rust/compiler/rustc_lint/src/levels.rs
2022-05-20 12:26:37 +02:00

804 lines
33 KiB
Rust

use crate::context::{CheckLintNameResult, LintStore};
use crate::late::unerased_lint_store;
use rustc_ast as ast;
use rustc_ast_pretty::pprust;
use rustc_data_structures::fx::FxHashMap;
use rustc_errors::{struct_span_err, Applicability, Diagnostic, MultiSpan};
use rustc_hir as hir;
use rustc_hir::{intravisit, HirId};
use rustc_middle::hir::nested_filter;
use rustc_middle::lint::{
struct_lint_level, LevelAndSource, LintDiagnosticBuilder, LintExpectation, LintLevelMap,
LintLevelSets, LintLevelSource, LintSet, LintStackIndex, COMMAND_LINE,
};
use rustc_middle::ty::query::Providers;
use rustc_middle::ty::{RegisteredTools, TyCtxt};
use rustc_session::lint::{
builtin::{self, FORBIDDEN_LINT_GROUPS, SINGLE_USE_LIFETIMES, UNFULFILLED_LINT_EXPECTATIONS},
Level, Lint, LintExpectationId, LintId,
};
use rustc_session::parse::{add_feature_diagnostics, feature_err};
use rustc_session::Session;
use rustc_span::symbol::{sym, Symbol};
use rustc_span::{Span, DUMMY_SP};
use tracing::debug;
fn lint_levels(tcx: TyCtxt<'_>, (): ()) -> LintLevelMap {
let store = unerased_lint_store(tcx);
let levels =
LintLevelsBuilder::new(tcx.sess, false, &store, &tcx.resolutions(()).registered_tools);
let mut builder = LintLevelMapBuilder { levels, tcx };
let krate = tcx.hir().krate();
builder.levels.id_to_set.reserve(krate.owners.len() + 1);
let push =
builder.levels.push(tcx.hir().attrs(hir::CRATE_HIR_ID), true, Some(hir::CRATE_HIR_ID));
builder.levels.register_id(hir::CRATE_HIR_ID);
tcx.hir().walk_toplevel_module(&mut builder);
builder.levels.pop(push);
builder.levels.update_unstable_expectation_ids();
builder.levels.build_map()
}
pub struct LintLevelsBuilder<'s> {
sess: &'s Session,
lint_expectations: Vec<(LintExpectationId, LintExpectation)>,
/// Each expectation has a stable and an unstable identifier. This map
/// is used to map from unstable to stable [`LintExpectationId`]s.
expectation_id_map: FxHashMap<LintExpectationId, LintExpectationId>,
sets: LintLevelSets,
id_to_set: FxHashMap<HirId, LintStackIndex>,
cur: LintStackIndex,
warn_about_weird_lints: bool,
store: &'s LintStore,
registered_tools: &'s RegisteredTools,
}
pub struct BuilderPush {
prev: LintStackIndex,
pub changed: bool,
}
impl<'s> LintLevelsBuilder<'s> {
pub fn new(
sess: &'s Session,
warn_about_weird_lints: bool,
store: &'s LintStore,
registered_tools: &'s RegisteredTools,
) -> Self {
let mut builder = LintLevelsBuilder {
sess,
lint_expectations: Default::default(),
expectation_id_map: Default::default(),
sets: LintLevelSets::new(),
cur: COMMAND_LINE,
id_to_set: Default::default(),
warn_about_weird_lints,
store,
registered_tools,
};
builder.process_command_line(sess, store);
assert_eq!(builder.sets.list.len(), 1);
builder
}
pub(crate) fn sess(&self) -> &Session {
self.sess
}
pub(crate) fn lint_store(&self) -> &LintStore {
self.store
}
fn current_specs(&self) -> &FxHashMap<LintId, LevelAndSource> {
&self.sets.list[self.cur].specs
}
fn current_specs_mut(&mut self) -> &mut FxHashMap<LintId, LevelAndSource> {
&mut self.sets.list[self.cur].specs
}
fn process_command_line(&mut self, sess: &Session, store: &LintStore) {
self.sets.lint_cap = sess.opts.lint_cap.unwrap_or(Level::Forbid);
self.cur =
self.sets.list.push(LintSet { specs: FxHashMap::default(), parent: COMMAND_LINE });
for &(ref lint_name, level) in &sess.opts.lint_opts {
store.check_lint_name_cmdline(sess, &lint_name, level, self.registered_tools);
let orig_level = level;
let lint_flag_val = Symbol::intern(lint_name);
let Ok(ids) = store.find_lints(&lint_name) else {
// errors handled in check_lint_name_cmdline above
continue
};
for id in ids {
// ForceWarn and Forbid cannot be overridden
if let Some((Level::ForceWarn | Level::Forbid, _)) = self.current_specs().get(&id) {
continue;
}
if self.check_gated_lint(id, DUMMY_SP) {
let src = LintLevelSource::CommandLine(lint_flag_val, orig_level);
self.current_specs_mut().insert(id, (level, src));
}
}
}
}
/// Attempts to insert the `id` to `level_src` map entry. If unsuccessful
/// (e.g. if a forbid was already inserted on the same scope), then emits a
/// diagnostic with no change to `specs`.
fn insert_spec(&mut self, id: LintId, (level, src): LevelAndSource) {
let (old_level, old_src) =
self.sets.get_lint_level(id.lint, self.cur, Some(self.current_specs()), &self.sess);
// Setting to a non-forbid level is an error if the lint previously had
// a forbid level. Note that this is not necessarily true even with a
// `#[forbid(..)]` attribute present, as that is overridden by `--cap-lints`.
//
// This means that this only errors if we're truly lowering the lint
// level from forbid.
if level != Level::Forbid {
if let Level::Forbid = old_level {
// Backwards compatibility check:
//
// We used to not consider `forbid(lint_group)`
// as preventing `allow(lint)` for some lint `lint` in
// `lint_group`. For now, issue a future-compatibility
// warning for this case.
let id_name = id.lint.name_lower();
let fcw_warning = match old_src {
LintLevelSource::Default => false,
LintLevelSource::Node(symbol, _, _) => self.store.is_lint_group(symbol),
LintLevelSource::CommandLine(symbol, _) => self.store.is_lint_group(symbol),
};
debug!(
"fcw_warning={:?}, specs.get(&id) = {:?}, old_src={:?}, id_name={:?}",
fcw_warning,
self.current_specs(),
old_src,
id_name
);
let decorate_diag = |diag: &mut Diagnostic| {
diag.span_label(src.span(), "overruled by previous forbid");
match old_src {
LintLevelSource::Default => {
diag.note(&format!(
"`forbid` lint level is the default for {}",
id.to_string()
));
}
LintLevelSource::Node(_, forbid_source_span, reason) => {
diag.span_label(forbid_source_span, "`forbid` level set here");
if let Some(rationale) = reason {
diag.note(rationale.as_str());
}
}
LintLevelSource::CommandLine(_, _) => {
diag.note("`forbid` lint level was set on command line");
}
}
};
if !fcw_warning {
let mut diag_builder = struct_span_err!(
self.sess,
src.span(),
E0453,
"{}({}) incompatible with previous forbid",
level.as_str(),
src.name(),
);
decorate_diag(&mut diag_builder);
diag_builder.emit();
} else {
self.struct_lint(
FORBIDDEN_LINT_GROUPS,
Some(src.span().into()),
|diag_builder| {
let mut diag_builder = diag_builder.build(&format!(
"{}({}) incompatible with previous forbid",
level.as_str(),
src.name(),
));
decorate_diag(&mut diag_builder);
diag_builder.emit();
},
);
}
// Retain the forbid lint level, unless we are
// issuing a FCW. In the FCW case, we want to
// respect the new setting.
if !fcw_warning {
return;
}
}
}
// The lint `unfulfilled_lint_expectations` can't be expected, as it would suppress itself.
// Handling expectations of this lint would add additional complexity with little to no
// benefit. The expect level for this lint will therefore be ignored.
if let Level::Expect(_) = level && id == LintId::of(UNFULFILLED_LINT_EXPECTATIONS) {
return;
}
if let Level::ForceWarn = old_level {
self.current_specs_mut().insert(id, (old_level, old_src));
} else {
self.current_specs_mut().insert(id, (level, src));
}
}
/// Pushes a list of AST lint attributes onto this context.
///
/// This function will return a `BuilderPush` object which should be passed
/// to `pop` when this scope for the attributes provided is exited.
///
/// This function will perform a number of tasks:
///
/// * It'll validate all lint-related attributes in `attrs`
/// * It'll mark all lint-related attributes as used
/// * Lint levels will be updated based on the attributes provided
/// * Lint attributes are validated, e.g., a `#[forbid]` can't be switched to
/// `#[allow]`
///
/// Don't forget to call `pop`!
pub(crate) fn push(
&mut self,
attrs: &[ast::Attribute],
is_crate_node: bool,
source_hir_id: Option<HirId>,
) -> BuilderPush {
let prev = self.cur;
self.cur = self.sets.list.push(LintSet { specs: FxHashMap::default(), parent: prev });
let sess = self.sess;
let bad_attr = |span| struct_span_err!(sess, span, E0452, "malformed lint attribute input");
for (attr_index, attr) in attrs.iter().enumerate() {
if attr.has_name(sym::automatically_derived) {
self.current_specs_mut().insert(
LintId::of(SINGLE_USE_LIFETIMES),
(Level::Allow, LintLevelSource::Default),
);
continue;
}
let level = match Level::from_attr(attr) {
None => continue,
Some(Level::Expect(unstable_id)) if let Some(hir_id) = source_hir_id => {
let stable_id = self.create_stable_id(unstable_id, hir_id, attr_index);
Level::Expect(stable_id)
}
Some(lvl) => lvl,
};
let Some(mut metas) = attr.meta_item_list() else {
continue
};
if metas.is_empty() {
// This emits the unused_attributes lint for `#[level()]`
continue;
}
// Before processing the lint names, look for a reason (RFC 2383)
// at the end.
let mut reason = None;
let tail_li = &metas[metas.len() - 1];
if let Some(item) = tail_li.meta_item() {
match item.kind {
ast::MetaItemKind::Word => {} // actual lint names handled later
ast::MetaItemKind::NameValue(ref name_value) => {
if item.path == sym::reason {
if let ast::LitKind::Str(rationale, _) = name_value.kind {
if !self.sess.features_untracked().lint_reasons {
feature_err(
&self.sess.parse_sess,
sym::lint_reasons,
item.span,
"lint reasons are experimental",
)
.emit();
}
reason = Some(rationale);
} else {
bad_attr(name_value.span)
.span_label(name_value.span, "reason must be a string literal")
.emit();
}
// found reason, reslice meta list to exclude it
metas.pop().unwrap();
} else {
bad_attr(item.span)
.span_label(item.span, "bad attribute argument")
.emit();
}
}
ast::MetaItemKind::List(_) => {
bad_attr(item.span).span_label(item.span, "bad attribute argument").emit();
}
}
}
for (lint_index, li) in metas.iter_mut().enumerate() {
let level = match level {
Level::Expect(mut id) => {
id.set_lint_index(Some(lint_index as u16));
Level::Expect(id)
}
level => level,
};
let sp = li.span();
let meta_item = match li {
ast::NestedMetaItem::MetaItem(meta_item) if meta_item.is_word() => meta_item,
_ => {
let mut err = bad_attr(sp);
let mut add_label = true;
if let Some(item) = li.meta_item() {
if let ast::MetaItemKind::NameValue(_) = item.kind {
if item.path == sym::reason {
err.span_label(sp, "reason in lint attribute must come last");
add_label = false;
}
}
}
if add_label {
err.span_label(sp, "bad attribute argument");
}
err.emit();
continue;
}
};
let tool_ident = if meta_item.path.segments.len() > 1 {
Some(meta_item.path.segments.remove(0).ident)
} else {
None
};
let tool_name = tool_ident.map(|ident| ident.name);
let name = pprust::path_to_string(&meta_item.path);
let lint_result =
self.store.check_lint_name(&name, tool_name, self.registered_tools);
match &lint_result {
CheckLintNameResult::Ok(ids) => {
// This checks for instances where the user writes `#[expect(unfulfilled_lint_expectations)]`
// in that case we want to avoid overriding the lint level but instead add an expectation that
// can't be fulfilled. The lint message will include an explanation, that the
// `unfulfilled_lint_expectations` lint can't be expected.
if let Level::Expect(expect_id) = level {
// The `unfulfilled_lint_expectations` lint is not part of any lint groups. Therefore. we
// only need to check the slice if it contains a single lint.
let is_unfulfilled_lint_expectations = match ids {
[lint] => *lint == LintId::of(UNFULFILLED_LINT_EXPECTATIONS),
_ => false,
};
self.lint_expectations.push((
expect_id,
LintExpectation::new(
reason,
sp,
is_unfulfilled_lint_expectations,
tool_name,
),
));
}
let src = LintLevelSource::Node(
meta_item.path.segments.last().expect("empty lint name").ident.name,
sp,
reason,
);
for &id in *ids {
if self.check_gated_lint(id, attr.span) {
self.insert_spec(id, (level, src));
}
}
}
CheckLintNameResult::Tool(result) => {
match *result {
Ok(ids) => {
let complete_name =
&format!("{}::{}", tool_ident.unwrap().name, name);
let src = LintLevelSource::Node(
Symbol::intern(complete_name),
sp,
reason,
);
for id in ids {
self.insert_spec(*id, (level, src));
}
if let Level::Expect(expect_id) = level {
self.lint_expectations.push((
expect_id,
LintExpectation::new(reason, sp, false, tool_name),
));
}
}
Err((Some(ids), ref new_lint_name)) => {
let lint = builtin::RENAMED_AND_REMOVED_LINTS;
let (lvl, src) = self.sets.get_lint_level(
lint,
self.cur,
Some(self.current_specs()),
&sess,
);
struct_lint_level(
self.sess,
lint,
lvl,
src,
Some(sp.into()),
|lint| {
let msg = format!(
"lint name `{}` is deprecated \
and may not have an effect in the future.",
name
);
lint.build(&msg)
.span_suggestion(
sp,
"change it to",
new_lint_name.to_string(),
Applicability::MachineApplicable,
)
.emit();
},
);
let src = LintLevelSource::Node(
Symbol::intern(&new_lint_name),
sp,
reason,
);
for id in ids {
self.insert_spec(*id, (level, src));
}
if let Level::Expect(expect_id) = level {
self.lint_expectations.push((
expect_id,
LintExpectation::new(reason, sp, false, tool_name),
));
}
}
Err((None, _)) => {
// If Tool(Err(None, _)) is returned, 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`. To detect
// this is the responsibility of the lint tool.
}
}
}
&CheckLintNameResult::NoTool => {
let mut err = struct_span_err!(
sess,
tool_ident.map_or(DUMMY_SP, |ident| ident.span),
E0710,
"unknown tool name `{}` found in scoped lint: `{}::{}`",
tool_name.unwrap(),
tool_name.unwrap(),
pprust::path_to_string(&meta_item.path),
);
if sess.is_nightly_build() {
err.help(&format!(
"add `#![register_tool({})]` to the crate root",
tool_name.unwrap()
));
}
err.emit();
continue;
}
_ if !self.warn_about_weird_lints => {}
CheckLintNameResult::Warning(msg, renamed) => {
let lint = builtin::RENAMED_AND_REMOVED_LINTS;
let (renamed_lint_level, src) = self.sets.get_lint_level(
lint,
self.cur,
Some(self.current_specs()),
&sess,
);
struct_lint_level(
self.sess,
lint,
renamed_lint_level,
src,
Some(sp.into()),
|lint| {
let mut err = lint.build(&msg);
if let Some(new_name) = &renamed {
err.span_suggestion(
sp,
"use the new name",
new_name.to_string(),
Applicability::MachineApplicable,
);
}
err.emit();
},
);
}
CheckLintNameResult::NoLint(suggestion) => {
let lint = builtin::UNKNOWN_LINTS;
let (level, src) = self.sets.get_lint_level(
lint,
self.cur,
Some(self.current_specs()),
self.sess,
);
struct_lint_level(self.sess, lint, level, src, Some(sp.into()), |lint| {
let name = if let Some(tool_ident) = tool_ident {
format!("{}::{}", tool_ident.name, name)
} else {
name.to_string()
};
let mut db = lint.build(&format!("unknown lint: `{}`", name));
if let Some(suggestion) = suggestion {
db.span_suggestion(
sp,
"did you mean",
suggestion.to_string(),
Applicability::MachineApplicable,
);
}
db.emit();
});
}
}
// If this lint was renamed, apply the new lint instead of ignoring the attribute.
// This happens outside of the match because the new lint should be applied even if
// we don't warn about the name change.
if let CheckLintNameResult::Warning(_, Some(new_name)) = lint_result {
// Ignore any errors or warnings that happen because the new name is inaccurate
// NOTE: `new_name` already includes the tool name, so we don't have to add it again.
if let CheckLintNameResult::Ok(ids) =
self.store.check_lint_name(&new_name, None, self.registered_tools)
{
let src = LintLevelSource::Node(Symbol::intern(&new_name), sp, reason);
for &id in ids {
if self.check_gated_lint(id, attr.span) {
self.insert_spec(id, (level, src));
}
}
if let Level::Expect(expect_id) = level {
self.lint_expectations.push((
expect_id,
LintExpectation::new(reason, sp, false, tool_name),
));
}
} else {
panic!("renamed lint does not exist: {}", new_name);
}
}
}
}
if !is_crate_node {
for (id, &(level, ref src)) in self.current_specs().iter() {
if !id.lint.crate_level_only {
continue;
}
let LintLevelSource::Node(lint_attr_name, lint_attr_span, _) = *src else {
continue
};
let lint = builtin::UNUSED_ATTRIBUTES;
let (lint_level, lint_src) =
self.sets.get_lint_level(lint, self.cur, Some(self.current_specs()), self.sess);
struct_lint_level(
self.sess,
lint,
lint_level,
lint_src,
Some(lint_attr_span.into()),
|lint| {
let mut db = lint.build(&format!(
"{}({}) is ignored unless specified at crate level",
level.as_str(),
lint_attr_name
));
db.emit();
},
);
// don't set a separate error for every lint in the group
break;
}
}
if self.current_specs().is_empty() {
self.sets.list.pop();
self.cur = prev;
}
BuilderPush { prev, changed: prev != self.cur }
}
fn create_stable_id(
&mut self,
unstable_id: LintExpectationId,
hir_id: HirId,
attr_index: usize,
) -> LintExpectationId {
let stable_id =
LintExpectationId::Stable { hir_id, attr_index: attr_index as u16, lint_index: None };
self.expectation_id_map.insert(unstable_id, stable_id);
stable_id
}
/// Checks if the lint is gated on a feature that is not enabled.
///
/// Returns `true` if the lint's feature is enabled.
fn check_gated_lint(&self, lint_id: LintId, span: Span) -> bool {
if let Some(feature) = lint_id.lint.feature_gate {
if !self.sess.features_untracked().enabled(feature) {
let lint = builtin::UNKNOWN_LINTS;
let (level, src) = self.lint_level(builtin::UNKNOWN_LINTS);
struct_lint_level(self.sess, lint, level, src, Some(span.into()), |lint_db| {
let mut db =
lint_db.build(&format!("unknown lint: `{}`", lint_id.lint.name_lower()));
db.note(&format!("the `{}` lint is unstable", lint_id.lint.name_lower(),));
add_feature_diagnostics(&mut db, &self.sess.parse_sess, feature);
db.emit();
});
return false;
}
}
true
}
/// Called after `push` when the scope of a set of attributes are exited.
pub fn pop(&mut self, push: BuilderPush) {
self.cur = push.prev;
}
/// Find the lint level for a lint.
pub fn lint_level(&self, lint: &'static Lint) -> (Level, LintLevelSource) {
self.sets.get_lint_level(lint, self.cur, None, self.sess)
}
/// Used to emit a lint-related diagnostic based on the current state of
/// this lint context.
pub fn struct_lint(
&self,
lint: &'static Lint,
span: Option<MultiSpan>,
decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
) {
let (level, src) = self.lint_level(lint);
struct_lint_level(self.sess, lint, level, src, span, decorate)
}
/// Registers the ID provided with the current set of lints stored in
/// this context.
pub fn register_id(&mut self, id: HirId) {
self.id_to_set.insert(id, self.cur);
}
fn update_unstable_expectation_ids(&self) {
self.sess.diagnostic().update_unstable_expectation_id(&self.expectation_id_map);
}
pub fn build_map(self) -> LintLevelMap {
LintLevelMap {
sets: self.sets,
id_to_set: self.id_to_set,
lint_expectations: self.lint_expectations,
}
}
}
struct LintLevelMapBuilder<'tcx> {
levels: LintLevelsBuilder<'tcx>,
tcx: TyCtxt<'tcx>,
}
impl LintLevelMapBuilder<'_> {
fn with_lint_attrs<F>(&mut self, id: hir::HirId, f: F)
where
F: FnOnce(&mut Self),
{
let is_crate_hir = id == hir::CRATE_HIR_ID;
let attrs = self.tcx.hir().attrs(id);
let push = self.levels.push(attrs, is_crate_hir, Some(id));
if push.changed {
self.levels.register_id(id);
}
f(self);
self.levels.pop(push);
}
}
impl<'tcx> intravisit::Visitor<'tcx> for LintLevelMapBuilder<'tcx> {
type NestedFilter = nested_filter::All;
fn nested_visit_map(&mut self) -> Self::Map {
self.tcx.hir()
}
fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
self.with_lint_attrs(param.hir_id, |builder| {
intravisit::walk_param(builder, param);
});
}
fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) {
self.with_lint_attrs(it.hir_id(), |builder| {
intravisit::walk_item(builder, it);
});
}
fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) {
self.with_lint_attrs(it.hir_id(), |builder| {
intravisit::walk_foreign_item(builder, it);
})
}
fn visit_stmt(&mut self, e: &'tcx hir::Stmt<'tcx>) {
// We will call `with_lint_attrs` when we walk
// the `StmtKind`. The outer statement itself doesn't
// define the lint levels.
intravisit::walk_stmt(self, e);
}
fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
self.with_lint_attrs(e.hir_id, |builder| {
intravisit::walk_expr(builder, e);
})
}
fn visit_field_def(&mut self, s: &'tcx hir::FieldDef<'tcx>) {
self.with_lint_attrs(s.hir_id, |builder| {
intravisit::walk_field_def(builder, s);
})
}
fn visit_variant(
&mut self,
v: &'tcx hir::Variant<'tcx>,
g: &'tcx hir::Generics<'tcx>,
item_id: hir::HirId,
) {
self.with_lint_attrs(v.id, |builder| {
intravisit::walk_variant(builder, v, g, item_id);
})
}
fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
self.with_lint_attrs(l.hir_id, |builder| {
intravisit::walk_local(builder, l);
})
}
fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) {
self.with_lint_attrs(a.hir_id, |builder| {
intravisit::walk_arm(builder, a);
})
}
fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
self.with_lint_attrs(trait_item.hir_id(), |builder| {
intravisit::walk_trait_item(builder, trait_item);
});
}
fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
self.with_lint_attrs(impl_item.hir_id(), |builder| {
intravisit::walk_impl_item(builder, impl_item);
});
}
}
pub fn provide(providers: &mut Providers) {
providers.lint_levels = lint_levels;
}