diff options
| -rw-r--r-- | CHANGELOG.md | 1 | ||||
| -rw-r--r-- | clippy_lints/src/declared_lints.rs | 1 | ||||
| -rw-r--r-- | clippy_lints/src/lib.rs | 2 | ||||
| -rw-r--r-- | clippy_lints/src/useless_concat.rs | 108 |
4 files changed, 112 insertions, 0 deletions
diff --git a/CHANGELOG.md b/CHANGELOG.md index 68c03a81337..84378f3f1c4 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -6438,6 +6438,7 @@ Released 2018-09-13 [`used_underscore_items`]: https://rust-lang.github.io/rust-clippy/master/index.html#used_underscore_items [`useless_asref`]: https://rust-lang.github.io/rust-clippy/master/index.html#useless_asref [`useless_attribute`]: https://rust-lang.github.io/rust-clippy/master/index.html#useless_attribute +[`useless_concat`]: https://rust-lang.github.io/rust-clippy/master/index.html#useless_concat [`useless_conversion`]: https://rust-lang.github.io/rust-clippy/master/index.html#useless_conversion [`useless_format`]: https://rust-lang.github.io/rust-clippy/master/index.html#useless_format [`useless_let_if_seq`]: https://rust-lang.github.io/rust-clippy/master/index.html#useless_let_if_seq diff --git a/clippy_lints/src/declared_lints.rs b/clippy_lints/src/declared_lints.rs index e046ab0b42b..69ef3d69bb8 100644 --- a/clippy_lints/src/declared_lints.rs +++ b/clippy_lints/src/declared_lints.rs @@ -762,6 +762,7 @@ pub static LINTS: &[&crate::LintInfo] = &[ crate::unwrap_in_result::UNWRAP_IN_RESULT_INFO, crate::upper_case_acronyms::UPPER_CASE_ACRONYMS_INFO, crate::use_self::USE_SELF_INFO, + crate::useless_concat::USELESS_CONCAT_INFO, crate::useless_conversion::USELESS_CONVERSION_INFO, crate::vec::USELESS_VEC_INFO, crate::vec_init_then_push::VEC_INIT_THEN_PUSH_INFO, diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs index 64fbc0252e2..a51e45bff7a 100644 --- a/clippy_lints/src/lib.rs +++ b/clippy_lints/src/lib.rs @@ -392,6 +392,7 @@ mod unwrap; mod unwrap_in_result; mod upper_case_acronyms; mod use_self; +mod useless_concat; mod useless_conversion; mod vec; mod vec_init_then_push; @@ -936,6 +937,7 @@ pub fn register_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) { store.register_late_pass(|_| Box::new(unnecessary_literal_bound::UnnecessaryLiteralBound)); store.register_early_pass(|| Box::new(empty_line_after::EmptyLineAfter::new())); store.register_late_pass(move |_| Box::new(arbitrary_source_item_ordering::ArbitrarySourceItemOrdering::new(conf))); + store.register_late_pass(|_| Box::new(useless_concat::UselessConcat)); store.register_late_pass(|_| Box::new(unneeded_struct_pattern::UnneededStructPattern)); store.register_late_pass(|_| Box::<unnecessary_semicolon::UnnecessarySemicolon>::default()); store.register_late_pass(move |_| Box::new(non_std_lazy_statics::NonStdLazyStatic::new(conf))); diff --git a/clippy_lints/src/useless_concat.rs b/clippy_lints/src/useless_concat.rs new file mode 100644 index 00000000000..3f68b93d4f5 --- /dev/null +++ b/clippy_lints/src/useless_concat.rs @@ -0,0 +1,108 @@ +use clippy_utils::diagnostics::span_lint_and_sugg; +use clippy_utils::macros::macro_backtrace; +use clippy_utils::source::snippet_opt; +use clippy_utils::{match_def_path, tokenize_with_text}; +use rustc_ast::LitKind; +use rustc_errors::Applicability; +use rustc_hir::{Expr, ExprKind}; +use rustc_lexer::TokenKind; +use rustc_lint::{LateContext, LateLintPass}; +use rustc_session::declare_lint_pass; + +declare_clippy_lint! { + /// ### What it does + /// Checks that the `concat!` macro has at least two arguments. + /// + /// ### Why is this bad? + /// If there are less than 2 arguments, then calling the macro is doing nothing. + /// + /// ### Example + /// ```no_run + /// let x = concat!("a"); + /// ``` + /// Use instead: + /// ```no_run + /// let x = "a"; + /// ``` + #[clippy::version = "1.85.0"] + pub USELESS_CONCAT, + complexity, + "checks that the `concat` macro has at least two arguments" +} + +declare_lint_pass!(UselessConcat => [USELESS_CONCAT]); + +impl LateLintPass<'_> for UselessConcat { + fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) { + // Check that the expression is generated by a macro. + if expr.span.from_expansion() + // Check that it's a string literal. + && let ExprKind::Lit(lit) = expr.kind + && let LitKind::Str(_, _) = lit.node + // Get the direct parent of the expression. + && let Some(macro_call) = macro_backtrace(expr.span).next() + // Check if the `concat` macro from the `core` library. + && match_def_path(cx, macro_call.def_id, &["core", "macros", "builtin", "concat"]) + // We get the original code to parse it. + && let Some(original_code) = snippet_opt(cx, macro_call.span) + // This check allows us to ensure that the code snippet: + // 1. Doesn't come from proc-macro expansion. + // 2. Doesn't come from foreign macro expansion. + // + // It works as follows: if the snippet we get doesn't contain `concat!(`, then it + // means it's not code written in the current crate so we shouldn't lint. + && let mut parts = original_code.split('!') + && parts.next().is_some_and(|p| p.trim() == "concat") + && parts.next().is_some_and(|p| p.trim().starts_with('(')) + { + let mut literal = None; + let mut nb_commas = 0; + let mut nb_idents = 0; + for (token_kind, token_s, _) in tokenize_with_text(&original_code) { + match token_kind { + TokenKind::Eof => break, + TokenKind::Literal { .. } => { + if literal.is_some() { + return; + } + literal = Some(token_s); + }, + TokenKind::Ident => nb_idents += 1, + TokenKind::Comma => { + nb_commas += 1; + if nb_commas > 1 { + return; + } + }, + // We're inside a macro definition and we are manipulating something we likely + // shouldn't, so aborting. + TokenKind::Dollar => return, + _ => {}, + } + } + let literal = match literal { + Some(lit) => { + // Literals can also be number, so we need to check this case too. + if lit.starts_with('"') { + lit.to_string() + } else { + format!("\"{lit}\"") + } + }, + None => "\"\"".to_string(), + }; + // There should always be the ident of the `concat` macro. + if nb_idents == 1 { + span_lint_and_sugg( + cx, + USELESS_CONCAT, + macro_call.span, + "unneeded use of `concat!` macro", + "replace with", + literal, + Applicability::MachineApplicable, + ); + } + } + } +} |