diff --git a/CHANGELOG.md b/CHANGELOG.md index dc83de665548..9cede8065ec7 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -3097,6 +3097,7 @@ Released 2018-09-13 [`comparison_chain`]: https://rust-lang.github.io/rust-clippy/master/index.html#comparison_chain [`comparison_to_empty`]: https://rust-lang.github.io/rust-clippy/master/index.html#comparison_to_empty [`copy_iterator`]: https://rust-lang.github.io/rust-clippy/master/index.html#copy_iterator +[`crate_in_macro_def`]: https://rust-lang.github.io/rust-clippy/master/index.html#crate_in_macro_def [`create_dir`]: https://rust-lang.github.io/rust-clippy/master/index.html#create_dir [`crosspointer_transmute`]: https://rust-lang.github.io/rust-clippy/master/index.html#crosspointer_transmute [`dbg_macro`]: https://rust-lang.github.io/rust-clippy/master/index.html#dbg_macro diff --git a/clippy_lints/src/crate_in_macro_def.rs b/clippy_lints/src/crate_in_macro_def.rs new file mode 100644 index 000000000000..fc141b4a6e3a --- /dev/null +++ b/clippy_lints/src/crate_in_macro_def.rs @@ -0,0 +1,125 @@ +use clippy_utils::diagnostics::span_lint_and_sugg; +use rustc_ast::ast::{AttrKind, Attribute, Item, ItemKind}; +use rustc_ast::token::{Token, TokenKind}; +use rustc_ast::tokenstream::{TokenStream, TokenTree}; +use rustc_errors::Applicability; +use rustc_lint::{EarlyContext, EarlyLintPass}; +use rustc_session::{declare_lint_pass, declare_tool_lint}; +use rustc_span::{symbol::sym, Span}; + +declare_clippy_lint! { + /// ### What it does + /// Checks for use of `crate` as opposed to `$crate` in a macro definition. + /// + /// ### Why is this bad? + /// `crate` refers to the macro call's crate, whereas `$crate` refers to the macro definition's + /// crate. Rarely is the former intended. See: + /// https://doc.rust-lang.org/reference/macros-by-example.html#hygiene + /// + /// ### Example + /// ```rust + /// #[macro_export] + /// macro_rules! print_message { + /// () => { + /// println!("{}", crate::MESSAGE); + /// }; + /// } + /// pub const MESSAGE: &str = "Hello!"; + /// ``` + /// Use instead: + /// ```rust + /// #[macro_export] + /// macro_rules! print_message { + /// () => { + /// println!("{}", $crate::MESSAGE); + /// }; + /// } + /// pub const MESSAGE: &str = "Hello!"; + /// ``` + /// + /// Note that if the use of `crate` is intentional, an `allow` attribute can be applied to the + /// macro definition, e.g.: + /// ```rust,ignore + /// #[allow(clippy::crate_in_macro_def)] + /// macro_rules! ok { ... crate::foo ... } + /// ``` + #[clippy::version = "1.61.0"] + pub CRATE_IN_MACRO_DEF, + suspicious, + "using `crate` in a macro definition" +} +declare_lint_pass!(CrateInMacroDef => [CRATE_IN_MACRO_DEF]); + +impl EarlyLintPass for CrateInMacroDef { + fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) { + if_chain! { + if item.attrs.iter().any(is_macro_export); + if let ItemKind::MacroDef(macro_def) = &item.kind; + let tts = macro_def.body.inner_tokens(); + if let Some(span) = contains_unhygienic_crate_reference(&tts); + then { + span_lint_and_sugg( + cx, + CRATE_IN_MACRO_DEF, + span, + "`crate` references the macro call's crate", + "to reference the macro definition's crate, use", + String::from("$crate"), + Applicability::MachineApplicable, + ); + } + } + } +} + +fn is_macro_export(attr: &Attribute) -> bool { + if_chain! { + if let AttrKind::Normal(attr_item, _) = &attr.kind; + if let [segment] = attr_item.path.segments.as_slice(); + then { + segment.ident.name == sym::macro_export + } else { + false + } + } +} + +fn contains_unhygienic_crate_reference(tts: &TokenStream) -> Option { + let mut prev_is_dollar = false; + let mut cursor = tts.trees(); + while let Some(curr) = cursor.next() { + if_chain! { + if !prev_is_dollar; + if let Some(span) = is_crate_keyword(&curr); + if let Some(next) = cursor.look_ahead(0); + if is_token(next, &TokenKind::ModSep); + then { + return Some(span); + } + } + if let TokenTree::Delimited(_, _, tts) = &curr { + let span = contains_unhygienic_crate_reference(tts); + if span.is_some() { + return span; + } + } + prev_is_dollar = is_token(&curr, &TokenKind::Dollar); + } + None +} + +fn is_crate_keyword(tt: &TokenTree) -> Option { + if_chain! { + if let TokenTree::Token(Token { kind: TokenKind::Ident(symbol, _), span }) = tt; + if symbol.as_str() == "crate"; + then { Some(*span) } else { None } + } +} + +fn is_token(tt: &TokenTree, kind: &TokenKind) -> bool { + if let TokenTree::Token(Token { kind: other, .. }) = tt { + kind == other + } else { + false + } +} diff --git a/clippy_lints/src/lib.register_all.rs b/clippy_lints/src/lib.register_all.rs index 132a46626762..1fb3ca1fd9b2 100644 --- a/clippy_lints/src/lib.register_all.rs +++ b/clippy_lints/src/lib.register_all.rs @@ -37,6 +37,7 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![ LintId::of(comparison_chain::COMPARISON_CHAIN), LintId::of(copies::IFS_SAME_COND), LintId::of(copies::IF_SAME_THEN_ELSE), + LintId::of(crate_in_macro_def::CRATE_IN_MACRO_DEF), LintId::of(default::FIELD_REASSIGN_WITH_DEFAULT), LintId::of(dereference::NEEDLESS_BORROW), LintId::of(derivable_impls::DERIVABLE_IMPLS), diff --git a/clippy_lints/src/lib.register_lints.rs b/clippy_lints/src/lib.register_lints.rs index 65ad64f19018..984939a74b8d 100644 --- a/clippy_lints/src/lib.register_lints.rs +++ b/clippy_lints/src/lib.register_lints.rs @@ -97,6 +97,7 @@ store.register_lints(&[ copies::IF_SAME_THEN_ELSE, copies::SAME_FUNCTIONS_IN_IF_CONDITION, copy_iterator::COPY_ITERATOR, + crate_in_macro_def::CRATE_IN_MACRO_DEF, create_dir::CREATE_DIR, dbg_macro::DBG_MACRO, default::DEFAULT_TRAIT_ACCESS, diff --git a/clippy_lints/src/lib.register_suspicious.rs b/clippy_lints/src/lib.register_suspicious.rs index fa3a88e1368c..0707e4f8f3d1 100644 --- a/clippy_lints/src/lib.register_suspicious.rs +++ b/clippy_lints/src/lib.register_suspicious.rs @@ -9,6 +9,7 @@ store.register_group(true, "clippy::suspicious", Some("clippy_suspicious"), vec! LintId::of(await_holding_invalid::AWAIT_HOLDING_REFCELL_REF), LintId::of(casts::CAST_ENUM_CONSTRUCTOR), LintId::of(casts::CAST_ENUM_TRUNCATION), + LintId::of(crate_in_macro_def::CRATE_IN_MACRO_DEF), LintId::of(eval_order_dependence::EVAL_ORDER_DEPENDENCE), LintId::of(float_equality_without_abs::FLOAT_EQUALITY_WITHOUT_ABS), LintId::of(format_impl::PRINT_IN_FORMAT_IMPL), diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs index f2a079991444..c8b57956b1b6 100644 --- a/clippy_lints/src/lib.rs +++ b/clippy_lints/src/lib.rs @@ -190,6 +190,7 @@ mod collapsible_match; mod comparison_chain; mod copies; mod copy_iterator; +mod crate_in_macro_def; mod create_dir; mod dbg_macro; mod default; @@ -867,6 +868,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: ignore_publish: cargo_ignore_publish, }) }); + store.register_early_pass(|| Box::new(crate_in_macro_def::CrateInMacroDef)); // add lints here, do not remove this comment, it's used in `new_lint` } diff --git a/tests/ui/crate_in_macro_def.fixed b/tests/ui/crate_in_macro_def.fixed new file mode 100644 index 000000000000..9fc594be311e --- /dev/null +++ b/tests/ui/crate_in_macro_def.fixed @@ -0,0 +1,56 @@ +// run-rustfix +#![warn(clippy::crate_in_macro_def)] + +mod hygienic { + #[macro_export] + macro_rules! print_message_hygienic { + () => { + println!("{}", $crate::hygienic::MESSAGE); + }; + } + + pub const MESSAGE: &str = "Hello!"; +} + +mod unhygienic { + #[macro_export] + macro_rules! print_message_unhygienic { + () => { + println!("{}", $crate::unhygienic::MESSAGE); + }; + } + + pub const MESSAGE: &str = "Hello!"; +} + +mod unhygienic_intentionally { + // For cases where the use of `crate` is intentional, applying `allow` to the macro definition + // should suppress the lint. + #[allow(clippy::crate_in_macro_def)] + #[macro_export] + macro_rules! print_message_unhygienic_intentionally { + () => { + println!("{}", crate::CALLER_PROVIDED_MESSAGE); + }; + } +} + +#[macro_use] +mod not_exported { + macro_rules! print_message_not_exported { + () => { + println!("{}", crate::not_exported::MESSAGE); + }; + } + + pub const MESSAGE: &str = "Hello!"; +} + +fn main() { + print_message_hygienic!(); + print_message_unhygienic!(); + print_message_unhygienic_intentionally!(); + print_message_not_exported!(); +} + +pub const CALLER_PROVIDED_MESSAGE: &str = "Hello!"; diff --git a/tests/ui/crate_in_macro_def.rs b/tests/ui/crate_in_macro_def.rs new file mode 100644 index 000000000000..ac456108e4ab --- /dev/null +++ b/tests/ui/crate_in_macro_def.rs @@ -0,0 +1,56 @@ +// run-rustfix +#![warn(clippy::crate_in_macro_def)] + +mod hygienic { + #[macro_export] + macro_rules! print_message_hygienic { + () => { + println!("{}", $crate::hygienic::MESSAGE); + }; + } + + pub const MESSAGE: &str = "Hello!"; +} + +mod unhygienic { + #[macro_export] + macro_rules! print_message_unhygienic { + () => { + println!("{}", crate::unhygienic::MESSAGE); + }; + } + + pub const MESSAGE: &str = "Hello!"; +} + +mod unhygienic_intentionally { + // For cases where the use of `crate` is intentional, applying `allow` to the macro definition + // should suppress the lint. + #[allow(clippy::crate_in_macro_def)] + #[macro_export] + macro_rules! print_message_unhygienic_intentionally { + () => { + println!("{}", crate::CALLER_PROVIDED_MESSAGE); + }; + } +} + +#[macro_use] +mod not_exported { + macro_rules! print_message_not_exported { + () => { + println!("{}", crate::not_exported::MESSAGE); + }; + } + + pub const MESSAGE: &str = "Hello!"; +} + +fn main() { + print_message_hygienic!(); + print_message_unhygienic!(); + print_message_unhygienic_intentionally!(); + print_message_not_exported!(); +} + +pub const CALLER_PROVIDED_MESSAGE: &str = "Hello!"; diff --git a/tests/ui/crate_in_macro_def.stderr b/tests/ui/crate_in_macro_def.stderr new file mode 100644 index 000000000000..9ac5937dcc06 --- /dev/null +++ b/tests/ui/crate_in_macro_def.stderr @@ -0,0 +1,10 @@ +error: `crate` references the macro call's crate + --> $DIR/crate_in_macro_def.rs:19:28 + | +LL | println!("{}", crate::unhygienic::MESSAGE); + | ^^^^^ help: to reference the macro definition's crate, use: `$crate` + | + = note: `-D clippy::crate-in-macro-def` implied by `-D warnings` + +error: aborting due to previous error +