diff --git a/compiler/rustc_lint/messages.ftl b/compiler/rustc_lint/messages.ftl index fb71cb6014026..ea5167e041b23 100644 --- a/compiler/rustc_lint/messages.ftl +++ b/compiler/rustc_lint/messages.ftl @@ -440,6 +440,9 @@ lint_lintpass_by_hand = implementing `LintPass` by hand lint_macro_expanded_macro_exports_accessed_by_absolute_paths = macro-expanded `macro_export` macros from the current crate cannot be referred to by absolute paths .note = the macro is defined here +lint_macro_expr_fragment_specifier_2024_migration = + the `expr` fragment specifier will accept more expressions in the 2024 edition. + .suggestion = to keep the existing behavior, use the `expr_2021` fragment specifier. lint_macro_is_private = macro `{$ident}` is private lint_macro_rule_never_used = rule #{$n} of macro `{$name}` is never used diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs index bcb714ae4ce2a..9178c5ae9d866 100644 --- a/compiler/rustc_lint/src/lib.rs +++ b/compiler/rustc_lint/src/lib.rs @@ -58,6 +58,7 @@ mod late; mod let_underscore; mod levels; mod lints; +mod macro_expr_fragment_specifier_2024_migration; mod map_unit_fn; mod methods; mod multiple_supertrait_upcastable; @@ -95,6 +96,7 @@ use impl_trait_overcaptures::ImplTraitOvercaptures; use internal::*; use invalid_from_utf8::*; use let_underscore::*; +use macro_expr_fragment_specifier_2024_migration::*; use map_unit_fn::*; use methods::*; use multiple_supertrait_upcastable::*; @@ -168,6 +170,7 @@ early_lint_methods!( IncompleteInternalFeatures: IncompleteInternalFeatures, RedundantSemicolons: RedundantSemicolons, UnusedDocComment: UnusedDocComment, + Expr2024: Expr2024, ] ] ); diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs index 84d46ef3b65d5..1e5b263a335f0 100644 --- a/compiler/rustc_lint/src/lints.rs +++ b/compiler/rustc_lint/src/lints.rs @@ -323,6 +323,13 @@ pub struct BuiltinTypeAliasGenericBounds<'a, 'b> { pub sub: Option>, } +#[derive(LintDiagnostic)] +#[diag(lint_macro_expr_fragment_specifier_2024_migration)] +pub struct MacroExprFragment2024 { + #[suggestion(code = "expr_2021", applicability = "machine-applicable")] + pub suggestion: Span, +} + pub struct BuiltinTypeAliasGenericBoundsSuggestion { pub suggestions: Vec<(Span, String)>, } diff --git a/compiler/rustc_lint/src/macro_expr_fragment_specifier_2024_migration.rs b/compiler/rustc_lint/src/macro_expr_fragment_specifier_2024_migration.rs new file mode 100644 index 0000000000000..91cf1dcd17f19 --- /dev/null +++ b/compiler/rustc_lint/src/macro_expr_fragment_specifier_2024_migration.rs @@ -0,0 +1,126 @@ +//! Migration code for the `expr_fragment_specifier_2024` +//! rule. +use tracing::debug; + +use rustc_ast::token::Token; +use rustc_ast::token::TokenKind; +use rustc_ast::tokenstream::TokenStream; +use rustc_ast::tokenstream::TokenTree; +use rustc_session::declare_lint; +use rustc_session::declare_lint_pass; +use rustc_session::lint::FutureIncompatibilityReason; +use rustc_span::edition::Edition; +use rustc_span::sym; + +use crate::lints::MacroExprFragment2024; +use crate::EarlyLintPass; + +declare_lint! { + /// The `edition_2024_expr_fragment_specifier` lint detects the use of `expr` fragments + /// during migration to the 2024 edition. + /// + /// The `expr` fragment specifier will accept more expressions in the 2024 edition. + /// To maintain the current behavior, use the `expr_2021` fragment specifier. + /// + /// ### Example + /// + /// ```rust,edition2021,no_run + /// #![deny(edition_2024_expr_fragment_specifier)] + /// macro_rules! m { + /// ($e:expr) => { + /// $e + /// } + /// } + /// + /// fn main() { + /// m!(1); + /// } + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// Rust [editions] allow the language to evolve without breaking + /// backwards compatibility. This lint catches code that uses new keywords + /// that are added to the language that are used as identifiers (such as a + /// variable name, function name, etc.). If you switch the compiler to a + /// new edition without updating the code, then it will fail to compile if + /// you are using a new keyword as an identifier. + /// + /// FIXME: change this: You can manually change the identifiers from `expr` to `expr2021`, + /// or use a [raw identifier], for example `r#gen`, to transition to a new edition. + /// + /// This lint solves the problem automatically. It is "allow" by default + /// because the code is perfectly valid in older editions. The [`cargo + /// fix`] tool with the `--edition` flag will switch this lint to "warn" + /// and automatically apply the suggested fix from the compiler (which is + /// to use a raw identifier). This provides a completely automated way to + /// update old code for a new edition. + /// + /// [editions]: https://doc.rust-lang.org/edition-guide/ + /// [raw identifier]: https://doc.rust-lang.org/reference/identifiers.html + /// [`cargo fix`]: https://doc.rust-lang.org/cargo/commands/cargo-fix.html + pub EDITION_2024_EXPR_FRAGMENT_SPECIFIER, + Allow, + "The `expr` fragment specifier will accept more expressions in the 2024 edition. \ + To keep the existing behavior, use the `expr_2021` fragment specifier.", + @future_incompatible = FutureIncompatibleInfo { + reason: FutureIncompatibilityReason::EditionSemanticsChange(Edition::Edition2024), + reference: "issue #123742 ", + }; +} + +declare_lint_pass!(Expr2024 => [EDITION_2024_EXPR_FRAGMENT_SPECIFIER,]); + +impl Expr2024 { + fn check_tokens(&mut self, cx: &crate::EarlyContext<'_>, tokens: &TokenStream) { + let mut prev_dollar = false; + for tt in tokens.trees() { + match tt { + TokenTree::Token(token, _) => { + if token.kind == TokenKind::Dollar { + prev_dollar = true; + continue; + } else { + if !prev_dollar { + self.check_ident_token(cx, token); + } + } + } + TokenTree::Delimited(.., tts) => self.check_tokens(cx, tts), + } + prev_dollar = false; + } + } + + fn check_ident_token(&mut self, cx: &crate::EarlyContext<'_>, token: &Token) { + debug!("check_ident_token: {:?}", token); + let (sym, edition) = match token.kind { + TokenKind::Ident(sym, _) => (sym, Edition::Edition2024), + _ => return, + }; + + debug!("token.span.edition(): {:?}", token.span.edition()); + if token.span.edition() >= edition { + return; + } + + if sym != sym::expr { + return; + } + + debug!("emitting lint"); + cx.builder.emit_span_lint( + &EDITION_2024_EXPR_FRAGMENT_SPECIFIER, + token.span.into(), + MacroExprFragment2024 { suggestion: token.span }, + ); + } +} + +impl EarlyLintPass for Expr2024 { + fn check_mac_def(&mut self, cx: &crate::EarlyContext<'_>, mc: &rustc_ast::MacroDef) { + self.check_tokens(cx, &mc.body.tokens); + } +}