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context.rs
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context.rs
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//! 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::levels::LintLevelsBuilder;
use crate::passes::{EarlyLintPassObject, LateLintPassObject};
use rustc_ast as ast;
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::sync;
use rustc_errors::{
add_elided_lifetime_in_path_suggestion, struct_span_err, Applicability, 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::lint::LintDiagnosticBuilder;
use rustc_middle::middle::privacy::AccessLevels;
use rustc_middle::middle::stability;
use rustc_middle::ty::layout::{LayoutError, TyAndLayout};
use rustc_middle::ty::print::with_no_trimmed_paths;
use rustc_middle::ty::{self, print::Printer, subst::GenericArg, Ty, TyCtxt};
use rustc_serialize::json::Json;
use rustc_session::lint::{BuiltinLintDiagnostics, ExternDepSpec};
use rustc_session::lint::{FutureIncompatibleInfo, Level, Lint, LintBuffer, LintId};
use rustc_session::Session;
use rustc_session::SessionLintStore;
use rustc_span::lev_distance::find_best_match_for_name;
use rustc_span::{symbol::Symbol, MultiSpan, Span, DUMMY_SP};
use rustc_target::abi::LayoutOf;
use tracing::debug;
use std::cell::Cell;
use std::iter;
use std::slice;
/// 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<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
pub early_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
pub late_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
/// This is unique in that we construct them per-module, so not once.
pub late_module_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
/// Lints indexed by name.
by_name: FxHashMap<String, TargetLint>,
/// Map of registered lint groups to what lints they expand to.
lint_groups: FxHashMap<&'static str, LintGroup>,
}
impl SessionLintStore for LintStore {
fn name_to_lint(&self, lint_name: &str) -> LintId {
let lints = self
.find_lints(lint_name)
.unwrap_or_else(|_| panic!("Failed to find lint with name `{}`", lint_name));
if let &[lint] = lints.as_slice() {
return lint;
} else {
panic!("Found mutliple lints with name `{}`: {:?}", lint_name, lints);
}
}
}
/// 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<LintId>,
from_plugin: bool,
depr: Option<LintAlias>,
}
pub enum CheckLintNameResult<'a> {
Ok(&'a [LintId]),
/// Lint doesn't exist. Potentially contains a suggestion for a correct lint name.
NoLint(Option<Symbol>),
/// The lint is either renamed or removed. This is the warning
/// message, and an optional new name (`None` if removed).
Warning(String, Option<String>),
/// 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) -> Vec<(&'static str, Vec<LintId>, bool)> {
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)
})
.collect()
}
pub fn register_early_pass(
&mut self,
pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
) {
self.early_passes.push(Box::new(pass));
}
/// Used by clippy.
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 Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
) {
self.late_passes.push(Box::new(pass));
}
pub fn register_late_mod_pass(
&mut self,
pass: impl Fn() -> LateLintPassObject + '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<LintId>,
) {
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 be available with either the old or the new name.
///
/// Using the old name will not give a warning.
/// You must register a lint with the new name before calling this function.
#[track_caller]
pub fn register_alias(&mut self, old_name: &str, new_name: &str) {
let target = match self.by_name.get(new_name) {
Some(&Id(lint_id)) => lint_id,
_ => bug!("cannot add alias {} for lint {} that does not exist", old_name, new_name),
};
match self.by_name.insert(old_name.to_string(), Id(target)) {
None | Some(Ignored) => {}
Some(x) => bug!("duplicate specification of lint {} (was {:?})", old_name, x),
}
}
/// 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 target = match self.by_name.get(new_name) {
Some(&Id(lint_id)) => lint_id,
_ => 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<Vec<LintId>, 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) {
let db = match self.check_lint_name(lint_name, None) {
CheckLintNameResult::Ok(_) => None,
CheckLintNameResult::Warning(ref msg, _) => Some(sess.struct_warn(msg)),
CheckLintNameResult::NoLint(suggestion) => {
let mut err =
struct_span_err!(sess, DUMMY_SP, E0602, "unknown lint: `{}`", lint_name);
if let Some(suggestion) = suggestion {
err.help(&format!("did you mean: `{}`", suggestion));
}
Some(err)
}
CheckLintNameResult::Tool(result) => match result {
Err((Some(_), new_name)) => Some(sess.struct_warn(&format!(
"lint name `{}` is deprecated \
and does not have an effect anymore. \
Use: {}",
lint_name, new_name
))),
_ => None,
},
};
if let Some(mut db) = db {
let msg = format!(
"requested on the command line with `{} {}`",
match level {
Level::Allow => "-A",
Level::Warn => "-W",
Level::ForceWarn => "--force-warns",
Level::Deny => "-D",
Level::Forbid => "-F",
},
lint_name
);
db.note(&msg);
db.emit();
}
}
/// 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::<Vec<_>>()
);
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<Symbol>,
) -> CheckLintNameResult<'_> {
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?
tracing::debug!("lints={:?}", self.by_name.keys().collect::<Vec<_>>());
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(ref 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(ref new_name, _)) => CheckLintNameResult::Warning(
format!("lint `{}` has been renamed to `{}`", complete_name, new_name),
Some(new_name.to_owned()),
),
Some(&Removed(ref 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(ref 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();
let symbols =
self.get_lints().iter().map(|l| Symbol::intern(&l.name_lower())).collect::<Vec<_>>();
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...
CheckLintNameResult::NoLint(Some(Symbol::intern(&name_lower)))
} else {
// ...if not, search for lints with a similar name
let suggestion = find_best_match_for_name(&symbols, 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(ref id)) => {
CheckLintNameResult::Tool(Err((Some(slice::from_ref(id)), complete_name)))
}
Some(other) => {
tracing::debug!("got renamed lint {:?}", other);
CheckLintNameResult::NoLint(None)
}
}
}
}
/// Context for lint checking after type checking.
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<hir::BodyId>,
/// 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<Option<&'tcx ty::TypeckResults<'tcx>>>,
/// Parameter environment for the item we are in.
pub param_env: ty::ParamEnv<'tcx>,
/// Items accessible from the crate being checked.
pub access_levels: &'tcx AccessLevels,
/// 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> {
/// Type context we're checking in.
pub sess: &'a Session,
/// The crate being checked.
pub krate: &'a ast::Crate,
pub builder: LintLevelsBuilder<'a>,
/// The store of registered lints and the lint levels.
pub lint_store: &'a LintStore,
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;
fn lookup_with_diagnostics(
&self,
lint: &'static Lint,
span: Option<impl Into<MultiSpan>>,
decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
diagnostic: BuiltinLintDiagnostics,
) {
self.lookup(lint, span, |lint| {
// We first generate a blank diagnostic.
let mut db = lint.build("");
// Now, set up surrounding context.
let sess = self.sess();
match diagnostic {
BuiltinLintDiagnostics::Normal => (),
BuiltinLintDiagnostics::BareTraitObject(span, is_global) => {
let (sugg, app) = match sess.source_map().span_to_snippet(span) {
Ok(s) if is_global => {
(format!("dyn ({})", s), Applicability::MachineApplicable)
}
Ok(s) => (format!("dyn {}", s), Applicability::MachineApplicable),
Err(_) => ("dyn <type>".to_string(), Applicability::HasPlaceholders),
};
db.span_suggestion(span, "use `dyn`", sugg, app);
}
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::<path>".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,
anon_lts,
) => {
add_elided_lifetime_in_path_suggestion(
sess.source_map(),
&mut db,
n,
path_span,
incl_angl_brckt,
insertion_span,
anon_lts,
);
}
BuiltinLintDiagnostics::UnknownCrateTypes(span, note, sugg) => {
db.span_suggestion(span, ¬e, sugg, Applicability::MaybeIncorrect);
}
BuiltinLintDiagnostics::UnusedImports(message, replaces) => {
if !replaces.is_empty() {
db.tool_only_multipart_suggestion(
&message,
replaces,
Applicability::MachineApplicable,
);
}
}
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(&mut 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.to_string(), 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::ExternDepSpec(krate, loc) => {
let json = match loc {
ExternDepSpec::Json(json) => {
db.help(&format!("remove unnecessary dependency `{}`", krate));
json
}
ExternDepSpec::Raw(raw) => {
db.help(&format!("remove unnecessary dependency `{}` at `{}`", krate, raw));
db.span_suggestion_with_style(
DUMMY_SP,
"raw extern location",
raw.clone(),
Applicability::Unspecified,
SuggestionStyle::CompletelyHidden,
);
Json::String(raw)
}
};
db.tool_only_suggestion_with_metadata(
"json extern location",
Applicability::Unspecified,
json
);
}
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",
" ".into(),
Applicability::MachineApplicable,
);
}
}
// Rewrap `db`, and pass control to the user.
decorate(LintDiagnosticBuilder::new(db));
});
}
// FIXME: These methods should not take an Into<MultiSpan> -- instead, callers should need to
// set the span in their `decorate` function (preferably using set_span).
fn lookup<S: Into<MultiSpan>>(
&self,
lint: &'static Lint,
span: Option<S>,
decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
);
fn struct_span_lint<S: Into<MultiSpan>>(
&self,
lint: &'static Lint,
span: S,
decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
) {
self.lookup(lint, Some(span), decorate);
}
/// Emit a lint at the appropriate level, with no associated span.
fn lint(&self, lint: &'static Lint, decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>)) {
self.lookup(lint, None as Option<Span>, decorate);
}
}
impl<'a> EarlyContext<'a> {
pub fn new(
sess: &'a Session,
lint_store: &'a LintStore,
krate: &'a ast::Crate,
buffered: LintBuffer,
warn_about_weird_lints: bool,
) -> EarlyContext<'a> {
EarlyContext {
sess,
krate,
lint_store,
builder: LintLevelsBuilder::new(sess, warn_about_weird_lints, lint_store, &krate.attrs),
buffered,
}
}
}
impl LintContext for LateContext<'_> {
type PassObject = LateLintPassObject;
/// Gets the overall compiler `Session` object.
fn sess(&self) -> &Session {
&self.tcx.sess
}
fn lints(&self) -> &LintStore {
&*self.lint_store
}
fn lookup<S: Into<MultiSpan>>(
&self,
lint: &'static Lint,
span: Option<S>,
decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
) {
let hir_id = self.last_node_with_lint_attrs;
match span {
Some(s) => self.tcx.struct_span_lint_hir(lint, hir_id, s, decorate),
None => self.tcx.struct_lint_node(lint, hir_id, decorate),
}
}
}
impl LintContext for EarlyContext<'_> {
type PassObject = EarlyLintPassObject;
/// Gets the overall compiler `Session` object.
fn sess(&self) -> &Session {
&self.sess
}
fn lints(&self) -> &LintStore {
&*self.lint_store
}
fn lookup<S: Into<MultiSpan>>(
&self,
lint: &'static Lint,
span: Option<S>,
decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
) {
self.builder.struct_lint(lint, span.map(|s| s.into()), decorate)
}
}
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(|| {
if self.tcx.has_typeck_results(id.owner.to_def_id()) {
Some(self.tcx.typeck(id.owner))
} else {
None
}
})
.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<Symbol> {
pub struct AbsolutePathPrinter<'tcx> {
pub tcx: TyCtxt<'tcx>,
}
impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
type Error = !;
type Path = Vec<Symbol>;
type Region = ();
type Type = ();
type DynExistential = ();
type Const = ();
fn tcx(&self) -> TyCtxt<'tcx> {
self.tcx
}
fn print_region(self, _region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
Ok(())
}
fn print_type(self, _ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
Ok(())
}
fn print_dyn_existential(
self,
_predicates: &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>,
) -> Result<Self::DynExistential, Self::Error> {
Ok(())
}
fn print_const(self, _ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
Ok(())
}
fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
Ok(vec![self.tcx.crate_name(cnum)])
}
fn path_qualified(
self,
self_ty: Ty<'tcx>,
trait_ref: Option<ty::TraitRef<'tcx>>,
) -> Result<Self::Path, Self::Error> {
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<Self::Path, Self::Error>,
_disambiguated_data: &DisambiguatedDefPathData,
self_ty: Ty<'tcx>,
trait_ref: Option<ty::TraitRef<'tcx>>,
) -> Result<Self::Path, Self::Error> {
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!(
"<impl {} for {}>",
trait_ref.print_only_trait_path(),
self_ty
))
}),
None => {
with_no_trimmed_paths(|| Symbol::intern(&format!("<impl {}>", self_ty)))
}
});
Ok(path)
}
fn path_append(
self,
print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
disambiguated_data: &DisambiguatedDefPathData,
) -> Result<Self::Path, Self::Error> {
let mut path = print_prefix(self)?;
// Skip `::{{constructor}}` on tuple/unit structs.
if let DefPathData::Ctor = disambiguated_data.data {
return Ok(path);
}
path.push(Symbol::intern(&disambiguated_data.data.to_string()));
Ok(path)