//! Implementation of lint checking. //! //! The lint checking is mostly consolidated into one pass which runs //! after all other analyses. Throughout compilation, lint warnings //! can be added via the `add_lint` method on the Session structure. This //! requires a span and an ID of the node that the lint is being added to. The //! lint isn't actually emitted at that time because it is unknown what the //! actual lint level at that location is. //! //! To actually emit lint warnings/errors, a separate pass is used. //! A context keeps track of the current state of all lint levels. //! Upon entering a node of the ast which can modify the lint settings, the //! previous lint state is pushed onto a stack and the ast is then recursed //! upon. As the ast is traversed, this keeps track of the current lint level //! for all lint attributes. use self::TargetLint::*; use crate::errors::{ CheckNameDeprecated, CheckNameUnknown, CheckNameUnknownTool, CheckNameWarning, RequestedLevel, UnsupportedGroup, }; use crate::levels::LintLevelsBuilder; use crate::passes::{EarlyLintPassObject, LateLintPassObject}; use rustc_ast::util::unicode::TEXT_FLOW_CONTROL_CHARS; use rustc_data_structures::fx::FxHashMap; use rustc_data_structures::sync; use rustc_errors::{add_elided_lifetime_in_path_suggestion, DiagnosticBuilder, DiagnosticMessage}; use rustc_errors::{Applicability, DecorateLint, MultiSpan, SuggestionStyle}; use rustc_hir as hir; use rustc_hir::def::Res; use rustc_hir::def_id::{CrateNum, DefId}; use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData}; use rustc_middle::middle::privacy::EffectiveVisibilities; use rustc_middle::middle::stability; use rustc_middle::ty::layout::{LayoutError, LayoutOfHelpers, TyAndLayout}; use rustc_middle::ty::print::with_no_trimmed_paths; use rustc_middle::ty::{self, print::Printer, subst::GenericArg, RegisteredTools, Ty, TyCtxt}; use rustc_session::lint::{BuiltinLintDiagnostics, LintExpectationId}; use rustc_session::lint::{FutureIncompatibleInfo, Level, Lint, LintBuffer, LintId}; use rustc_session::Session; use rustc_span::edit_distance::find_best_match_for_name; use rustc_span::symbol::{sym, Ident, Symbol}; use rustc_span::{BytePos, Span}; use rustc_target::abi; use std::cell::Cell; use std::iter; use std::slice; type EarlyLintPassFactory = dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync; type LateLintPassFactory = dyn for<'tcx> Fn(TyCtxt<'tcx>) -> LateLintPassObject<'tcx> + sync::Send + sync::Sync; /// Information about the registered lints. /// /// This is basically the subset of `Context` that we can /// build early in the compile pipeline. pub struct LintStore { /// Registered lints. lints: Vec<&'static Lint>, /// Constructor functions for each variety of lint pass. /// /// These should only be called once, but since we want to avoid locks or /// interior mutability, we don't enforce this (and lints should, in theory, /// be compatible with being constructed more than once, though not /// necessarily in a sane manner. This is safe though.) pub pre_expansion_passes: Vec>, pub early_passes: Vec>, pub late_passes: Vec>, /// This is unique in that we construct them per-module, so not once. pub late_module_passes: Vec>, /// Lints indexed by name. by_name: FxHashMap, /// Map of registered lint groups to what lints they expand to. lint_groups: FxHashMap<&'static str, LintGroup>, } /// The target of the `by_name` map, which accounts for renaming/deprecation. #[derive(Debug)] enum TargetLint { /// A direct lint target Id(LintId), /// Temporary renaming, used for easing migration pain; see #16545 Renamed(String, LintId), /// Lint with this name existed previously, but has been removed/deprecated. /// The string argument is the reason for removal. Removed(String), /// A lint name that should give no warnings and have no effect. /// /// This is used by rustc to avoid warning about old rustdoc lints before rustdoc registers them as tool lints. Ignored, } pub enum FindLintError { NotFound, Removed, } struct LintAlias { name: &'static str, /// Whether deprecation warnings should be suppressed for this alias. silent: bool, } struct LintGroup { lint_ids: Vec, from_plugin: bool, depr: Option, } #[derive(Debug)] pub enum CheckLintNameResult<'a> { Ok(&'a [LintId]), /// Lint doesn't exist. Potentially contains a suggestion for a correct lint name. NoLint(Option), /// The lint refers to a tool that has not been registered. NoTool, /// The lint is either renamed or removed. This is the warning /// message, and an optional new name (`None` if removed). Warning(String, Option), /// The lint is from a tool. If the Option is None, then either /// the lint does not exist in the tool or the code was not /// compiled with the tool and therefore the lint was never /// added to the `LintStore`. Otherwise the `LintId` will be /// returned as if it where a rustc lint. Tool(Result<&'a [LintId], (Option<&'a [LintId]>, String)>), } impl LintStore { pub fn new() -> LintStore { LintStore { lints: vec![], pre_expansion_passes: vec![], early_passes: vec![], late_passes: vec![], late_module_passes: vec![], by_name: Default::default(), lint_groups: Default::default(), } } pub fn get_lints<'t>(&'t self) -> &'t [&'static Lint] { &self.lints } pub fn get_lint_groups<'t>( &'t self, ) -> impl Iterator, bool)> + 't { // This function is not used in a way which observes the order of lints. #[allow(rustc::potential_query_instability)] self.lint_groups .iter() .filter(|(_, LintGroup { depr, .. })| { // Don't display deprecated lint groups. depr.is_none() }) .map(|(k, LintGroup { lint_ids, from_plugin, .. })| { (*k, lint_ids.clone(), *from_plugin) }) } pub fn register_early_pass( &mut self, pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync, ) { self.early_passes.push(Box::new(pass)); } /// This lint pass is softly deprecated. It misses expanded code and has caused a few /// errors in the past. Currently, it is only used in Clippy. New implementations /// should avoid using this interface, as it might be removed in the future. /// /// * See [rust#69838](https://github.com/rust-lang/rust/pull/69838) /// * See [rust-clippy#5518](https://github.com/rust-lang/rust-clippy/pull/5518) pub fn register_pre_expansion_pass( &mut self, pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync, ) { self.pre_expansion_passes.push(Box::new(pass)); } pub fn register_late_pass( &mut self, pass: impl for<'tcx> Fn(TyCtxt<'tcx>) -> LateLintPassObject<'tcx> + 'static + sync::Send + sync::Sync, ) { self.late_passes.push(Box::new(pass)); } pub fn register_late_mod_pass( &mut self, pass: impl for<'tcx> Fn(TyCtxt<'tcx>) -> LateLintPassObject<'tcx> + 'static + sync::Send + sync::Sync, ) { self.late_module_passes.push(Box::new(pass)); } /// Helper method for register_early/late_pass pub fn register_lints(&mut self, lints: &[&'static Lint]) { for lint in lints { self.lints.push(lint); let id = LintId::of(lint); if self.by_name.insert(lint.name_lower(), Id(id)).is_some() { bug!("duplicate specification of lint {}", lint.name_lower()) } if let Some(FutureIncompatibleInfo { reason, .. }) = lint.future_incompatible { if let Some(edition) = reason.edition() { self.lint_groups .entry(edition.lint_name()) .or_insert(LintGroup { lint_ids: vec![], from_plugin: lint.is_plugin, depr: None, }) .lint_ids .push(id); } else { // Lints belonging to the `future_incompatible` lint group are lints where a // future version of rustc will cause existing code to stop compiling. // Lints tied to an edition don't count because they are opt-in. self.lint_groups .entry("future_incompatible") .or_insert(LintGroup { lint_ids: vec![], from_plugin: lint.is_plugin, depr: None, }) .lint_ids .push(id); } } } } pub fn register_group_alias(&mut self, lint_name: &'static str, alias: &'static str) { self.lint_groups.insert( alias, LintGroup { lint_ids: vec![], from_plugin: false, depr: Some(LintAlias { name: lint_name, silent: true }), }, ); } pub fn register_group( &mut self, from_plugin: bool, name: &'static str, deprecated_name: Option<&'static str>, to: Vec, ) { let new = self .lint_groups .insert(name, LintGroup { lint_ids: to, from_plugin, depr: None }) .is_none(); if let Some(deprecated) = deprecated_name { self.lint_groups.insert( deprecated, LintGroup { lint_ids: vec![], from_plugin, depr: Some(LintAlias { name, silent: false }), }, ); } if !new { bug!("duplicate specification of lint group {}", name); } } /// This lint should give no warning and have no effect. /// /// This is used by rustc to avoid warning about old rustdoc lints before rustdoc registers them as tool lints. #[track_caller] pub fn register_ignored(&mut self, name: &str) { if self.by_name.insert(name.to_string(), Ignored).is_some() { bug!("duplicate specification of lint {}", name); } } /// This lint has been renamed; warn about using the new name and apply the lint. #[track_caller] pub fn register_renamed(&mut self, old_name: &str, new_name: &str) { let Some(&Id(target)) = self.by_name.get(new_name) else { bug!("invalid lint renaming of {} to {}", old_name, new_name); }; self.by_name.insert(old_name.to_string(), Renamed(new_name.to_string(), target)); } pub fn register_removed(&mut self, name: &str, reason: &str) { self.by_name.insert(name.into(), Removed(reason.into())); } pub fn find_lints(&self, mut lint_name: &str) -> Result, FindLintError> { match self.by_name.get(lint_name) { Some(&Id(lint_id)) => Ok(vec![lint_id]), Some(&Renamed(_, lint_id)) => Ok(vec![lint_id]), Some(&Removed(_)) => Err(FindLintError::Removed), Some(&Ignored) => Ok(vec![]), None => loop { return match self.lint_groups.get(lint_name) { Some(LintGroup { lint_ids, depr, .. }) => { if let Some(LintAlias { name, .. }) = depr { lint_name = name; continue; } Ok(lint_ids.clone()) } None => Err(FindLintError::Removed), }; }, } } /// Checks the validity of lint names derived from the command line. pub fn check_lint_name_cmdline( &self, sess: &Session, lint_name: &str, level: Level, registered_tools: &RegisteredTools, ) { let (tool_name, lint_name_only) = parse_lint_and_tool_name(lint_name); if lint_name_only == crate::WARNINGS.name_lower() && matches!(level, Level::ForceWarn(_)) { sess.emit_err(UnsupportedGroup { lint_group: crate::WARNINGS.name_lower() }); return; } let lint_name = lint_name.to_string(); match self.check_lint_name(lint_name_only, tool_name, registered_tools) { CheckLintNameResult::Warning(msg, _) => { sess.emit_warning(CheckNameWarning { msg, sub: RequestedLevel { level, lint_name }, }); } CheckLintNameResult::NoLint(suggestion) => { sess.emit_err(CheckNameUnknown { lint_name: lint_name.clone(), suggestion, sub: RequestedLevel { level, lint_name }, }); } CheckLintNameResult::Tool(Err((Some(_), new_name))) => { sess.emit_warning(CheckNameDeprecated { lint_name: lint_name.clone(), new_name, sub: RequestedLevel { level, lint_name }, }); } CheckLintNameResult::NoTool => { sess.emit_err(CheckNameUnknownTool { tool_name: tool_name.unwrap(), sub: RequestedLevel { level, lint_name }, }); } _ => {} }; } /// True if this symbol represents a lint group name. pub fn is_lint_group(&self, lint_name: Symbol) -> bool { debug!( "is_lint_group(lint_name={:?}, lint_groups={:?})", lint_name, self.lint_groups.keys().collect::>() ); let lint_name_str = lint_name.as_str(); self.lint_groups.contains_key(lint_name_str) || { let warnings_name_str = crate::WARNINGS.name_lower(); lint_name_str == warnings_name_str } } /// Checks the name of a lint for its existence, and whether it was /// renamed or removed. Generates a DiagnosticBuilder containing a /// warning for renamed and removed lints. This is over both lint /// names from attributes and those passed on the command line. Since /// it emits non-fatal warnings and there are *two* lint passes that /// inspect attributes, this is only run from the late pass to avoid /// printing duplicate warnings. pub fn check_lint_name( &self, lint_name: &str, tool_name: Option, registered_tools: &RegisteredTools, ) -> CheckLintNameResult<'_> { if let Some(tool_name) = tool_name { // FIXME: rustc and rustdoc are considered tools for lints, but not for attributes. if tool_name != sym::rustc && tool_name != sym::rustdoc && !registered_tools.contains(&Ident::with_dummy_span(tool_name)) { return CheckLintNameResult::NoTool; } } let complete_name = if let Some(tool_name) = tool_name { format!("{}::{}", tool_name, lint_name) } else { lint_name.to_string() }; // If the lint was scoped with `tool::` check if the tool lint exists if let Some(tool_name) = tool_name { match self.by_name.get(&complete_name) { None => match self.lint_groups.get(&*complete_name) { // If the lint isn't registered, there are two possibilities: None => { // 1. The tool is currently running, so this lint really doesn't exist. // FIXME: should this handle tools that never register a lint, like rustfmt? debug!("lints={:?}", self.by_name.keys().collect::>()); let tool_prefix = format!("{}::", tool_name); return if self.by_name.keys().any(|lint| lint.starts_with(&tool_prefix)) { self.no_lint_suggestion(&complete_name) } else { // 2. The tool isn't currently running, so no lints will be registered. // To avoid giving a false positive, ignore all unknown lints. CheckLintNameResult::Tool(Err((None, String::new()))) }; } Some(LintGroup { lint_ids, .. }) => { return CheckLintNameResult::Tool(Ok(&lint_ids)); } }, Some(Id(id)) => return CheckLintNameResult::Tool(Ok(slice::from_ref(id))), // If the lint was registered as removed or renamed by the lint tool, we don't need // to treat tool_lints and rustc lints different and can use the code below. _ => {} } } match self.by_name.get(&complete_name) { Some(Renamed(new_name, _)) => CheckLintNameResult::Warning( format!("lint `{}` has been renamed to `{}`", complete_name, new_name), Some(new_name.to_owned()), ), Some(Removed(reason)) => CheckLintNameResult::Warning( format!("lint `{}` has been removed: {}", complete_name, reason), None, ), None => match self.lint_groups.get(&*complete_name) { // If neither the lint, nor the lint group exists check if there is a `clippy::` // variant of this lint None => self.check_tool_name_for_backwards_compat(&complete_name, "clippy"), Some(LintGroup { lint_ids, depr, .. }) => { // Check if the lint group name is deprecated if let Some(LintAlias { name, silent }) = depr { let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap(); return if *silent { CheckLintNameResult::Ok(&lint_ids) } else { CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string()))) }; } CheckLintNameResult::Ok(&lint_ids) } }, Some(Id(id)) => CheckLintNameResult::Ok(slice::from_ref(id)), Some(&Ignored) => CheckLintNameResult::Ok(&[]), } } fn no_lint_suggestion(&self, lint_name: &str) -> CheckLintNameResult<'_> { let name_lower = lint_name.to_lowercase(); if lint_name.chars().any(char::is_uppercase) && self.find_lints(&name_lower).is_ok() { // First check if the lint name is (partly) in upper case instead of lower case... return CheckLintNameResult::NoLint(Some(Symbol::intern(&name_lower))); } // ...if not, search for lints with a similar name // Note: find_best_match_for_name depends on the sort order of its input vector. // To ensure deterministic output, sort elements of the lint_groups hash map. // Also, never suggest deprecated lint groups. let mut groups: Vec<_> = self .lint_groups .iter() .filter_map(|(k, LintGroup { depr, .. })| depr.is_none().then_some(k)) .collect(); groups.sort(); let groups = groups.iter().map(|k| Symbol::intern(k)); let lints = self.lints.iter().map(|l| Symbol::intern(&l.name_lower())); let names: Vec = groups.chain(lints).collect(); let suggestion = find_best_match_for_name(&names, Symbol::intern(&name_lower), None); CheckLintNameResult::NoLint(suggestion) } fn check_tool_name_for_backwards_compat( &self, lint_name: &str, tool_name: &str, ) -> CheckLintNameResult<'_> { let complete_name = format!("{}::{}", tool_name, lint_name); match self.by_name.get(&complete_name) { None => match self.lint_groups.get(&*complete_name) { // Now we are sure, that this lint exists nowhere None => self.no_lint_suggestion(lint_name), Some(LintGroup { lint_ids, depr, .. }) => { // Reaching this would be weird, but let's cover this case anyway if let Some(LintAlias { name, silent }) = depr { let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap(); return if *silent { CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name))) } else { CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string()))) }; } CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name))) } }, Some(Id(id)) => { CheckLintNameResult::Tool(Err((Some(slice::from_ref(id)), complete_name))) } Some(other) => { debug!("got renamed lint {:?}", other); CheckLintNameResult::NoLint(None) } } } } /// Context for lint checking outside of type inference. pub struct LateContext<'tcx> { /// Type context we're checking in. pub tcx: TyCtxt<'tcx>, /// Current body, or `None` if outside a body. pub enclosing_body: Option, /// Type-checking results for the current body. Access using the `typeck_results` /// and `maybe_typeck_results` methods, which handle querying the typeck results on demand. // FIXME(eddyb) move all the code accessing internal fields like this, // to this module, to avoid exposing it to lint logic. pub(super) cached_typeck_results: Cell>>, /// Parameter environment for the item we are in. pub param_env: ty::ParamEnv<'tcx>, /// Items accessible from the crate being checked. pub effective_visibilities: &'tcx EffectiveVisibilities, /// The store of registered lints and the lint levels. pub lint_store: &'tcx LintStore, pub last_node_with_lint_attrs: hir::HirId, /// Generic type parameters in scope for the item we are in. pub generics: Option<&'tcx hir::Generics<'tcx>>, /// We are only looking at one module pub only_module: bool, } /// Context for lint checking of the AST, after expansion, before lowering to HIR. pub struct EarlyContext<'a> { pub builder: LintLevelsBuilder<'a, crate::levels::TopDown>, pub buffered: LintBuffer, } pub trait LintPassObject: Sized {} impl LintPassObject for EarlyLintPassObject {} impl LintPassObject for LateLintPassObject<'_> {} pub trait LintContext: Sized { type PassObject: LintPassObject; fn sess(&self) -> &Session; fn lints(&self) -> &LintStore; /// Emit a lint at the appropriate level, with an optional associated span and an existing diagnostic. /// /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation. /// /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature #[rustc_lint_diagnostics] fn lookup_with_diagnostics( &self, lint: &'static Lint, span: Option>, msg: impl Into, decorate: impl for<'a, 'b> FnOnce( &'b mut DiagnosticBuilder<'a, ()>, ) -> &'b mut DiagnosticBuilder<'a, ()>, diagnostic: BuiltinLintDiagnostics, ) { // We first generate a blank diagnostic. self.lookup(lint, span, msg,|db| { // Now, set up surrounding context. let sess = self.sess(); match diagnostic { BuiltinLintDiagnostics::UnicodeTextFlow(span, content) => { let spans: Vec<_> = content .char_indices() .filter_map(|(i, c)| { TEXT_FLOW_CONTROL_CHARS.contains(&c).then(|| { let lo = span.lo() + BytePos(2 + i as u32); (c, span.with_lo(lo).with_hi(lo + BytePos(c.len_utf8() as u32))) }) }) .collect(); let (an, s) = match spans.len() { 1 => ("an ", ""), _ => ("", "s"), }; db.span_label(span, &format!( "this comment contains {}invisible unicode text flow control codepoint{}", an, s, )); for (c, span) in &spans { db.span_label(*span, format!("{:?}", c)); } db.note( "these kind of unicode codepoints change the way text flows on \ applications that support them, but can cause confusion because they \ change the order of characters on the screen", ); if !spans.is_empty() { db.multipart_suggestion_with_style( "if their presence wasn't intentional, you can remove them", spans.into_iter().map(|(_, span)| (span, "".to_string())).collect(), Applicability::MachineApplicable, SuggestionStyle::HideCodeAlways, ); } }, BuiltinLintDiagnostics::Normal => (), BuiltinLintDiagnostics::AbsPathWithModule(span) => { let (sugg, app) = match sess.source_map().span_to_snippet(span) { Ok(ref s) => { // FIXME(Manishearth) ideally the emitting code // can tell us whether or not this is global let opt_colon = if s.trim_start().starts_with("::") { "" } else { "::" }; (format!("crate{}{}", opt_colon, s), Applicability::MachineApplicable) } Err(_) => ("crate::".to_string(), Applicability::HasPlaceholders), }; db.span_suggestion(span, "use `crate`", sugg, app); } BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(span) => { db.span_label( span, "names from parent modules are not accessible without an explicit import", ); } BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths( span_def, ) => { db.span_note(span_def, "the macro is defined here"); } BuiltinLintDiagnostics::ElidedLifetimesInPaths( n, path_span, incl_angl_brckt, insertion_span, ) => { add_elided_lifetime_in_path_suggestion( sess.source_map(), db, n, path_span, incl_angl_brckt, insertion_span, ); } BuiltinLintDiagnostics::UnknownCrateTypes(span, note, sugg) => { db.span_suggestion(span, ¬e, sugg, Applicability::MaybeIncorrect); } BuiltinLintDiagnostics::UnusedImports(message, replaces, in_test_module) => { if !replaces.is_empty() { db.tool_only_multipart_suggestion( &message, replaces, Applicability::MachineApplicable, ); } if let Some(span) = in_test_module { db.span_help( self.sess().source_map().guess_head_span(span), "consider adding a `#[cfg(test)]` to the containing module", ); } } BuiltinLintDiagnostics::RedundantImport(spans, ident) => { for (span, is_imported) in spans { let introduced = if is_imported { "imported" } else { "defined" }; db.span_label( span, format!("the item `{}` is already {} here", ident, introduced), ); } } BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span) => { stability::deprecation_suggestion(db, "macro", suggestion, span) } BuiltinLintDiagnostics::UnusedDocComment(span) => { db.span_label(span, "rustdoc does not generate documentation for macro invocations"); db.help("to document an item produced by a macro, \ the macro must produce the documentation as part of its expansion"); } BuiltinLintDiagnostics::PatternsInFnsWithoutBody(span, ident) => { db.span_suggestion(span, "remove `mut` from the parameter", ident, Applicability::MachineApplicable); } BuiltinLintDiagnostics::MissingAbi(span, default_abi) => { db.span_label(span, "ABI should be specified here"); db.help(&format!("the default ABI is {}", default_abi.name())); } BuiltinLintDiagnostics::LegacyDeriveHelpers(span) => { db.span_label(span, "the attribute is introduced here"); } BuiltinLintDiagnostics::ProcMacroBackCompat(note) => { db.note(¬e); } BuiltinLintDiagnostics::OrPatternsBackCompat(span,suggestion) => { db.span_suggestion(span, "use pat_param to preserve semantics", suggestion, Applicability::MachineApplicable); } BuiltinLintDiagnostics::ReservedPrefix(span) => { db.span_label(span, "unknown prefix"); db.span_suggestion_verbose( span.shrink_to_hi(), "insert whitespace here to avoid this being parsed as a prefix in Rust 2021", " ", Applicability::MachineApplicable, ); } BuiltinLintDiagnostics::UnusedBuiltinAttribute { attr_name, macro_name, invoc_span } => { db.span_note( invoc_span, &format!("the built-in attribute `{attr_name}` will be ignored, since it's applied to the macro invocation `{macro_name}`") ); } BuiltinLintDiagnostics::TrailingMacro(is_trailing, name) => { if is_trailing { db.note("macro invocations at the end of a block are treated as expressions"); db.note(&format!("to ignore the value produced by the macro, add a semicolon after the invocation of `{name}`")); } } BuiltinLintDiagnostics::BreakWithLabelAndLoop(span) => { db.multipart_suggestion( "wrap this expression in parentheses", vec![(span.shrink_to_lo(), "(".to_string()), (span.shrink_to_hi(), ")".to_string())], Applicability::MachineApplicable ); } BuiltinLintDiagnostics::NamedAsmLabel(help) => { db.help(&help); db.note("see the asm section of Rust By Example for more information"); }, BuiltinLintDiagnostics::UnexpectedCfg((name, name_span), None) => { let Some(names_valid) = &sess.parse_sess.check_config.names_valid else { bug!("it shouldn't be possible to have a diagnostic on a name if name checking is not enabled"); }; let possibilities: Vec = names_valid.iter().map(|s| *s).collect(); // Suggest the most probable if we found one if let Some(best_match) = find_best_match_for_name(&possibilities, name, None) { db.span_suggestion(name_span, "did you mean", best_match, Applicability::MaybeIncorrect); } }, BuiltinLintDiagnostics::UnexpectedCfg((name, name_span), Some((value, value_span))) => { let Some(values) = &sess.parse_sess.check_config.values_valid.get(&name) else { bug!("it shouldn't be possible to have a diagnostic on a value whose name is not in values"); }; let possibilities: Vec = values.iter().map(|&s| s).collect(); // Show the full list if all possible values for a given name, but don't do it // for names as the possibilities could be very long if !possibilities.is_empty() { { let mut possibilities = possibilities.iter().map(Symbol::as_str).collect::>(); possibilities.sort(); let possibilities = possibilities.join(", "); db.note(&format!("expected values for `{name}` are: {possibilities}")); } // Suggest the most probable if we found one if let Some(best_match) = find_best_match_for_name(&possibilities, value, None) { db.span_suggestion(value_span, "did you mean", format!("\"{best_match}\""), Applicability::MaybeIncorrect); } } else { db.note(&format!("no expected value for `{name}`")); if name != sym::feature { db.span_suggestion(name_span.shrink_to_hi().to(value_span), "remove the value", "", Applicability::MaybeIncorrect); } } }, BuiltinLintDiagnostics::DeprecatedWhereclauseLocation(new_span, suggestion) => { db.multipart_suggestion( "move it to the end of the type declaration", vec![(db.span.primary_span().unwrap(), "".to_string()), (new_span, suggestion)], Applicability::MachineApplicable, ); db.note( "see issue #89122 for more information", ); }, BuiltinLintDiagnostics::SingleUseLifetime { param_span, use_span: Some((use_span, elide)), deletion_span, } => { debug!(?param_span, ?use_span, ?deletion_span); db.span_label(param_span, "this lifetime..."); db.span_label(use_span, "...is used only here"); if let Some(deletion_span) = deletion_span { let msg = "elide the single-use lifetime"; let (use_span, replace_lt) = if elide { let use_span = sess.source_map().span_extend_while( use_span, char::is_whitespace, ).unwrap_or(use_span); (use_span, String::new()) } else { (use_span, "'_".to_owned()) }; debug!(?deletion_span, ?use_span); // issue 107998 for the case such as a wrong function pointer type // `deletion_span` is empty and there is no need to report lifetime uses here let suggestions = if deletion_span.is_empty() { vec![(use_span, replace_lt)] } else { vec![(deletion_span, String::new()), (use_span, replace_lt)] }; db.multipart_suggestion( msg, suggestions, Applicability::MachineApplicable, ); } }, BuiltinLintDiagnostics::SingleUseLifetime { param_span: _, use_span: None, deletion_span, } => { debug!(?deletion_span); if let Some(deletion_span) = deletion_span { db.span_suggestion( deletion_span, "elide the unused lifetime", "", Applicability::MachineApplicable, ); } }, BuiltinLintDiagnostics::NamedArgumentUsedPositionally{ position_sp_to_replace, position_sp_for_msg, named_arg_sp, named_arg_name, is_formatting_arg} => { db.span_label(named_arg_sp, "this named argument is referred to by position in formatting string"); if let Some(positional_arg_for_msg) = position_sp_for_msg { let msg = format!("this formatting argument uses named argument `{}` by position", named_arg_name); db.span_label(positional_arg_for_msg, msg); } if let Some(positional_arg_to_replace) = position_sp_to_replace { let name = if is_formatting_arg { named_arg_name + "$" } else { named_arg_name }; let span_to_replace = if let Ok(positional_arg_content) = self.sess().source_map().span_to_snippet(positional_arg_to_replace) && positional_arg_content.starts_with(':') { positional_arg_to_replace.shrink_to_lo() } else { positional_arg_to_replace }; db.span_suggestion_verbose( span_to_replace, "use the named argument by name to avoid ambiguity", name, Applicability::MaybeIncorrect, ); } } BuiltinLintDiagnostics::ByteSliceInPackedStructWithDerive => { db.help("consider implementing the trait by hand, or remove the `packed` attribute"); } BuiltinLintDiagnostics::UnusedExternCrate { removal_span }=> { db.span_suggestion( removal_span, "remove it", "", Applicability::MachineApplicable, ); } BuiltinLintDiagnostics::ExternCrateNotIdiomatic { vis_span, ident_span }=> { let suggestion_span = vis_span.between(ident_span); db.span_suggestion_verbose( suggestion_span, "convert it to a `use`", if vis_span.is_empty() { "use " } else { " use " }, Applicability::MachineApplicable, ); } } // Rewrap `db`, and pass control to the user. decorate(db) }); } // FIXME: These methods should not take an Into -- instead, callers should need to // set the span in their `decorate` function (preferably using set_span). /// Emit a lint at the appropriate level, with an optional associated span. /// /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation. /// /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature #[rustc_lint_diagnostics] fn lookup>( &self, lint: &'static Lint, span: Option, msg: impl Into, decorate: impl for<'a, 'b> FnOnce( &'b mut DiagnosticBuilder<'a, ()>, ) -> &'b mut DiagnosticBuilder<'a, ()>, ); /// Emit a lint at `span` from a lint struct (some type that implements `DecorateLint`, /// typically generated by `#[derive(LintDiagnostic)]`). fn emit_spanned_lint>( &self, lint: &'static Lint, span: S, decorator: impl for<'a> DecorateLint<'a, ()>, ) { self.lookup(lint, Some(span), decorator.msg(), |diag| decorator.decorate_lint(diag)); } /// Emit a lint at the appropriate level, with an associated span. /// /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation. /// /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature #[rustc_lint_diagnostics] fn struct_span_lint>( &self, lint: &'static Lint, span: S, msg: impl Into, decorate: impl for<'a, 'b> FnOnce( &'b mut DiagnosticBuilder<'a, ()>, ) -> &'b mut DiagnosticBuilder<'a, ()>, ) { self.lookup(lint, Some(span), msg, decorate); } /// Emit a lint from a lint struct (some type that implements `DecorateLint`, typically /// generated by `#[derive(LintDiagnostic)]`). fn emit_lint(&self, lint: &'static Lint, decorator: impl for<'a> DecorateLint<'a, ()>) { self.lookup(lint, None as Option, decorator.msg(), |diag| { decorator.decorate_lint(diag) }); } /// Emit a lint at the appropriate level, with no associated span. /// /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation. /// /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature #[rustc_lint_diagnostics] fn lint( &self, lint: &'static Lint, msg: impl Into, decorate: impl for<'a, 'b> FnOnce( &'b mut DiagnosticBuilder<'a, ()>, ) -> &'b mut DiagnosticBuilder<'a, ()>, ) { self.lookup(lint, None as Option, msg, decorate); } /// This returns the lint level for the given lint at the current location. fn get_lint_level(&self, lint: &'static Lint) -> Level; /// This function can be used to manually fulfill an expectation. This can /// be used for lints which contain several spans, and should be suppressed, /// if either location was marked with an expectation. /// /// Note that this function should only be called for [`LintExpectationId`]s /// retrieved from the current lint pass. Buffered or manually created ids can /// cause ICEs. #[rustc_lint_diagnostics] fn fulfill_expectation(&self, expectation: LintExpectationId) { // We need to make sure that submitted expectation ids are correctly fulfilled suppressed // and stored between compilation sessions. To not manually do these steps, we simply create // a dummy diagnostic and emit is as usual, which will be suppressed and stored like a normal // expected lint diagnostic. self.sess() .struct_expect( "this is a dummy diagnostic, to submit and store an expectation", expectation, ) .emit(); } } impl<'a> EarlyContext<'a> { pub(crate) fn new( sess: &'a Session, warn_about_weird_lints: bool, lint_store: &'a LintStore, registered_tools: &'a RegisteredTools, buffered: LintBuffer, ) -> EarlyContext<'a> { EarlyContext { builder: LintLevelsBuilder::new( sess, warn_about_weird_lints, lint_store, registered_tools, ), buffered, } } } impl<'tcx> LintContext for LateContext<'tcx> { type PassObject = LateLintPassObject<'tcx>; /// Gets the overall compiler `Session` object. fn sess(&self) -> &Session { &self.tcx.sess } fn lints(&self) -> &LintStore { &*self.lint_store } #[rustc_lint_diagnostics] fn lookup>( &self, lint: &'static Lint, span: Option, msg: impl Into, decorate: impl for<'a, 'b> FnOnce( &'b mut DiagnosticBuilder<'a, ()>, ) -> &'b mut DiagnosticBuilder<'a, ()>, ) { let hir_id = self.last_node_with_lint_attrs; match span { Some(s) => self.tcx.struct_span_lint_hir(lint, hir_id, s, msg, decorate), None => self.tcx.struct_lint_node(lint, hir_id, msg, decorate), } } fn get_lint_level(&self, lint: &'static Lint) -> Level { self.tcx.lint_level_at_node(lint, self.last_node_with_lint_attrs).0 } } impl LintContext for EarlyContext<'_> { type PassObject = EarlyLintPassObject; /// Gets the overall compiler `Session` object. fn sess(&self) -> &Session { &self.builder.sess() } fn lints(&self) -> &LintStore { self.builder.lint_store() } #[rustc_lint_diagnostics] fn lookup>( &self, lint: &'static Lint, span: Option, msg: impl Into, decorate: impl for<'a, 'b> FnOnce( &'b mut DiagnosticBuilder<'a, ()>, ) -> &'b mut DiagnosticBuilder<'a, ()>, ) { self.builder.struct_lint(lint, span.map(|s| s.into()), msg, decorate) } fn get_lint_level(&self, lint: &'static Lint) -> Level { self.builder.lint_level(lint).0 } } impl<'tcx> LateContext<'tcx> { /// Gets the type-checking results for the current body, /// or `None` if outside a body. pub fn maybe_typeck_results(&self) -> Option<&'tcx ty::TypeckResults<'tcx>> { self.cached_typeck_results.get().or_else(|| { self.enclosing_body.map(|body| { let typeck_results = self.tcx.typeck_body(body); self.cached_typeck_results.set(Some(typeck_results)); typeck_results }) }) } /// Gets the type-checking results for the current body. /// As this will ICE if called outside bodies, only call when working with /// `Expr` or `Pat` nodes (they are guaranteed to be found only in bodies). #[track_caller] pub fn typeck_results(&self) -> &'tcx ty::TypeckResults<'tcx> { self.maybe_typeck_results().expect("`LateContext::typeck_results` called outside of body") } /// Returns the final resolution of a `QPath`, or `Res::Err` if unavailable. /// Unlike `.typeck_results().qpath_res(qpath, id)`, this can be used even outside /// bodies (e.g. for paths in `hir::Ty`), without any risk of ICE-ing. pub fn qpath_res(&self, qpath: &hir::QPath<'_>, id: hir::HirId) -> Res { match *qpath { hir::QPath::Resolved(_, ref path) => path.res, hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => self .maybe_typeck_results() .filter(|typeck_results| typeck_results.hir_owner == id.owner) .or_else(|| { self.tcx .has_typeck_results(id.owner.to_def_id()) .then(|| self.tcx.typeck(id.owner.def_id)) }) .and_then(|typeck_results| typeck_results.type_dependent_def(id)) .map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)), } } /// Check if a `DefId`'s path matches the given absolute type path usage. /// /// Anonymous scopes such as `extern` imports are matched with `kw::Empty`; /// inherent `impl` blocks are matched with the name of the type. /// /// Instead of using this method, it is often preferable to instead use /// `rustc_diagnostic_item` or a `lang_item`. This is less prone to errors /// as paths get invalidated if the target definition moves. /// /// # Examples /// /// ```rust,ignore (no context or def id available) /// if cx.match_def_path(def_id, &[sym::core, sym::option, sym::Option]) { /// // The given `def_id` is that of an `Option` type /// } /// ``` /// /// Used by clippy, but should be replaced by diagnostic items eventually. pub fn match_def_path(&self, def_id: DefId, path: &[Symbol]) -> bool { let names = self.get_def_path(def_id); names.len() == path.len() && iter::zip(names, path).all(|(a, &b)| a == b) } /// Gets the absolute path of `def_id` as a vector of `Symbol`. /// /// # Examples /// /// ```rust,ignore (no context or def id available) /// let def_path = cx.get_def_path(def_id); /// if let &[sym::core, sym::option, sym::Option] = &def_path[..] { /// // The given `def_id` is that of an `Option` type /// } /// ``` pub fn get_def_path(&self, def_id: DefId) -> Vec { pub struct AbsolutePathPrinter<'tcx> { pub tcx: TyCtxt<'tcx>, } impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> { type Error = !; type Path = Vec; type Region = (); type Type = (); type DynExistential = (); type Const = (); fn tcx(&self) -> TyCtxt<'tcx> { self.tcx } fn print_region(self, _region: ty::Region<'_>) -> Result { Ok(()) } fn print_type(self, _ty: Ty<'tcx>) -> Result { Ok(()) } fn print_dyn_existential( self, _predicates: &'tcx ty::List>, ) -> Result { Ok(()) } fn print_const(self, _ct: ty::Const<'tcx>) -> Result { Ok(()) } fn path_crate(self, cnum: CrateNum) -> Result { Ok(vec![self.tcx.crate_name(cnum)]) } fn path_qualified( self, self_ty: Ty<'tcx>, trait_ref: Option>, ) -> Result { if trait_ref.is_none() { if let ty::Adt(def, substs) = self_ty.kind() { return self.print_def_path(def.did(), substs); } } // This shouldn't ever be needed, but just in case: with_no_trimmed_paths!({ Ok(vec![match trait_ref { Some(trait_ref) => Symbol::intern(&format!("{:?}", trait_ref)), None => Symbol::intern(&format!("<{}>", self_ty)), }]) }) } fn path_append_impl( self, print_prefix: impl FnOnce(Self) -> Result, _disambiguated_data: &DisambiguatedDefPathData, self_ty: Ty<'tcx>, trait_ref: Option>, ) -> Result { let mut path = print_prefix(self)?; // This shouldn't ever be needed, but just in case: path.push(match trait_ref { Some(trait_ref) => { with_no_trimmed_paths!(Symbol::intern(&format!( "", trait_ref.print_only_trait_path(), self_ty ))) } None => { with_no_trimmed_paths!(Symbol::intern(&format!("", self_ty))) } }); Ok(path) } fn path_append( self, print_prefix: impl FnOnce(Self) -> Result, disambiguated_data: &DisambiguatedDefPathData, ) -> Result { let mut path = print_prefix(self)?; // Skip `::{{extern}}` blocks and `::{{constructor}}` on tuple/unit structs. if let DefPathData::ForeignMod | DefPathData::Ctor = disambiguated_data.data { return Ok(path); } path.push(Symbol::intern(&disambiguated_data.data.to_string())); Ok(path) } fn path_generic_args( self, print_prefix: impl FnOnce(Self) -> Result, _args: &[GenericArg<'tcx>], ) -> Result { print_prefix(self) } } AbsolutePathPrinter { tcx: self.tcx }.print_def_path(def_id, &[]).unwrap() } /// Returns the associated type `name` for `self_ty` as an implementation of `trait_id`. /// Do not invoke without first verifying that the type implements the trait. pub fn get_associated_type( &self, self_ty: Ty<'tcx>, trait_id: DefId, name: &str, ) -> Option> { let tcx = self.tcx; tcx.associated_items(trait_id) .find_by_name_and_kind(tcx, Ident::from_str(name), ty::AssocKind::Type, trait_id) .and_then(|assoc| { let proj = tcx.mk_projection(assoc.def_id, [self_ty]); tcx.try_normalize_erasing_regions(self.param_env, proj).ok() }) } } impl<'tcx> abi::HasDataLayout for LateContext<'tcx> { #[inline] fn data_layout(&self) -> &abi::TargetDataLayout { &self.tcx.data_layout } } impl<'tcx> ty::layout::HasTyCtxt<'tcx> for LateContext<'tcx> { #[inline] fn tcx(&self) -> TyCtxt<'tcx> { self.tcx } } impl<'tcx> ty::layout::HasParamEnv<'tcx> for LateContext<'tcx> { #[inline] fn param_env(&self) -> ty::ParamEnv<'tcx> { self.param_env } } impl<'tcx> LayoutOfHelpers<'tcx> for LateContext<'tcx> { type LayoutOfResult = Result, LayoutError<'tcx>>; #[inline] fn handle_layout_err(&self, err: LayoutError<'tcx>, _: Span, _: Ty<'tcx>) -> LayoutError<'tcx> { err } } pub fn parse_lint_and_tool_name(lint_name: &str) -> (Option, &str) { match lint_name.split_once("::") { Some((tool_name, lint_name)) => { let tool_name = Symbol::intern(tool_name); (Some(tool_name), lint_name) } None => (None, lint_name), } }