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//! Lints, aka compiler warnings.
//!
//! A 'lint' check is a kind of miscellaneous constraint that a user _might_
//! want to enforce, but might reasonably want to permit as well, on a
//! module-by-module basis. They contrast with static constraints enforced by
//! other phases of the compiler, which are generally required to hold in order
//! to compile the program at all.
//!
//! Most lints can be written as `LintPass` instances. These run after
//! all other analyses. The `LintPass`es built into rustc are defined
//! within `builtin.rs`, which has further comments on how to add such a lint.
//! rustc can also load user-defined lint plugins via the plugin mechanism.
//!
//! Some of rustc's lints are defined elsewhere in the compiler and work by
//! calling `add_lint()` on the overall `Session` object. This works when
//! it happens before the main lint pass, which emits the lints stored by
//! `add_lint()`. To emit lints after the main lint pass (from codegen, for
//! example) requires more effort. See `emit_lint` and `GatherNodeLevels`
//! in `context.rs`.
pub use self::Level::*;
pub use self::LintSource::*;
use rustc_data_structures::sync;
use crate::hir::def_id::{CrateNum, LOCAL_CRATE};
use crate::hir::intravisit;
use crate::hir;
use crate::lint::builtin::BuiltinLintDiagnostics;
use crate::lint::builtin::parser::{ILL_FORMED_ATTRIBUTE_INPUT, META_VARIABLE_MISUSE};
use crate::session::{Session, DiagnosticMessageId};
use crate::ty::TyCtxt;
use crate::ty::query::Providers;
use crate::util::nodemap::NodeMap;
use errors::{DiagnosticBuilder, DiagnosticId};
use std::{hash, ptr};
use syntax::ast;
use syntax::source_map::{MultiSpan, ExpnKind, DesugaringKind};
use syntax::early_buffered_lints::BufferedEarlyLintId;
use syntax::edition::Edition;
use syntax::ext::base::MacroKind;
use syntax::symbol::{Symbol, sym};
use syntax_pos::Span;
pub use crate::lint::context::{LateContext, EarlyContext, LintContext, LintStore,
check_crate, check_ast_crate, late_lint_mod, CheckLintNameResult,
FutureIncompatibleInfo, BufferedEarlyLint,};
/// Specification of a single lint.
#[derive(Copy, Clone, Debug)]
pub struct Lint {
/// A string identifier for the lint.
///
/// This identifies the lint in attributes and in command-line arguments.
/// In those contexts it is always lowercase, but this field is compared
/// in a way which is case-insensitive for ASCII characters. This allows
/// `declare_lint!()` invocations to follow the convention of upper-case
/// statics without repeating the name.
///
/// The name is written with underscores, e.g., "unused_imports".
/// On the command line, underscores become dashes.
pub name: &'static str,
/// Default level for the lint.
pub default_level: Level,
/// Description of the lint or the issue it detects.
///
/// e.g., "imports that are never used"
pub desc: &'static str,
/// Starting at the given edition, default to the given lint level. If this is `None`, then use
/// `default_level`.
pub edition_lint_opts: Option<(Edition, Level)>,
/// `true` if this lint is reported even inside expansions of external macros.
pub report_in_external_macro: bool,
}
impl Lint {
/// Returns the `rust::lint::Lint` for a `syntax::early_buffered_lints::BufferedEarlyLintId`.
pub fn from_parser_lint_id(lint_id: BufferedEarlyLintId) -> &'static Self {
match lint_id {
BufferedEarlyLintId::IllFormedAttributeInput => ILL_FORMED_ATTRIBUTE_INPUT,
BufferedEarlyLintId::MetaVariableMisuse => META_VARIABLE_MISUSE,
}
}
/// Gets the lint's name, with ASCII letters converted to lowercase.
pub fn name_lower(&self) -> String {
self.name.to_ascii_lowercase()
}
pub fn default_level(&self, session: &Session) -> Level {
self.edition_lint_opts
.filter(|(e, _)| *e <= session.edition())
.map(|(_, l)| l)
.unwrap_or(self.default_level)
}
}
/// Declares a static item of type `&'static Lint`.
#[macro_export]
macro_rules! declare_lint {
($vis: vis $NAME: ident, $Level: ident, $desc: expr) => (
declare_lint!{$vis $NAME, $Level, $desc, false}
);
($vis: vis $NAME: ident, $Level: ident, $desc: expr, report_in_external_macro: $rep: expr) => (
declare_lint!{$vis $NAME, $Level, $desc, $rep}
);
($vis: vis $NAME: ident, $Level: ident, $desc: expr, $external: expr) => (
$vis static $NAME: &$crate::lint::Lint = &$crate::lint::Lint {
name: stringify!($NAME),
default_level: $crate::lint::$Level,
desc: $desc,
edition_lint_opts: None,
report_in_external_macro: $external,
};
);
($vis: vis $NAME: ident, $Level: ident, $desc: expr,
$lint_edition: expr => $edition_level: ident
) => (
$vis static $NAME: &$crate::lint::Lint = &$crate::lint::Lint {
name: stringify!($NAME),
default_level: $crate::lint::$Level,
desc: $desc,
edition_lint_opts: Some(($lint_edition, $crate::lint::Level::$edition_level)),
report_in_external_macro: false,
};
);
}
#[macro_export]
macro_rules! declare_tool_lint {
(
$(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level: ident, $desc: expr
) => (
declare_tool_lint!{$(#[$attr])* $vis $tool::$NAME, $Level, $desc, false}
);
(
$(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level:ident, $desc:expr,
report_in_external_macro: $rep:expr
) => (
declare_tool_lint!{$(#[$attr])* $vis $tool::$NAME, $Level, $desc, $rep}
);
(
$(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level:ident, $desc:expr,
$external:expr
) => (
$(#[$attr])*
$vis static $NAME: &$crate::lint::Lint = &$crate::lint::Lint {
name: &concat!(stringify!($tool), "::", stringify!($NAME)),
default_level: $crate::lint::$Level,
desc: $desc,
edition_lint_opts: None,
report_in_external_macro: $external,
};
);
}
/// Declares a static `LintArray` and return it as an expression.
#[macro_export]
macro_rules! lint_array {
($( $lint:expr ),* ,) => { lint_array!( $($lint),* ) };
($( $lint:expr ),*) => {{
vec![$($lint),*]
}}
}
pub type LintArray = Vec<&'static Lint>;
pub trait LintPass {
fn name(&self) -> &'static str;
/// Gets descriptions of the lints this `LintPass` object can emit.
///
/// N.B., there is no enforcement that the object only emits lints it registered.
/// And some `rustc` internal `LintPass`es register lints to be emitted by other
/// parts of the compiler. If you want enforced access restrictions for your
/// `Lint`, make it a private `static` item in its own module.
fn get_lints(&self) -> LintArray;
}
/// Implements `LintPass for $name` with the given list of `Lint` statics.
#[macro_export]
macro_rules! impl_lint_pass {
($name:ident => [$($lint:expr),* $(,)?]) => {
impl LintPass for $name {
fn name(&self) -> &'static str { stringify!($name) }
fn get_lints(&self) -> LintArray { $crate::lint_array!($($lint),*) }
}
};
}
/// Declares a type named `$name` which implements `LintPass`.
/// To the right of `=>` a comma separated list of `Lint` statics is given.
#[macro_export]
macro_rules! declare_lint_pass {
($(#[$m:meta])* $name:ident => [$($lint:expr),* $(,)?]) => {
$(#[$m])* #[derive(Copy, Clone)] pub struct $name;
$crate::impl_lint_pass!($name => [$($lint),*]);
};
}
#[macro_export]
macro_rules! late_lint_methods {
($macro:path, $args:tt, [$hir:tt]) => (
$macro!($args, [$hir], [
fn check_body(a: &$hir hir::Body);
fn check_body_post(a: &$hir hir::Body);
fn check_name(a: Span, b: ast::Name);
fn check_crate(a: &$hir hir::Crate);
fn check_crate_post(a: &$hir hir::Crate);
fn check_mod(a: &$hir hir::Mod, b: Span, c: hir::HirId);
fn check_mod_post(a: &$hir hir::Mod, b: Span, c: hir::HirId);
fn check_foreign_item(a: &$hir hir::ForeignItem);
fn check_foreign_item_post(a: &$hir hir::ForeignItem);
fn check_item(a: &$hir hir::Item);
fn check_item_post(a: &$hir hir::Item);
fn check_local(a: &$hir hir::Local);
fn check_block(a: &$hir hir::Block);
fn check_block_post(a: &$hir hir::Block);
fn check_stmt(a: &$hir hir::Stmt);
fn check_arm(a: &$hir hir::Arm);
fn check_pat(a: &$hir hir::Pat);
fn check_expr(a: &$hir hir::Expr);
fn check_expr_post(a: &$hir hir::Expr);
fn check_ty(a: &$hir hir::Ty);
fn check_generic_param(a: &$hir hir::GenericParam);
fn check_generics(a: &$hir hir::Generics);
fn check_where_predicate(a: &$hir hir::WherePredicate);
fn check_poly_trait_ref(a: &$hir hir::PolyTraitRef, b: hir::TraitBoundModifier);
fn check_fn(
a: hir::intravisit::FnKind<$hir>,
b: &$hir hir::FnDecl,
c: &$hir hir::Body,
d: Span,
e: hir::HirId);
fn check_fn_post(
a: hir::intravisit::FnKind<$hir>,
b: &$hir hir::FnDecl,
c: &$hir hir::Body,
d: Span,
e: hir::HirId
);
fn check_trait_item(a: &$hir hir::TraitItem);
fn check_trait_item_post(a: &$hir hir::TraitItem);
fn check_impl_item(a: &$hir hir::ImplItem);
fn check_impl_item_post(a: &$hir hir::ImplItem);
fn check_struct_def(
a: &$hir hir::VariantData,
b: ast::Name,
c: &$hir hir::Generics,
d: hir::HirId
);
fn check_struct_def_post(
a: &$hir hir::VariantData,
b: ast::Name,
c: &$hir hir::Generics,
d: hir::HirId
);
fn check_struct_field(a: &$hir hir::StructField);
fn check_variant(a: &$hir hir::Variant, b: &$hir hir::Generics);
fn check_variant_post(a: &$hir hir::Variant, b: &$hir hir::Generics);
fn check_lifetime(a: &$hir hir::Lifetime);
fn check_path(a: &$hir hir::Path, b: hir::HirId);
fn check_attribute(a: &$hir ast::Attribute);
/// Called when entering a syntax node that can have lint attributes such
/// as `#[allow(...)]`. Called with *all* the attributes of that node.
fn enter_lint_attrs(a: &$hir [ast::Attribute]);
/// Counterpart to `enter_lint_attrs`.
fn exit_lint_attrs(a: &$hir [ast::Attribute]);
]);
)
}
/// Trait for types providing lint checks.
///
/// Each `check` method checks a single syntax node, and should not
/// invoke methods recursively (unlike `Visitor`). By default they
/// do nothing.
//
// FIXME: eliminate the duplication with `Visitor`. But this also
// contains a few lint-specific methods with no equivalent in `Visitor`.
macro_rules! expand_lint_pass_methods {
($context:ty, [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
$(#[inline(always)] fn $name(&mut self, _: $context, $(_: $arg),*) {})*
)
}
macro_rules! declare_late_lint_pass {
([], [$hir:tt], [$($methods:tt)*]) => (
pub trait LateLintPass<'a, $hir>: LintPass {
fn fresh_late_pass(&self) -> LateLintPassObject {
panic!()
}
expand_lint_pass_methods!(&LateContext<'a, $hir>, [$($methods)*]);
}
)
}
late_lint_methods!(declare_late_lint_pass, [], ['tcx]);
#[macro_export]
macro_rules! expand_combined_late_lint_pass_method {
([$($passes:ident),*], $self: ident, $name: ident, $params:tt) => ({
$($self.$passes.$name $params;)*
})
}
#[macro_export]
macro_rules! expand_combined_late_lint_pass_methods {
($passes:tt, [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
$(fn $name(&mut self, context: &LateContext<'a, 'tcx>, $($param: $arg),*) {
expand_combined_late_lint_pass_method!($passes, self, $name, (context, $($param),*));
})*
)
}
#[macro_export]
macro_rules! declare_combined_late_lint_pass {
([$v:vis $name:ident, [$($passes:ident: $constructor:expr,)*]], [$hir:tt], $methods:tt) => (
#[allow(non_snake_case)]
$v struct $name {
$($passes: $passes,)*
}
impl $name {
$v fn new() -> Self {
Self {
$($passes: $constructor,)*
}
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for $name {
expand_combined_late_lint_pass_methods!([$($passes),*], $methods);
}
impl LintPass for $name {
fn name(&self) -> &'static str {
panic!()
}
fn get_lints(&self) -> LintArray {
let mut lints = Vec::new();
$(lints.extend_from_slice(&self.$passes.get_lints());)*
lints
}
}
)
}
#[macro_export]
macro_rules! early_lint_methods {
($macro:path, $args:tt) => (
$macro!($args, [
fn check_ident(a: ast::Ident);
fn check_crate(a: &ast::Crate);
fn check_crate_post(a: &ast::Crate);
fn check_mod(a: &ast::Mod, b: Span, c: ast::NodeId);
fn check_mod_post(a: &ast::Mod, b: Span, c: ast::NodeId);
fn check_foreign_item(a: &ast::ForeignItem);
fn check_foreign_item_post(a: &ast::ForeignItem);
fn check_item(a: &ast::Item);
fn check_item_post(a: &ast::Item);
fn check_local(a: &ast::Local);
fn check_block(a: &ast::Block);
fn check_block_post(a: &ast::Block);
fn check_stmt(a: &ast::Stmt);
fn check_arm(a: &ast::Arm);
fn check_pat(a: &ast::Pat);
fn check_pat_post(a: &ast::Pat);
fn check_expr(a: &ast::Expr);
fn check_expr_post(a: &ast::Expr);
fn check_ty(a: &ast::Ty);
fn check_generic_param(a: &ast::GenericParam);
fn check_generics(a: &ast::Generics);
fn check_where_predicate(a: &ast::WherePredicate);
fn check_poly_trait_ref(a: &ast::PolyTraitRef,
b: &ast::TraitBoundModifier);
fn check_fn(a: syntax::visit::FnKind<'_>, b: &ast::FnDecl, c: Span, d_: ast::NodeId);
fn check_fn_post(
a: syntax::visit::FnKind<'_>,
b: &ast::FnDecl,
c: Span,
d: ast::NodeId
);
fn check_trait_item(a: &ast::TraitItem);
fn check_trait_item_post(a: &ast::TraitItem);
fn check_impl_item(a: &ast::ImplItem);
fn check_impl_item_post(a: &ast::ImplItem);
fn check_struct_def(
a: &ast::VariantData,
b: ast::Ident,
c: &ast::Generics,
d: ast::NodeId
);
fn check_struct_def_post(
a: &ast::VariantData,
b: ast::Ident,
c: &ast::Generics,
d: ast::NodeId
);
fn check_struct_field(a: &ast::StructField);
fn check_variant(a: &ast::Variant, b: &ast::Generics);
fn check_variant_post(a: &ast::Variant, b: &ast::Generics);
fn check_lifetime(a: &ast::Lifetime);
fn check_path(a: &ast::Path, b: ast::NodeId);
fn check_attribute(a: &ast::Attribute);
fn check_mac_def(a: &ast::MacroDef, b: ast::NodeId);
fn check_mac(a: &ast::Mac);
/// Called when entering a syntax node that can have lint attributes such
/// as `#[allow(...)]`. Called with *all* the attributes of that node.
fn enter_lint_attrs(a: &[ast::Attribute]);
/// Counterpart to `enter_lint_attrs`.
fn exit_lint_attrs(a: &[ast::Attribute]);
]);
)
}
macro_rules! expand_early_lint_pass_methods {
($context:ty, [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
$(#[inline(always)] fn $name(&mut self, _: $context, $(_: $arg),*) {})*
)
}
macro_rules! declare_early_lint_pass {
([], [$($methods:tt)*]) => (
pub trait EarlyLintPass: LintPass {
expand_early_lint_pass_methods!(&EarlyContext<'_>, [$($methods)*]);
}
)
}
early_lint_methods!(declare_early_lint_pass, []);
#[macro_export]
macro_rules! expand_combined_early_lint_pass_method {
([$($passes:ident),*], $self: ident, $name: ident, $params:tt) => ({
$($self.$passes.$name $params;)*
})
}
#[macro_export]
macro_rules! expand_combined_early_lint_pass_methods {
($passes:tt, [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
$(fn $name(&mut self, context: &EarlyContext<'_>, $($param: $arg),*) {
expand_combined_early_lint_pass_method!($passes, self, $name, (context, $($param),*));
})*
)
}
#[macro_export]
macro_rules! declare_combined_early_lint_pass {
([$v:vis $name:ident, [$($passes:ident: $constructor:expr,)*]], $methods:tt) => (
#[allow(non_snake_case)]
$v struct $name {
$($passes: $passes,)*
}
impl $name {
$v fn new() -> Self {
Self {
$($passes: $constructor,)*
}
}
}
impl EarlyLintPass for $name {
expand_combined_early_lint_pass_methods!([$($passes),*], $methods);
}
impl LintPass for $name {
fn name(&self) -> &'static str {
panic!()
}
fn get_lints(&self) -> LintArray {
let mut lints = Vec::new();
$(lints.extend_from_slice(&self.$passes.get_lints());)*
lints
}
}
)
}
/// A lint pass boxed up as a trait object.
pub type EarlyLintPassObject = Box<dyn EarlyLintPass + sync::Send + sync::Sync + 'static>;
pub type LateLintPassObject = Box<dyn for<'a, 'tcx> LateLintPass<'a, 'tcx> + sync::Send
+ sync::Sync + 'static>;
/// Identifies a lint known to the compiler.
#[derive(Clone, Copy, Debug)]
pub struct LintId {
// Identity is based on pointer equality of this field.
lint: &'static Lint,
}
impl PartialEq for LintId {
fn eq(&self, other: &LintId) -> bool {
ptr::eq(self.lint, other.lint)
}
}
impl Eq for LintId { }
impl hash::Hash for LintId {
fn hash<H: hash::Hasher>(&self, state: &mut H) {
let ptr = self.lint as *const Lint;
ptr.hash(state);
}
}
impl LintId {
/// Gets the `LintId` for a `Lint`.
pub fn of(lint: &'static Lint) -> LintId {
LintId {
lint,
}
}
pub fn lint_name_raw(&self) -> &'static str {
self.lint.name
}
/// Gets the name of the lint.
pub fn to_string(&self) -> String {
self.lint.name_lower()
}
}
/// Setting for how to handle a lint.
#[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
pub enum Level {
Allow, Warn, Deny, Forbid,
}
impl_stable_hash_for!(enum self::Level {
Allow,
Warn,
Deny,
Forbid
});
impl Level {
/// Converts a level to a lower-case string.
pub fn as_str(self) -> &'static str {
match self {
Allow => "allow",
Warn => "warn",
Deny => "deny",
Forbid => "forbid",
}
}
/// Converts a lower-case string to a level.
pub fn from_str(x: &str) -> Option<Level> {
match x {
"allow" => Some(Allow),
"warn" => Some(Warn),
"deny" => Some(Deny),
"forbid" => Some(Forbid),
_ => None,
}
}
/// Converts a symbol to a level.
pub fn from_symbol(x: Symbol) -> Option<Level> {
match x {
sym::allow => Some(Allow),
sym::warn => Some(Warn),
sym::deny => Some(Deny),
sym::forbid => Some(Forbid),
_ => None,
}
}
}
/// How a lint level was set.
#[derive(Clone, Copy, PartialEq, Eq)]
pub enum LintSource {
/// Lint is at the default level as declared
/// in rustc or a plugin.
Default,
/// Lint level was set by an attribute.
Node(ast::Name, Span, Option<Symbol> /* RFC 2383 reason */),
/// Lint level was set by a command-line flag.
CommandLine(Symbol),
}
impl_stable_hash_for!(enum self::LintSource {
Default,
Node(name, span, reason),
CommandLine(text)
});
pub type LevelSource = (Level, LintSource);
pub mod builtin;
pub mod internal;
mod context;
mod levels;
pub use self::levels::{LintLevelSets, LintLevelMap};
#[derive(Default)]
pub struct LintBuffer {
map: NodeMap<Vec<BufferedEarlyLint>>,
}
impl LintBuffer {
pub fn add_lint(&mut self,
lint: &'static Lint,
id: ast::NodeId,
sp: MultiSpan,
msg: &str,
diagnostic: BuiltinLintDiagnostics) {
let early_lint = BufferedEarlyLint {
lint_id: LintId::of(lint),
ast_id: id,
span: sp,
msg: msg.to_string(),
diagnostic
};
let arr = self.map.entry(id).or_default();
if !arr.contains(&early_lint) {
arr.push(early_lint);
}
}
pub fn take(&mut self, id: ast::NodeId) -> Vec<BufferedEarlyLint> {
self.map.remove(&id).unwrap_or_default()
}
pub fn get_any(&self) -> Option<&[BufferedEarlyLint]> {
let key = self.map.keys().next().map(|k| *k);
key.map(|k| &self.map[&k][..])
}
}
pub fn struct_lint_level<'a>(sess: &'a Session,
lint: &'static Lint,
level: Level,
src: LintSource,
span: Option<MultiSpan>,
msg: &str)
-> DiagnosticBuilder<'a>
{
let mut err = match (level, span) {
(Level::Allow, _) => return sess.diagnostic().struct_dummy(),
(Level::Warn, Some(span)) => sess.struct_span_warn(span, msg),
(Level::Warn, None) => sess.struct_warn(msg),
(Level::Deny, Some(span)) |
(Level::Forbid, Some(span)) => sess.struct_span_err(span, msg),
(Level::Deny, None) |
(Level::Forbid, None) => sess.struct_err(msg),
};
let name = lint.name_lower();
match src {
LintSource::Default => {
sess.diag_note_once(
&mut err,
DiagnosticMessageId::from(lint),
&format!("`#[{}({})]` on by default", level.as_str(), name));
}
LintSource::CommandLine(lint_flag_val) => {
let flag = match level {
Level::Warn => "-W",
Level::Deny => "-D",
Level::Forbid => "-F",
Level::Allow => panic!(),
};
let hyphen_case_lint_name = name.replace("_", "-");
if lint_flag_val.as_str() == name {
sess.diag_note_once(
&mut err,
DiagnosticMessageId::from(lint),
&format!("requested on the command line with `{} {}`",
flag, hyphen_case_lint_name));
} else {
let hyphen_case_flag_val = lint_flag_val.as_str().replace("_", "-");
sess.diag_note_once(
&mut err,
DiagnosticMessageId::from(lint),
&format!("`{} {}` implied by `{} {}`",
flag, hyphen_case_lint_name, flag,
hyphen_case_flag_val));
}
}
LintSource::Node(lint_attr_name, src, reason) => {
if let Some(rationale) = reason {
err.note(&rationale.as_str());
}
sess.diag_span_note_once(&mut err, DiagnosticMessageId::from(lint),
src, "lint level defined here");
if lint_attr_name.as_str() != name {
let level_str = level.as_str();
sess.diag_note_once(&mut err, DiagnosticMessageId::from(lint),
&format!("`#[{}({})]` implied by `#[{}({})]`",
level_str, name, level_str, lint_attr_name));
}
}
}
err.code(DiagnosticId::Lint(name));
// Check for future incompatibility lints and issue a stronger warning.
let lints = sess.lint_store.borrow();
let lint_id = LintId::of(lint);
let future_incompatible = lints.future_incompatible(lint_id);
if let Some(future_incompatible) = future_incompatible {
const STANDARD_MESSAGE: &str =
"this was previously accepted by the compiler but is being phased out; \
it will become a hard error";
let explanation = if lint_id == LintId::of(builtin::UNSTABLE_NAME_COLLISIONS) {
"once this method is added to the standard library, \
the ambiguity may cause an error or change in behavior!"
.to_owned()
} else if lint_id == LintId::of(builtin::MUTABLE_BORROW_RESERVATION_CONFLICT) {
"this borrowing pattern was not meant to be accepted, \
and may become a hard error in the future"
.to_owned()
} else if let Some(edition) = future_incompatible.edition {
format!("{} in the {} edition!", STANDARD_MESSAGE, edition)
} else {
format!("{} in a future release!", STANDARD_MESSAGE)
};
let citation = format!("for more information, see {}",
future_incompatible.reference);
err.warn(&explanation);
err.note(&citation);
}
// If this code originates in a foreign macro, aka something that this crate
// did not itself author, then it's likely that there's nothing this crate
// can do about it. We probably want to skip the lint entirely.
if err.span.primary_spans().iter().any(|s| in_external_macro(sess, *s)) {
// Any suggestions made here are likely to be incorrect, so anything we
// emit shouldn't be automatically fixed by rustfix.
err.allow_suggestions(false);
// If this is a future incompatible lint it'll become a hard error, so
// we have to emit *something*. Also allow lints to whitelist themselves
// on a case-by-case basis for emission in a foreign macro.
if future_incompatible.is_none() && !lint.report_in_external_macro {
err.cancel()
}
}
return err
}
pub fn maybe_lint_level_root(tcx: TyCtxt<'_>, id: hir::HirId) -> bool {
let attrs = tcx.hir().attrs(id);
attrs.iter().any(|attr| Level::from_symbol(attr.name_or_empty()).is_some())
}
fn lint_levels(tcx: TyCtxt<'_>, cnum: CrateNum) -> &LintLevelMap {
assert_eq!(cnum, LOCAL_CRATE);
let mut builder = LintLevelMapBuilder {
levels: LintLevelSets::builder(tcx.sess),
tcx: tcx,
};
let krate = tcx.hir().krate();
let push = builder.levels.push(&krate.attrs);
builder.levels.register_id(hir::CRATE_HIR_ID);
for macro_def in &krate.exported_macros {
builder.levels.register_id(macro_def.hir_id);
}
intravisit::walk_crate(&mut builder, krate);
builder.levels.pop(push);
tcx.arena.alloc(builder.levels.build_map())
}
struct LintLevelMapBuilder<'tcx> {
levels: levels::LintLevelsBuilder<'tcx>,
tcx: TyCtxt<'tcx>,
}
impl LintLevelMapBuilder<'tcx> {
fn with_lint_attrs<F>(&mut self,
id: hir::HirId,
attrs: &[ast::Attribute],
f: F)
where F: FnOnce(&mut Self)
{
let push = self.levels.push(attrs);
if push.changed {
self.levels.register_id(id);
}
f(self);
self.levels.pop(push);
}
}
impl intravisit::Visitor<'tcx> for LintLevelMapBuilder<'tcx> {
fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
intravisit::NestedVisitorMap::All(&self.tcx.hir())
}
fn visit_item(&mut self, it: &'tcx hir::Item) {
self.with_lint_attrs(it.hir_id, &it.attrs, |builder| {
intravisit::walk_item(builder, it);
});
}
fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem) {
self.with_lint_attrs(it.hir_id, &it.attrs, |builder| {
intravisit::walk_foreign_item(builder, it);
})
}
fn visit_expr(&mut self, e: &'tcx hir::Expr) {
self.with_lint_attrs(e.hir_id, &e.attrs, |builder| {
intravisit::walk_expr(builder, e);
})
}
fn visit_struct_field(&mut self, s: &'tcx hir::StructField) {
self.with_lint_attrs(s.hir_id, &s.attrs, |builder| {
intravisit::walk_struct_field(builder, s);
})
}
fn visit_variant(&mut self,
v: &'tcx hir::Variant,
g: &'tcx hir::Generics,
item_id: hir::HirId) {
self.with_lint_attrs(v.node.id, &v.node.attrs, |builder| {
intravisit::walk_variant(builder, v, g, item_id);
})
}
fn visit_local(&mut self, l: &'tcx hir::Local) {
self.with_lint_attrs(l.hir_id, &l.attrs, |builder| {
intravisit::walk_local(builder, l);
})
}
fn visit_arm(&mut self, a: &'tcx hir::Arm) {
self.with_lint_attrs(a.hir_id, &a.attrs, |builder| {
intravisit::walk_arm(builder, a);
})
}
fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem) {
self.with_lint_attrs(trait_item.hir_id, &trait_item.attrs, |builder| {
intravisit::walk_trait_item(builder, trait_item);
});
}
fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem) {
self.with_lint_attrs(impl_item.hir_id, &impl_item.attrs, |builder| {
intravisit::walk_impl_item(builder, impl_item);
});
}
}
pub fn provide(providers: &mut Providers<'_>) {
providers.lint_levels = lint_levels;
}
/// Returns whether `span` originates in a foreign crate's external macro.
///
/// This is used to test whether a lint should not even begin to figure out whether it should
/// be reported on the current node.
pub fn in_external_macro(sess: &Session, span: Span) -> bool {
let info = match span.ctxt().outer_expn_info() {
Some(info) => info,
// no ExpnInfo means this span doesn't come from a macro
None => return false,
};
match info.kind {
ExpnKind::Root | ExpnKind::Desugaring(DesugaringKind::ForLoop) => false,
ExpnKind::Desugaring(_) => true, // well, it's "external"
ExpnKind::Macro(MacroKind::Bang, _) => {
if info.def_site.is_dummy() {
// dummy span for the def_site means it's an external macro
return true;
}
match sess.source_map().span_to_snippet(info.def_site) {
Ok(code) => !code.starts_with("macro_rules"),
// no snippet = external macro or compiler-builtin expansion
Err(_) => true,
}
}
ExpnKind::Macro(..) => true, // definitely a plugin
}
}
/// Returns whether `span` originates in a derive macro's expansion
pub fn in_derive_expansion(span: Span) -> bool {
if let Some(info) = span.ctxt().outer_expn_info() {
if let ExpnKind::Macro(MacroKind::Derive, _) = info.kind {
return true;
}
}
false
}
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