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Diffstat (limited to 'compiler/rustc_lint/src/builtin.rs')
| -rw-r--r-- | compiler/rustc_lint/src/builtin.rs | 3172 |
1 files changed, 3172 insertions, 0 deletions
diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs new file mode 100644 index 000000000..bd58021f7 --- /dev/null +++ b/compiler/rustc_lint/src/builtin.rs @@ -0,0 +1,3172 @@ +//! Lints in the Rust compiler. +//! +//! This contains lints which can feasibly be implemented as their own +//! AST visitor. Also see `rustc_session::lint::builtin`, which contains the +//! definitions of lints that are emitted directly inside the main compiler. +//! +//! To add a new lint to rustc, declare it here using `declare_lint!()`. +//! Then add code to emit the new lint in the appropriate circumstances. +//! You can do that in an existing `LintPass` if it makes sense, or in a +//! new `LintPass`, or using `Session::add_lint` elsewhere in the +//! compiler. Only do the latter if the check can't be written cleanly as a +//! `LintPass` (also, note that such lints will need to be defined in +//! `rustc_session::lint::builtin`, not here). +//! +//! If you define a new `EarlyLintPass`, you will also need to add it to the +//! `add_early_builtin!` or `add_early_builtin_with_new!` invocation in +//! `lib.rs`. Use the former for unit-like structs and the latter for structs +//! with a `pub fn new()`. +//! +//! If you define a new `LateLintPass`, you will also need to add it to the +//! `late_lint_methods!` invocation in `lib.rs`. + +use crate::{ + types::{transparent_newtype_field, CItemKind}, + EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext, +}; +use rustc_ast::attr; +use rustc_ast::tokenstream::{TokenStream, TokenTree}; +use rustc_ast::visit::{FnCtxt, FnKind}; +use rustc_ast::{self as ast, *}; +use rustc_ast_pretty::pprust::{self, expr_to_string}; +use rustc_data_structures::fx::{FxHashMap, FxHashSet}; +use rustc_data_structures::stack::ensure_sufficient_stack; +use rustc_errors::{ + fluent, Applicability, Diagnostic, DiagnosticMessage, DiagnosticStyledString, + LintDiagnosticBuilder, MultiSpan, +}; +use rustc_feature::{deprecated_attributes, AttributeGate, BuiltinAttribute, GateIssue, Stability}; +use rustc_hir as hir; +use rustc_hir::def::{DefKind, Res}; +use rustc_hir::def_id::{DefId, LocalDefId, LocalDefIdSet, CRATE_DEF_ID}; +use rustc_hir::{ForeignItemKind, GenericParamKind, HirId, PatKind, PredicateOrigin}; +use rustc_index::vec::Idx; +use rustc_middle::lint::in_external_macro; +use rustc_middle::ty::layout::{LayoutError, LayoutOf}; +use rustc_middle::ty::print::with_no_trimmed_paths; +use rustc_middle::ty::subst::GenericArgKind; +use rustc_middle::ty::Instance; +use rustc_middle::ty::{self, Ty, TyCtxt}; +use rustc_session::lint::{BuiltinLintDiagnostics, FutureIncompatibilityReason}; +use rustc_span::edition::Edition; +use rustc_span::source_map::Spanned; +use rustc_span::symbol::{kw, sym, Ident, Symbol}; +use rustc_span::{BytePos, InnerSpan, Span}; +use rustc_target::abi::VariantIdx; +use rustc_trait_selection::traits::{self, misc::can_type_implement_copy}; + +use crate::nonstandard_style::{method_context, MethodLateContext}; + +use std::fmt::Write; +use tracing::{debug, trace}; + +// hardwired lints from librustc_middle +pub use rustc_session::lint::builtin::*; + +declare_lint! { + /// The `while_true` lint detects `while true { }`. + /// + /// ### Example + /// + /// ```rust,no_run + /// while true { + /// + /// } + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// `while true` should be replaced with `loop`. A `loop` expression is + /// the preferred way to write an infinite loop because it more directly + /// expresses the intent of the loop. + WHILE_TRUE, + Warn, + "suggest using `loop { }` instead of `while true { }`" +} + +declare_lint_pass!(WhileTrue => [WHILE_TRUE]); + +/// Traverse through any amount of parenthesis and return the first non-parens expression. +fn pierce_parens(mut expr: &ast::Expr) -> &ast::Expr { + while let ast::ExprKind::Paren(sub) = &expr.kind { + expr = sub; + } + expr +} + +impl EarlyLintPass for WhileTrue { + fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) { + if let ast::ExprKind::While(cond, _, label) = &e.kind { + if let ast::ExprKind::Lit(ref lit) = pierce_parens(cond).kind { + if let ast::LitKind::Bool(true) = lit.kind { + if !lit.span.from_expansion() { + let condition_span = e.span.with_hi(cond.span.hi()); + cx.struct_span_lint(WHILE_TRUE, condition_span, |lint| { + lint.build(fluent::lint::builtin_while_true) + .span_suggestion_short( + condition_span, + fluent::lint::suggestion, + format!( + "{}loop", + label.map_or_else(String::new, |label| format!( + "{}: ", + label.ident, + )) + ), + Applicability::MachineApplicable, + ) + .emit(); + }) + } + } + } + } + } +} + +declare_lint! { + /// The `box_pointers` lints use of the Box type. + /// + /// ### Example + /// + /// ```rust,compile_fail + /// #![deny(box_pointers)] + /// struct Foo { + /// x: Box<isize>, + /// } + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// This lint is mostly historical, and not particularly useful. `Box<T>` + /// used to be built into the language, and the only way to do heap + /// allocation. Today's Rust can call into other allocators, etc. + BOX_POINTERS, + Allow, + "use of owned (Box type) heap memory" +} + +declare_lint_pass!(BoxPointers => [BOX_POINTERS]); + +impl BoxPointers { + fn check_heap_type(&self, cx: &LateContext<'_>, span: Span, ty: Ty<'_>) { + for leaf in ty.walk() { + if let GenericArgKind::Type(leaf_ty) = leaf.unpack() { + if leaf_ty.is_box() { + cx.struct_span_lint(BOX_POINTERS, span, |lint| { + lint.build(fluent::lint::builtin_box_pointers).set_arg("ty", ty).emit(); + }); + } + } + } + } +} + +impl<'tcx> LateLintPass<'tcx> for BoxPointers { + fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) { + match it.kind { + hir::ItemKind::Fn(..) + | hir::ItemKind::TyAlias(..) + | hir::ItemKind::Enum(..) + | hir::ItemKind::Struct(..) + | hir::ItemKind::Union(..) => { + self.check_heap_type(cx, it.span, cx.tcx.type_of(it.def_id)) + } + _ => (), + } + + // If it's a struct, we also have to check the fields' types + match it.kind { + hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => { + for struct_field in struct_def.fields() { + let def_id = cx.tcx.hir().local_def_id(struct_field.hir_id); + self.check_heap_type(cx, struct_field.span, cx.tcx.type_of(def_id)); + } + } + _ => (), + } + } + + fn check_expr(&mut self, cx: &LateContext<'_>, e: &hir::Expr<'_>) { + let ty = cx.typeck_results().node_type(e.hir_id); + self.check_heap_type(cx, e.span, ty); + } +} + +declare_lint! { + /// The `non_shorthand_field_patterns` lint detects using `Struct { x: x }` + /// instead of `Struct { x }` in a pattern. + /// + /// ### Example + /// + /// ```rust + /// struct Point { + /// x: i32, + /// y: i32, + /// } + /// + /// + /// fn main() { + /// let p = Point { + /// x: 5, + /// y: 5, + /// }; + /// + /// match p { + /// Point { x: x, y: y } => (), + /// } + /// } + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// The preferred style is to avoid the repetition of specifying both the + /// field name and the binding name if both identifiers are the same. + NON_SHORTHAND_FIELD_PATTERNS, + Warn, + "using `Struct { x: x }` instead of `Struct { x }` in a pattern" +} + +declare_lint_pass!(NonShorthandFieldPatterns => [NON_SHORTHAND_FIELD_PATTERNS]); + +impl<'tcx> LateLintPass<'tcx> for NonShorthandFieldPatterns { + fn check_pat(&mut self, cx: &LateContext<'_>, pat: &hir::Pat<'_>) { + if let PatKind::Struct(ref qpath, field_pats, _) = pat.kind { + let variant = cx + .typeck_results() + .pat_ty(pat) + .ty_adt_def() + .expect("struct pattern type is not an ADT") + .variant_of_res(cx.qpath_res(qpath, pat.hir_id)); + for fieldpat in field_pats { + if fieldpat.is_shorthand { + continue; + } + if fieldpat.span.from_expansion() { + // Don't lint if this is a macro expansion: macro authors + // shouldn't have to worry about this kind of style issue + // (Issue #49588) + continue; + } + if let PatKind::Binding(binding_annot, _, ident, None) = fieldpat.pat.kind { + if cx.tcx.find_field_index(ident, &variant) + == Some(cx.tcx.field_index(fieldpat.hir_id, cx.typeck_results())) + { + cx.struct_span_lint(NON_SHORTHAND_FIELD_PATTERNS, fieldpat.span, |lint| { + let binding = match binding_annot { + hir::BindingAnnotation::Unannotated => None, + hir::BindingAnnotation::Mutable => Some("mut"), + hir::BindingAnnotation::Ref => Some("ref"), + hir::BindingAnnotation::RefMut => Some("ref mut"), + }; + let suggested_ident = if let Some(binding) = binding { + format!("{} {}", binding, ident) + } else { + ident.to_string() + }; + lint.build(fluent::lint::builtin_non_shorthand_field_patterns) + .set_arg("ident", ident.clone()) + .span_suggestion( + fieldpat.span, + fluent::lint::suggestion, + suggested_ident, + Applicability::MachineApplicable, + ) + .emit(); + }); + } + } + } + } + } +} + +declare_lint! { + /// The `unsafe_code` lint catches usage of `unsafe` code. + /// + /// ### Example + /// + /// ```rust,compile_fail + /// #![deny(unsafe_code)] + /// fn main() { + /// unsafe { + /// + /// } + /// } + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// This lint is intended to restrict the usage of `unsafe`, which can be + /// difficult to use correctly. + UNSAFE_CODE, + Allow, + "usage of `unsafe` code" +} + +declare_lint_pass!(UnsafeCode => [UNSAFE_CODE]); + +impl UnsafeCode { + fn report_unsafe( + &self, + cx: &EarlyContext<'_>, + span: Span, + decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>), + ) { + // This comes from a macro that has `#[allow_internal_unsafe]`. + if span.allows_unsafe() { + return; + } + + cx.struct_span_lint(UNSAFE_CODE, span, decorate); + } + + fn report_overridden_symbol_name( + &self, + cx: &EarlyContext<'_>, + span: Span, + msg: DiagnosticMessage, + ) { + self.report_unsafe(cx, span, |lint| { + lint.build(msg).note(fluent::lint::builtin_overridden_symbol_name).emit(); + }) + } + + fn report_overridden_symbol_section( + &self, + cx: &EarlyContext<'_>, + span: Span, + msg: DiagnosticMessage, + ) { + self.report_unsafe(cx, span, |lint| { + lint.build(msg).note(fluent::lint::builtin_overridden_symbol_section).emit(); + }) + } +} + +impl EarlyLintPass for UnsafeCode { + fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) { + if attr.has_name(sym::allow_internal_unsafe) { + self.report_unsafe(cx, attr.span, |lint| { + lint.build(fluent::lint::builtin_allow_internal_unsafe).emit(); + }); + } + } + + fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) { + if let ast::ExprKind::Block(ref blk, _) = e.kind { + // Don't warn about generated blocks; that'll just pollute the output. + if blk.rules == ast::BlockCheckMode::Unsafe(ast::UserProvided) { + self.report_unsafe(cx, blk.span, |lint| { + lint.build(fluent::lint::builtin_unsafe_block).emit(); + }); + } + } + } + + fn check_item(&mut self, cx: &EarlyContext<'_>, it: &ast::Item) { + match it.kind { + ast::ItemKind::Trait(box ast::Trait { unsafety: ast::Unsafe::Yes(_), .. }) => self + .report_unsafe(cx, it.span, |lint| { + lint.build(fluent::lint::builtin_unsafe_trait).emit(); + }), + + ast::ItemKind::Impl(box ast::Impl { unsafety: ast::Unsafe::Yes(_), .. }) => self + .report_unsafe(cx, it.span, |lint| { + lint.build(fluent::lint::builtin_unsafe_impl).emit(); + }), + + ast::ItemKind::Fn(..) => { + if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::no_mangle) { + self.report_overridden_symbol_name( + cx, + attr.span, + fluent::lint::builtin_no_mangle_fn, + ); + } + + if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) { + self.report_overridden_symbol_name( + cx, + attr.span, + fluent::lint::builtin_export_name_fn, + ); + } + + if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::link_section) { + self.report_overridden_symbol_section( + cx, + attr.span, + fluent::lint::builtin_link_section_fn, + ); + } + } + + ast::ItemKind::Static(..) => { + if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::no_mangle) { + self.report_overridden_symbol_name( + cx, + attr.span, + fluent::lint::builtin_no_mangle_static, + ); + } + + if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) { + self.report_overridden_symbol_name( + cx, + attr.span, + fluent::lint::builtin_export_name_static, + ); + } + + if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::link_section) { + self.report_overridden_symbol_section( + cx, + attr.span, + fluent::lint::builtin_link_section_static, + ); + } + } + + _ => {} + } + } + + fn check_impl_item(&mut self, cx: &EarlyContext<'_>, it: &ast::AssocItem) { + if let ast::AssocItemKind::Fn(..) = it.kind { + if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::no_mangle) { + self.report_overridden_symbol_name( + cx, + attr.span, + fluent::lint::builtin_no_mangle_method, + ); + } + if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) { + self.report_overridden_symbol_name( + cx, + attr.span, + fluent::lint::builtin_export_name_method, + ); + } + } + } + + fn check_fn(&mut self, cx: &EarlyContext<'_>, fk: FnKind<'_>, span: Span, _: ast::NodeId) { + if let FnKind::Fn( + ctxt, + _, + ast::FnSig { header: ast::FnHeader { unsafety: ast::Unsafe::Yes(_), .. }, .. }, + _, + _, + body, + ) = fk + { + let msg = match ctxt { + FnCtxt::Foreign => return, + FnCtxt::Free => fluent::lint::builtin_decl_unsafe_fn, + FnCtxt::Assoc(_) if body.is_none() => fluent::lint::builtin_decl_unsafe_method, + FnCtxt::Assoc(_) => fluent::lint::builtin_impl_unsafe_method, + }; + self.report_unsafe(cx, span, |lint| { + lint.build(msg).emit(); + }); + } + } +} + +declare_lint! { + /// The `missing_docs` lint detects missing documentation for public items. + /// + /// ### Example + /// + /// ```rust,compile_fail + /// #![deny(missing_docs)] + /// pub fn foo() {} + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// This lint is intended to ensure that a library is well-documented. + /// Items without documentation can be difficult for users to understand + /// how to use properly. + /// + /// This lint is "allow" by default because it can be noisy, and not all + /// projects may want to enforce everything to be documented. + pub MISSING_DOCS, + Allow, + "detects missing documentation for public members", + report_in_external_macro +} + +pub struct MissingDoc { + /// Stack of whether `#[doc(hidden)]` is set at each level which has lint attributes. + doc_hidden_stack: Vec<bool>, +} + +impl_lint_pass!(MissingDoc => [MISSING_DOCS]); + +fn has_doc(attr: &ast::Attribute) -> bool { + if attr.is_doc_comment() { + return true; + } + + if !attr.has_name(sym::doc) { + return false; + } + + if attr.value_str().is_some() { + return true; + } + + if let Some(list) = attr.meta_item_list() { + for meta in list { + if meta.has_name(sym::hidden) { + return true; + } + } + } + + false +} + +impl MissingDoc { + pub fn new() -> MissingDoc { + MissingDoc { doc_hidden_stack: vec![false] } + } + + fn doc_hidden(&self) -> bool { + *self.doc_hidden_stack.last().expect("empty doc_hidden_stack") + } + + fn check_missing_docs_attrs( + &self, + cx: &LateContext<'_>, + def_id: LocalDefId, + article: &'static str, + desc: &'static str, + ) { + // If we're building a test harness, then warning about + // documentation is probably not really relevant right now. + if cx.sess().opts.test { + return; + } + + // `#[doc(hidden)]` disables missing_docs check. + if self.doc_hidden() { + return; + } + + // Only check publicly-visible items, using the result from the privacy pass. + // It's an option so the crate root can also use this function (it doesn't + // have a `NodeId`). + if def_id != CRATE_DEF_ID { + if !cx.access_levels.is_exported(def_id) { + return; + } + } + + let attrs = cx.tcx.hir().attrs(cx.tcx.hir().local_def_id_to_hir_id(def_id)); + let has_doc = attrs.iter().any(has_doc); + if !has_doc { + cx.struct_span_lint(MISSING_DOCS, cx.tcx.def_span(def_id), |lint| { + lint.build(fluent::lint::builtin_missing_doc) + .set_arg("article", article) + .set_arg("desc", desc) + .emit(); + }); + } + } +} + +impl<'tcx> LateLintPass<'tcx> for MissingDoc { + fn enter_lint_attrs(&mut self, _cx: &LateContext<'_>, attrs: &[ast::Attribute]) { + let doc_hidden = self.doc_hidden() + || attrs.iter().any(|attr| { + attr.has_name(sym::doc) + && match attr.meta_item_list() { + None => false, + Some(l) => attr::list_contains_name(&l, sym::hidden), + } + }); + self.doc_hidden_stack.push(doc_hidden); + } + + fn exit_lint_attrs(&mut self, _: &LateContext<'_>, _attrs: &[ast::Attribute]) { + self.doc_hidden_stack.pop().expect("empty doc_hidden_stack"); + } + + fn check_crate(&mut self, cx: &LateContext<'_>) { + self.check_missing_docs_attrs(cx, CRATE_DEF_ID, "the", "crate"); + } + + fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) { + match it.kind { + hir::ItemKind::Trait(..) => { + // Issue #11592: traits are always considered exported, even when private. + if cx.tcx.visibility(it.def_id) + == ty::Visibility::Restricted( + cx.tcx.parent_module_from_def_id(it.def_id).to_def_id(), + ) + { + return; + } + } + hir::ItemKind::TyAlias(..) + | hir::ItemKind::Fn(..) + | hir::ItemKind::Macro(..) + | hir::ItemKind::Mod(..) + | hir::ItemKind::Enum(..) + | hir::ItemKind::Struct(..) + | hir::ItemKind::Union(..) + | hir::ItemKind::Const(..) + | hir::ItemKind::Static(..) => {} + + _ => return, + }; + + let (article, desc) = cx.tcx.article_and_description(it.def_id.to_def_id()); + + self.check_missing_docs_attrs(cx, it.def_id, article, desc); + } + + fn check_trait_item(&mut self, cx: &LateContext<'_>, trait_item: &hir::TraitItem<'_>) { + let (article, desc) = cx.tcx.article_and_description(trait_item.def_id.to_def_id()); + + self.check_missing_docs_attrs(cx, trait_item.def_id, article, desc); + } + + fn check_impl_item(&mut self, cx: &LateContext<'_>, impl_item: &hir::ImplItem<'_>) { + // If the method is an impl for a trait, don't doc. + if method_context(cx, impl_item.hir_id()) == MethodLateContext::TraitImpl { + return; + } + + // If the method is an impl for an item with docs_hidden, don't doc. + if method_context(cx, impl_item.hir_id()) == MethodLateContext::PlainImpl { + let parent = cx.tcx.hir().get_parent_item(impl_item.hir_id()); + let impl_ty = cx.tcx.type_of(parent); + let outerdef = match impl_ty.kind() { + ty::Adt(def, _) => Some(def.did()), + ty::Foreign(def_id) => Some(*def_id), + _ => None, + }; + let is_hidden = match outerdef { + Some(id) => cx.tcx.is_doc_hidden(id), + None => false, + }; + if is_hidden { + return; + } + } + + let (article, desc) = cx.tcx.article_and_description(impl_item.def_id.to_def_id()); + self.check_missing_docs_attrs(cx, impl_item.def_id, article, desc); + } + + fn check_foreign_item(&mut self, cx: &LateContext<'_>, foreign_item: &hir::ForeignItem<'_>) { + let (article, desc) = cx.tcx.article_and_description(foreign_item.def_id.to_def_id()); + self.check_missing_docs_attrs(cx, foreign_item.def_id, article, desc); + } + + fn check_field_def(&mut self, cx: &LateContext<'_>, sf: &hir::FieldDef<'_>) { + if !sf.is_positional() { + let def_id = cx.tcx.hir().local_def_id(sf.hir_id); + self.check_missing_docs_attrs(cx, def_id, "a", "struct field") + } + } + + fn check_variant(&mut self, cx: &LateContext<'_>, v: &hir::Variant<'_>) { + self.check_missing_docs_attrs(cx, cx.tcx.hir().local_def_id(v.id), "a", "variant"); + } +} + +declare_lint! { + /// The `missing_copy_implementations` lint detects potentially-forgotten + /// implementations of [`Copy`]. + /// + /// [`Copy`]: https://doc.rust-lang.org/std/marker/trait.Copy.html + /// + /// ### Example + /// + /// ```rust,compile_fail + /// #![deny(missing_copy_implementations)] + /// pub struct Foo { + /// pub field: i32 + /// } + /// # fn main() {} + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// Historically (before 1.0), types were automatically marked as `Copy` + /// if possible. This was changed so that it required an explicit opt-in + /// by implementing the `Copy` trait. As part of this change, a lint was + /// added to alert if a copyable type was not marked `Copy`. + /// + /// This lint is "allow" by default because this code isn't bad; it is + /// common to write newtypes like this specifically so that a `Copy` type + /// is no longer `Copy`. `Copy` types can result in unintended copies of + /// large data which can impact performance. + pub MISSING_COPY_IMPLEMENTATIONS, + Allow, + "detects potentially-forgotten implementations of `Copy`" +} + +declare_lint_pass!(MissingCopyImplementations => [MISSING_COPY_IMPLEMENTATIONS]); + +impl<'tcx> LateLintPass<'tcx> for MissingCopyImplementations { + fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) { + if !cx.access_levels.is_reachable(item.def_id) { + return; + } + let (def, ty) = match item.kind { + hir::ItemKind::Struct(_, ref ast_generics) => { + if !ast_generics.params.is_empty() { + return; + } + let def = cx.tcx.adt_def(item.def_id); + (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[]))) + } + hir::ItemKind::Union(_, ref ast_generics) => { + if !ast_generics.params.is_empty() { + return; + } + let def = cx.tcx.adt_def(item.def_id); + (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[]))) + } + hir::ItemKind::Enum(_, ref ast_generics) => { + if !ast_generics.params.is_empty() { + return; + } + let def = cx.tcx.adt_def(item.def_id); + (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[]))) + } + _ => return, + }; + if def.has_dtor(cx.tcx) { + return; + } + let param_env = ty::ParamEnv::empty(); + if ty.is_copy_modulo_regions(cx.tcx.at(item.span), param_env) { + return; + } + if can_type_implement_copy( + cx.tcx, + param_env, + ty, + traits::ObligationCause::misc(item.span, item.hir_id()), + ) + .is_ok() + { + cx.struct_span_lint(MISSING_COPY_IMPLEMENTATIONS, item.span, |lint| { + lint.build(fluent::lint::builtin_missing_copy_impl).emit(); + }) + } + } +} + +declare_lint! { + /// The `missing_debug_implementations` lint detects missing + /// implementations of [`fmt::Debug`]. + /// + /// [`fmt::Debug`]: https://doc.rust-lang.org/std/fmt/trait.Debug.html + /// + /// ### Example + /// + /// ```rust,compile_fail + /// #![deny(missing_debug_implementations)] + /// pub struct Foo; + /// # fn main() {} + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// Having a `Debug` implementation on all types can assist with + /// debugging, as it provides a convenient way to format and display a + /// value. Using the `#[derive(Debug)]` attribute will automatically + /// generate a typical implementation, or a custom implementation can be + /// added by manually implementing the `Debug` trait. + /// + /// This lint is "allow" by default because adding `Debug` to all types can + /// have a negative impact on compile time and code size. It also requires + /// boilerplate to be added to every type, which can be an impediment. + MISSING_DEBUG_IMPLEMENTATIONS, + Allow, + "detects missing implementations of Debug" +} + +#[derive(Default)] +pub struct MissingDebugImplementations { + impling_types: Option<LocalDefIdSet>, +} + +impl_lint_pass!(MissingDebugImplementations => [MISSING_DEBUG_IMPLEMENTATIONS]); + +impl<'tcx> LateLintPass<'tcx> for MissingDebugImplementations { + fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) { + if !cx.access_levels.is_reachable(item.def_id) { + return; + } + + match item.kind { + hir::ItemKind::Struct(..) | hir::ItemKind::Union(..) | hir::ItemKind::Enum(..) => {} + _ => return, + } + + let Some(debug) = cx.tcx.get_diagnostic_item(sym::Debug) else { + return + }; + + if self.impling_types.is_none() { + let mut impls = LocalDefIdSet::default(); + cx.tcx.for_each_impl(debug, |d| { + if let Some(ty_def) = cx.tcx.type_of(d).ty_adt_def() { + if let Some(def_id) = ty_def.did().as_local() { + impls.insert(def_id); + } + } + }); + + self.impling_types = Some(impls); + debug!("{:?}", self.impling_types); + } + + if !self.impling_types.as_ref().unwrap().contains(&item.def_id) { + cx.struct_span_lint(MISSING_DEBUG_IMPLEMENTATIONS, item.span, |lint| { + lint.build(fluent::lint::builtin_missing_debug_impl) + .set_arg("debug", cx.tcx.def_path_str(debug)) + .emit(); + }); + } + } +} + +declare_lint! { + /// The `anonymous_parameters` lint detects anonymous parameters in trait + /// definitions. + /// + /// ### Example + /// + /// ```rust,edition2015,compile_fail + /// #![deny(anonymous_parameters)] + /// // edition 2015 + /// pub trait Foo { + /// fn foo(usize); + /// } + /// fn main() {} + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// This syntax is mostly a historical accident, and can be worked around + /// quite easily by adding an `_` pattern or a descriptive identifier: + /// + /// ```rust + /// trait Foo { + /// fn foo(_: usize); + /// } + /// ``` + /// + /// This syntax is now a hard error in the 2018 edition. In the 2015 + /// edition, this lint is "warn" by default. This lint + /// enables the [`cargo fix`] tool with the `--edition` flag to + /// automatically transition old code from the 2015 edition to 2018. The + /// tool will run this lint and automatically apply the + /// suggested fix from the compiler (which is to add `_` to each + /// parameter). This provides a completely automated way to update old + /// code for a new edition. See [issue #41686] for more details. + /// + /// [issue #41686]: https://github.com/rust-lang/rust/issues/41686 + /// [`cargo fix`]: https://doc.rust-lang.org/cargo/commands/cargo-fix.html + pub ANONYMOUS_PARAMETERS, + Warn, + "detects anonymous parameters", + @future_incompatible = FutureIncompatibleInfo { + reference: "issue #41686 <https://github.com/rust-lang/rust/issues/41686>", + reason: FutureIncompatibilityReason::EditionError(Edition::Edition2018), + }; +} + +declare_lint_pass!( + /// Checks for use of anonymous parameters (RFC 1685). + AnonymousParameters => [ANONYMOUS_PARAMETERS] +); + +impl EarlyLintPass for AnonymousParameters { + fn check_trait_item(&mut self, cx: &EarlyContext<'_>, it: &ast::AssocItem) { + if cx.sess().edition() != Edition::Edition2015 { + // This is a hard error in future editions; avoid linting and erroring + return; + } + if let ast::AssocItemKind::Fn(box Fn { ref sig, .. }) = it.kind { + for arg in sig.decl.inputs.iter() { + if let ast::PatKind::Ident(_, ident, None) = arg.pat.kind { + if ident.name == kw::Empty { + cx.struct_span_lint(ANONYMOUS_PARAMETERS, arg.pat.span, |lint| { + let ty_snip = cx.sess().source_map().span_to_snippet(arg.ty.span); + + let (ty_snip, appl) = if let Ok(ref snip) = ty_snip { + (snip.as_str(), Applicability::MachineApplicable) + } else { + ("<type>", Applicability::HasPlaceholders) + }; + + lint.build(fluent::lint::builtin_anonymous_params) + .span_suggestion( + arg.pat.span, + fluent::lint::suggestion, + format!("_: {}", ty_snip), + appl, + ) + .emit(); + }) + } + } + } + } + } +} + +/// Check for use of attributes which have been deprecated. +#[derive(Clone)] +pub struct DeprecatedAttr { + // This is not free to compute, so we want to keep it around, rather than + // compute it for every attribute. + depr_attrs: Vec<&'static BuiltinAttribute>, +} + +impl_lint_pass!(DeprecatedAttr => []); + +impl DeprecatedAttr { + pub fn new() -> DeprecatedAttr { + DeprecatedAttr { depr_attrs: deprecated_attributes() } + } +} + +impl EarlyLintPass for DeprecatedAttr { + fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) { + for BuiltinAttribute { name, gate, .. } in &self.depr_attrs { + if attr.ident().map(|ident| ident.name) == Some(*name) { + if let &AttributeGate::Gated( + Stability::Deprecated(link, suggestion), + name, + reason, + _, + ) = gate + { + cx.struct_span_lint(DEPRECATED, attr.span, |lint| { + // FIXME(davidtwco) translatable deprecated attr + lint.build(fluent::lint::builtin_deprecated_attr_link) + .set_arg("name", name) + .set_arg("reason", reason) + .set_arg("link", link) + .span_suggestion_short( + attr.span, + suggestion.map(|s| s.into()).unwrap_or( + fluent::lint::builtin_deprecated_attr_default_suggestion, + ), + "", + Applicability::MachineApplicable, + ) + .emit(); + }); + } + return; + } + } + if attr.has_name(sym::no_start) || attr.has_name(sym::crate_id) { + cx.struct_span_lint(DEPRECATED, attr.span, |lint| { + lint.build(fluent::lint::builtin_deprecated_attr_used) + .set_arg("name", pprust::path_to_string(&attr.get_normal_item().path)) + .span_suggestion_short( + attr.span, + fluent::lint::builtin_deprecated_attr_default_suggestion, + "", + Applicability::MachineApplicable, + ) + .emit(); + }); + } + } +} + +fn warn_if_doc(cx: &EarlyContext<'_>, node_span: Span, node_kind: &str, attrs: &[ast::Attribute]) { + use rustc_ast::token::CommentKind; + + let mut attrs = attrs.iter().peekable(); + + // Accumulate a single span for sugared doc comments. + let mut sugared_span: Option<Span> = None; + + while let Some(attr) = attrs.next() { + let is_doc_comment = attr.is_doc_comment(); + if is_doc_comment { + sugared_span = + Some(sugared_span.map_or(attr.span, |span| span.with_hi(attr.span.hi()))); + } + + if attrs.peek().map_or(false, |next_attr| next_attr.is_doc_comment()) { + continue; + } + + let span = sugared_span.take().unwrap_or(attr.span); + + if is_doc_comment || attr.has_name(sym::doc) { + cx.struct_span_lint(UNUSED_DOC_COMMENTS, span, |lint| { + let mut err = lint.build(fluent::lint::builtin_unused_doc_comment); + err.set_arg("kind", node_kind); + err.span_label(node_span, fluent::lint::label); + match attr.kind { + AttrKind::DocComment(CommentKind::Line, _) | AttrKind::Normal(..) => { + err.help(fluent::lint::plain_help); + } + AttrKind::DocComment(CommentKind::Block, _) => { + err.help(fluent::lint::block_help); + } + } + err.emit(); + }); + } + } +} + +impl EarlyLintPass for UnusedDocComment { + fn check_stmt(&mut self, cx: &EarlyContext<'_>, stmt: &ast::Stmt) { + let kind = match stmt.kind { + ast::StmtKind::Local(..) => "statements", + // Disabled pending discussion in #78306 + ast::StmtKind::Item(..) => return, + // expressions will be reported by `check_expr`. + ast::StmtKind::Empty + | ast::StmtKind::Semi(_) + | ast::StmtKind::Expr(_) + | ast::StmtKind::MacCall(_) => return, + }; + + warn_if_doc(cx, stmt.span, kind, stmt.kind.attrs()); + } + + fn check_arm(&mut self, cx: &EarlyContext<'_>, arm: &ast::Arm) { + let arm_span = arm.pat.span.with_hi(arm.body.span.hi()); + warn_if_doc(cx, arm_span, "match arms", &arm.attrs); + } + + fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) { + warn_if_doc(cx, expr.span, "expressions", &expr.attrs); + } + + fn check_generic_param(&mut self, cx: &EarlyContext<'_>, param: &ast::GenericParam) { + warn_if_doc(cx, param.ident.span, "generic parameters", ¶m.attrs); + } + + fn check_block(&mut self, cx: &EarlyContext<'_>, block: &ast::Block) { + warn_if_doc(cx, block.span, "blocks", &block.attrs()); + } + + fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) { + if let ast::ItemKind::ForeignMod(_) = item.kind { + warn_if_doc(cx, item.span, "extern blocks", &item.attrs); + } + } +} + +declare_lint! { + /// The `no_mangle_const_items` lint detects any `const` items with the + /// [`no_mangle` attribute]. + /// + /// [`no_mangle` attribute]: https://doc.rust-lang.org/reference/abi.html#the-no_mangle-attribute + /// + /// ### Example + /// + /// ```rust,compile_fail + /// #[no_mangle] + /// const FOO: i32 = 5; + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// Constants do not have their symbols exported, and therefore, this + /// probably means you meant to use a [`static`], not a [`const`]. + /// + /// [`static`]: https://doc.rust-lang.org/reference/items/static-items.html + /// [`const`]: https://doc.rust-lang.org/reference/items/constant-items.html + NO_MANGLE_CONST_ITEMS, + Deny, + "const items will not have their symbols exported" +} + +declare_lint! { + /// The `no_mangle_generic_items` lint detects generic items that must be + /// mangled. + /// + /// ### Example + /// + /// ```rust + /// #[no_mangle] + /// fn foo<T>(t: T) { + /// + /// } + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// A function with generics must have its symbol mangled to accommodate + /// the generic parameter. The [`no_mangle` attribute] has no effect in + /// this situation, and should be removed. + /// + /// [`no_mangle` attribute]: https://doc.rust-lang.org/reference/abi.html#the-no_mangle-attribute + NO_MANGLE_GENERIC_ITEMS, + Warn, + "generic items must be mangled" +} + +declare_lint_pass!(InvalidNoMangleItems => [NO_MANGLE_CONST_ITEMS, NO_MANGLE_GENERIC_ITEMS]); + +impl<'tcx> LateLintPass<'tcx> for InvalidNoMangleItems { + fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) { + let attrs = cx.tcx.hir().attrs(it.hir_id()); + let check_no_mangle_on_generic_fn = |no_mangle_attr: &ast::Attribute, + impl_generics: Option<&hir::Generics<'_>>, + generics: &hir::Generics<'_>, + span| { + for param in + generics.params.iter().chain(impl_generics.map(|g| g.params).into_iter().flatten()) + { + match param.kind { + GenericParamKind::Lifetime { .. } => {} + GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => { + cx.struct_span_lint(NO_MANGLE_GENERIC_ITEMS, span, |lint| { + lint.build(fluent::lint::builtin_no_mangle_generic) + .span_suggestion_short( + no_mangle_attr.span, + fluent::lint::suggestion, + "", + // Use of `#[no_mangle]` suggests FFI intent; correct + // fix may be to monomorphize source by hand + Applicability::MaybeIncorrect, + ) + .emit(); + }); + break; + } + } + } + }; + match it.kind { + hir::ItemKind::Fn(.., ref generics, _) => { + if let Some(no_mangle_attr) = cx.sess().find_by_name(attrs, sym::no_mangle) { + check_no_mangle_on_generic_fn(no_mangle_attr, None, generics, it.span); + } + } + hir::ItemKind::Const(..) => { + if cx.sess().contains_name(attrs, sym::no_mangle) { + // Const items do not refer to a particular location in memory, and therefore + // don't have anything to attach a symbol to + cx.struct_span_lint(NO_MANGLE_CONST_ITEMS, it.span, |lint| { + let mut err = lint.build(fluent::lint::builtin_const_no_mangle); + + // account for "pub const" (#45562) + let start = cx + .tcx + .sess + .source_map() + .span_to_snippet(it.span) + .map(|snippet| snippet.find("const").unwrap_or(0)) + .unwrap_or(0) as u32; + // `const` is 5 chars + let const_span = it.span.with_hi(BytePos(it.span.lo().0 + start + 5)); + err.span_suggestion( + const_span, + fluent::lint::suggestion, + "pub static", + Applicability::MachineApplicable, + ); + err.emit(); + }); + } + } + hir::ItemKind::Impl(hir::Impl { generics, items, .. }) => { + for it in *items { + if let hir::AssocItemKind::Fn { .. } = it.kind { + if let Some(no_mangle_attr) = cx + .sess() + .find_by_name(cx.tcx.hir().attrs(it.id.hir_id()), sym::no_mangle) + { + check_no_mangle_on_generic_fn( + no_mangle_attr, + Some(generics), + cx.tcx.hir().get_generics(it.id.def_id).unwrap(), + it.span, + ); + } + } + } + } + _ => {} + } + } +} + +declare_lint! { + /// The `mutable_transmutes` lint catches transmuting from `&T` to `&mut + /// T` because it is [undefined behavior]. + /// + /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html + /// + /// ### Example + /// + /// ```rust,compile_fail + /// unsafe { + /// let y = std::mem::transmute::<&i32, &mut i32>(&5); + /// } + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// Certain assumptions are made about aliasing of data, and this transmute + /// violates those assumptions. Consider using [`UnsafeCell`] instead. + /// + /// [`UnsafeCell`]: https://doc.rust-lang.org/std/cell/struct.UnsafeCell.html + MUTABLE_TRANSMUTES, + Deny, + "transmuting &T to &mut T is undefined behavior, even if the reference is unused" +} + +declare_lint_pass!(MutableTransmutes => [MUTABLE_TRANSMUTES]); + +impl<'tcx> LateLintPass<'tcx> for MutableTransmutes { + fn check_expr(&mut self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) { + if let Some((&ty::Ref(_, _, from_mt), &ty::Ref(_, _, to_mt))) = + get_transmute_from_to(cx, expr).map(|(ty1, ty2)| (ty1.kind(), ty2.kind())) + { + if to_mt == hir::Mutability::Mut && from_mt == hir::Mutability::Not { + cx.struct_span_lint(MUTABLE_TRANSMUTES, expr.span, |lint| { + lint.build(fluent::lint::builtin_mutable_transmutes).emit(); + }); + } + } + + fn get_transmute_from_to<'tcx>( + cx: &LateContext<'tcx>, + expr: &hir::Expr<'_>, + ) -> Option<(Ty<'tcx>, Ty<'tcx>)> { + let def = if let hir::ExprKind::Path(ref qpath) = expr.kind { + cx.qpath_res(qpath, expr.hir_id) + } else { + return None; + }; + if let Res::Def(DefKind::Fn, did) = def { + if !def_id_is_transmute(cx, did) { + return None; + } + let sig = cx.typeck_results().node_type(expr.hir_id).fn_sig(cx.tcx); + let from = sig.inputs().skip_binder()[0]; + let to = sig.output().skip_binder(); + return Some((from, to)); + } + None + } + + fn def_id_is_transmute(cx: &LateContext<'_>, def_id: DefId) -> bool { + cx.tcx.is_intrinsic(def_id) && cx.tcx.item_name(def_id) == sym::transmute + } + } +} + +declare_lint! { + /// The `unstable_features` is deprecated and should no longer be used. + UNSTABLE_FEATURES, + Allow, + "enabling unstable features (deprecated. do not use)" +} + +declare_lint_pass!( + /// Forbids using the `#[feature(...)]` attribute + UnstableFeatures => [UNSTABLE_FEATURES] +); + +impl<'tcx> LateLintPass<'tcx> for UnstableFeatures { + fn check_attribute(&mut self, cx: &LateContext<'_>, attr: &ast::Attribute) { + if attr.has_name(sym::feature) { + if let Some(items) = attr.meta_item_list() { + for item in items { + cx.struct_span_lint(UNSTABLE_FEATURES, item.span(), |lint| { + lint.build(fluent::lint::builtin_unstable_features).emit(); + }); + } + } + } + } +} + +declare_lint! { + /// The `unreachable_pub` lint triggers for `pub` items not reachable from + /// the crate root. + /// + /// ### Example + /// + /// ```rust,compile_fail + /// #![deny(unreachable_pub)] + /// mod foo { + /// pub mod bar { + /// + /// } + /// } + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// A bare `pub` visibility may be misleading if the item is not actually + /// publicly exported from the crate. The `pub(crate)` visibility is + /// recommended to be used instead, which more clearly expresses the intent + /// that the item is only visible within its own crate. + /// + /// This lint is "allow" by default because it will trigger for a large + /// amount existing Rust code, and has some false-positives. Eventually it + /// is desired for this to become warn-by-default. + pub UNREACHABLE_PUB, + Allow, + "`pub` items not reachable from crate root" +} + +declare_lint_pass!( + /// Lint for items marked `pub` that aren't reachable from other crates. + UnreachablePub => [UNREACHABLE_PUB] +); + +impl UnreachablePub { + fn perform_lint( + &self, + cx: &LateContext<'_>, + what: &str, + def_id: LocalDefId, + vis_span: Span, + exportable: bool, + ) { + let mut applicability = Applicability::MachineApplicable; + if cx.tcx.visibility(def_id).is_public() && !cx.access_levels.is_reachable(def_id) { + if vis_span.from_expansion() { + applicability = Applicability::MaybeIncorrect; + } + let def_span = cx.tcx.def_span(def_id); + cx.struct_span_lint(UNREACHABLE_PUB, def_span, |lint| { + let mut err = lint.build(fluent::lint::builtin_unreachable_pub); + err.set_arg("what", what); + + err.span_suggestion( + vis_span, + fluent::lint::suggestion, + "pub(crate)", + applicability, + ); + if exportable { + err.help(fluent::lint::help); + } + err.emit(); + }); + } + } +} + +impl<'tcx> LateLintPass<'tcx> for UnreachablePub { + fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) { + // Do not warn for fake `use` statements. + if let hir::ItemKind::Use(_, hir::UseKind::ListStem) = &item.kind { + return; + } + self.perform_lint(cx, "item", item.def_id, item.vis_span, true); + } + + fn check_foreign_item(&mut self, cx: &LateContext<'_>, foreign_item: &hir::ForeignItem<'tcx>) { + self.perform_lint(cx, "item", foreign_item.def_id, foreign_item.vis_span, true); + } + + fn check_field_def(&mut self, cx: &LateContext<'_>, field: &hir::FieldDef<'_>) { + let def_id = cx.tcx.hir().local_def_id(field.hir_id); + self.perform_lint(cx, "field", def_id, field.vis_span, false); + } + + fn check_impl_item(&mut self, cx: &LateContext<'_>, impl_item: &hir::ImplItem<'_>) { + // Only lint inherent impl items. + if cx.tcx.associated_item(impl_item.def_id).trait_item_def_id.is_none() { + self.perform_lint(cx, "item", impl_item.def_id, impl_item.vis_span, false); + } + } +} + +declare_lint! { + /// The `type_alias_bounds` lint detects bounds in type aliases. + /// + /// ### Example + /// + /// ```rust + /// type SendVec<T: Send> = Vec<T>; + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// The trait bounds in a type alias are currently ignored, and should not + /// be included to avoid confusion. This was previously allowed + /// unintentionally; this may become a hard error in the future. + TYPE_ALIAS_BOUNDS, + Warn, + "bounds in type aliases are not enforced" +} + +declare_lint_pass!( + /// Lint for trait and lifetime bounds in type aliases being mostly ignored. + /// They are relevant when using associated types, but otherwise neither checked + /// at definition site nor enforced at use site. + TypeAliasBounds => [TYPE_ALIAS_BOUNDS] +); + +impl TypeAliasBounds { + fn is_type_variable_assoc(qpath: &hir::QPath<'_>) -> bool { + match *qpath { + hir::QPath::TypeRelative(ref ty, _) => { + // If this is a type variable, we found a `T::Assoc`. + match ty.kind { + hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => { + matches!(path.res, Res::Def(DefKind::TyParam, _)) + } + _ => false, + } + } + hir::QPath::Resolved(..) | hir::QPath::LangItem(..) => false, + } + } + + fn suggest_changing_assoc_types(ty: &hir::Ty<'_>, err: &mut Diagnostic) { + // Access to associates types should use `<T as Bound>::Assoc`, which does not need a + // bound. Let's see if this type does that. + + // We use a HIR visitor to walk the type. + use rustc_hir::intravisit::{self, Visitor}; + struct WalkAssocTypes<'a> { + err: &'a mut Diagnostic, + } + impl Visitor<'_> for WalkAssocTypes<'_> { + fn visit_qpath(&mut self, qpath: &hir::QPath<'_>, id: hir::HirId, span: Span) { + if TypeAliasBounds::is_type_variable_assoc(qpath) { + self.err.span_help(span, fluent::lint::builtin_type_alias_bounds_help); + } + intravisit::walk_qpath(self, qpath, id, span) + } + } + + // Let's go for a walk! + let mut visitor = WalkAssocTypes { err }; + visitor.visit_ty(ty); + } +} + +impl<'tcx> LateLintPass<'tcx> for TypeAliasBounds { + fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) { + let hir::ItemKind::TyAlias(ty, type_alias_generics) = &item.kind else { + return + }; + if let hir::TyKind::OpaqueDef(..) = ty.kind { + // Bounds are respected for `type X = impl Trait` + return; + } + // There must not be a where clause + if type_alias_generics.predicates.is_empty() { + return; + } + + let mut where_spans = Vec::new(); + let mut inline_spans = Vec::new(); + let mut inline_sugg = Vec::new(); + for p in type_alias_generics.predicates { + let span = p.span(); + if p.in_where_clause() { + where_spans.push(span); + } else { + for b in p.bounds() { + inline_spans.push(b.span()); + } + inline_sugg.push((span, String::new())); + } + } + + let mut suggested_changing_assoc_types = false; + if !where_spans.is_empty() { + cx.lint(TYPE_ALIAS_BOUNDS, |lint| { + let mut err = lint.build(fluent::lint::builtin_type_alias_where_clause); + err.set_span(where_spans); + err.span_suggestion( + type_alias_generics.where_clause_span, + fluent::lint::suggestion, + "", + Applicability::MachineApplicable, + ); + if !suggested_changing_assoc_types { + TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err); + suggested_changing_assoc_types = true; + } + err.emit(); + }); + } + + if !inline_spans.is_empty() { + cx.lint(TYPE_ALIAS_BOUNDS, |lint| { + let mut err = lint.build(fluent::lint::builtin_type_alias_generic_bounds); + err.set_span(inline_spans); + err.multipart_suggestion( + fluent::lint::suggestion, + inline_sugg, + Applicability::MachineApplicable, + ); + if !suggested_changing_assoc_types { + TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err); + } + err.emit(); + }); + } + } +} + +declare_lint_pass!( + /// Lint constants that are erroneous. + /// Without this lint, we might not get any diagnostic if the constant is + /// unused within this crate, even though downstream crates can't use it + /// without producing an error. + UnusedBrokenConst => [] +); + +impl<'tcx> LateLintPass<'tcx> for UnusedBrokenConst { + fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) { + match it.kind { + hir::ItemKind::Const(_, body_id) => { + let def_id = cx.tcx.hir().body_owner_def_id(body_id).to_def_id(); + // trigger the query once for all constants since that will already report the errors + cx.tcx.ensure().const_eval_poly(def_id); + } + hir::ItemKind::Static(_, _, body_id) => { + let def_id = cx.tcx.hir().body_owner_def_id(body_id).to_def_id(); + cx.tcx.ensure().eval_static_initializer(def_id); + } + _ => {} + } + } +} + +declare_lint! { + /// The `trivial_bounds` lint detects trait bounds that don't depend on + /// any type parameters. + /// + /// ### Example + /// + /// ```rust + /// #![feature(trivial_bounds)] + /// pub struct A where i32: Copy; + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// Usually you would not write a trait bound that you know is always + /// true, or never true. However, when using macros, the macro may not + /// know whether or not the constraint would hold or not at the time when + /// generating the code. Currently, the compiler does not alert you if the + /// constraint is always true, and generates an error if it is never true. + /// The `trivial_bounds` feature changes this to be a warning in both + /// cases, giving macros more freedom and flexibility to generate code, + /// while still providing a signal when writing non-macro code that + /// something is amiss. + /// + /// See [RFC 2056] for more details. This feature is currently only + /// available on the nightly channel, see [tracking issue #48214]. + /// + /// [RFC 2056]: https://github.com/rust-lang/rfcs/blob/master/text/2056-allow-trivial-where-clause-constraints.md + /// [tracking issue #48214]: https://github.com/rust-lang/rust/issues/48214 + TRIVIAL_BOUNDS, + Warn, + "these bounds don't depend on an type parameters" +} + +declare_lint_pass!( + /// Lint for trait and lifetime bounds that don't depend on type parameters + /// which either do nothing, or stop the item from being used. + TrivialConstraints => [TRIVIAL_BOUNDS] +); + +impl<'tcx> LateLintPass<'tcx> for TrivialConstraints { + fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'tcx>) { + use rustc_middle::ty::visit::TypeVisitable; + use rustc_middle::ty::PredicateKind::*; + + if cx.tcx.features().trivial_bounds { + let predicates = cx.tcx.predicates_of(item.def_id); + for &(predicate, span) in predicates.predicates { + let predicate_kind_name = match predicate.kind().skip_binder() { + Trait(..) => "trait", + TypeOutlives(..) | + RegionOutlives(..) => "lifetime", + + // Ignore projections, as they can only be global + // if the trait bound is global + Projection(..) | + // Ignore bounds that a user can't type + WellFormed(..) | + ObjectSafe(..) | + ClosureKind(..) | + Subtype(..) | + Coerce(..) | + ConstEvaluatable(..) | + ConstEquate(..) | + TypeWellFormedFromEnv(..) => continue, + }; + if predicate.is_global() { + cx.struct_span_lint(TRIVIAL_BOUNDS, span, |lint| { + lint.build(fluent::lint::builtin_trivial_bounds) + .set_arg("predicate_kind_name", predicate_kind_name) + .set_arg("predicate", predicate) + .emit(); + }); + } + } + } + } +} + +declare_lint_pass!( + /// Does nothing as a lint pass, but registers some `Lint`s + /// which are used by other parts of the compiler. + SoftLints => [ + WHILE_TRUE, + BOX_POINTERS, + NON_SHORTHAND_FIELD_PATTERNS, + UNSAFE_CODE, + MISSING_DOCS, + MISSING_COPY_IMPLEMENTATIONS, + MISSING_DEBUG_IMPLEMENTATIONS, + ANONYMOUS_PARAMETERS, + UNUSED_DOC_COMMENTS, + NO_MANGLE_CONST_ITEMS, + NO_MANGLE_GENERIC_ITEMS, + MUTABLE_TRANSMUTES, + UNSTABLE_FEATURES, + UNREACHABLE_PUB, + TYPE_ALIAS_BOUNDS, + TRIVIAL_BOUNDS + ] +); + +declare_lint! { + /// The `ellipsis_inclusive_range_patterns` lint detects the [`...` range + /// pattern], which is deprecated. + /// + /// [`...` range pattern]: https://doc.rust-lang.org/reference/patterns.html#range-patterns + /// + /// ### Example + /// + /// ```rust,edition2018 + /// let x = 123; + /// match x { + /// 0...100 => {} + /// _ => {} + /// } + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// The `...` range pattern syntax was changed to `..=` to avoid potential + /// confusion with the [`..` range expression]. Use the new form instead. + /// + /// [`..` range expression]: https://doc.rust-lang.org/reference/expressions/range-expr.html + pub ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, + Warn, + "`...` range patterns are deprecated", + @future_incompatible = FutureIncompatibleInfo { + reference: "<https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>", + reason: FutureIncompatibilityReason::EditionError(Edition::Edition2021), + }; +} + +#[derive(Default)] +pub struct EllipsisInclusiveRangePatterns { + /// If `Some(_)`, suppress all subsequent pattern + /// warnings for better diagnostics. + node_id: Option<ast::NodeId>, +} + +impl_lint_pass!(EllipsisInclusiveRangePatterns => [ELLIPSIS_INCLUSIVE_RANGE_PATTERNS]); + +impl EarlyLintPass for EllipsisInclusiveRangePatterns { + fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &ast::Pat) { + if self.node_id.is_some() { + // Don't recursively warn about patterns inside range endpoints. + return; + } + + use self::ast::{PatKind, RangeSyntax::DotDotDot}; + + /// If `pat` is a `...` pattern, return the start and end of the range, as well as the span + /// corresponding to the ellipsis. + fn matches_ellipsis_pat(pat: &ast::Pat) -> Option<(Option<&Expr>, &Expr, Span)> { + match &pat.kind { + PatKind::Range( + a, + Some(b), + Spanned { span, node: RangeEnd::Included(DotDotDot) }, + ) => Some((a.as_deref(), b, *span)), + _ => None, + } + } + + let (parenthesise, endpoints) = match &pat.kind { + PatKind::Ref(subpat, _) => (true, matches_ellipsis_pat(&subpat)), + _ => (false, matches_ellipsis_pat(pat)), + }; + + if let Some((start, end, join)) = endpoints { + let msg = fluent::lint::builtin_ellipsis_inclusive_range_patterns; + let suggestion = fluent::lint::suggestion; + if parenthesise { + self.node_id = Some(pat.id); + let end = expr_to_string(&end); + let replace = match start { + Some(start) => format!("&({}..={})", expr_to_string(&start), end), + None => format!("&(..={})", end), + }; + if join.edition() >= Edition::Edition2021 { + let mut err = cx.sess().struct_span_err_with_code( + pat.span, + msg, + rustc_errors::error_code!(E0783), + ); + err.span_suggestion( + pat.span, + suggestion, + replace, + Applicability::MachineApplicable, + ) + .emit(); + } else { + cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, pat.span, |lint| { + lint.build(msg) + .span_suggestion( + pat.span, + suggestion, + replace, + Applicability::MachineApplicable, + ) + .emit(); + }); + } + } else { + let replace = "..="; + if join.edition() >= Edition::Edition2021 { + let mut err = cx.sess().struct_span_err_with_code( + pat.span, + msg, + rustc_errors::error_code!(E0783), + ); + err.span_suggestion_short( + join, + suggestion, + replace, + Applicability::MachineApplicable, + ) + .emit(); + } else { + cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, join, |lint| { + lint.build(msg) + .span_suggestion_short( + join, + suggestion, + replace, + Applicability::MachineApplicable, + ) + .emit(); + }); + } + }; + } + } + + fn check_pat_post(&mut self, _cx: &EarlyContext<'_>, pat: &ast::Pat) { + if let Some(node_id) = self.node_id { + if pat.id == node_id { + self.node_id = None + } + } + } +} + +declare_lint! { + /// The `unnameable_test_items` lint detects [`#[test]`][test] functions + /// that are not able to be run by the test harness because they are in a + /// position where they are not nameable. + /// + /// [test]: https://doc.rust-lang.org/reference/attributes/testing.html#the-test-attribute + /// + /// ### Example + /// + /// ```rust,test + /// fn main() { + /// #[test] + /// fn foo() { + /// // This test will not fail because it does not run. + /// assert_eq!(1, 2); + /// } + /// } + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// In order for the test harness to run a test, the test function must be + /// located in a position where it can be accessed from the crate root. + /// This generally means it must be defined in a module, and not anywhere + /// else such as inside another function. The compiler previously allowed + /// this without an error, so a lint was added as an alert that a test is + /// not being used. Whether or not this should be allowed has not yet been + /// decided, see [RFC 2471] and [issue #36629]. + /// + /// [RFC 2471]: https://github.com/rust-lang/rfcs/pull/2471#issuecomment-397414443 + /// [issue #36629]: https://github.com/rust-lang/rust/issues/36629 + UNNAMEABLE_TEST_ITEMS, + Warn, + "detects an item that cannot be named being marked as `#[test_case]`", + report_in_external_macro +} + +pub struct UnnameableTestItems { + boundary: Option<LocalDefId>, // Id of the item under which things are not nameable + items_nameable: bool, +} + +impl_lint_pass!(UnnameableTestItems => [UNNAMEABLE_TEST_ITEMS]); + +impl UnnameableTestItems { + pub fn new() -> Self { + Self { boundary: None, items_nameable: true } + } +} + +impl<'tcx> LateLintPass<'tcx> for UnnameableTestItems { + fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) { + if self.items_nameable { + if let hir::ItemKind::Mod(..) = it.kind { + } else { + self.items_nameable = false; + self.boundary = Some(it.def_id); + } + return; + } + + let attrs = cx.tcx.hir().attrs(it.hir_id()); + if let Some(attr) = cx.sess().find_by_name(attrs, sym::rustc_test_marker) { + cx.struct_span_lint(UNNAMEABLE_TEST_ITEMS, attr.span, |lint| { + lint.build(fluent::lint::builtin_unnameable_test_items).emit(); + }); + } + } + + fn check_item_post(&mut self, _cx: &LateContext<'_>, it: &hir::Item<'_>) { + if !self.items_nameable && self.boundary == Some(it.def_id) { + self.items_nameable = true; + } + } +} + +declare_lint! { + /// The `keyword_idents` lint detects edition keywords being used as an + /// identifier. + /// + /// ### Example + /// + /// ```rust,edition2015,compile_fail + /// #![deny(keyword_idents)] + /// // edition 2015 + /// fn dyn() {} + /// ``` + /// + /// {{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. + /// + /// You can manually change the identifiers to a non-keyword, or use a + /// [raw identifier], for example `r#dyn`, 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 KEYWORD_IDENTS, + Allow, + "detects edition keywords being used as an identifier", + @future_incompatible = FutureIncompatibleInfo { + reference: "issue #49716 <https://github.com/rust-lang/rust/issues/49716>", + reason: FutureIncompatibilityReason::EditionError(Edition::Edition2018), + }; +} + +declare_lint_pass!( + /// Check for uses of edition keywords used as an identifier. + KeywordIdents => [KEYWORD_IDENTS] +); + +struct UnderMacro(bool); + +impl KeywordIdents { + fn check_tokens(&mut self, cx: &EarlyContext<'_>, tokens: TokenStream) { + for tt in tokens.into_trees() { + match tt { + // Only report non-raw idents. + TokenTree::Token(token, _) => { + if let Some((ident, false)) = token.ident() { + self.check_ident_token(cx, UnderMacro(true), ident); + } + } + TokenTree::Delimited(_, _, tts) => self.check_tokens(cx, tts), + } + } + } + + fn check_ident_token( + &mut self, + cx: &EarlyContext<'_>, + UnderMacro(under_macro): UnderMacro, + ident: Ident, + ) { + let next_edition = match cx.sess().edition() { + Edition::Edition2015 => { + match ident.name { + kw::Async | kw::Await | kw::Try => Edition::Edition2018, + + // rust-lang/rust#56327: Conservatively do not + // attempt to report occurrences of `dyn` within + // macro definitions or invocations, because `dyn` + // can legitimately occur as a contextual keyword + // in 2015 code denoting its 2018 meaning, and we + // do not want rustfix to inject bugs into working + // code by rewriting such occurrences. + // + // But if we see `dyn` outside of a macro, we know + // its precise role in the parsed AST and thus are + // assured this is truly an attempt to use it as + // an identifier. + kw::Dyn if !under_macro => Edition::Edition2018, + + _ => return, + } + } + + // There are no new keywords yet for the 2018 edition and beyond. + _ => return, + }; + + // Don't lint `r#foo`. + if cx.sess().parse_sess.raw_identifier_spans.borrow().contains(&ident.span) { + return; + } + + cx.struct_span_lint(KEYWORD_IDENTS, ident.span, |lint| { + lint.build(fluent::lint::builtin_keyword_idents) + .set_arg("kw", ident.clone()) + .set_arg("next", next_edition) + .span_suggestion( + ident.span, + fluent::lint::suggestion, + format!("r#{}", ident), + Applicability::MachineApplicable, + ) + .emit(); + }); + } +} + +impl EarlyLintPass for KeywordIdents { + fn check_mac_def(&mut self, cx: &EarlyContext<'_>, mac_def: &ast::MacroDef, _id: ast::NodeId) { + self.check_tokens(cx, mac_def.body.inner_tokens()); + } + fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &ast::MacCall) { + self.check_tokens(cx, mac.args.inner_tokens()); + } + fn check_ident(&mut self, cx: &EarlyContext<'_>, ident: Ident) { + self.check_ident_token(cx, UnderMacro(false), ident); + } +} + +declare_lint_pass!(ExplicitOutlivesRequirements => [EXPLICIT_OUTLIVES_REQUIREMENTS]); + +impl ExplicitOutlivesRequirements { + fn lifetimes_outliving_lifetime<'tcx>( + inferred_outlives: &'tcx [(ty::Predicate<'tcx>, Span)], + index: u32, + ) -> Vec<ty::Region<'tcx>> { + inferred_outlives + .iter() + .filter_map(|(pred, _)| match pred.kind().skip_binder() { + ty::PredicateKind::RegionOutlives(ty::OutlivesPredicate(a, b)) => match *a { + ty::ReEarlyBound(ebr) if ebr.index == index => Some(b), + _ => None, + }, + _ => None, + }) + .collect() + } + + fn lifetimes_outliving_type<'tcx>( + inferred_outlives: &'tcx [(ty::Predicate<'tcx>, Span)], + index: u32, + ) -> Vec<ty::Region<'tcx>> { + inferred_outlives + .iter() + .filter_map(|(pred, _)| match pred.kind().skip_binder() { + ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(a, b)) => { + a.is_param(index).then_some(b) + } + _ => None, + }) + .collect() + } + + fn collect_outlives_bound_spans<'tcx>( + &self, + tcx: TyCtxt<'tcx>, + bounds: &hir::GenericBounds<'_>, + inferred_outlives: &[ty::Region<'tcx>], + ) -> Vec<(usize, Span)> { + use rustc_middle::middle::resolve_lifetime::Region; + + bounds + .iter() + .enumerate() + .filter_map(|(i, bound)| { + if let hir::GenericBound::Outlives(lifetime) = bound { + let is_inferred = match tcx.named_region(lifetime.hir_id) { + Some(Region::EarlyBound(index, ..)) => inferred_outlives.iter().any(|r| { + if let ty::ReEarlyBound(ebr) = **r { ebr.index == index } else { false } + }), + _ => false, + }; + is_inferred.then_some((i, bound.span())) + } else { + None + } + }) + .filter(|(_, span)| !in_external_macro(tcx.sess, *span)) + .collect() + } + + fn consolidate_outlives_bound_spans( + &self, + lo: Span, + bounds: &hir::GenericBounds<'_>, + bound_spans: Vec<(usize, Span)>, + ) -> Vec<Span> { + if bounds.is_empty() { + return Vec::new(); + } + if bound_spans.len() == bounds.len() { + let (_, last_bound_span) = bound_spans[bound_spans.len() - 1]; + // If all bounds are inferable, we want to delete the colon, so + // start from just after the parameter (span passed as argument) + vec![lo.to(last_bound_span)] + } else { + let mut merged = Vec::new(); + let mut last_merged_i = None; + + let mut from_start = true; + for (i, bound_span) in bound_spans { + match last_merged_i { + // If the first bound is inferable, our span should also eat the leading `+`. + None if i == 0 => { + merged.push(bound_span.to(bounds[1].span().shrink_to_lo())); + last_merged_i = Some(0); + } + // If consecutive bounds are inferable, merge their spans + Some(h) if i == h + 1 => { + if let Some(tail) = merged.last_mut() { + // Also eat the trailing `+` if the first + // more-than-one bound is inferable + let to_span = if from_start && i < bounds.len() { + bounds[i + 1].span().shrink_to_lo() + } else { + bound_span + }; + *tail = tail.to(to_span); + last_merged_i = Some(i); + } else { + bug!("another bound-span visited earlier"); + } + } + _ => { + // When we find a non-inferable bound, subsequent inferable bounds + // won't be consecutive from the start (and we'll eat the leading + // `+` rather than the trailing one) + from_start = false; + merged.push(bounds[i - 1].span().shrink_to_hi().to(bound_span)); + last_merged_i = Some(i); + } + } + } + merged + } + } +} + +impl<'tcx> LateLintPass<'tcx> for ExplicitOutlivesRequirements { + fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) { + use rustc_middle::middle::resolve_lifetime::Region; + + let def_id = item.def_id; + if let hir::ItemKind::Struct(_, ref hir_generics) + | hir::ItemKind::Enum(_, ref hir_generics) + | hir::ItemKind::Union(_, ref hir_generics) = item.kind + { + let inferred_outlives = cx.tcx.inferred_outlives_of(def_id); + if inferred_outlives.is_empty() { + return; + } + + let ty_generics = cx.tcx.generics_of(def_id); + + let mut bound_count = 0; + let mut lint_spans = Vec::new(); + let mut where_lint_spans = Vec::new(); + let mut dropped_predicate_count = 0; + let num_predicates = hir_generics.predicates.len(); + for (i, where_predicate) in hir_generics.predicates.iter().enumerate() { + let (relevant_lifetimes, bounds, span, in_where_clause) = match where_predicate { + hir::WherePredicate::RegionPredicate(predicate) => { + if let Some(Region::EarlyBound(index, ..)) = + cx.tcx.named_region(predicate.lifetime.hir_id) + { + ( + Self::lifetimes_outliving_lifetime(inferred_outlives, index), + &predicate.bounds, + predicate.span, + predicate.in_where_clause, + ) + } else { + continue; + } + } + hir::WherePredicate::BoundPredicate(predicate) => { + // FIXME we can also infer bounds on associated types, + // and should check for them here. + match predicate.bounded_ty.kind { + hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => { + let Res::Def(DefKind::TyParam, def_id) = path.res else { + continue + }; + let index = ty_generics.param_def_id_to_index[&def_id]; + ( + Self::lifetimes_outliving_type(inferred_outlives, index), + &predicate.bounds, + predicate.span, + predicate.origin == PredicateOrigin::WhereClause, + ) + } + _ => { + continue; + } + } + } + _ => continue, + }; + if relevant_lifetimes.is_empty() { + continue; + } + + let bound_spans = + self.collect_outlives_bound_spans(cx.tcx, bounds, &relevant_lifetimes); + bound_count += bound_spans.len(); + + let drop_predicate = bound_spans.len() == bounds.len(); + if drop_predicate { + dropped_predicate_count += 1; + } + + if drop_predicate && !in_where_clause { + lint_spans.push(span); + } else if drop_predicate && i + 1 < num_predicates { + // If all the bounds on a predicate were inferable and there are + // further predicates, we want to eat the trailing comma. + let next_predicate_span = hir_generics.predicates[i + 1].span(); + where_lint_spans.push(span.to(next_predicate_span.shrink_to_lo())); + } else { + where_lint_spans.extend(self.consolidate_outlives_bound_spans( + span.shrink_to_lo(), + bounds, + bound_spans, + )); + } + } + + // If all predicates are inferable, drop the entire clause + // (including the `where`) + if hir_generics.has_where_clause_predicates && dropped_predicate_count == num_predicates + { + let where_span = hir_generics.where_clause_span; + // Extend the where clause back to the closing `>` of the + // generics, except for tuple struct, which have the `where` + // after the fields of the struct. + let full_where_span = + if let hir::ItemKind::Struct(hir::VariantData::Tuple(..), _) = item.kind { + where_span + } else { + hir_generics.span.shrink_to_hi().to(where_span) + }; + lint_spans.push(full_where_span); + } else { + lint_spans.extend(where_lint_spans); + } + + if !lint_spans.is_empty() { + cx.struct_span_lint(EXPLICIT_OUTLIVES_REQUIREMENTS, lint_spans.clone(), |lint| { + lint.build(fluent::lint::builtin_explicit_outlives) + .set_arg("count", bound_count) + .multipart_suggestion( + fluent::lint::suggestion, + lint_spans + .into_iter() + .map(|span| (span, String::new())) + .collect::<Vec<_>>(), + Applicability::MachineApplicable, + ) + .emit(); + }); + } + } + } +} + +declare_lint! { + /// The `incomplete_features` lint detects unstable features enabled with + /// the [`feature` attribute] that may function improperly in some or all + /// cases. + /// + /// [`feature` attribute]: https://doc.rust-lang.org/nightly/unstable-book/ + /// + /// ### Example + /// + /// ```rust + /// #![feature(generic_const_exprs)] + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// Although it is encouraged for people to experiment with unstable + /// features, some of them are known to be incomplete or faulty. This lint + /// is a signal that the feature has not yet been finished, and you may + /// experience problems with it. + pub INCOMPLETE_FEATURES, + Warn, + "incomplete features that may function improperly in some or all cases" +} + +declare_lint_pass!( + /// Check for used feature gates in `INCOMPLETE_FEATURES` in `rustc_feature/src/active.rs`. + IncompleteFeatures => [INCOMPLETE_FEATURES] +); + +impl EarlyLintPass for IncompleteFeatures { + fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) { + let features = cx.sess().features_untracked(); + features + .declared_lang_features + .iter() + .map(|(name, span, _)| (name, span)) + .chain(features.declared_lib_features.iter().map(|(name, span)| (name, span))) + .filter(|(&name, _)| features.incomplete(name)) + .for_each(|(&name, &span)| { + cx.struct_span_lint(INCOMPLETE_FEATURES, span, |lint| { + let mut builder = lint.build(fluent::lint::builtin_incomplete_features); + builder.set_arg("name", name); + if let Some(n) = rustc_feature::find_feature_issue(name, GateIssue::Language) { + builder.set_arg("n", n); + builder.note(fluent::lint::note); + } + if HAS_MIN_FEATURES.contains(&name) { + builder.help(fluent::lint::help); + } + builder.emit(); + }) + }); + } +} + +const HAS_MIN_FEATURES: &[Symbol] = &[sym::specialization]; + +declare_lint! { + /// The `invalid_value` lint detects creating a value that is not valid, + /// such as a null reference. + /// + /// ### Example + /// + /// ```rust,no_run + /// # #![allow(unused)] + /// unsafe { + /// let x: &'static i32 = std::mem::zeroed(); + /// } + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// In some situations the compiler can detect that the code is creating + /// an invalid value, which should be avoided. + /// + /// In particular, this lint will check for improper use of + /// [`mem::zeroed`], [`mem::uninitialized`], [`mem::transmute`], and + /// [`MaybeUninit::assume_init`] that can cause [undefined behavior]. The + /// lint should provide extra information to indicate what the problem is + /// and a possible solution. + /// + /// [`mem::zeroed`]: https://doc.rust-lang.org/std/mem/fn.zeroed.html + /// [`mem::uninitialized`]: https://doc.rust-lang.org/std/mem/fn.uninitialized.html + /// [`mem::transmute`]: https://doc.rust-lang.org/std/mem/fn.transmute.html + /// [`MaybeUninit::assume_init`]: https://doc.rust-lang.org/std/mem/union.MaybeUninit.html#method.assume_init + /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html + pub INVALID_VALUE, + Warn, + "an invalid value is being created (such as a null reference)" +} + +declare_lint_pass!(InvalidValue => [INVALID_VALUE]); + +impl<'tcx> LateLintPass<'tcx> for InvalidValue { + fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &hir::Expr<'_>) { + #[derive(Debug, Copy, Clone, PartialEq)] + enum InitKind { + Zeroed, + Uninit, + } + + /// Information about why a type cannot be initialized this way. + /// Contains an error message and optionally a span to point at. + type InitError = (String, Option<Span>); + + /// Test if this constant is all-0. + fn is_zero(expr: &hir::Expr<'_>) -> bool { + use hir::ExprKind::*; + use rustc_ast::LitKind::*; + match &expr.kind { + Lit(lit) => { + if let Int(i, _) = lit.node { + i == 0 + } else { + false + } + } + Tup(tup) => tup.iter().all(is_zero), + _ => false, + } + } + + /// Determine if this expression is a "dangerous initialization". + fn is_dangerous_init(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<InitKind> { + if let hir::ExprKind::Call(ref path_expr, ref args) = expr.kind { + // Find calls to `mem::{uninitialized,zeroed}` methods. + if let hir::ExprKind::Path(ref qpath) = path_expr.kind { + let def_id = cx.qpath_res(qpath, path_expr.hir_id).opt_def_id()?; + match cx.tcx.get_diagnostic_name(def_id) { + Some(sym::mem_zeroed) => return Some(InitKind::Zeroed), + Some(sym::mem_uninitialized) => return Some(InitKind::Uninit), + Some(sym::transmute) if is_zero(&args[0]) => return Some(InitKind::Zeroed), + _ => {} + } + } + } else if let hir::ExprKind::MethodCall(_, ref args, _) = expr.kind { + // Find problematic calls to `MaybeUninit::assume_init`. + let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id)?; + if cx.tcx.is_diagnostic_item(sym::assume_init, def_id) { + // This is a call to *some* method named `assume_init`. + // See if the `self` parameter is one of the dangerous constructors. + if let hir::ExprKind::Call(ref path_expr, _) = args[0].kind { + if let hir::ExprKind::Path(ref qpath) = path_expr.kind { + let def_id = cx.qpath_res(qpath, path_expr.hir_id).opt_def_id()?; + match cx.tcx.get_diagnostic_name(def_id) { + Some(sym::maybe_uninit_zeroed) => return Some(InitKind::Zeroed), + Some(sym::maybe_uninit_uninit) => return Some(InitKind::Uninit), + _ => {} + } + } + } + } + } + + None + } + + /// Test if this enum has several actually "existing" variants. + /// Zero-sized uninhabited variants do not always have a tag assigned and thus do not "exist". + fn is_multi_variant<'tcx>(adt: ty::AdtDef<'tcx>) -> bool { + // As an approximation, we only count dataless variants. Those are definitely inhabited. + let existing_variants = adt.variants().iter().filter(|v| v.fields.is_empty()).count(); + existing_variants > 1 + } + + /// Return `Some` only if we are sure this type does *not* + /// allow zero initialization. + fn ty_find_init_error<'tcx>( + cx: &LateContext<'tcx>, + ty: Ty<'tcx>, + init: InitKind, + ) -> Option<InitError> { + use rustc_type_ir::sty::TyKind::*; + match ty.kind() { + // Primitive types that don't like 0 as a value. + Ref(..) => Some(("references must be non-null".to_string(), None)), + Adt(..) if ty.is_box() => Some(("`Box` must be non-null".to_string(), None)), + FnPtr(..) => Some(("function pointers must be non-null".to_string(), None)), + Never => Some(("the `!` type has no valid value".to_string(), None)), + RawPtr(tm) if matches!(tm.ty.kind(), Dynamic(..)) => + // raw ptr to dyn Trait + { + Some(("the vtable of a wide raw pointer must be non-null".to_string(), None)) + } + // Primitive types with other constraints. + Bool if init == InitKind::Uninit => { + Some(("booleans must be either `true` or `false`".to_string(), None)) + } + Char if init == InitKind::Uninit => { + Some(("characters must be a valid Unicode codepoint".to_string(), None)) + } + // Recurse and checks for some compound types. + Adt(adt_def, substs) if !adt_def.is_union() => { + // First check if this ADT has a layout attribute (like `NonNull` and friends). + use std::ops::Bound; + match cx.tcx.layout_scalar_valid_range(adt_def.did()) { + // We exploit here that `layout_scalar_valid_range` will never + // return `Bound::Excluded`. (And we have tests checking that we + // handle the attribute correctly.) + (Bound::Included(lo), _) if lo > 0 => { + return Some((format!("`{}` must be non-null", ty), None)); + } + (Bound::Included(_), _) | (_, Bound::Included(_)) + if init == InitKind::Uninit => + { + return Some(( + format!( + "`{}` must be initialized inside its custom valid range", + ty, + ), + None, + )); + } + _ => {} + } + // Now, recurse. + match adt_def.variants().len() { + 0 => Some(("enums with no variants have no valid value".to_string(), None)), + 1 => { + // Struct, or enum with exactly one variant. + // Proceed recursively, check all fields. + let variant = &adt_def.variant(VariantIdx::from_u32(0)); + variant.fields.iter().find_map(|field| { + ty_find_init_error(cx, field.ty(cx.tcx, substs), init).map( + |(mut msg, span)| { + if span.is_none() { + // Point to this field, should be helpful for figuring + // out where the source of the error is. + let span = cx.tcx.def_span(field.did); + write!( + &mut msg, + " (in this {} field)", + adt_def.descr() + ) + .unwrap(); + (msg, Some(span)) + } else { + // Just forward. + (msg, span) + } + }, + ) + }) + } + // Multi-variant enum. + _ => { + if init == InitKind::Uninit && is_multi_variant(*adt_def) { + let span = cx.tcx.def_span(adt_def.did()); + Some(( + "enums have to be initialized to a variant".to_string(), + Some(span), + )) + } else { + // In principle, for zero-initialization we could figure out which variant corresponds + // to tag 0, and check that... but for now we just accept all zero-initializations. + None + } + } + } + } + Tuple(..) => { + // Proceed recursively, check all fields. + ty.tuple_fields().iter().find_map(|field| ty_find_init_error(cx, field, init)) + } + Array(ty, len) => { + if matches!(len.try_eval_usize(cx.tcx, cx.param_env), Some(v) if v > 0) { + // Array length known at array non-empty -- recurse. + ty_find_init_error(cx, *ty, init) + } else { + // Empty array or size unknown. + None + } + } + // Conservative fallback. + _ => None, + } + } + + if let Some(init) = is_dangerous_init(cx, expr) { + // This conjures an instance of a type out of nothing, + // using zeroed or uninitialized memory. + // We are extremely conservative with what we warn about. + let conjured_ty = cx.typeck_results().expr_ty(expr); + if let Some((msg, span)) = + with_no_trimmed_paths!(ty_find_init_error(cx, conjured_ty, init)) + { + // FIXME(davidtwco): make translatable + cx.struct_span_lint(INVALID_VALUE, expr.span, |lint| { + let mut err = lint.build(&format!( + "the type `{}` does not permit {}", + conjured_ty, + match init { + InitKind::Zeroed => "zero-initialization", + InitKind::Uninit => "being left uninitialized", + }, + )); + err.span_label(expr.span, "this code causes undefined behavior when executed"); + err.span_label( + expr.span, + "help: use `MaybeUninit<T>` instead, \ + and only call `assume_init` after initialization is done", + ); + if let Some(span) = span { + err.span_note(span, &msg); + } else { + err.note(&msg); + } + err.emit(); + }); + } + } + } +} + +declare_lint! { + /// The `clashing_extern_declarations` lint detects when an `extern fn` + /// has been declared with the same name but different types. + /// + /// ### Example + /// + /// ```rust + /// mod m { + /// extern "C" { + /// fn foo(); + /// } + /// } + /// + /// extern "C" { + /// fn foo(_: u32); + /// } + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// Because two symbols of the same name cannot be resolved to two + /// different functions at link time, and one function cannot possibly + /// have two types, a clashing extern declaration is almost certainly a + /// mistake. Check to make sure that the `extern` definitions are correct + /// and equivalent, and possibly consider unifying them in one location. + /// + /// This lint does not run between crates because a project may have + /// dependencies which both rely on the same extern function, but declare + /// it in a different (but valid) way. For example, they may both declare + /// an opaque type for one or more of the arguments (which would end up + /// distinct types), or use types that are valid conversions in the + /// language the `extern fn` is defined in. In these cases, the compiler + /// can't say that the clashing declaration is incorrect. + pub CLASHING_EXTERN_DECLARATIONS, + Warn, + "detects when an extern fn has been declared with the same name but different types" +} + +pub struct ClashingExternDeclarations { + /// Map of function symbol name to the first-seen hir id for that symbol name.. If seen_decls + /// contains an entry for key K, it means a symbol with name K has been seen by this lint and + /// the symbol should be reported as a clashing declaration. + // FIXME: Technically, we could just store a &'tcx str here without issue; however, the + // `impl_lint_pass` macro doesn't currently support lints parametric over a lifetime. + seen_decls: FxHashMap<Symbol, HirId>, +} + +/// Differentiate between whether the name for an extern decl came from the link_name attribute or +/// just from declaration itself. This is important because we don't want to report clashes on +/// symbol name if they don't actually clash because one or the other links against a symbol with a +/// different name. +enum SymbolName { + /// The name of the symbol + the span of the annotation which introduced the link name. + Link(Symbol, Span), + /// No link name, so just the name of the symbol. + Normal(Symbol), +} + +impl SymbolName { + fn get_name(&self) -> Symbol { + match self { + SymbolName::Link(s, _) | SymbolName::Normal(s) => *s, + } + } +} + +impl ClashingExternDeclarations { + pub(crate) fn new() -> Self { + ClashingExternDeclarations { seen_decls: FxHashMap::default() } + } + /// Insert a new foreign item into the seen set. If a symbol with the same name already exists + /// for the item, return its HirId without updating the set. + fn insert(&mut self, tcx: TyCtxt<'_>, fi: &hir::ForeignItem<'_>) -> Option<HirId> { + let did = fi.def_id.to_def_id(); + let instance = Instance::new(did, ty::List::identity_for_item(tcx, did)); + let name = Symbol::intern(tcx.symbol_name(instance).name); + if let Some(&hir_id) = self.seen_decls.get(&name) { + // Avoid updating the map with the new entry when we do find a collision. We want to + // make sure we're always pointing to the first definition as the previous declaration. + // This lets us avoid emitting "knock-on" diagnostics. + Some(hir_id) + } else { + self.seen_decls.insert(name, fi.hir_id()) + } + } + + /// Get the name of the symbol that's linked against for a given extern declaration. That is, + /// the name specified in a #[link_name = ...] attribute if one was specified, else, just the + /// symbol's name. + fn name_of_extern_decl(tcx: TyCtxt<'_>, fi: &hir::ForeignItem<'_>) -> SymbolName { + if let Some((overridden_link_name, overridden_link_name_span)) = + tcx.codegen_fn_attrs(fi.def_id).link_name.map(|overridden_link_name| { + // FIXME: Instead of searching through the attributes again to get span + // information, we could have codegen_fn_attrs also give span information back for + // where the attribute was defined. However, until this is found to be a + // bottleneck, this does just fine. + ( + overridden_link_name, + tcx.get_attr(fi.def_id.to_def_id(), sym::link_name).unwrap().span, + ) + }) + { + SymbolName::Link(overridden_link_name, overridden_link_name_span) + } else { + SymbolName::Normal(fi.ident.name) + } + } + + /// Checks whether two types are structurally the same enough that the declarations shouldn't + /// clash. We need this so we don't emit a lint when two modules both declare an extern struct, + /// with the same members (as the declarations shouldn't clash). + fn structurally_same_type<'tcx>( + cx: &LateContext<'tcx>, + a: Ty<'tcx>, + b: Ty<'tcx>, + ckind: CItemKind, + ) -> bool { + fn structurally_same_type_impl<'tcx>( + seen_types: &mut FxHashSet<(Ty<'tcx>, Ty<'tcx>)>, + cx: &LateContext<'tcx>, + a: Ty<'tcx>, + b: Ty<'tcx>, + ckind: CItemKind, + ) -> bool { + debug!("structurally_same_type_impl(cx, a = {:?}, b = {:?})", a, b); + let tcx = cx.tcx; + + // Given a transparent newtype, reach through and grab the inner + // type unless the newtype makes the type non-null. + let non_transparent_ty = |ty: Ty<'tcx>| -> Ty<'tcx> { + let mut ty = ty; + loop { + if let ty::Adt(def, substs) = *ty.kind() { + let is_transparent = def.repr().transparent(); + let is_non_null = crate::types::nonnull_optimization_guaranteed(tcx, def); + debug!( + "non_transparent_ty({:?}) -- type is transparent? {}, type is non-null? {}", + ty, is_transparent, is_non_null + ); + if is_transparent && !is_non_null { + debug_assert!(def.variants().len() == 1); + let v = &def.variant(VariantIdx::new(0)); + ty = transparent_newtype_field(tcx, v) + .expect( + "single-variant transparent structure with zero-sized field", + ) + .ty(tcx, substs); + continue; + } + } + debug!("non_transparent_ty -> {:?}", ty); + return ty; + } + }; + + let a = non_transparent_ty(a); + let b = non_transparent_ty(b); + + if !seen_types.insert((a, b)) { + // We've encountered a cycle. There's no point going any further -- the types are + // structurally the same. + return true; + } + let tcx = cx.tcx; + if a == b { + // All nominally-same types are structurally same, too. + true + } else { + // Do a full, depth-first comparison between the two. + use rustc_type_ir::sty::TyKind::*; + let a_kind = a.kind(); + let b_kind = b.kind(); + + let compare_layouts = |a, b| -> Result<bool, LayoutError<'tcx>> { + debug!("compare_layouts({:?}, {:?})", a, b); + let a_layout = &cx.layout_of(a)?.layout.abi(); + let b_layout = &cx.layout_of(b)?.layout.abi(); + debug!( + "comparing layouts: {:?} == {:?} = {}", + a_layout, + b_layout, + a_layout == b_layout + ); + Ok(a_layout == b_layout) + }; + + #[allow(rustc::usage_of_ty_tykind)] + let is_primitive_or_pointer = |kind: &ty::TyKind<'_>| { + kind.is_primitive() || matches!(kind, RawPtr(..) | Ref(..)) + }; + + ensure_sufficient_stack(|| { + match (a_kind, b_kind) { + (Adt(a_def, _), Adt(b_def, _)) => { + // We can immediately rule out these types as structurally same if + // their layouts differ. + match compare_layouts(a, b) { + Ok(false) => return false, + _ => (), // otherwise, continue onto the full, fields comparison + } + + // Grab a flattened representation of all fields. + let a_fields = a_def.variants().iter().flat_map(|v| v.fields.iter()); + let b_fields = b_def.variants().iter().flat_map(|v| v.fields.iter()); + + // Perform a structural comparison for each field. + a_fields.eq_by( + b_fields, + |&ty::FieldDef { did: a_did, .. }, + &ty::FieldDef { did: b_did, .. }| { + structurally_same_type_impl( + seen_types, + cx, + tcx.type_of(a_did), + tcx.type_of(b_did), + ckind, + ) + }, + ) + } + (Array(a_ty, a_const), Array(b_ty, b_const)) => { + // For arrays, we also check the constness of the type. + a_const.kind() == b_const.kind() + && structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind) + } + (Slice(a_ty), Slice(b_ty)) => { + structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind) + } + (RawPtr(a_tymut), RawPtr(b_tymut)) => { + a_tymut.mutbl == b_tymut.mutbl + && structurally_same_type_impl( + seen_types, cx, a_tymut.ty, b_tymut.ty, ckind, + ) + } + (Ref(_a_region, a_ty, a_mut), Ref(_b_region, b_ty, b_mut)) => { + // For structural sameness, we don't need the region to be same. + a_mut == b_mut + && structurally_same_type_impl(seen_types, cx, *a_ty, *b_ty, ckind) + } + (FnDef(..), FnDef(..)) => { + let a_poly_sig = a.fn_sig(tcx); + let b_poly_sig = b.fn_sig(tcx); + + // We don't compare regions, but leaving bound regions around ICEs, so + // we erase them. + let a_sig = tcx.erase_late_bound_regions(a_poly_sig); + let b_sig = tcx.erase_late_bound_regions(b_poly_sig); + + (a_sig.abi, a_sig.unsafety, a_sig.c_variadic) + == (b_sig.abi, b_sig.unsafety, b_sig.c_variadic) + && a_sig.inputs().iter().eq_by(b_sig.inputs().iter(), |a, b| { + structurally_same_type_impl(seen_types, cx, *a, *b, ckind) + }) + && structurally_same_type_impl( + seen_types, + cx, + a_sig.output(), + b_sig.output(), + ckind, + ) + } + (Tuple(a_substs), Tuple(b_substs)) => { + a_substs.iter().eq_by(b_substs.iter(), |a_ty, b_ty| { + structurally_same_type_impl(seen_types, cx, a_ty, b_ty, ckind) + }) + } + // For these, it's not quite as easy to define structural-sameness quite so easily. + // For the purposes of this lint, take the conservative approach and mark them as + // not structurally same. + (Dynamic(..), Dynamic(..)) + | (Error(..), Error(..)) + | (Closure(..), Closure(..)) + | (Generator(..), Generator(..)) + | (GeneratorWitness(..), GeneratorWitness(..)) + | (Projection(..), Projection(..)) + | (Opaque(..), Opaque(..)) => false, + + // These definitely should have been caught above. + (Bool, Bool) | (Char, Char) | (Never, Never) | (Str, Str) => unreachable!(), + + // An Adt and a primitive or pointer type. This can be FFI-safe if non-null + // enum layout optimisation is being applied. + (Adt(..), other_kind) | (other_kind, Adt(..)) + if is_primitive_or_pointer(other_kind) => + { + let (primitive, adt) = + if is_primitive_or_pointer(a.kind()) { (a, b) } else { (b, a) }; + if let Some(ty) = crate::types::repr_nullable_ptr(cx, adt, ckind) { + ty == primitive + } else { + compare_layouts(a, b).unwrap_or(false) + } + } + // Otherwise, just compare the layouts. This may fail to lint for some + // incompatible types, but at the very least, will stop reads into + // uninitialised memory. + _ => compare_layouts(a, b).unwrap_or(false), + } + }) + } + } + let mut seen_types = FxHashSet::default(); + structurally_same_type_impl(&mut seen_types, cx, a, b, ckind) + } +} + +impl_lint_pass!(ClashingExternDeclarations => [CLASHING_EXTERN_DECLARATIONS]); + +impl<'tcx> LateLintPass<'tcx> for ClashingExternDeclarations { + fn check_foreign_item(&mut self, cx: &LateContext<'tcx>, this_fi: &hir::ForeignItem<'_>) { + trace!("ClashingExternDeclarations: check_foreign_item: {:?}", this_fi); + if let ForeignItemKind::Fn(..) = this_fi.kind { + let tcx = cx.tcx; + if let Some(existing_hid) = self.insert(tcx, this_fi) { + let existing_decl_ty = tcx.type_of(tcx.hir().local_def_id(existing_hid)); + let this_decl_ty = tcx.type_of(this_fi.def_id); + debug!( + "ClashingExternDeclarations: Comparing existing {:?}: {:?} to this {:?}: {:?}", + existing_hid, existing_decl_ty, this_fi.def_id, this_decl_ty + ); + // Check that the declarations match. + if !Self::structurally_same_type( + cx, + existing_decl_ty, + this_decl_ty, + CItemKind::Declaration, + ) { + let orig_fi = tcx.hir().expect_foreign_item(existing_hid.expect_owner()); + let orig = Self::name_of_extern_decl(tcx, orig_fi); + + // We want to ensure that we use spans for both decls that include where the + // name was defined, whether that was from the link_name attribute or not. + let get_relevant_span = + |fi: &hir::ForeignItem<'_>| match Self::name_of_extern_decl(tcx, fi) { + SymbolName::Normal(_) => fi.span, + SymbolName::Link(_, annot_span) => fi.span.to(annot_span), + }; + // Finally, emit the diagnostic. + tcx.struct_span_lint_hir( + CLASHING_EXTERN_DECLARATIONS, + this_fi.hir_id(), + get_relevant_span(this_fi), + |lint| { + let mut expected_str = DiagnosticStyledString::new(); + expected_str.push(existing_decl_ty.fn_sig(tcx).to_string(), false); + let mut found_str = DiagnosticStyledString::new(); + found_str.push(this_decl_ty.fn_sig(tcx).to_string(), true); + + lint.build(if orig.get_name() == this_fi.ident.name { + fluent::lint::builtin_clashing_extern_same_name + } else { + fluent::lint::builtin_clashing_extern_diff_name + }) + .set_arg("this_fi", this_fi.ident.name) + .set_arg("orig", orig.get_name()) + .span_label( + get_relevant_span(orig_fi), + fluent::lint::previous_decl_label, + ) + .span_label(get_relevant_span(this_fi), fluent::lint::mismatch_label) + // FIXME(davidtwco): translatable expected/found + .note_expected_found(&"", expected_str, &"", found_str) + .emit(); + }, + ); + } + } + } + } +} + +declare_lint! { + /// The `deref_nullptr` lint detects when an null pointer is dereferenced, + /// which causes [undefined behavior]. + /// + /// ### Example + /// + /// ```rust,no_run + /// # #![allow(unused)] + /// use std::ptr; + /// unsafe { + /// let x = &*ptr::null::<i32>(); + /// let x = ptr::addr_of!(*ptr::null::<i32>()); + /// let x = *(0 as *const i32); + /// } + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// Dereferencing a null pointer causes [undefined behavior] even as a place expression, + /// like `&*(0 as *const i32)` or `addr_of!(*(0 as *const i32))`. + /// + /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html + pub DEREF_NULLPTR, + Warn, + "detects when an null pointer is dereferenced" +} + +declare_lint_pass!(DerefNullPtr => [DEREF_NULLPTR]); + +impl<'tcx> LateLintPass<'tcx> for DerefNullPtr { + fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &hir::Expr<'_>) { + /// test if expression is a null ptr + fn is_null_ptr(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> bool { + match &expr.kind { + rustc_hir::ExprKind::Cast(ref expr, ref ty) => { + if let rustc_hir::TyKind::Ptr(_) = ty.kind { + return is_zero(expr) || is_null_ptr(cx, expr); + } + } + // check for call to `core::ptr::null` or `core::ptr::null_mut` + rustc_hir::ExprKind::Call(ref path, _) => { + if let rustc_hir::ExprKind::Path(ref qpath) = path.kind { + if let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id() { + return matches!( + cx.tcx.get_diagnostic_name(def_id), + Some(sym::ptr_null | sym::ptr_null_mut) + ); + } + } + } + _ => {} + } + false + } + + /// test if expression is the literal `0` + fn is_zero(expr: &hir::Expr<'_>) -> bool { + match &expr.kind { + rustc_hir::ExprKind::Lit(ref lit) => { + if let LitKind::Int(a, _) = lit.node { + return a == 0; + } + } + _ => {} + } + false + } + + if let rustc_hir::ExprKind::Unary(rustc_hir::UnOp::Deref, expr_deref) = expr.kind { + if is_null_ptr(cx, expr_deref) { + cx.struct_span_lint(DEREF_NULLPTR, expr.span, |lint| { + let mut err = lint.build(fluent::lint::builtin_deref_nullptr); + err.span_label(expr.span, fluent::lint::label); + err.emit(); + }); + } + } + } +} + +declare_lint! { + /// The `named_asm_labels` lint detects the use of named labels in the + /// inline `asm!` macro. + /// + /// ### Example + /// + /// ```rust,compile_fail + /// use std::arch::asm; + /// + /// fn main() { + /// unsafe { + /// asm!("foo: bar"); + /// } + /// } + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// LLVM is allowed to duplicate inline assembly blocks for any + /// reason, for example when it is in a function that gets inlined. Because + /// of this, GNU assembler [local labels] *must* be used instead of labels + /// with a name. Using named labels might cause assembler or linker errors. + /// + /// See the explanation in [Rust By Example] for more details. + /// + /// [local labels]: https://sourceware.org/binutils/docs/as/Symbol-Names.html#Local-Labels + /// [Rust By Example]: https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels + pub NAMED_ASM_LABELS, + Deny, + "named labels in inline assembly", +} + +declare_lint_pass!(NamedAsmLabels => [NAMED_ASM_LABELS]); + +impl<'tcx> LateLintPass<'tcx> for NamedAsmLabels { + fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) { + if let hir::Expr { + kind: hir::ExprKind::InlineAsm(hir::InlineAsm { template_strs, .. }), + .. + } = expr + { + for (template_sym, template_snippet, template_span) in template_strs.iter() { + let template_str = template_sym.as_str(); + let find_label_span = |needle: &str| -> Option<Span> { + if let Some(template_snippet) = template_snippet { + let snippet = template_snippet.as_str(); + if let Some(pos) = snippet.find(needle) { + let end = pos + + snippet[pos..] + .find(|c| c == ':') + .unwrap_or(snippet[pos..].len() - 1); + let inner = InnerSpan::new(pos, end); + return Some(template_span.from_inner(inner)); + } + } + + None + }; + + let mut found_labels = Vec::new(); + + // A semicolon might not actually be specified as a separator for all targets, but it seems like LLVM accepts it always + let statements = template_str.split(|c| matches!(c, '\n' | ';')); + for statement in statements { + // If there's a comment, trim it from the statement + let statement = statement.find("//").map_or(statement, |idx| &statement[..idx]); + let mut start_idx = 0; + for (idx, _) in statement.match_indices(':') { + let possible_label = statement[start_idx..idx].trim(); + let mut chars = possible_label.chars(); + let Some(c) = chars.next() else { + // Empty string means a leading ':' in this section, which is not a label + break + }; + // A label starts with an alphabetic character or . or _ and continues with alphanumeric characters, _, or $ + if (c.is_alphabetic() || matches!(c, '.' | '_')) + && chars.all(|c| c.is_alphanumeric() || matches!(c, '_' | '$')) + { + found_labels.push(possible_label); + } else { + // If we encounter a non-label, there cannot be any further labels, so stop checking + break; + } + + start_idx = idx + 1; + } + } + + debug!("NamedAsmLabels::check_expr(): found_labels: {:#?}", &found_labels); + + if found_labels.len() > 0 { + let spans = found_labels + .into_iter() + .filter_map(|label| find_label_span(label)) + .collect::<Vec<Span>>(); + // If there were labels but we couldn't find a span, combine the warnings and use the template span + let target_spans: MultiSpan = + if spans.len() > 0 { spans.into() } else { (*template_span).into() }; + + cx.lookup_with_diagnostics( + NAMED_ASM_LABELS, + Some(target_spans), + |diag| { + diag.build(fluent::lint::builtin_asm_labels).emit(); + }, + BuiltinLintDiagnostics::NamedAsmLabel( + "only local labels of the form `<number>:` should be used in inline asm" + .to_string(), + ), + ); + } + } + } + } +} |