) { + span_lint(cx, NO_EFFECT_REPLACE, expr.span, "replacing text with itself"); + } +} + +fn lit_string_value(node: &LitKind) -> Option<String> { + match node { + LitKind::Char(value) => Some(value.to_string()), + LitKind::Str(value, _) => Some(value.as_str().to_owned()), + _ => None, + } +} diff --git a/tests/ui/no_effect_replace.rs b/tests/ui/no_effect_replace.rs new file mode 100644 index 00000000000..ad17d53f789 --- /dev/null +++ b/tests/ui/no_effect_replace.rs @@ -0,0 +1,51 @@ +#![warn(clippy::no_effect_replace)] + +fn main() { + let _ = "12345".replace('1', "1"); + let _ = "12345".replace("12", "12"); + let _ = String::new().replace("12", "12"); + + let _ = "12345".replacen('1', "1", 1); + let _ = "12345".replacen("12", "12", 1); + let _ = String::new().replacen("12", "12", 1); + + let _ = "12345".replace("12", "22"); + let _ = "12345".replacen("12", "22", 1); + + let mut x = X::default(); + let _ = "hello".replace(&x.f(), &x.f()); + let _ = "hello".replace(&x.f(), &x.ff()); + + let _ = "hello".replace(&y(), &y()); + let _ = "hello".replace(&y(), &z()); + + let _ = Replaceme.replace("a", "a"); +} + +#[derive(Default)] +struct X {} + +impl X { + fn f(&mut self) -> String { + "he".to_string() + } + + fn ff(&mut self) -> String { + "hh".to_string() + } +} + +fn y() -> String { + "he".to_string() +} + +fn z() -> String { + "hh".to_string() +} + +struct Replaceme; +impl Replaceme { + pub fn replace(&mut self, a: &str, b: &str) -> Self { + Self + } +} diff --git a/tests/ui/no_effect_replace.stderr b/tests/ui/no_effect_replace.stderr new file mode 100644 index 00000000000..53a28aa73b7 --- /dev/null +++ b/tests/ui/no_effect_replace.stderr @@ -0,0 +1,52 @@ +error: replacing text with itself + --> $DIR/no_effect_replace.rs:4:13 + | +LL | let _ = "12345".replace('1', "1"); + | ^^^^^^^^^^^^^^^^^^^^^^^^^ + | + = note: `-D clippy::no-effect-replace` implied by `-D warnings` + +error: replacing text with itself + --> $DIR/no_effect_replace.rs:5:13 + | +LL | let _ = "12345".replace("12", "12"); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: replacing text with itself + --> $DIR/no_effect_replace.rs:6:13 + | +LL | let _ = String::new().replace("12", "12"); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: replacing text with itself + --> $DIR/no_effect_replace.rs:8:13 + | +LL | let _ = "12345".replacen('1', "1", 1); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: replacing text with itself + --> $DIR/no_effect_replace.rs:9:13 + | +LL | let _ = "12345".replacen("12", "12", 1); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: replacing text with itself + --> $DIR/no_effect_replace.rs:10:13 + | +LL | let _ = String::new().replacen("12", "12", 1); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: replacing text with itself + --> $DIR/no_effect_replace.rs:16:13 + | +LL | let _ = "hello".replace(&x.f(), &x.f()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: replacing text with itself + --> $DIR/no_effect_replace.rs:19:13 + | +LL | let _ = "hello".replace(&y(), &y()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: aborting due to 8 previous errors + |