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| 1 | +use clippy_utils::diagnostics::span_lint_and_sugg; |
| 2 | +use rustc_ast::ast::{AttrKind, Attribute, Item, ItemKind}; |
| 3 | +use rustc_ast::token::{Token, TokenKind}; |
| 4 | +use rustc_ast::tokenstream::{TokenStream, TokenTree}; |
| 5 | +use rustc_errors::Applicability; |
| 6 | +use rustc_lint::{EarlyContext, EarlyLintPass}; |
| 7 | +use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| 8 | +use rustc_span::{symbol::sym, Span}; |
| 9 | + |
| 10 | +declare_clippy_lint! { |
| 11 | + /// ### What it does |
| 12 | + /// Checks for use of `crate` as opposed to `$crate` in a macro definition. |
| 13 | + /// |
| 14 | + /// ### Why is this bad? |
| 15 | + /// `crate` refers to the macro call's crate, whereas `$crate` refers to the macro definition's |
| 16 | + /// crate. Rarely is the former intended. See: |
| 17 | + /// https://doc.rust-lang.org/reference/macros-by-example.html#hygiene |
| 18 | + /// |
| 19 | + /// ### Example |
| 20 | + /// ```rust |
| 21 | + /// #[macro_export] |
| 22 | + /// macro_rules! print_message { |
| 23 | + /// () => { |
| 24 | + /// println!("{}", crate::MESSAGE); |
| 25 | + /// }; |
| 26 | + /// } |
| 27 | + /// pub const MESSAGE: &str = "Hello!"; |
| 28 | + /// ``` |
| 29 | + /// Use instead: |
| 30 | + /// ```rust |
| 31 | + /// #[macro_export] |
| 32 | + /// macro_rules! print_message { |
| 33 | + /// () => { |
| 34 | + /// println!("{}", $crate::MESSAGE); |
| 35 | + /// }; |
| 36 | + /// } |
| 37 | + /// pub const MESSAGE: &str = "Hello!"; |
| 38 | + /// ``` |
| 39 | + /// |
| 40 | + /// Note that if the use of `crate` is intentional, an `allow` attribute can be applied to the |
| 41 | + /// macro definition, e.g.: |
| 42 | + /// ```rust,ignore |
| 43 | + /// #[allow(clippy::crate_in_macro_def)] |
| 44 | + /// macro_rules! ok { ... crate::foo ... } |
| 45 | + /// ``` |
| 46 | + #[clippy::version = "1.61.0"] |
| 47 | + pub CRATE_IN_MACRO_DEF, |
| 48 | + suspicious, |
| 49 | + "using `crate` in a macro definition" |
| 50 | +} |
| 51 | +declare_lint_pass!(CrateInMacroDef => [CRATE_IN_MACRO_DEF]); |
| 52 | + |
| 53 | +impl EarlyLintPass for CrateInMacroDef { |
| 54 | + fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) { |
| 55 | + if_chain! { |
| 56 | + if item.attrs.iter().any(is_macro_export); |
| 57 | + if let ItemKind::MacroDef(macro_def) = &item.kind; |
| 58 | + let tts = macro_def.body.inner_tokens(); |
| 59 | + if let Some(span) = contains_unhygienic_crate_reference(&tts); |
| 60 | + then { |
| 61 | + span_lint_and_sugg( |
| 62 | + cx, |
| 63 | + CRATE_IN_MACRO_DEF, |
| 64 | + span, |
| 65 | + "`crate` references the macro call's crate", |
| 66 | + "to reference the macro definition's crate, use", |
| 67 | + String::from("$crate"), |
| 68 | + Applicability::MachineApplicable, |
| 69 | + ); |
| 70 | + } |
| 71 | + } |
| 72 | + } |
| 73 | +} |
| 74 | + |
| 75 | +fn is_macro_export(attr: &Attribute) -> bool { |
| 76 | + if_chain! { |
| 77 | + if let AttrKind::Normal(attr_item, _) = &attr.kind; |
| 78 | + if let [segment] = attr_item.path.segments.as_slice(); |
| 79 | + then { |
| 80 | + segment.ident.name == sym::macro_export |
| 81 | + } else { |
| 82 | + false |
| 83 | + } |
| 84 | + } |
| 85 | +} |
| 86 | + |
| 87 | +fn contains_unhygienic_crate_reference(tts: &TokenStream) -> Option<Span> { |
| 88 | + let mut prev_is_dollar = false; |
| 89 | + let mut cursor = tts.trees(); |
| 90 | + while let Some(curr) = cursor.next() { |
| 91 | + if_chain! { |
| 92 | + if !prev_is_dollar; |
| 93 | + if let Some(span) = is_crate_keyword(&curr); |
| 94 | + if let Some(next) = cursor.look_ahead(0); |
| 95 | + if is_token(next, &TokenKind::ModSep); |
| 96 | + then { |
| 97 | + return Some(span); |
| 98 | + } |
| 99 | + } |
| 100 | + if let TokenTree::Delimited(_, _, tts) = &curr { |
| 101 | + let span = contains_unhygienic_crate_reference(tts); |
| 102 | + if span.is_some() { |
| 103 | + return span; |
| 104 | + } |
| 105 | + } |
| 106 | + prev_is_dollar = is_token(&curr, &TokenKind::Dollar); |
| 107 | + } |
| 108 | + None |
| 109 | +} |
| 110 | + |
| 111 | +fn is_crate_keyword(tt: &TokenTree) -> Option<Span> { |
| 112 | + if_chain! { |
| 113 | + if let TokenTree::Token(Token { kind: TokenKind::Ident(symbol, _), span }) = tt; |
| 114 | + if symbol.as_str() == "crate"; |
| 115 | + then { Some(*span) } else { None } |
| 116 | + } |
| 117 | +} |
| 118 | + |
| 119 | +fn is_token(tt: &TokenTree, kind: &TokenKind) -> bool { |
| 120 | + if let TokenTree::Token(Token { kind: other, .. }) = tt { |
| 121 | + kind == other |
| 122 | + } else { |
| 123 | + false |
| 124 | + } |
| 125 | +} |
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