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android / toolchain / rustc / 89a0a0cd9cbd0a0138a09bd877bbc73859a8c330 / . / src / tools / clippy / clippy_utils / src / lib.rs
blob: 3ebfc5e00e1426e8a63a83b3a09da3890655fd53 [file] [log] [blame]
#![feature(array_chunks)]
#![feature(box_patterns)]
#![feature(control_flow_enum)]
#![feature(let_chains)]
#![feature(lint_reasons)]
#![feature(never_type)]
#![feature(once_cell)]
#![feature(rustc_private)]
#![recursion_limit = "512"]
#![cfg_attr(feature = "deny-warnings", deny(warnings))]
#![allow(clippy::missing_errors_doc, clippy::missing_panics_doc, clippy::must_use_candidate)]
// warn on the same lints as `clippy_lints`
#![warn(trivial_casts, trivial_numeric_casts)]
// warn on lints, that are included in `rust-lang/rust`s bootstrap
#![warn(rust_2018_idioms, unused_lifetimes)]
// warn on rustc internal lints
#![warn(rustc::internal)]
// FIXME: switch to something more ergonomic here, once available.
// (Currently there is no way to opt into sysroot crates without `extern crate`.)
extern crate rustc_ast;
extern crate rustc_ast_pretty;
extern crate rustc_attr;
extern crate rustc_data_structures;
extern crate rustc_errors;
extern crate rustc_hir;
extern crate rustc_hir_typeck;
extern crate rustc_index;
extern crate rustc_infer;
extern crate rustc_lexer;
extern crate rustc_lint;
extern crate rustc_middle;
extern crate rustc_mir_dataflow;
extern crate rustc_parse_format;
extern crate rustc_session;
extern crate rustc_span;
extern crate rustc_target;
extern crate rustc_trait_selection;
#[macro_use]
pub mod sym_helper;
pub mod ast_utils;
pub mod attrs;
mod check_proc_macro;
pub mod comparisons;
pub mod consts;
pub mod diagnostics;
pub mod eager_or_lazy;
pub mod higher;
mod hir_utils;
pub mod macros;
pub mod mir;
pub mod msrvs;
pub mod numeric_literal;
pub mod paths;
pub mod ptr;
pub mod qualify_min_const_fn;
pub mod source;
pub mod str_utils;
pub mod sugg;
pub mod ty;
pub mod usage;
pub mod visitors;
pub use self::attrs::*;
pub use self::check_proc_macro::{is_from_proc_macro, is_span_if, is_span_match};
pub use self::hir_utils::{
both, count_eq, eq_expr_value, hash_expr, hash_stmt, over, HirEqInterExpr, SpanlessEq, SpanlessHash,
};
use core::ops::ControlFlow;
use std::collections::hash_map::Entry;
use std::hash::BuildHasherDefault;
use std::sync::OnceLock;
use std::sync::{Mutex, MutexGuard};
use if_chain::if_chain;
use rustc_ast::ast::{self, LitKind};
use rustc_ast::Attribute;
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::unhash::UnhashMap;
use rustc_hir as hir;
use rustc_hir::def::{DefKind, Namespace, Res};
use rustc_hir::def_id::{CrateNum, DefId, LocalDefId};
use rustc_hir::hir_id::{HirIdMap, HirIdSet};
use rustc_hir::intravisit::{walk_expr, FnKind, Visitor};
use rustc_hir::LangItem::{OptionNone, ResultErr, ResultOk};
use rustc_hir::{
def, Arm, ArrayLen, BindingAnnotation, Block, BlockCheckMode, Body, Closure, Constness, Destination, Expr,
ExprKind, FnDecl, HirId, Impl, ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local, MatchSource,
Mutability, Node, Param, Pat, PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind, TraitItem, TraitItemKind,
TraitRef, TyKind, UnOp,
};
use rustc_lexer::{tokenize, TokenKind};
use rustc_lint::{LateContext, Level, Lint, LintContext};
use rustc_middle::hir::place::PlaceBase;
use rustc_middle::ty as rustc_ty;
use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
use rustc_middle::ty::binding::BindingMode;
use rustc_middle::ty::fast_reject::SimplifiedTypeGen::{
ArraySimplifiedType, BoolSimplifiedType, CharSimplifiedType, FloatSimplifiedType, IntSimplifiedType,
PtrSimplifiedType, SliceSimplifiedType, StrSimplifiedType, UintSimplifiedType,
};
use rustc_middle::ty::{
layout::IntegerExt, BorrowKind, ClosureKind, DefIdTree, Ty, TyCtxt, TypeAndMut, TypeVisitable, UpvarCapture,
};
use rustc_middle::ty::{FloatTy, IntTy, UintTy};
use rustc_semver::RustcVersion;
use rustc_session::Session;
use rustc_span::hygiene::{ExpnKind, MacroKind};
use rustc_span::source_map::original_sp;
use rustc_span::source_map::SourceMap;
use rustc_span::sym;
use rustc_span::symbol::{kw, Symbol};
use rustc_span::{Span, DUMMY_SP};
use rustc_target::abi::Integer;
use crate::consts::{constant, Constant};
use crate::ty::{can_partially_move_ty, expr_sig, is_copy, is_recursively_primitive_type, ty_is_fn_once_param};
use crate::visitors::for_each_expr;
pub fn parse_msrv(msrv: &str, sess: Option<&Session>, span: Option<Span>) -> Option<RustcVersion> {
if let Ok(version) = RustcVersion::parse(msrv) {
return Some(version);
} else if let Some(sess) = sess {
if let Some(span) = span {
sess.span_err(span, format!("`{msrv}` is not a valid Rust version"));
}
}
None
}
pub fn meets_msrv(msrv: Option<RustcVersion>, lint_msrv: RustcVersion) -> bool {
msrv.map_or(true, |msrv| msrv.meets(lint_msrv))
}
#[macro_export]
macro_rules! extract_msrv_attr {
($context:ident) => {
fn enter_lint_attrs(&mut self, cx: &rustc_lint::$context<'_>, attrs: &[rustc_ast::ast::Attribute]) {
let sess = rustc_lint::LintContext::sess(cx);
match $crate::get_unique_inner_attr(sess, attrs, "msrv") {
Some(msrv_attr) => {
if let Some(msrv) = msrv_attr.value_str() {
self.msrv = $crate::parse_msrv(&msrv.to_string(), Some(sess), Some(msrv_attr.span));
} else {
sess.span_err(msrv_attr.span, "bad clippy attribute");
}
},
_ => (),
}
}
};
}
/// If the given expression is a local binding, find the initializer expression.
/// If that initializer expression is another local binding, find its initializer again.
/// This process repeats as long as possible (but usually no more than once). Initializer
/// expressions with adjustments are ignored. If this is not desired, use [`find_binding_init`]
/// instead.
///
/// Examples:
/// ```
/// let abc = 1;
/// // ^ output
/// let def = abc;
/// dbg!(def);
/// // ^^^ input
///
/// // or...
/// let abc = 1;
/// let def = abc + 2;
/// // ^^^^^^^ output
/// dbg!(def);
/// // ^^^ input
/// ```
pub fn expr_or_init<'a, 'b, 'tcx: 'b>(cx: &LateContext<'tcx>, mut expr: &'a Expr<'b>) -> &'a Expr<'b> {
while let Some(init) = path_to_local(expr)
.and_then(|id| find_binding_init(cx, id))
.filter(|init| cx.typeck_results().expr_adjustments(init).is_empty())
{
expr = init;
}
expr
}
/// Finds the initializer expression for a local binding. Returns `None` if the binding is mutable.
/// By only considering immutable bindings, we guarantee that the returned expression represents the
/// value of the binding wherever it is referenced.
///
/// Example: For `let x = 1`, if the `HirId` of `x` is provided, the `Expr` `1` is returned.
/// Note: If you have an expression that references a binding `x`, use `path_to_local` to get the
/// canonical binding `HirId`.
pub fn find_binding_init<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Expr<'tcx>> {
let hir = cx.tcx.hir();
if_chain! {
if let Some(Node::Pat(pat)) = hir.find(hir_id);
if matches!(pat.kind, PatKind::Binding(BindingAnnotation::NONE, ..));
let parent = hir.get_parent_node(hir_id);
if let Some(Node::Local(local)) = hir.find(parent);
then {
return local.init;
}
}
None
}
/// Returns `true` if the given `NodeId` is inside a constant context
///
/// # Example
///
/// ```rust,ignore
/// if in_constant(cx, expr.hir_id) {
/// // Do something
/// }
/// ```
pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
let parent_id = cx.tcx.hir().get_parent_item(id).def_id;
match cx.tcx.hir().get_by_def_id(parent_id) {
Node::Item(&Item {
kind: ItemKind::Const(..) | ItemKind::Static(..),
..
})
| Node::TraitItem(&TraitItem {
kind: TraitItemKind::Const(..),
..
})
| Node::ImplItem(&ImplItem {
kind: ImplItemKind::Const(..),
..
})
| Node::AnonConst(_) => true,
Node::Item(&Item {
kind: ItemKind::Fn(ref sig, ..),
..
})
| Node::ImplItem(&ImplItem {
kind: ImplItemKind::Fn(ref sig, _),
..
}) => sig.header.constness == Constness::Const,
_ => false,
}
}
/// Checks if a `Res` refers to a constructor of a `LangItem`
/// For example, use this to check whether a function call or a pattern is `Some(..)`.
pub fn is_res_lang_ctor(cx: &LateContext<'_>, res: Res, lang_item: LangItem) -> bool {
if let Res::Def(DefKind::Ctor(..), id) = res
&& let Ok(lang_id) = cx.tcx.lang_items().require(lang_item)
&& let Some(id) = cx.tcx.opt_parent(id)
{
id == lang_id
} else {
false
}
}
pub fn is_res_diagnostic_ctor(cx: &LateContext<'_>, res: Res, diag_item: Symbol) -> bool {
if let Res::Def(DefKind::Ctor(..), id) = res
&& let Some(id) = cx.tcx.opt_parent(id)
{
cx.tcx.is_diagnostic_item(diag_item, id)
} else {
false
}
}
/// Checks if a `QPath` resolves to a constructor of a diagnostic item.
pub fn is_diagnostic_ctor(cx: &LateContext<'_>, qpath: &QPath<'_>, diagnostic_item: Symbol) -> bool {
if let QPath::Resolved(_, path) = qpath {
if let Res::Def(DefKind::Ctor(..), ctor_id) = path.res {
return cx.tcx.is_diagnostic_item(diagnostic_item, cx.tcx.parent(ctor_id));
}
}
false
}
/// Checks if the `DefId` matches the given diagnostic item or it's constructor.
pub fn is_diagnostic_item_or_ctor(cx: &LateContext<'_>, did: DefId, item: Symbol) -> bool {
let did = match cx.tcx.def_kind(did) {
DefKind::Ctor(..) => cx.tcx.parent(did),
// Constructors for types in external crates seem to have `DefKind::Variant`
DefKind::Variant => match cx.tcx.opt_parent(did) {
Some(did) if matches!(cx.tcx.def_kind(did), DefKind::Variant) => did,
_ => did,
},
_ => did,
};
cx.tcx.is_diagnostic_item(item, did)
}
/// Checks if the `DefId` matches the given `LangItem` or it's constructor.
pub fn is_lang_item_or_ctor(cx: &LateContext<'_>, did: DefId, item: LangItem) -> bool {
let did = match cx.tcx.def_kind(did) {
DefKind::Ctor(..) => cx.tcx.parent(did),
// Constructors for types in external crates seem to have `DefKind::Variant`
DefKind::Variant => match cx.tcx.opt_parent(did) {
Some(did) if matches!(cx.tcx.def_kind(did), DefKind::Variant) => did,
_ => did,
},
_ => did,
};
cx.tcx.lang_items().require(item).map_or(false, |id| id == did)
}
pub fn is_unit_expr(expr: &Expr<'_>) -> bool {
matches!(
expr.kind,
ExprKind::Block(
Block {
stmts: [],
expr: None,
..
},
_
) | ExprKind::Tup([])
)
}
/// Checks if given pattern is a wildcard (`_`)
pub fn is_wild(pat: &Pat<'_>) -> bool {
matches!(pat.kind, PatKind::Wild)
}
/// Checks if the method call given in `expr` belongs to the given trait.
/// This is a deprecated function, consider using [`is_trait_method`].
pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
let trt_id = cx.tcx.trait_of_item(def_id);
trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
}
/// Checks if a method is defined in an impl of a diagnostic item
pub fn is_diag_item_method(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
return cx.tcx.is_diagnostic_item(diag_item, adt.did());
}
}
false
}
/// Checks if a method is in a diagnostic item trait
pub fn is_diag_trait_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool {
if let Some(trait_did) = cx.tcx.trait_of_item(def_id) {
return cx.tcx.is_diagnostic_item(diag_item, trait_did);
}
false
}
/// Checks if the method call given in `expr` belongs to the given trait.
pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
cx.typeck_results()
.type_dependent_def_id(expr.hir_id)
.map_or(false, |did| is_diag_trait_item(cx, did, diag_item))
}
/// Checks if the given expression is a path referring an item on the trait
/// that is marked with the given diagnostic item.
///
/// For checking method call expressions instead of path expressions, use
/// [`is_trait_method`].
///
/// For example, this can be used to find if an expression like `u64::default`
/// refers to an item of the trait `Default`, which is associated with the
/// `diag_item` of `sym::Default`.
pub fn is_trait_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
if let hir::ExprKind::Path(ref qpath) = expr.kind {
cx.qpath_res(qpath, expr.hir_id)
.opt_def_id()
.map_or(false, |def_id| is_diag_trait_item(cx, def_id, diag_item))
} else {
false
}
}
pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
match *path {
QPath::Resolved(_, path) => path.segments.last().expect("A path must have at least one segment"),
QPath::TypeRelative(_, seg) => seg,
QPath::LangItem(..) => panic!("last_path_segment: lang item has no path segments"),
}
}
pub fn qpath_generic_tys<'tcx>(qpath: &QPath<'tcx>) -> impl Iterator<Item = &'tcx hir::Ty<'tcx>> {
last_path_segment(qpath)
.args
.map_or(&[][..], |a| a.args)
.iter()
.filter_map(|a| match a {
hir::GenericArg::Type(ty) => Some(*ty),
_ => None,
})
}
/// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
/// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
/// `QPath::Resolved.1.res.opt_def_id()`.
///
/// Matches a `QPath` against a slice of segment string literals.
///
/// There is also `match_path` if you are dealing with a `rustc_hir::Path` instead of a
/// `rustc_hir::QPath`.
///
/// # Examples
/// ```rust,ignore
/// match_qpath(path, &["std", "rt", "begin_unwind"])
/// ```
pub fn match_qpath(path: &QPath<'_>, segments: &[&str]) -> bool {
match *path {
QPath::Resolved(_, path) => match_path(path, segments),
QPath::TypeRelative(ty, segment) => match ty.kind {
TyKind::Path(ref inner_path) => {
if let [prefix @ .., end] = segments {
if match_qpath(inner_path, prefix) {
return segment.ident.name.as_str() == *end;
}
}
false
},
_ => false,
},
QPath::LangItem(..) => false,
}
}
/// If the expression is a path, resolves it to a `DefId` and checks if it matches the given path.
///
/// Please use `is_path_diagnostic_item` if the target is a diagnostic item.
pub fn is_expr_path_def_path(cx: &LateContext<'_>, expr: &Expr<'_>, segments: &[&str]) -> bool {
path_def_id(cx, expr).map_or(false, |id| match_def_path(cx, id, segments))
}
/// If `maybe_path` is a path node which resolves to an item, resolves it to a `DefId` and checks if
/// it matches the given diagnostic item.
pub fn is_path_diagnostic_item<'tcx>(
cx: &LateContext<'_>,
maybe_path: &impl MaybePath<'tcx>,
diag_item: Symbol,
) -> bool {
path_def_id(cx, maybe_path).map_or(false, |id| cx.tcx.is_diagnostic_item(diag_item, id))
}
/// THIS METHOD IS DEPRECATED and will eventually be removed since it does not match against the
/// entire path or resolved `DefId`. Prefer using `match_def_path`. Consider getting a `DefId` from
/// `QPath::Resolved.1.res.opt_def_id()`.
///
/// Matches a `Path` against a slice of segment string literals.
///
/// There is also `match_qpath` if you are dealing with a `rustc_hir::QPath` instead of a
/// `rustc_hir::Path`.
///
/// # Examples
///
/// ```rust,ignore
/// if match_path(&trait_ref.path, &paths::HASH) {
/// // This is the `std::hash::Hash` trait.
/// }
///
/// if match_path(ty_path, &["rustc", "lint", "Lint"]) {
/// // This is a `rustc_middle::lint::Lint`.
/// }
/// ```
pub fn match_path(path: &Path<'_>, segments: &[&str]) -> bool {
path.segments
.iter()
.rev()
.zip(segments.iter().rev())
.all(|(a, b)| a.ident.name.as_str() == *b)
}
/// If the expression is a path to a local, returns the canonical `HirId` of the local.
pub fn path_to_local(expr: &Expr<'_>) -> Option<HirId> {
if let ExprKind::Path(QPath::Resolved(None, path)) = expr.kind {
if let Res::Local(id) = path.res {
return Some(id);
}
}
None
}
/// Returns true if the expression is a path to a local with the specified `HirId`.
/// Use this function to see if an expression matches a function argument or a match binding.
pub fn path_to_local_id(expr: &Expr<'_>, id: HirId) -> bool {
path_to_local(expr) == Some(id)
}
pub trait MaybePath<'hir> {
fn hir_id(&self) -> HirId;
fn qpath_opt(&self) -> Option<&QPath<'hir>>;
}
macro_rules! maybe_path {
($ty:ident, $kind:ident) => {
impl<'hir> MaybePath<'hir> for hir::$ty<'hir> {
fn hir_id(&self) -> HirId {
self.hir_id
}
fn qpath_opt(&self) -> Option<&QPath<'hir>> {
match &self.kind {
hir::$kind::Path(qpath) => Some(qpath),
_ => None,
}
}
}
};
}
maybe_path!(Expr, ExprKind);
maybe_path!(Pat, PatKind);
maybe_path!(Ty, TyKind);
/// If `maybe_path` is a path node, resolves it, otherwise returns `Res::Err`
pub fn path_res<'tcx>(cx: &LateContext<'_>, maybe_path: &impl MaybePath<'tcx>) -> Res {
match maybe_path.qpath_opt() {
None => Res::Err,
Some(qpath) => cx.qpath_res(qpath, maybe_path.hir_id()),
}
}
/// If `maybe_path` is a path node which resolves to an item, retrieves the item ID
pub fn path_def_id<'tcx>(cx: &LateContext<'_>, maybe_path: &impl MaybePath<'tcx>) -> Option<DefId> {
path_res(cx, maybe_path).opt_def_id()
}
fn find_primitive<'tcx>(tcx: TyCtxt<'tcx>, name: &str) -> impl Iterator<Item = DefId> + 'tcx {
let single = |ty| tcx.incoherent_impls(ty).iter().copied();
let empty = || [].iter().copied();
match name {
"bool" => single(BoolSimplifiedType),
"char" => single(CharSimplifiedType),
"str" => single(StrSimplifiedType),
"array" => single(ArraySimplifiedType),
"slice" => single(SliceSimplifiedType),
// FIXME: rustdoc documents these two using just `pointer`.
//
// Maybe this is something we should do here too.
"const_ptr" => single(PtrSimplifiedType(Mutability::Not)),
"mut_ptr" => single(PtrSimplifiedType(Mutability::Mut)),
"isize" => single(IntSimplifiedType(IntTy::Isize)),
"i8" => single(IntSimplifiedType(IntTy::I8)),
"i16" => single(IntSimplifiedType(IntTy::I16)),
"i32" => single(IntSimplifiedType(IntTy::I32)),
"i64" => single(IntSimplifiedType(IntTy::I64)),
"i128" => single(IntSimplifiedType(IntTy::I128)),
"usize" => single(UintSimplifiedType(UintTy::Usize)),
"u8" => single(UintSimplifiedType(UintTy::U8)),
"u16" => single(UintSimplifiedType(UintTy::U16)),
"u32" => single(UintSimplifiedType(UintTy::U32)),
"u64" => single(UintSimplifiedType(UintTy::U64)),
"u128" => single(UintSimplifiedType(UintTy::U128)),
"f32" => single(FloatSimplifiedType(FloatTy::F32)),
"f64" => single(FloatSimplifiedType(FloatTy::F64)),
_ => empty(),
}
}
/// Resolves a def path like `std::vec::Vec`. `namespace_hint` can be supplied to disambiguate
/// between `std::vec` the module and `std::vec` the macro
///
/// This function is expensive and should be used sparingly.
pub fn def_path_res(cx: &LateContext<'_>, path: &[&str], namespace_hint: Option<Namespace>) -> Res {
fn item_child_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: &str, matches_ns: impl Fn(Res) -> bool) -> Option<Res> {
match tcx.def_kind(def_id) {
DefKind::Mod | DefKind::Enum | DefKind::Trait => tcx
.module_children(def_id)
.iter()
.find(|item| item.ident.name.as_str() == name && matches_ns(item.res.expect_non_local()))
.map(|child| child.res.expect_non_local()),
DefKind::Impl => tcx
.associated_item_def_ids(def_id)
.iter()
.copied()
.find(|assoc_def_id| tcx.item_name(*assoc_def_id).as_str() == name)
.map(|assoc_def_id| Res::Def(tcx.def_kind(assoc_def_id), assoc_def_id)),
DefKind::Struct | DefKind::Union => tcx
.adt_def(def_id)
.non_enum_variant()
.fields
.iter()
.find(|f| f.name.as_str() == name)
.map(|f| Res::Def(DefKind::Field, f.did)),
_ => None,
}
}
fn find_crate(tcx: TyCtxt<'_>, name: &str) -> Option<DefId> {
tcx.crates(())
.iter()
.copied()
.find(|&num| tcx.crate_name(num).as_str() == name)
.map(CrateNum::as_def_id)
}
let (base, path) = match *path {
[primitive] => {
return PrimTy::from_name(Symbol::intern(primitive)).map_or(Res::Err, Res::PrimTy);
},
[base, ref path @ ..] => (base, path),
_ => return Res::Err,
};
let tcx = cx.tcx;
let starts = find_primitive(tcx, base)
.chain(find_crate(tcx, base))
.map(|id| Res::Def(tcx.def_kind(id), id));
for first in starts {
let last = path
.iter()
.copied()
.enumerate()
// for each segment, find the child item
.try_fold(first, |res, (idx, segment)| {
let matches_ns = |res: Res| {
// If at the last segment in the path, respect the namespace hint
if idx == path.len() - 1 {
match namespace_hint {
Some(ns) => res.matches_ns(ns),
None => true,
}
} else {
res.matches_ns(Namespace::TypeNS)
}
};
let def_id = res.def_id();
if let Some(item) = item_child_by_name(tcx, def_id, segment, matches_ns) {
Some(item)
} else if matches!(res, Res::Def(DefKind::Enum | DefKind::Struct, _)) {
// it is not a child item so check inherent impl items
tcx.inherent_impls(def_id)
.iter()
.find_map(|&impl_def_id| item_child_by_name(tcx, impl_def_id, segment, matches_ns))
} else {
None
}
});
if let Some(last) = last {
return last;
}
}
Res::Err
}
/// Convenience function to get the `DefId` of a trait by path.
/// It could be a trait or trait alias.
///
/// This function is expensive and should be used sparingly.
pub fn get_trait_def_id(cx: &LateContext<'_>, path: &[&str]) -> Option<DefId> {
match def_path_res(cx, path, Some(Namespace::TypeNS)) {
Res::Def(DefKind::Trait | DefKind::TraitAlias, trait_id) => Some(trait_id),
_ => None,
}
}
/// Gets the `hir::TraitRef` of the trait the given method is implemented for.
///
/// Use this if you want to find the `TraitRef` of the `Add` trait in this example:
///
/// ```rust
/// struct Point(isize, isize);
///
/// impl std::ops::Add for Point {
/// type Output = Self;
///
/// fn add(self, other: Self) -> Self {
/// Point(0, 0)
/// }
/// }
/// ```
pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, def_id: LocalDefId) -> Option<&'tcx TraitRef<'tcx>> {
// Get the implemented trait for the current function
let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id);
let parent_impl = cx.tcx.hir().get_parent_item(hir_id);
if_chain! {
if parent_impl != hir::CRATE_OWNER_ID;
if let hir::Node::Item(item) = cx.tcx.hir().get_by_def_id(parent_impl.def_id);
if let hir::ItemKind::Impl(impl_) = &item.kind;
then {
return impl_.of_trait.as_ref();
}
}
None
}
/// This method will return tuple of projection stack and root of the expression,
/// used in `can_mut_borrow_both`.
///
/// For example, if `e` represents the `v[0].a.b[x]`
/// this method will return a tuple, composed of a `Vec`
/// containing the `Expr`s for `v[0], v[0].a, v[0].a.b, v[0].a.b[x]`
/// and an `Expr` for root of them, `v`
fn projection_stack<'a, 'hir>(mut e: &'a Expr<'hir>) -> (Vec<&'a Expr<'hir>>, &'a Expr<'hir>) {
let mut result = vec![];
let root = loop {
match e.kind {
ExprKind::Index(ep, _) | ExprKind::Field(ep, _) => {
result.push(e);
e = ep;
},
_ => break e,
};
};
result.reverse();
(result, root)
}
/// Gets the mutability of the custom deref adjustment, if any.
pub fn expr_custom_deref_adjustment(cx: &LateContext<'_>, e: &Expr<'_>) -> Option<Mutability> {
cx.typeck_results()
.expr_adjustments(e)
.iter()
.find_map(|a| match a.kind {
Adjust::Deref(Some(d)) => Some(Some(d.mutbl)),
Adjust::Deref(None) => None,
_ => Some(None),
})
.and_then(|x| x)
}
/// Checks if two expressions can be mutably borrowed simultaneously
/// and they aren't dependent on borrowing same thing twice
pub fn can_mut_borrow_both(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>) -> bool {
let (s1, r1) = projection_stack(e1);
let (s2, r2) = projection_stack(e2);
if !eq_expr_value(cx, r1, r2) {
return true;
}
if expr_custom_deref_adjustment(cx, r1).is_some() || expr_custom_deref_adjustment(cx, r2).is_some() {
return false;
}
for (x1, x2) in s1.iter().zip(s2.iter()) {
if expr_custom_deref_adjustment(cx, x1).is_some() || expr_custom_deref_adjustment(cx, x2).is_some() {
return false;
}
match (&x1.kind, &x2.kind) {
(ExprKind::Field(_, i1), ExprKind::Field(_, i2)) => {
if i1 != i2 {
return true;
}
},
(ExprKind::Index(_, i1), ExprKind::Index(_, i2)) => {
if !eq_expr_value(cx, i1, i2) {
return false;
}
},
_ => return false,
}
}
false
}
/// Returns true if the `def_id` associated with the `path` is recognized as a "default-equivalent"
/// constructor from the std library
fn is_default_equivalent_ctor(cx: &LateContext<'_>, def_id: DefId, path: &QPath<'_>) -> bool {
let std_types_symbols = &[
sym::String,
sym::Vec,
sym::VecDeque,
sym::LinkedList,
sym::HashMap,
sym::BTreeMap,
sym::HashSet,
sym::BTreeSet,
sym::BinaryHeap,
];
if let QPath::TypeRelative(_, method) = path {
if method.ident.name == sym::new {
if let Some(impl_did) = cx.tcx.impl_of_method(def_id) {
if let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() {
return std_types_symbols
.iter()
.any(|&symbol| cx.tcx.is_diagnostic_item(symbol, adt.did()));
}
}
}
}
false
}
/// Return true if the expr is equal to `Default::default` when evaluated.
pub fn is_default_equivalent_call(cx: &LateContext<'_>, repl_func: &Expr<'_>) -> bool {
if_chain! {
if let hir::ExprKind::Path(ref repl_func_qpath) = repl_func.kind;
if let Some(repl_def_id) = cx.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id();
if is_diag_trait_item(cx, repl_def_id, sym::Default)
|| is_default_equivalent_ctor(cx, repl_def_id, repl_func_qpath);
then { true } else { false }
}
}
/// Returns true if the expr is equal to `Default::default()` of it's type when evaluated.
/// It doesn't cover all cases, for example indirect function calls (some of std
/// functions are supported) but it is the best we have.
pub fn is_default_equivalent(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
match &e.kind {
ExprKind::Lit(lit) => match lit.node {
LitKind::Bool(false) | LitKind::Int(0, _) => true,
LitKind::Str(s, _) => s.is_empty(),
_ => false,
},
ExprKind::Tup(items) | ExprKind::Array(items) => items.iter().all(|x| is_default_equivalent(cx, x)),
ExprKind::Repeat(x, ArrayLen::Body(len)) => if_chain! {
if let ExprKind::Lit(ref const_lit) = cx.tcx.hir().body(len.body).value.kind;
if let LitKind::Int(v, _) = const_lit.node;
if v <= 32 && is_default_equivalent(cx, x);
then {
true
}
else {
false
}
},
ExprKind::Call(repl_func, []) => is_default_equivalent_call(cx, repl_func),
ExprKind::Call(from_func, [ref arg]) => is_default_equivalent_from(cx, from_func, arg),
ExprKind::Path(qpath) => is_res_lang_ctor(cx, cx.qpath_res(qpath, e.hir_id), OptionNone),
ExprKind::AddrOf(rustc_hir::BorrowKind::Ref, _, expr) => matches!(expr.kind, ExprKind::Array([])),
_ => false,
}
}
fn is_default_equivalent_from(cx: &LateContext<'_>, from_func: &Expr<'_>, arg: &Expr<'_>) -> bool {
if let ExprKind::Path(QPath::TypeRelative(ty, seg)) = from_func.kind &&
seg.ident.name == sym::from
{
match arg.kind {
ExprKind::Lit(hir::Lit {
node: LitKind::Str(ref sym, _),
..
}) => return sym.is_empty() && is_path_diagnostic_item(cx, ty, sym::String),
ExprKind::Array([]) => return is_path_diagnostic_item(cx, ty, sym::Vec),
ExprKind::Repeat(_, ArrayLen::Body(len)) => {
if let ExprKind::Lit(ref const_lit) = cx.tcx.hir().body(len.body).value.kind &&
let LitKind::Int(v, _) = const_lit.node
{
return v == 0 && is_path_diagnostic_item(cx, ty, sym::Vec);
}
}
_ => (),
}
}
false
}
/// Checks if the top level expression can be moved into a closure as is.
/// Currently checks for:
/// * Break/Continue outside the given loop HIR ids.
/// * Yield/Return statements.
/// * Inline assembly.
/// * Usages of a field of a local where the type of the local can be partially moved.
///
/// For example, given the following function:
///
/// ```
/// fn f<'a>(iter: &mut impl Iterator<Item = (usize, &'a mut String)>) {
/// for item in iter {
/// let s = item.1;
/// if item.0 > 10 {
/// continue;
/// } else {
/// s.clear();
/// }
/// }
/// }
/// ```
///
/// When called on the expression `item.0` this will return false unless the local `item` is in the
/// `ignore_locals` set. The type `(usize, &mut String)` can have the second element moved, so it
/// isn't always safe to move into a closure when only a single field is needed.
///
/// When called on the `continue` expression this will return false unless the outer loop expression
/// is in the `loop_ids` set.
///
/// Note that this check is not recursive, so passing the `if` expression will always return true
/// even though sub-expressions might return false.
pub fn can_move_expr_to_closure_no_visit<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx Expr<'_>,
loop_ids: &[HirId],
ignore_locals: &HirIdSet,
) -> bool {
match expr.kind {
ExprKind::Break(Destination { target_id: Ok(id), .. }, _)
| ExprKind::Continue(Destination { target_id: Ok(id), .. })
if loop_ids.contains(&id) =>
{
true
},
ExprKind::Break(..)
| ExprKind::Continue(_)
| ExprKind::Ret(_)
| ExprKind::Yield(..)
| ExprKind::InlineAsm(_) => false,
// Accessing a field of a local value can only be done if the type isn't
// partially moved.
ExprKind::Field(
&Expr {
hir_id,
kind:
ExprKind::Path(QPath::Resolved(
_,
Path {
res: Res::Local(local_id),
..
},
)),
..
},
_,
) if !ignore_locals.contains(local_id) && can_partially_move_ty(cx, cx.typeck_results().node_type(hir_id)) => {
// TODO: check if the local has been partially moved. Assume it has for now.
false
},
_ => true,
}
}
/// How a local is captured by a closure
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum CaptureKind {
Value,
Ref(Mutability),
}
impl CaptureKind {
pub fn is_imm_ref(self) -> bool {
self == Self::Ref(Mutability::Not)
}
}
impl std::ops::BitOr for CaptureKind {
type Output = Self;
fn bitor(self, rhs: Self) -> Self::Output {
match (self, rhs) {
(CaptureKind::Value, _) | (_, CaptureKind::Value) => CaptureKind::Value,
(CaptureKind::Ref(Mutability::Mut), CaptureKind::Ref(_))
| (CaptureKind::Ref(_), CaptureKind::Ref(Mutability::Mut)) => CaptureKind::Ref(Mutability::Mut),
(CaptureKind::Ref(Mutability::Not), CaptureKind::Ref(Mutability::Not)) => CaptureKind::Ref(Mutability::Not),
}
}
}
impl std::ops::BitOrAssign for CaptureKind {
fn bitor_assign(&mut self, rhs: Self) {
*self = *self | rhs;
}
}
/// Given an expression referencing a local, determines how it would be captured in a closure.
/// Note as this will walk up to parent expressions until the capture can be determined it should
/// only be used while making a closure somewhere a value is consumed. e.g. a block, match arm, or
/// function argument (other than a receiver).
pub fn capture_local_usage<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> CaptureKind {
fn pat_capture_kind(cx: &LateContext<'_>, pat: &Pat<'_>) -> CaptureKind {
let mut capture = CaptureKind::Ref(Mutability::Not);
pat.each_binding_or_first(&mut |_, id, span, _| match cx
.typeck_results()
.extract_binding_mode(cx.sess(), id, span)
.unwrap()
{
BindingMode::BindByValue(_) if !is_copy(cx, cx.typeck_results().node_type(id)) => {
capture = CaptureKind::Value;
},
BindingMode::BindByReference(Mutability::Mut) if capture != CaptureKind::Value => {
capture = CaptureKind::Ref(Mutability::Mut);
},
_ => (),
});
capture
}
debug_assert!(matches!(
e.kind,
ExprKind::Path(QPath::Resolved(None, Path { res: Res::Local(_), .. }))
));
let mut child_id = e.hir_id;
let mut capture = CaptureKind::Value;
let mut capture_expr_ty = e;
for (parent_id, parent) in cx.tcx.hir().parent_iter(e.hir_id) {
if let [
Adjustment {
kind: Adjust::Deref(_) | Adjust::Borrow(AutoBorrow::Ref(..)),
target,
},
ref adjust @ ..,
] = *cx
.typeck_results()
.adjustments()
.get(child_id)
.map_or(&[][..], |x| &**x)
{
if let rustc_ty::RawPtr(TypeAndMut { mutbl: mutability, .. }) | rustc_ty::Ref(_, _, mutability) =
*adjust.last().map_or(target, |a| a.target).kind()
{
return CaptureKind::Ref(mutability);
}
}
match parent {
Node::Expr(e) => match e.kind {
ExprKind::AddrOf(_, mutability, _) => return CaptureKind::Ref(mutability),
ExprKind::Index(..) | ExprKind::Unary(UnOp::Deref, _) => capture = CaptureKind::Ref(Mutability::Not),
ExprKind::Assign(lhs, ..) | ExprKind::AssignOp(_, lhs, _) if lhs.hir_id == child_id => {
return CaptureKind::Ref(Mutability::Mut);
},
ExprKind::Field(..) => {
if capture == CaptureKind::Value {
capture_expr_ty = e;
}
},
ExprKind::Let(let_expr) => {
let mutability = match pat_capture_kind(cx, let_expr.pat) {
CaptureKind::Value => Mutability::Not,
CaptureKind::Ref(m) => m,
};
return CaptureKind::Ref(mutability);
},
ExprKind::Match(_, arms, _) => {
let mut mutability = Mutability::Not;
for capture in arms.iter().map(|arm| pat_capture_kind(cx, arm.pat)) {
match capture {
CaptureKind::Value => break,
CaptureKind::Ref(Mutability::Mut) => mutability = Mutability::Mut,
CaptureKind::Ref(Mutability::Not) => (),
}
}
return CaptureKind::Ref(mutability);
},
_ => break,
},
Node::Local(l) => match pat_capture_kind(cx, l.pat) {
CaptureKind::Value => break,
capture @ CaptureKind::Ref(_) => return capture,
},
_ => break,
}
child_id = parent_id;
}
if capture == CaptureKind::Value && is_copy(cx, cx.typeck_results().expr_ty(capture_expr_ty)) {
// Copy types are never automatically captured by value.
CaptureKind::Ref(Mutability::Not)
} else {
capture
}
}
/// Checks if the expression can be moved into a closure as is. This will return a list of captures
/// if so, otherwise, `None`.
pub fn can_move_expr_to_closure<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<HirIdMap<CaptureKind>> {
struct V<'cx, 'tcx> {
cx: &'cx LateContext<'tcx>,
// Stack of potential break targets contained in the expression.
loops: Vec<HirId>,
/// Local variables created in the expression. These don't need to be captured.
locals: HirIdSet,
/// Whether this expression can be turned into a closure.
allow_closure: bool,
/// Locals which need to be captured, and whether they need to be by value, reference, or
/// mutable reference.
captures: HirIdMap<CaptureKind>,
}
impl<'tcx> Visitor<'tcx> for V<'_, 'tcx> {
fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
if !self.allow_closure {
return;
}
match e.kind {
ExprKind::Path(QPath::Resolved(None, &Path { res: Res::Local(l), .. })) => {
if !self.locals.contains(&l) {
let cap = capture_local_usage(self.cx, e);
self.captures.entry(l).and_modify(|e| *e |= cap).or_insert(cap);
}
},
ExprKind::Closure { .. } => {
let closure_id = self.cx.tcx.hir().local_def_id(e.hir_id);
for capture in self.cx.typeck_results().closure_min_captures_flattened(closure_id) {
let local_id = match capture.place.base {
PlaceBase::Local(id) => id,
PlaceBase::Upvar(var) => var.var_path.hir_id,
_ => continue,
};
if !self.locals.contains(&local_id) {
let capture = match capture.info.capture_kind {
UpvarCapture::ByValue => CaptureKind::Value,
UpvarCapture::ByRef(kind) => match kind {
BorrowKind::ImmBorrow => CaptureKind::Ref(Mutability::Not),
BorrowKind::UniqueImmBorrow | BorrowKind::MutBorrow => {
CaptureKind::Ref(Mutability::Mut)
},
},
};
self.captures
.entry(local_id)
.and_modify(|e| *e |= capture)
.or_insert(capture);
}
}
},
ExprKind::Loop(b, ..) => {
self.loops.push(e.hir_id);
self.visit_block(b);
self.loops.pop();
},
_ => {
self.allow_closure &= can_move_expr_to_closure_no_visit(self.cx, e, &self.loops, &self.locals);
walk_expr(self, e);
},
}
}
fn visit_pat(&mut self, p: &'tcx Pat<'tcx>) {
p.each_binding_or_first(&mut |_, id, _, _| {
self.locals.insert(id);
});
}
}
let mut v = V {
cx,
allow_closure: true,
loops: Vec::new(),
locals: HirIdSet::default(),
captures: HirIdMap::default(),
};
v.visit_expr(expr);
v.allow_closure.then_some(v.captures)
}
/// Arguments of a method: the receiver and all the additional arguments.
pub type MethodArguments<'tcx> = Vec<(&'tcx Expr<'tcx>, &'tcx [Expr<'tcx>])>;
/// Returns the method names and argument list of nested method call expressions that make up
/// `expr`. method/span lists are sorted with the most recent call first.
pub fn method_calls<'tcx>(expr: &'tcx Expr<'tcx>, max_depth: usize) -> (Vec<Symbol>, MethodArguments<'tcx>, Vec<Span>) {
let mut method_names = Vec::with_capacity(max_depth);
let mut arg_lists = Vec::with_capacity(max_depth);
let mut spans = Vec::with_capacity(max_depth);
let mut current = expr;
for _ in 0..max_depth {
if let ExprKind::MethodCall(path, receiver, args, _) = &current.kind {
if receiver.span.from_expansion() || args.iter().any(|e| e.span.from_expansion()) {
break;
}
method_names.push(path.ident.name);
arg_lists.push((*receiver, &**args));
spans.push(path.ident.span);
current = receiver;
} else {
break;
}
}
(method_names, arg_lists, spans)
}
/// Matches an `Expr` against a chain of methods, and return the matched `Expr`s.
///
/// For example, if `expr` represents the `.baz()` in `foo.bar().baz()`,
/// `method_chain_args(expr, &["bar", "baz"])` will return a `Vec`
/// containing the `Expr`s for
/// `.bar()` and `.baz()`
pub fn method_chain_args<'a>(expr: &'a Expr<'_>, methods: &[&str]) -> Option<Vec<(&'a Expr<'a>, &'a [Expr<'a>])>> {
let mut current = expr;
let mut matched = Vec::with_capacity(methods.len());
for method_name in methods.iter().rev() {
// method chains are stored last -> first
if let ExprKind::MethodCall(path, receiver, args, _) = current.kind {
if path.ident.name.as_str() == *method_name {
if receiver.span.from_expansion() || args.iter().any(|e| e.span.from_expansion()) {
return None;
}
matched.push((receiver, args)); // build up `matched` backwards
current = receiver; // go to parent expression
} else {
return None;
}
} else {
return None;
}
}
// Reverse `matched` so that it is in the same order as `methods`.
matched.reverse();
Some(matched)
}
/// Returns `true` if the provided `def_id` is an entrypoint to a program.
pub fn is_entrypoint_fn(cx: &LateContext<'_>, def_id: DefId) -> bool {
cx.tcx
.entry_fn(())
.map_or(false, |(entry_fn_def_id, _)| def_id == entry_fn_def_id)
}
/// Returns `true` if the expression is in the program's `#[panic_handler]`.
pub fn is_in_panic_handler(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
let parent = cx.tcx.hir().get_parent_item(e.hir_id);
Some(parent.to_def_id()) == cx.tcx.lang_items().panic_impl()
}
/// Gets the name of the item the expression is in, if available.
pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id).def_id;
match cx.tcx.hir().find_by_def_id(parent_id) {
Some(
Node::Item(Item { ident, .. })
| Node::TraitItem(TraitItem { ident, .. })
| Node::ImplItem(ImplItem { ident, .. }),
) => Some(ident.name),
_ => None,
}
}
pub struct ContainsName {
pub name: Symbol,
pub result: bool,
}
impl<'tcx> Visitor<'tcx> for ContainsName {
fn visit_name(&mut self, name: Symbol) {
if self.name == name {
self.result = true;
}
}
}
/// Checks if an `Expr` contains a certain name.
pub fn contains_name(name: Symbol, expr: &Expr<'_>) -> bool {
let mut cn = ContainsName { name, result: false };
cn.visit_expr(expr);
cn.result
}
/// Returns `true` if `expr` contains a return expression
pub fn contains_return(expr: &hir::Expr<'_>) -> bool {
for_each_expr(expr, |e| {
if matches!(e.kind, hir::ExprKind::Ret(..)) {
ControlFlow::Break(())
} else {
ControlFlow::Continue(())
}
})
.is_some()
}
/// Extends the span to the beginning of the spans line, incl. whitespaces.
///
/// ```rust
/// let x = ();
/// // ^^
/// // will be converted to
/// let x = ();
/// // ^^^^^^^^^^^^^^
/// ```
fn line_span<T: LintContext>(cx: &T, span: Span) -> Span {
let span = original_sp(span, DUMMY_SP);
let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap();
let line_no = source_map_and_line.line;
let line_start = source_map_and_line.sf.lines(|lines| lines[line_no]);
span.with_lo(line_start)
}
/// Gets the parent node, if any.
pub fn get_parent_node(tcx: TyCtxt<'_>, id: HirId) -> Option<Node<'_>> {
tcx.hir().parent_iter(id).next().map(|(_, node)| node)
}
/// Gets the parent expression, if any –- this is useful to constrain a lint.
pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
get_parent_expr_for_hir(cx, e.hir_id)
}
/// This retrieves the parent for the given `HirId` if it's an expression. This is useful for
/// constraint lints
pub fn get_parent_expr_for_hir<'tcx>(cx: &LateContext<'tcx>, hir_id: hir::HirId) -> Option<&'tcx Expr<'tcx>> {
match get_parent_node(cx.tcx, hir_id) {
Some(Node::Expr(parent)) => Some(parent),
_ => None,
}
}
pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<&'tcx Block<'tcx>> {
let map = &cx.tcx.hir();
let enclosing_node = map
.get_enclosing_scope(hir_id)
.and_then(|enclosing_id| map.find(enclosing_id));
enclosing_node.and_then(|node| match node {
Node::Block(block) => Some(block),
Node::Item(&Item {
kind: ItemKind::Fn(_, _, eid),
..
})
| Node::ImplItem(&ImplItem {
kind: ImplItemKind::Fn(_, eid),
..
}) => match cx.tcx.hir().body(eid).value.kind {
ExprKind::Block(block, _) => Some(block),
_ => None,
},
_ => None,
})
}
/// Gets the loop or closure enclosing the given expression, if any.
pub fn get_enclosing_loop_or_multi_call_closure<'tcx>(
cx: &LateContext<'tcx>,
expr: &Expr<'_>,
) -> Option<&'tcx Expr<'tcx>> {
for (_, node) in cx.tcx.hir().parent_iter(expr.hir_id) {
match node {
Node::Expr(e) => match e.kind {
ExprKind::Closure { .. } => {
if let rustc_ty::Closure(_, subs) = cx.typeck_results().expr_ty(e).kind()
&& subs.as_closure().kind() == ClosureKind::FnOnce
{
continue;
}
let is_once = walk_to_expr_usage(cx, e, |node, id| {
let Node::Expr(e) = node else {
return None;
};
match e.kind {
ExprKind::Call(f, _) if f.hir_id == id => Some(()),
ExprKind::Call(f, args) => {
let i = args.iter().position(|arg| arg.hir_id == id)?;
let sig = expr_sig(cx, f)?;
let predicates = sig
.predicates_id()
.map_or(cx.param_env, |id| cx.tcx.param_env(id))
.caller_bounds();
sig.input(i).and_then(|ty| {
ty_is_fn_once_param(cx.tcx, ty.skip_binder(), predicates).then_some(())
})
},
ExprKind::MethodCall(_, receiver, args, _) => {
let i = std::iter::once(receiver)
.chain(args.iter())
.position(|arg| arg.hir_id == id)?;
let id = cx.typeck_results().type_dependent_def_id(e.hir_id)?;
let ty = cx.tcx.fn_sig(id).skip_binder().inputs()[i];
ty_is_fn_once_param(cx.tcx, ty, cx.tcx.param_env(id).caller_bounds()).then_some(())
},
_ => None,
}
})
.is_some();
if !is_once {
return Some(e);
}
},
ExprKind::Loop(..) => return Some(e),
_ => (),
},
Node::Stmt(_) | Node::Block(_) | Node::Local(_) | Node::Arm(_) => (),
_ => break,
}
}
None
}
/// Gets the parent node if it's an impl block.
pub fn get_parent_as_impl(tcx: TyCtxt<'_>, id: HirId) -> Option<&Impl<'_>> {
match tcx.hir().parent_iter(id).next() {
Some((
_,
Node::Item(Item {
kind: ItemKind::Impl(imp),
..
}),
)) => Some(imp),
_ => None,
}
}
/// Removes blocks around an expression, only if the block contains just one expression
/// and no statements. Unsafe blocks are not removed.
///
/// Examples:
/// * `{}` -> `{}`
/// * `{ x }` -> `x`
/// * `{{ x }}` -> `x`
/// * `{ x; }` -> `{ x; }`
/// * `{ x; y }` -> `{ x; y }`
/// * `{ unsafe { x } }` -> `unsafe { x }`
pub fn peel_blocks<'a>(mut expr: &'a Expr<'a>) -> &'a Expr<'a> {
while let ExprKind::Block(
Block {
stmts: [],
expr: Some(inner),
rules: BlockCheckMode::DefaultBlock,
..
},
_,
) = expr.kind
{
expr = inner;
}
expr
}
/// Removes blocks around an expression, only if the block contains just one expression
/// or just one expression statement with a semicolon. Unsafe blocks are not removed.
///
/// Examples:
/// * `{}` -> `{}`
/// * `{ x }` -> `x`
/// * `{ x; }` -> `x`
/// * `{{ x; }}` -> `x`
/// * `{ x; y }` -> `{ x; y }`
/// * `{ unsafe { x } }` -> `unsafe { x }`
pub fn peel_blocks_with_stmt<'a>(mut expr: &'a Expr<'a>) -> &'a Expr<'a> {
while let ExprKind::Block(
Block {
stmts: [],
expr: Some(inner),
rules: BlockCheckMode::DefaultBlock,
..
}
| Block {
stmts:
[
Stmt {
kind: StmtKind::Expr(inner) | StmtKind::Semi(inner),
..
},
],
expr: None,
rules: BlockCheckMode::DefaultBlock,
..
},
_,
) = expr.kind
{
expr = inner;
}
expr
}
/// Checks if the given expression is the else clause of either an `if` or `if let` expression.
pub fn is_else_clause(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
let mut iter = tcx.hir().parent_iter(expr.hir_id);
match iter.next() {
Some((
_,
Node::Expr(Expr {
kind: ExprKind::If(_, _, Some(else_expr)),
..
}),
)) => else_expr.hir_id == expr.hir_id,
_ => false,
}
}
/// Checks whether the given expression is a constant integer of the given value.
/// unlike `is_integer_literal`, this version does const folding
pub fn is_integer_const(cx: &LateContext<'_>, e: &Expr<'_>, value: u128) -> bool {
if is_integer_literal(e, value) {
return true;
}
let enclosing_body = cx.tcx.hir().enclosing_body_owner(e.hir_id);
if let Some((Constant::Int(v), _)) = constant(cx, cx.tcx.typeck(enclosing_body), e) {
return value == v;
}
false
}
/// Checks whether the given expression is a constant literal of the given value.
pub fn is_integer_literal(expr: &Expr<'_>, value: u128) -> bool {
// FIXME: use constant folding
if let ExprKind::Lit(ref spanned) = expr.kind {
if let LitKind::Int(v, _) = spanned.node {
return v == value;
}
}
false
}
/// Returns `true` if the given `Expr` has been coerced before.
///
/// Examples of coercions can be found in the Nomicon at
/// <https://doc.rust-lang.org/nomicon/coercions.html>.
///
/// See `rustc_middle::ty::adjustment::Adjustment` and `rustc_hir_analysis::check::coercion` for
/// more information on adjustments and coercions.
pub fn is_adjusted(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
cx.typeck_results().adjustments().get(e.hir_id).is_some()
}
/// Returns the pre-expansion span if this comes from an expansion of the
/// macro `name`.
/// See also [`is_direct_expn_of`].
#[must_use]
pub fn is_expn_of(mut span: Span, name: &str) -> Option<Span> {
loop {
if span.from_expansion() {
let data = span.ctxt().outer_expn_data();
let new_span = data.call_site;
if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
if mac_name.as_str() == name {
return Some(new_span);
}
}
span = new_span;
} else {
return None;
}
}
}
/// Returns the pre-expansion span if the span directly comes from an expansion
/// of the macro `name`.
/// The difference with [`is_expn_of`] is that in
/// ```rust
/// # macro_rules! foo { ($name:tt!$args:tt) => { $name!$args } }
/// # macro_rules! bar { ($e:expr) => { $e } }
/// foo!(bar!(42));
/// ```
/// `42` is considered expanded from `foo!` and `bar!` by `is_expn_of` but only
/// from `bar!` by `is_direct_expn_of`.
#[must_use]
pub fn is_direct_expn_of(span: Span, name: &str) -> Option<Span> {
if span.from_expansion() {
let data = span.ctxt().outer_expn_data();
let new_span = data.call_site;
if let ExpnKind::Macro(MacroKind::Bang, mac_name) = data.kind {
if mac_name.as_str() == name {
return Some(new_span);
}
}
}
None
}
/// Convenience function to get the return type of a function.
pub fn return_ty<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId) -> Ty<'tcx> {
let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
let ret_ty = cx.tcx.fn_sig(fn_def_id).output();
cx.tcx.erase_late_bound_regions(ret_ty)
}
/// Convenience function to get the nth argument type of a function.
pub fn nth_arg<'tcx>(cx: &LateContext<'tcx>, fn_item: hir::HirId, nth: usize) -> Ty<'tcx> {
let fn_def_id = cx.tcx.hir().local_def_id(fn_item);
let arg = cx.tcx.fn_sig(fn_def_id).input(nth);
cx.tcx.erase_late_bound_regions(arg)
}
/// Checks if an expression is constructing a tuple-like enum variant or struct
pub fn is_ctor_or_promotable_const_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
if let ExprKind::Call(fun, _) = expr.kind {
if let ExprKind::Path(ref qp) = fun.kind {
let res = cx.qpath_res(qp, fun.hir_id);
return match res {
def::Res::Def(DefKind::Variant | DefKind::Ctor(..), ..) => true,
def::Res::Def(_, def_id) => cx.tcx.is_promotable_const_fn(def_id),
_ => false,
};
}
}
false
}
/// Returns `true` if a pattern is refutable.
// TODO: should be implemented using rustc/mir_build/thir machinery
pub fn is_refutable(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
fn is_enum_variant(cx: &LateContext<'_>, qpath: &QPath<'_>, id: HirId) -> bool {
matches!(
cx.qpath_res(qpath, id),
def::Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(def::CtorOf::Variant, _), _)
)
}
fn are_refutable<'a, I: IntoIterator<Item = &'a Pat<'a>>>(cx: &LateContext<'_>, i: I) -> bool {
i.into_iter().any(|pat| is_refutable(cx, pat))
}
match pat.kind {
PatKind::Wild => false,
PatKind::Binding(_, _, _, pat) => pat.map_or(false, |pat| is_refutable(cx, pat)),
PatKind::Box(pat) | PatKind::Ref(pat, _) => is_refutable(cx, pat),
PatKind::Lit(..) | PatKind::Range(..) => true,
PatKind::Path(ref qpath) => is_enum_variant(cx, qpath, pat.hir_id),
PatKind::Or(pats) => {
// TODO: should be the honest check, that pats is exhaustive set
are_refutable(cx, pats)
},
PatKind::Tuple(pats, _) => are_refutable(cx, pats),
PatKind::Struct(ref qpath, fields, _) => {
is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, fields.iter().map(|field| field.pat))
},
PatKind::TupleStruct(ref qpath, pats, _) => is_enum_variant(cx, qpath, pat.hir_id) || are_refutable(cx, pats),
PatKind::Slice(head, middle, tail) => {
match &cx.typeck_results().node_type(pat.hir_id).kind() {
rustc_ty::Slice(..) => {
// [..] is the only irrefutable slice pattern.
!head.is_empty() || middle.is_none() || !tail.is_empty()
},
rustc_ty::Array(..) => are_refutable(cx, head.iter().chain(middle).chain(tail.iter())),
_ => {
// unreachable!()
true
},
}
},
}
}
/// If the pattern is an `or` pattern, call the function once for each sub pattern. Otherwise, call
/// the function once on the given pattern.
pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>, mut f: F) {
if let PatKind::Or(pats) = pat.kind {
pats.iter().for_each(f);
} else {
f(pat);
}
}
pub fn is_self(slf: &Param<'_>) -> bool {
if let PatKind::Binding(.., name, _) = slf.pat.kind {
name.name == kw::SelfLower
} else {
false
}
}
pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
if let TyKind::Path(QPath::Resolved(None, path)) = slf.kind {
if let Res::SelfTyParam { .. } | Res::SelfTyAlias { .. } = path.res {
return true;
}
}
false
}
pub fn iter_input_pats<'tcx>(decl: &FnDecl<'_>, body: &'tcx Body<'_>) -> impl Iterator<Item = &'tcx Param<'tcx>> {
(0..decl.inputs.len()).map(move |i| &body.params[i])
}
/// Checks if a given expression is a match expression expanded from the `?`
/// operator or the `try` macro.
pub fn is_try<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
fn is_ok(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
if_chain! {
if let PatKind::TupleStruct(ref path, pat, ddpos) = arm.pat.kind;
if ddpos.as_opt_usize().is_none();
if is_res_lang_ctor(cx, cx.qpath_res(path, arm.pat.hir_id), ResultOk);
if let PatKind::Binding(_, hir_id, _, None) = pat[0].kind;
if path_to_local_id(arm.body, hir_id);
then {
return true;
}
}
false
}
fn is_err(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
if let PatKind::TupleStruct(ref path, _, _) = arm.pat.kind {
is_res_lang_ctor(cx, cx.qpath_res(path, arm.pat.hir_id), ResultErr)
} else {
false
}
}
if let ExprKind::Match(_, arms, ref source) = expr.kind {
// desugared from a `?` operator
if *source == MatchSource::TryDesugar {
return Some(expr);
}
if_chain! {
if arms.len() == 2;
if arms[0].guard.is_none();
if arms[1].guard.is_none();
if (is_ok(cx, &arms[0]) && is_err(cx, &arms[1])) || (is_ok(cx, &arms[1]) && is_err(cx, &arms[0]));
then {
return Some(expr);
}
}
}
None
}
/// Returns `true` if the lint is allowed in the current context. This is useful for
/// skipping long running code when it's unnecessary
///
/// This function should check the lint level for the same node, that the lint will
/// be emitted at. If the information is buffered to be emitted at a later point, please
/// make sure to use `span_lint_hir` functions to emit the lint. This ensures that
/// expectations at the checked nodes will be fulfilled.
pub fn is_lint_allowed(cx: &LateContext<'_>, lint: &'static Lint, id: HirId) -> bool {
cx.tcx.lint_level_at_node(lint, id).0 == Level::Allow
}
pub fn strip_pat_refs<'hir>(mut pat: &'hir Pat<'hir>) -> &'hir Pat<'hir> {
while let PatKind::Ref(subpat, _) = pat.kind {
pat = subpat;
}
pat
}
pub fn int_bits(tcx: TyCtxt<'_>, ity: rustc_ty::IntTy) -> u64 {
Integer::from_int_ty(&tcx, ity).size().bits()
}
#[expect(clippy::cast_possible_wrap)]
/// Turn a constant int byte representation into an i128
pub fn sext(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::IntTy) -> i128 {
let amt = 128 - int_bits(tcx, ity);
((u as i128) << amt) >> amt
}
#[expect(clippy::cast_sign_loss)]
/// clip unused bytes
pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: rustc_ty::IntTy) -> u128 {
let amt = 128 - int_bits(tcx, ity);
((u as u128) << amt) >> amt
}
/// clip unused bytes
pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: rustc_ty::UintTy) -> u128 {
let bits = Integer::from_uint_ty(&tcx, ity).size().bits();
let amt = 128 - bits;
(u << amt) >> amt
}
pub fn has_attr(attrs: &[ast::Attribute], symbol: Symbol) -> bool {
attrs.iter().any(|attr| attr.has_name(symbol))
}
pub fn any_parent_has_attr(tcx: TyCtxt<'_>, node: HirId, symbol: Symbol) -> bool {
let map = &tcx.hir();
let mut prev_enclosing_node = None;
let mut enclosing_node = node;
while Some(enclosing_node) != prev_enclosing_node {
if has_attr(map.attrs(enclosing_node), symbol) {
return true;
}
prev_enclosing_node = Some(enclosing_node);
enclosing_node = map.get_parent_item(enclosing_node).into();
}
false
}
pub fn any_parent_is_automatically_derived(tcx: TyCtxt<'_>, node: HirId) -> bool {
any_parent_has_attr(tcx, node, sym::automatically_derived)
}
/// Matches a function call with the given path and returns the arguments.
///
/// Usage:
///
/// ```rust,ignore
/// if let Some(args) = match_function_call(cx, cmp_max_call, &paths::CMP_MAX);
/// ```
/// This function is deprecated. Use [`match_function_call_with_def_id`].
pub fn match_function_call<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx Expr<'_>,
path: &[&str],
) -> Option<&'tcx [Expr<'tcx>]> {
if_chain! {
if let ExprKind::Call(fun, args) = expr.kind;
if let ExprKind::Path(ref qpath) = fun.kind;
if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
if match_def_path(cx, fun_def_id, path);
then {
return Some(args);
}
};
None
}
pub fn match_function_call_with_def_id<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx Expr<'_>,
fun_def_id: DefId,
) -> Option<&'tcx [Expr<'tcx>]> {
if_chain! {
if let ExprKind::Call(fun, args) = expr.kind;
if let ExprKind::Path(ref qpath) = fun.kind;
if cx.qpath_res(qpath, fun.hir_id).opt_def_id() == Some(fun_def_id);
then {
return Some(args);
}
};
None
}
/// Checks if the given `DefId` matches any of the paths. Returns the index of matching path, if
/// any.
///
/// Please use `tcx.get_diagnostic_name` if the targets are all diagnostic items.
pub fn match_any_def_paths(cx: &LateContext<'_>, did: DefId, paths: &[&[&str]]) -> Option<usize> {
let search_path = cx.get_def_path(did);
paths
.iter()
.position(|p| p.iter().map(|x| Symbol::intern(x)).eq(search_path.iter().copied()))
}
/// Checks if the given `DefId` matches the path.
pub fn match_def_path<'tcx>(cx: &LateContext<'tcx>, did: DefId, syms: &[&str]) -> bool {
// We should probably move to Symbols in Clippy as well rather than interning every time.
let path = cx.get_def_path(did);
syms.iter().map(|x| Symbol::intern(x)).eq(path.iter().copied())
}
/// Checks if the given `DefId` matches the `libc` item.
pub fn match_libc_symbol(cx: &LateContext<'_>, did: DefId, name: &str) -> bool {
let path = cx.get_def_path(did);
// libc is meant to be used as a flat list of names, but they're all actually defined in different
// modules based on the target platform. Ignore everything but crate name and the item name.
path.first().map_or(false, |s| s.as_str() == "libc") && path.last().map_or(false, |s| s.as_str() == name)
}
/// Returns the list of condition expressions and the list of blocks in a
/// sequence of `if/else`.
/// E.g., this returns `([a, b], [c, d, e])` for the expression
/// `if a { c } else if b { d } else { e }`.
pub fn if_sequence<'tcx>(mut expr: &'tcx Expr<'tcx>) -> (Vec<&'tcx Expr<'tcx>>, Vec<&'tcx Block<'tcx>>) {
let mut conds = Vec::new();
let mut blocks: Vec<&Block<'_>> = Vec::new();
while let Some(higher::IfOrIfLet { cond, then, r#else }) = higher::IfOrIfLet::hir(expr) {
conds.push(cond);
if let ExprKind::Block(block, _) = then.kind {
blocks.push(block);
} else {
panic!("ExprKind::If node is not an ExprKind::Block");
}
if let Some(else_expr) = r#else {
expr = else_expr;
} else {
break;
}
}
// final `else {..}`
if !blocks.is_empty() {
if let ExprKind::Block(block, _) = expr.kind {
blocks.push(block);
}
}
(conds, blocks)
}
/// Checks if the given function kind is an async function.
pub fn is_async_fn(kind: FnKind<'_>) -> bool {
matches!(kind, FnKind::ItemFn(_, _, header) if header.asyncness == IsAsync::Async)
}
/// Peels away all the compiler generated code surrounding the body of an async function,
pub fn get_async_fn_body<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'_>) -> Option<&'tcx Expr<'tcx>> {
if let ExprKind::Call(
_,
&[
Expr {
kind: ExprKind::Closure(&Closure { body, .. }),
..
},
],
) = body.value.kind
{
if let ExprKind::Block(
Block {
stmts: [],
expr:
Some(Expr {
kind: ExprKind::DropTemps(expr),
..
}),
..
},
_,
) = tcx.hir().body(body).value.kind
{
return Some(expr);
}
};
None
}
// check if expr is calling method or function with #[must_use] attribute
pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
let did = match expr.kind {
ExprKind::Call(path, _) => if_chain! {
if let ExprKind::Path(ref qpath) = path.kind;
if let def::Res::Def(_, did) = cx.qpath_res(qpath, path.hir_id);
then {
Some(did)
} else {
None
}
},
ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
_ => None,
};
did.map_or(false, |did| cx.tcx.has_attr(did, sym::must_use))
}
/// Checks if an expression represents the identity function
/// Only examines closures and `std::convert::identity`
pub fn is_expr_identity_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
/// Checks if a function's body represents the identity function. Looks for bodies of the form:
/// * `|x| x`
/// * `|x| return x`
/// * `|x| { return x }`
/// * `|x| { return x; }`
fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool {
let id = if_chain! {
if let [param] = func.params;
if let PatKind::Binding(_, id, _, _) = param.pat.kind;
then {
id
} else {
return false;
}
};
let mut expr = func.value;
loop {
match expr.kind {
#[rustfmt::skip]
ExprKind::Block(&Block { stmts: [], expr: Some(e), .. }, _, )
| ExprKind::Ret(Some(e)) => expr = e,
#[rustfmt::skip]
ExprKind::Block(&Block { stmts: [stmt], expr: None, .. }, _) => {
if_chain! {
if let StmtKind::Semi(e) | StmtKind::Expr(e) = stmt.kind;
if let ExprKind::Ret(Some(ret_val)) = e.kind;
then {
expr = ret_val;
} else {
return false;
}
}
},
_ => return path_to_local_id(expr, id) && cx.typeck_results().expr_adjustments(expr).is_empty(),
}
}
}
match expr.kind {
ExprKind::Closure(&Closure { body, .. }) => is_body_identity_function(cx, cx.tcx.hir().body(body)),
_ => path_def_id(cx, expr).map_or(false, |id| match_def_path(cx, id, &paths::CONVERT_IDENTITY)),
}
}
/// Gets the node where an expression is either used, or it's type is unified with another branch.
/// Returns both the node and the `HirId` of the closest child node.
pub fn get_expr_use_or_unification_node<'tcx>(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<(Node<'tcx>, HirId)> {
let mut child_id = expr.hir_id;
let mut iter = tcx.hir().parent_iter(child_id);
loop {
match iter.next() {
None => break None,
Some((id, Node::Block(_))) => child_id = id,
Some((id, Node::Arm(arm))) if arm.body.hir_id == child_id => child_id = id,
Some((_, Node::Expr(expr))) => match expr.kind {
ExprKind::Match(_, [arm], _) if arm.hir_id == child_id => child_id = expr.hir_id,
ExprKind::Block(..) | ExprKind::DropTemps(_) => child_id = expr.hir_id,
ExprKind::If(_, then_expr, None) if then_expr.hir_id == child_id => break None,
_ => break Some((Node::Expr(expr), child_id)),
},
Some((_, node)) => break Some((node, child_id)),
}
}
}
/// Checks if the result of an expression is used, or it's type is unified with another branch.
pub fn is_expr_used_or_unified(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
!matches!(
get_expr_use_or_unification_node(tcx, expr),
None | Some((
Node::Stmt(Stmt {
kind: StmtKind::Expr(_)
| StmtKind::Semi(_)
| StmtKind::Local(Local {
pat: Pat {
kind: PatKind::Wild,
..
},
..
}),
..
}),
_
))
)
}
/// Checks if the expression is the final expression returned from a block.
pub fn is_expr_final_block_expr(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
matches!(get_parent_node(tcx, expr.hir_id), Some(Node::Block(..)))
}
pub fn std_or_core(cx: &LateContext<'_>) -> Option<&'static str> {
if !is_no_std_crate(cx) {
Some("std")
} else if !is_no_core_crate(cx) {
Some("core")
} else {
None
}
}
pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool {
cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
if let ast::AttrKind::Normal(ref normal) = attr.kind {
normal.item.path == sym::no_std
} else {
false
}
})
}
pub fn is_no_core_crate(cx: &LateContext<'_>) -> bool {
cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
if let ast::AttrKind::Normal(ref normal) = attr.kind {
normal.item.path == sym::no_core
} else {
false
}
})
}
/// Check if parent of a hir node is a trait implementation block.
/// For example, `f` in
/// ```rust
/// # struct S;
/// # trait Trait { fn f(); }
/// impl Trait for S {
/// fn f() {}
/// }
/// ```
pub fn is_trait_impl_item(cx: &LateContext<'_>, hir_id: HirId) -> bool {
if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
} else {
false
}
}
/// Check if it's even possible to satisfy the `where` clause for the item.
///
/// `trivial_bounds` feature allows functions with unsatisfiable bounds, for example:
///
/// ```ignore
/// fn foo() where i32: Iterator {
/// for _ in 2i32 {}
/// }
/// ```
pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
use rustc_trait_selection::traits;
let predicates = cx
.tcx
.predicates_of(did)
.predicates
.iter()
.filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None });
traits::impossible_predicates(
cx.tcx,
traits::elaborate_predicates(cx.tcx, predicates)
.map(|o| o.predicate)
.collect::<Vec<_>>(),
)
}
/// Returns the `DefId` of the callee if the given expression is a function or method call.
pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
match &expr.kind {
ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
ExprKind::Call(
Expr {
kind: ExprKind::Path(qpath),
hir_id: path_hir_id,
..
},
..,
) => {
// Only return Fn-like DefIds, not the DefIds of statics/consts/etc that contain or
// deref to fn pointers, dyn Fn, impl Fn - #8850
if let Res::Def(DefKind::Fn | DefKind::Ctor(..) | DefKind::AssocFn, id) =
cx.typeck_results().qpath_res(qpath, *path_hir_id)
{
Some(id)
} else {
None
}
},
_ => None,
}
}
/// Returns `Option<String>` where String is a textual representation of the type encapsulated in
/// the slice iff the given expression is a slice of primitives (as defined in the
/// `is_recursively_primitive_type` function) and `None` otherwise.
pub fn is_slice_of_primitives(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
let expr_type = cx.typeck_results().expr_ty_adjusted(expr);
let expr_kind = expr_type.kind();
let is_primitive = match expr_kind {
rustc_ty::Slice(element_type) => is_recursively_primitive_type(*element_type),
rustc_ty::Ref(_, inner_ty, _) if matches!(inner_ty.kind(), &rustc_ty::Slice(_)) => {
if let rustc_ty::Slice(element_type) = inner_ty.kind() {
is_recursively_primitive_type(*element_type)
} else {
unreachable!()
}
},
_ => false,
};
if is_primitive {
// if we have wrappers like Array, Slice or Tuple, print these
// and get the type enclosed in the slice ref
match expr_type.peel_refs().walk().nth(1).unwrap().expect_ty().kind() {
rustc_ty::Slice(..) => return Some("slice".into()),
rustc_ty::Array(..) => return Some("array".into()),
rustc_ty::Tuple(..) => return Some("tuple".into()),
_ => {
// is_recursively_primitive_type() should have taken care
// of the rest and we can rely on the type that is found
let refs_peeled = expr_type.peel_refs();
return Some(refs_peeled.walk().last().unwrap().to_string());
},
}
}
None
}
/// returns list of all pairs (a, b) from `exprs` such that `eq(a, b)`
/// `hash` must be comformed with `eq`
pub fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)>
where
Hash: Fn(&T) -> u64,
Eq: Fn(&T, &T) -> bool,
{
match exprs {
[a, b] if eq(a, b) => return vec![(a, b)],
_ if exprs.len() <= 2 => return vec![],
_ => {},
}
let mut match_expr_list: Vec<(&T, &T)> = Vec::new();
let mut map: UnhashMap<u64, Vec<&_>> =
UnhashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default());
for expr in exprs {
match map.entry(hash(expr)) {
Entry::Occupied(mut o) => {
for o in o.get() {
if eq(o, expr) {
match_expr_list.push((o, expr));
}
}
o.get_mut().push(expr);
},
Entry::Vacant(v) => {
v.insert(vec![expr]);
},
}
}
match_expr_list
}
/// Peels off all references on the pattern. Returns the underlying pattern and the number of
/// references removed.
pub fn peel_hir_pat_refs<'a>(pat: &'a Pat<'a>) -> (&'a Pat<'a>, usize) {
fn peel<'a>(pat: &'a Pat<'a>, count: usize) -> (&'a Pat<'a>, usize) {
if let PatKind::Ref(pat, _) = pat.kind {
peel(pat, count + 1)
} else {
(pat, count)
}
}
peel(pat, 0)
}
/// Peels of expressions while the given closure returns `Some`.
pub fn peel_hir_expr_while<'tcx>(
mut expr: &'tcx Expr<'tcx>,
mut f: impl FnMut(&'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>>,
) -> &'tcx Expr<'tcx> {
while let Some(e) = f(expr) {
expr = e;
}
expr
}
/// Peels off up to the given number of references on the expression. Returns the underlying
/// expression and the number of references removed.
pub fn peel_n_hir_expr_refs<'a>(expr: &'a Expr<'a>, count: usize) -> (&'a Expr<'a>, usize) {
let mut remaining = count;
let e = peel_hir_expr_while(expr, |e| match e.kind {
ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) if remaining != 0 => {
remaining -= 1;
Some(e)
},
_ => None,
});
(e, count - remaining)
}
/// Peels off all references on the expression. Returns the underlying expression and the number of
/// references removed.
pub fn peel_hir_expr_refs<'a>(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
let mut count = 0;
let e = peel_hir_expr_while(expr, |e| match e.kind {
ExprKind::AddrOf(ast::BorrowKind::Ref, _, e) => {
count += 1;
Some(e)
},
_ => None,
});
(e, count)
}
/// Peels off all references on the type. Returns the underlying type and the number of references
/// removed.
pub fn peel_hir_ty_refs<'a>(mut ty: &'a hir::Ty<'a>) -> (&'a hir::Ty<'a>, usize) {
let mut count = 0;
loop {
match &ty.kind {
TyKind::Rptr(_, ref_ty) => {
ty = ref_ty.ty;
count += 1;
},
_ => break (ty, count),
}
}
}
/// Removes `AddrOf` operators (`&`) or deref operators (`*`), but only if a reference type is
/// dereferenced. An overloaded deref such as `Vec` to slice would not be removed.
pub fn peel_ref_operators<'hir>(cx: &LateContext<'_>, mut expr: &'hir Expr<'hir>) -> &'hir Expr<'hir> {
loop {
match expr.kind {
ExprKind::AddrOf(_, _, e) => expr = e,
ExprKind::Unary(UnOp::Deref, e) if cx.typeck_results().expr_ty(e).is_ref() => expr = e,
_ => break,
}
}
expr
}
pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
if let Res::Def(_, def_id) = path.res {
return cx.tcx.has_attr(def_id, sym::cfg) || cx.tcx.has_attr(def_id, sym::cfg_attr);
}
}
false
}
static TEST_ITEM_NAMES_CACHE: OnceLock<Mutex<FxHashMap<LocalDefId, Vec<Symbol>>>> = OnceLock::new();
fn with_test_item_names(tcx: TyCtxt<'_>, module: LocalDefId, f: impl Fn(&[Symbol]) -> bool) -> bool {
let cache = TEST_ITEM_NAMES_CACHE.get_or_init(|| Mutex::new(FxHashMap::default()));
let mut map: MutexGuard<'_, FxHashMap<LocalDefId, Vec<Symbol>>> = cache.lock().unwrap();
let value = map.entry(module);
match value {
Entry::Occupied(entry) => f(entry.get()),
Entry::Vacant(entry) => {
let mut names = Vec::new();
for id in tcx.hir().module_items(module) {
if matches!(tcx.def_kind(id.owner_id), DefKind::Const)
&& let item = tcx.hir().item(id)
&& let ItemKind::Const(ty, _body) = item.kind {
if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
// We could also check for the type name `test::TestDescAndFn`
if let Res::Def(DefKind::Struct, _) = path.res {
let has_test_marker = tcx
.hir()
.attrs(item.hir_id())
.iter()
.any(|a| a.has_name(sym::rustc_test_marker));
if has_test_marker {
names.push(item.ident.name);
}
}
}
}
}
names.sort_unstable();
f(entry.insert(names))
},
}
}
/// Checks if the function containing the given `HirId` is a `#[test]` function
///
/// Note: Add `// compile-flags: --test` to UI tests with a `#[test]` function
pub fn is_in_test_function(tcx: TyCtxt<'_>, id: hir::HirId) -> bool {
with_test_item_names(tcx, tcx.parent_module(id), |names| {
tcx.hir()
.parent_iter(id)
// Since you can nest functions we need to collect all until we leave
// function scope
.any(|(_id, node)| {
if let Node::Item(item) = node {
if let ItemKind::Fn(_, _, _) = item.kind {
// Note that we have sorted the item names in the visitor,
// so the binary_search gets the same as `contains`, but faster.
return names.binary_search(&item.ident.name).is_ok();
}
}
false
})
})
}
/// Checks if the item containing the given `HirId` has `#[cfg(test)]` attribute applied
///
/// Note: Add `// compile-flags: --test` to UI tests with a `#[cfg(test)]` function
pub fn is_in_cfg_test(tcx: TyCtxt<'_>, id: hir::HirId) -> bool {
fn is_cfg_test(attr: &Attribute) -> bool {
if attr.has_name(sym::cfg)
&& let Some(items) = attr.meta_item_list()
&& let [item] = &*items
&& item.has_name(sym::test)
{
true
} else {
false
}
}
tcx.hir()
.parent_iter(id)
.flat_map(|(parent_id, _)| tcx.hir().attrs(parent_id))
.any(is_cfg_test)
}
/// Checks whether item either has `test` attribute applied, or
/// is a module with `test` in its name.
///
/// Note: Add `// compile-flags: --test` to UI tests with a `#[test]` function
pub fn is_test_module_or_function(tcx: TyCtxt<'_>, item: &Item<'_>) -> bool {
is_in_test_function(tcx, item.hir_id())
|| matches!(item.kind, ItemKind::Mod(..))
&& item.ident.name.as_str().split('_').any(|a| a == "test" || a == "tests")
}
/// Walks the HIR tree from the given expression, up to the node where the value produced by the
/// expression is consumed. Calls the function for every node encountered this way until it returns
/// `Some`.
///
/// This allows walking through `if`, `match`, `break`, block expressions to find where the value
/// produced by the expression is consumed.
pub fn walk_to_expr_usage<'tcx, T>(
cx: &LateContext<'tcx>,
e: &Expr<'tcx>,
mut f: impl FnMut(Node<'tcx>, HirId) -> Option<T>,
) -> Option<T> {
let map = cx.tcx.hir();
let mut iter = map.parent_iter(e.hir_id);
let mut child_id = e.hir_id;
while let Some((parent_id, parent)) = iter.next() {
if let Some(x) = f(parent, child_id) {
return Some(x);
}
let parent = match parent {
Node::Expr(e) => e,
Node::Block(Block { expr: Some(body), .. }) | Node::Arm(Arm { body, .. }) if body.hir_id == child_id => {
child_id = parent_id;
continue;
},
Node::Arm(a) if a.body.hir_id == child_id => {
child_id = parent_id;
continue;
},
_ => return None,
};
match parent.kind {
ExprKind::If(child, ..) | ExprKind::Match(child, ..) if child.hir_id != child_id => child_id = parent_id,
ExprKind::Break(Destination { target_id: Ok(id), .. }, _) => {
child_id = id;
iter = map.parent_iter(id);
},
ExprKind::Block(..) => child_id = parent_id,
_ => return None,
}
}
None
}
/// Checks whether a given span has any comment token
/// This checks for all types of comment: line "//", block "/**", doc "///" "//!"
pub fn span_contains_comment(sm: &SourceMap, span: Span) -> bool {
let Ok(snippet) = sm.span_to_snippet(span) else { return false };
return tokenize(&snippet).any(|token| {
matches!(
token.kind,
TokenKind::BlockComment { .. } | TokenKind::LineComment { .. }
)
});
}
/// Return all the comments a given span contains
/// Comments are returned wrapped with their relevant delimiters
pub fn span_extract_comment(sm: &SourceMap, span: Span) -> String {
let snippet = sm.span_to_snippet(span).unwrap_or_default();
let mut comments_buf: Vec<String> = Vec::new();
let mut index: usize = 0;
for token in tokenize(&snippet) {
let token_range = index..(index + token.len as usize);
index += token.len as usize;
match token.kind {
TokenKind::BlockComment { .. } | TokenKind::LineComment { .. } => {
if let Some(comment) = snippet.get(token_range) {
comments_buf.push(comment.to_string());
}
},
_ => (),
}
}
comments_buf.join("\n")
}
macro_rules! op_utils {
($($name:ident $assign:ident)*) => {
/// Binary operation traits like `LangItem::Add`
pub static BINOP_TRAITS: &[LangItem] = &[$(LangItem::$name,)*];
/// Operator-Assign traits like `LangItem::AddAssign`
pub static OP_ASSIGN_TRAITS: &[LangItem] = &[$(LangItem::$assign,)*];
/// Converts `BinOpKind::Add` to `(LangItem::Add, LangItem::AddAssign)`, for example
pub fn binop_traits(kind: hir::BinOpKind) -> Option<(LangItem, LangItem)> {
match kind {
$(hir::BinOpKind::$name => Some((LangItem::$name, LangItem::$assign)),)*
_ => None,
}
}
};
}
op_utils! {
Add AddAssign
Sub SubAssign
Mul MulAssign
Div DivAssign
Rem RemAssign
BitXor BitXorAssign
BitAnd BitAndAssign
BitOr BitOrAssign
Shl ShlAssign
Shr ShrAssign
}