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//! THIR datatypes and definitions. See the [rustc dev guide] for more info.
//!
//! If you compare the THIR [`ExprKind`] to [`hir::ExprKind`], you will see it is
//! a good bit simpler. In fact, a number of the more straight-forward
//! MIR simplifications are already done in the lowering to THIR. For
//! example, method calls and overloaded operators are absent: they are
//! expected to be converted into [`ExprKind::Call`] instances.
//!
//! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/thir.html
use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
use rustc_errors::{DiagnosticArgValue, IntoDiagnosticArg};
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_hir::RangeEnd;
use rustc_index::newtype_index;
use rustc_index::IndexVec;
use rustc_middle::middle::region;
use rustc_middle::mir::interpret::AllocId;
use rustc_middle::mir::{self, BinOp, BorrowKind, FakeReadCause, Mutability, UnOp};
use rustc_middle::ty::adjustment::PointerCoercion;
use rustc_middle::ty::GenericArgsRef;
use rustc_middle::ty::{self, AdtDef, FnSig, List, Ty, UpvarArgs};
use rustc_middle::ty::{CanonicalUserType, CanonicalUserTypeAnnotation};
use rustc_span::def_id::LocalDefId;
use rustc_span::{sym, Span, Symbol, DUMMY_SP};
use rustc_target::abi::{FieldIdx, VariantIdx};
use rustc_target::asm::InlineAsmRegOrRegClass;
use std::fmt;
use std::ops::Index;
pub mod visit;
macro_rules! thir_with_elements {
(
$($field_name:ident: $field_ty:ty,)*
@elements:
$($name:ident: $id:ty => $value:ty => $format:literal,)*
) => {
$(
newtype_index! {
#[derive(HashStable)]
#[debug_format = $format]
pub struct $id {}
}
)*
/// A container for a THIR body.
///
/// This can be indexed directly by any THIR index (e.g. [`ExprId`]).
#[derive(Debug, HashStable, Clone)]
pub struct Thir<'tcx> {
$(
pub $field_name: $field_ty,
)*
$(
pub $name: IndexVec<$id, $value>,
)*
}
impl<'tcx> Thir<'tcx> {
pub fn new($($field_name: $field_ty,)*) -> Thir<'tcx> {
Thir {
$(
$field_name,
)*
$(
$name: IndexVec::new(),
)*
}
}
}
$(
impl<'tcx> Index<$id> for Thir<'tcx> {
type Output = $value;
fn index(&self, index: $id) -> &Self::Output {
&self.$name[index]
}
}
)*
}
}
pub const UPVAR_ENV_PARAM: ParamId = ParamId::from_u32(0);
thir_with_elements! {
body_type: BodyTy<'tcx>,
@elements:
arms: ArmId => Arm<'tcx> => "a{}",
blocks: BlockId => Block => "b{}",
exprs: ExprId => Expr<'tcx> => "e{}",
stmts: StmtId => Stmt<'tcx> => "s{}",
params: ParamId => Param<'tcx> => "p{}",
}
#[derive(Debug, HashStable, Clone)]
pub enum BodyTy<'tcx> {
Const(Ty<'tcx>),
Fn(FnSig<'tcx>),
}
/// Description of a type-checked function parameter.
#[derive(Clone, Debug, HashStable)]
pub struct Param<'tcx> {
/// The pattern that appears in the parameter list, or None for implicit parameters.
pub pat: Option<Box<Pat<'tcx>>>,
/// The possibly inferred type.
pub ty: Ty<'tcx>,
/// Span of the explicitly provided type, or None if inferred for closures.
pub ty_span: Option<Span>,
/// Whether this param is `self`, and how it is bound.
pub self_kind: Option<hir::ImplicitSelfKind>,
/// HirId for lints.
pub hir_id: Option<hir::HirId>,
}
#[derive(Copy, Clone, Debug, HashStable)]
pub enum LintLevel {
Inherited,
Explicit(hir::HirId),
}
#[derive(Clone, Debug, HashStable)]
pub struct Block {
/// Whether the block itself has a label. Used by `label: {}`
/// and `try` blocks.
///
/// This does *not* include labels on loops, e.g. `'label: loop {}`.
pub targeted_by_break: bool,
pub region_scope: region::Scope,
pub opt_destruction_scope: Option<region::Scope>,
/// The span of the block, including the opening braces,
/// the label, and the `unsafe` keyword, if present.
pub span: Span,
/// The statements in the blocK.
pub stmts: Box<[StmtId]>,
/// The trailing expression of the block, if any.
pub expr: Option<ExprId>,
pub safety_mode: BlockSafety,
}
type UserTy<'tcx> = Option<Box<CanonicalUserType<'tcx>>>;
#[derive(Clone, Debug, HashStable)]
pub struct AdtExpr<'tcx> {
/// The ADT we're constructing.
pub adt_def: AdtDef<'tcx>,
/// The variant of the ADT.
pub variant_index: VariantIdx,
pub args: GenericArgsRef<'tcx>,
/// Optional user-given args: for something like `let x =
/// Bar::<T> { ... }`.
pub user_ty: UserTy<'tcx>,
pub fields: Box<[FieldExpr]>,
/// The base, e.g. `Foo {x: 1, .. base}`.
pub base: Option<FruInfo<'tcx>>,
}
#[derive(Clone, Debug, HashStable)]
pub struct ClosureExpr<'tcx> {
pub closure_id: LocalDefId,
pub args: UpvarArgs<'tcx>,
pub upvars: Box<[ExprId]>,
pub movability: Option<hir::Movability>,
pub fake_reads: Vec<(ExprId, FakeReadCause, hir::HirId)>,
}
#[derive(Clone, Debug, HashStable)]
pub struct InlineAsmExpr<'tcx> {
pub template: &'tcx [InlineAsmTemplatePiece],
pub operands: Box<[InlineAsmOperand<'tcx>]>,
pub options: InlineAsmOptions,
pub line_spans: &'tcx [Span],
}
#[derive(Copy, Clone, Debug, HashStable)]
pub enum BlockSafety {
Safe,
/// A compiler-generated unsafe block
BuiltinUnsafe,
/// An `unsafe` block. The `HirId` is the ID of the block.
ExplicitUnsafe(hir::HirId),
}
#[derive(Clone, Debug, HashStable)]
pub struct Stmt<'tcx> {
pub kind: StmtKind<'tcx>,
pub opt_destruction_scope: Option<region::Scope>,
}
#[derive(Clone, Debug, HashStable)]
pub enum StmtKind<'tcx> {
/// An expression with a trailing semicolon.
Expr {
/// The scope for this statement; may be used as lifetime of temporaries.
scope: region::Scope,
/// The expression being evaluated in this statement.
expr: ExprId,
},
/// A `let` binding.
Let {
/// The scope for variables bound in this `let`; it covers this and
/// all the remaining statements in the block.
remainder_scope: region::Scope,
/// The scope for the initialization itself; might be used as
/// lifetime of temporaries.
init_scope: region::Scope,
/// `let <PAT> = ...`
///
/// If a type annotation is included, it is added as an ascription pattern.
pattern: Box<Pat<'tcx>>,
/// `let pat: ty = <INIT>`
initializer: Option<ExprId>,
/// `let pat: ty = <INIT> else { <ELSE> }`
else_block: Option<BlockId>,
/// The lint level for this `let` statement.
lint_level: LintLevel,
/// Span of the `let <PAT> = <INIT>` part.
span: Span,
},
}
#[derive(Clone, Debug, Copy, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable)]
pub struct LocalVarId(pub hir::HirId);
/// A THIR expression.
#[derive(Clone, Debug, HashStable)]
pub struct Expr<'tcx> {
/// kind of expression
pub kind: ExprKind<'tcx>,
/// The type of this expression
pub ty: Ty<'tcx>,
/// The lifetime of this expression if it should be spilled into a
/// temporary; should be `None` only if in a constant context
pub temp_lifetime: Option<region::Scope>,
/// span of the expression in the source
pub span: Span,
}
#[derive(Clone, Debug, HashStable)]
pub enum ExprKind<'tcx> {
/// `Scope`s are used to explicitly mark destruction scopes,
/// and to track the `HirId` of the expressions within the scope.
Scope {
region_scope: region::Scope,
lint_level: LintLevel,
value: ExprId,
},
/// A `box <value>` expression.
Box {
value: ExprId,
},
/// An `if` expression.
If {
if_then_scope: region::Scope,
cond: ExprId,
then: ExprId,
else_opt: Option<ExprId>,
},
/// A function call. Method calls and overloaded operators are converted to plain function calls.
Call {
/// The type of the function. This is often a [`FnDef`] or a [`FnPtr`].
///
/// [`FnDef`]: ty::TyKind::FnDef
/// [`FnPtr`]: ty::TyKind::FnPtr
ty: Ty<'tcx>,
/// The function itself.
fun: ExprId,
/// The arguments passed to the function.
///
/// Note: in some cases (like calling a closure), the function call `f(...args)` gets
/// rewritten as a call to a function trait method (e.g. `FnOnce::call_once(f, (...args))`).
args: Box<[ExprId]>,
/// Whether this is from an overloaded operator rather than a
/// function call from HIR. `true` for overloaded function call.
from_hir_call: bool,
/// The span of the function, without the dot and receiver
/// (e.g. `foo(a, b)` in `x.foo(a, b)`).
fn_span: Span,
},
/// A *non-overloaded* dereference.
Deref {
arg: ExprId,
},
/// A *non-overloaded* binary operation.
Binary {
op: BinOp,
lhs: ExprId,
rhs: ExprId,
},
/// A logical operation. This is distinct from `BinaryOp` because
/// the operands need to be lazily evaluated.
LogicalOp {
op: LogicalOp,
lhs: ExprId,
rhs: ExprId,
},
/// A *non-overloaded* unary operation. Note that here the deref (`*`)
/// operator is represented by `ExprKind::Deref`.
Unary {
op: UnOp,
arg: ExprId,
},
/// A cast: `<source> as <type>`. The type we cast to is the type of
/// the parent expression.
Cast {
source: ExprId,
},
Use {
source: ExprId,
}, // Use a lexpr to get a vexpr.
/// A coercion from `!` to any type.
NeverToAny {
source: ExprId,
},
/// A pointer coercion. More information can be found in [`PointerCoercion`].
/// Pointer casts that cannot be done by coercions are represented by [`ExprKind::Cast`].
PointerCoercion {
cast: PointerCoercion,
source: ExprId,
},
/// A `loop` expression.
Loop {
body: ExprId,
},
Let {
expr: ExprId,
pat: Box<Pat<'tcx>>,
},
/// A `match` expression.
Match {
scrutinee: ExprId,
scrutinee_hir_id: hir::HirId,
arms: Box<[ArmId]>,
},
/// A block.
Block {
block: BlockId,
},
/// An assignment: `lhs = rhs`.
Assign {
lhs: ExprId,
rhs: ExprId,
},
/// A *non-overloaded* operation assignment, e.g. `lhs += rhs`.
AssignOp {
op: BinOp,
lhs: ExprId,
rhs: ExprId,
},
/// Access to a field of a struct, a tuple, an union, or an enum.
Field {
lhs: ExprId,
/// Variant containing the field.
variant_index: VariantIdx,
/// This can be a named (`.foo`) or unnamed (`.0`) field.
name: FieldIdx,
},
/// A *non-overloaded* indexing operation.
Index {
lhs: ExprId,
index: ExprId,
},
/// A local variable.
VarRef {
id: LocalVarId,
},
/// Used to represent upvars mentioned in a closure/generator
UpvarRef {
/// DefId of the closure/generator
closure_def_id: DefId,
/// HirId of the root variable
var_hir_id: LocalVarId,
},
/// A borrow, e.g. `&arg`.
Borrow {
borrow_kind: BorrowKind,
arg: ExprId,
},
/// A `&raw [const|mut] $place_expr` raw borrow resulting in type `*[const|mut] T`.
AddressOf {
mutability: hir::Mutability,
arg: ExprId,
},
/// A `break` expression.
Break {
label: region::Scope,
value: Option<ExprId>,
},
/// A `continue` expression.
Continue {
label: region::Scope,
},
/// A `return` expression.
Return {
value: Option<ExprId>,
},
/// A `become` expression.
Become {
value: ExprId,
},
/// An inline `const` block, e.g. `const {}`.
ConstBlock {
did: DefId,
args: GenericArgsRef<'tcx>,
},
/// An array literal constructed from one repeated element, e.g. `[1; 5]`.
Repeat {
value: ExprId,
count: ty::Const<'tcx>,
},
/// An array, e.g. `[a, b, c, d]`.
Array {
fields: Box<[ExprId]>,
},
/// A tuple, e.g. `(a, b, c, d)`.
Tuple {
fields: Box<[ExprId]>,
},
/// An ADT constructor, e.g. `Foo {x: 1, y: 2}`.
Adt(Box<AdtExpr<'tcx>>),
/// A type ascription on a place.
PlaceTypeAscription {
source: ExprId,
/// Type that the user gave to this expression
user_ty: UserTy<'tcx>,
},
/// A type ascription on a value, e.g. `42: i32`.
ValueTypeAscription {
source: ExprId,
/// Type that the user gave to this expression
user_ty: UserTy<'tcx>,
},
/// A closure definition.
Closure(Box<ClosureExpr<'tcx>>),
/// A literal.
Literal {
lit: &'tcx hir::Lit,
neg: bool,
},
/// For literals that don't correspond to anything in the HIR
NonHirLiteral {
lit: ty::ScalarInt,
user_ty: UserTy<'tcx>,
},
/// A literal of a ZST type.
ZstLiteral {
user_ty: UserTy<'tcx>,
},
/// Associated constants and named constants
NamedConst {
def_id: DefId,
args: GenericArgsRef<'tcx>,
user_ty: UserTy<'tcx>,
},
ConstParam {
param: ty::ParamConst,
def_id: DefId,
},
// FIXME improve docs for `StaticRef` by distinguishing it from `NamedConst`
/// A literal containing the address of a `static`.
///
/// This is only distinguished from `Literal` so that we can register some
/// info for diagnostics.
StaticRef {
alloc_id: AllocId,
ty: Ty<'tcx>,
def_id: DefId,
},
/// Inline assembly, i.e. `asm!()`.
InlineAsm(Box<InlineAsmExpr<'tcx>>),
/// Field offset (`offset_of!`)
OffsetOf {
container: Ty<'tcx>,
fields: &'tcx List<FieldIdx>,
},
/// An expression taking a reference to a thread local.
ThreadLocalRef(DefId),
/// A `yield` expression.
Yield {
value: ExprId,
},
}
/// Represents the association of a field identifier and an expression.
///
/// This is used in struct constructors.
#[derive(Clone, Debug, HashStable)]
pub struct FieldExpr {
pub name: FieldIdx,
pub expr: ExprId,
}
#[derive(Clone, Debug, HashStable)]
pub struct FruInfo<'tcx> {
pub base: ExprId,
pub field_types: Box<[Ty<'tcx>]>,
}
/// A `match` arm.
#[derive(Clone, Debug, HashStable)]
pub struct Arm<'tcx> {
pub pattern: Box<Pat<'tcx>>,
pub guard: Option<Guard<'tcx>>,
pub body: ExprId,
pub lint_level: LintLevel,
pub scope: region::Scope,
pub span: Span,
}
/// A `match` guard.
#[derive(Clone, Debug, HashStable)]
pub enum Guard<'tcx> {
If(ExprId),
IfLet(Box<Pat<'tcx>>, ExprId),
}
#[derive(Copy, Clone, Debug, HashStable)]
pub enum LogicalOp {
/// The `&&` operator.
And,
/// The `||` operator.
Or,
}
#[derive(Clone, Debug, HashStable)]
pub enum InlineAsmOperand<'tcx> {
In {
reg: InlineAsmRegOrRegClass,
expr: ExprId,
},
Out {
reg: InlineAsmRegOrRegClass,
late: bool,
expr: Option<ExprId>,
},
InOut {
reg: InlineAsmRegOrRegClass,
late: bool,
expr: ExprId,
},
SplitInOut {
reg: InlineAsmRegOrRegClass,
late: bool,
in_expr: ExprId,
out_expr: Option<ExprId>,
},
Const {
value: mir::Const<'tcx>,
span: Span,
},
SymFn {
value: mir::Const<'tcx>,
span: Span,
},
SymStatic {
def_id: DefId,
},
}
#[derive(Copy, Clone, Debug, PartialEq, HashStable)]
pub enum BindingMode {
ByValue,
ByRef(BorrowKind),
}
#[derive(Clone, Debug, HashStable)]
pub struct FieldPat<'tcx> {
pub field: FieldIdx,
pub pattern: Box<Pat<'tcx>>,
}
#[derive(Clone, Debug, HashStable)]
pub struct Pat<'tcx> {
pub ty: Ty<'tcx>,
pub span: Span,
pub kind: PatKind<'tcx>,
}
impl<'tcx> Pat<'tcx> {
pub fn wildcard_from_ty(ty: Ty<'tcx>) -> Self {
Pat { ty, span: DUMMY_SP, kind: PatKind::Wild }
}
pub fn simple_ident(&self) -> Option<Symbol> {
match self.kind {
PatKind::Binding { name, mode: BindingMode::ByValue, subpattern: None, .. } => {
Some(name)
}
_ => None,
}
}
/// Call `f` on every "binding" in a pattern, e.g., on `a` in
/// `match foo() { Some(a) => (), None => () }`
pub fn each_binding(&self, mut f: impl FnMut(Symbol, BindingMode, Ty<'tcx>, Span)) {
self.walk_always(|p| {
if let PatKind::Binding { name, mode, ty, .. } = p.kind {
f(name, mode, ty, p.span);
}
});
}
/// Walk the pattern in left-to-right order.
///
/// If `it(pat)` returns `false`, the children are not visited.
pub fn walk(&self, mut it: impl FnMut(&Pat<'tcx>) -> bool) {
self.walk_(&mut it)
}
fn walk_(&self, it: &mut impl FnMut(&Pat<'tcx>) -> bool) {
if !it(self) {
return;
}
use PatKind::*;
match &self.kind {
Wild | Range(..) | Binding { subpattern: None, .. } | Constant { .. } => {}
AscribeUserType { subpattern, .. }
| Binding { subpattern: Some(subpattern), .. }
| Deref { subpattern } => subpattern.walk_(it),
Leaf { subpatterns } | Variant { subpatterns, .. } => {
subpatterns.iter().for_each(|field| field.pattern.walk_(it))
}
Or { pats } => pats.iter().for_each(|p| p.walk_(it)),
Array { box ref prefix, ref slice, box ref suffix }
| Slice { box ref prefix, ref slice, box ref suffix } => {
prefix.iter().chain(slice.iter()).chain(suffix.iter()).for_each(|p| p.walk_(it))
}
}
}
/// Walk the pattern in left-to-right order.
///
/// If you always want to recurse, prefer this method over `walk`.
pub fn walk_always(&self, mut it: impl FnMut(&Pat<'tcx>)) {
self.walk(|p| {
it(p);
true
})
}
}
impl<'tcx> IntoDiagnosticArg for Pat<'tcx> {
fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
format!("{self}").into_diagnostic_arg()
}
}
#[derive(Clone, Debug, HashStable)]
pub struct Ascription<'tcx> {
pub annotation: CanonicalUserTypeAnnotation<'tcx>,
/// Variance to use when relating the `user_ty` to the **type of the value being
/// matched**. Typically, this is `Variance::Covariant`, since the value being matched must
/// have a type that is some subtype of the ascribed type.
///
/// Note that this variance does not apply for any bindings within subpatterns. The type
/// assigned to those bindings must be exactly equal to the `user_ty` given here.
///
/// The only place where this field is not `Covariant` is when matching constants, where
/// we currently use `Contravariant` -- this is because the constant type just needs to
/// be "comparable" to the type of the input value. So, for example:
///
/// ```text
/// match x { "foo" => .. }
/// ```
///
/// requires that `&'static str <: T_x`, where `T_x` is the type of `x`. Really, we should
/// probably be checking for a `PartialEq` impl instead, but this preserves the behavior
/// of the old type-check for now. See #57280 for details.
pub variance: ty::Variance,
}
#[derive(Clone, Debug, HashStable)]
pub enum PatKind<'tcx> {
/// A wildcard pattern: `_`.
Wild,
AscribeUserType {
ascription: Ascription<'tcx>,
subpattern: Box<Pat<'tcx>>,
},
/// `x`, `ref x`, `x @ P`, etc.
Binding {
mutability: Mutability,
name: Symbol,
mode: BindingMode,
var: LocalVarId,
ty: Ty<'tcx>,
subpattern: Option<Box<Pat<'tcx>>>,
/// Is this the leftmost occurrence of the binding, i.e., is `var` the
/// `HirId` of this pattern?
is_primary: bool,
},
/// `Foo(...)` or `Foo{...}` or `Foo`, where `Foo` is a variant name from an ADT with
/// multiple variants.
Variant {
adt_def: AdtDef<'tcx>,
args: GenericArgsRef<'tcx>,
variant_index: VariantIdx,
subpatterns: Vec<FieldPat<'tcx>>,
},
/// `(...)`, `Foo(...)`, `Foo{...}`, or `Foo`, where `Foo` is a variant name from an ADT with
/// a single variant.
Leaf {
subpatterns: Vec<FieldPat<'tcx>>,
},
/// `box P`, `&P`, `&mut P`, etc.
Deref {
subpattern: Box<Pat<'tcx>>,
},
/// One of the following:
/// * `&str` (represented as a valtree), which will be handled as a string pattern and thus
/// exhaustiveness checking will detect if you use the same string twice in different
/// patterns.
/// * integer, bool, char or float (represented as a valtree), which will be handled by
/// exhaustiveness to cover exactly its own value, similar to `&str`, but these values are
/// much simpler.
/// * Opaque constants (represented as `mir::ConstValue`), that must not be matched
/// structurally. So anything that does not derive `PartialEq` and `Eq`.
///
/// These are always compared with the matched place using (the semantics of) `PartialEq`.
Constant {
value: mir::Const<'tcx>,
},
Range(Box<PatRange<'tcx>>),
/// Matches against a slice, checking the length and extracting elements.
/// irrefutable when there is a slice pattern and both `prefix` and `suffix` are empty.
/// e.g., `&[ref xs @ ..]`.
Slice {
prefix: Box<[Box<Pat<'tcx>>]>,
slice: Option<Box<Pat<'tcx>>>,
suffix: Box<[Box<Pat<'tcx>>]>,
},
/// Fixed match against an array; irrefutable.
Array {
prefix: Box<[Box<Pat<'tcx>>]>,
slice: Option<Box<Pat<'tcx>>>,
suffix: Box<[Box<Pat<'tcx>>]>,
},
/// An or-pattern, e.g. `p | q`.
/// Invariant: `pats.len() >= 2`.
Or {
pats: Box<[Box<Pat<'tcx>>]>,
},
}
#[derive(Clone, Debug, PartialEq, HashStable)]
pub struct PatRange<'tcx> {
pub lo: mir::Const<'tcx>,
pub hi: mir::Const<'tcx>,
pub end: RangeEnd,
}
impl<'tcx> fmt::Display for Pat<'tcx> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// Printing lists is a chore.
let mut first = true;
let mut start_or_continue = |s| {
if first {
first = false;
""
} else {
s
}
};
let mut start_or_comma = || start_or_continue(", ");
match self.kind {
PatKind::Wild => write!(f, "_"),
PatKind::AscribeUserType { ref subpattern, .. } => write!(f, "{subpattern}: _"),
PatKind::Binding { mutability, name, mode, ref subpattern, .. } => {
let is_mut = match mode {
BindingMode::ByValue => mutability == Mutability::Mut,
BindingMode::ByRef(bk) => {
write!(f, "ref ")?;
matches!(bk, BorrowKind::Mut { .. })
}
};
if is_mut {
write!(f, "mut ")?;
}
write!(f, "{name}")?;
if let Some(ref subpattern) = *subpattern {
write!(f, " @ {subpattern}")?;
}
Ok(())
}
PatKind::Variant { ref subpatterns, .. } | PatKind::Leaf { ref subpatterns } => {
let variant_and_name = match self.kind {
PatKind::Variant { adt_def, variant_index, .. } => ty::tls::with(|tcx| {
let variant = adt_def.variant(variant_index);
let adt_did = adt_def.did();
let name = if tcx.get_diagnostic_item(sym::Option) == Some(adt_did)
|| tcx.get_diagnostic_item(sym::Result) == Some(adt_did)
{
variant.name.to_string()
} else {
format!("{}::{}", tcx.def_path_str(adt_def.did()), variant.name)
};
Some((variant, name))
}),
_ => self.ty.ty_adt_def().and_then(|adt_def| {
if !adt_def.is_enum() {
ty::tls::with(|tcx| {
Some((adt_def.non_enum_variant(), tcx.def_path_str(adt_def.did())))
})
} else {
None
}
}),
};
if let Some((variant, name)) = &variant_and_name {
write!(f, "{name}")?;
// Only for Adt we can have `S {...}`,
// which we handle separately here.
if variant.ctor.is_none() {
write!(f, " {{ ")?;
let mut printed = 0;
for p in subpatterns {
if let PatKind::Wild = p.pattern.kind {
continue;
}
let name = variant.fields[p.field].name;
write!(f, "{}{}: {}", start_or_comma(), name, p.pattern)?;
printed += 1;
}
if printed < variant.fields.len() {
write!(f, "{}..", start_or_comma())?;
}
return write!(f, " }}");
}
}
let num_fields =
variant_and_name.as_ref().map_or(subpatterns.len(), |(v, _)| v.fields.len());
if num_fields != 0 || variant_and_name.is_none() {
write!(f, "(")?;
for i in 0..num_fields {
write!(f, "{}", start_or_comma())?;
// Common case: the field is where we expect it.
if let Some(p) = subpatterns.get(i) {
if p.field.index() == i {
write!(f, "{}", p.pattern)?;
continue;
}
}
// Otherwise, we have to go looking for it.
if let Some(p) = subpatterns.iter().find(|p| p.field.index() == i) {
write!(f, "{}", p.pattern)?;
} else {
write!(f, "_")?;
}
}
write!(f, ")")?;
}
Ok(())
}
PatKind::Deref { ref subpattern } => {
match self.ty.kind() {
ty::Adt(def, _) if def.is_box() => write!(f, "box ")?,
ty::Ref(_, _, mutbl) => {
write!(f, "&{}", mutbl.prefix_str())?;
}
_ => bug!("{} is a bad Deref pattern type", self.ty),
}
write!(f, "{subpattern}")
}
PatKind::Constant { value } => write!(f, "{value}"),
PatKind::Range(box PatRange { lo, hi, end }) => {
write!(f, "{lo}")?;
write!(f, "{end}")?;
write!(f, "{hi}")
}
PatKind::Slice { ref prefix, ref slice, ref suffix }
| PatKind::Array { ref prefix, ref slice, ref suffix } => {
write!(f, "[")?;
for p in prefix.iter() {
write!(f, "{}{}", start_or_comma(), p)?;
}
if let Some(ref slice) = *slice {
write!(f, "{}", start_or_comma())?;
match slice.kind {
PatKind::Wild => {}
_ => write!(f, "{slice}")?,
}
write!(f, "..")?;
}
for p in suffix.iter() {
write!(f, "{}{}", start_or_comma(), p)?;
}
write!(f, "]")
}
PatKind::Or { ref pats } => {
for pat in pats.iter() {
write!(f, "{}{}", start_or_continue(" | "), pat)?;
}
Ok(())
}
}
}
}
// Some nodes are used a lot. Make sure they don't unintentionally get bigger.
#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
mod size_asserts {
use super::*;
// tidy-alphabetical-start
static_assert_size!(Block, 56);
static_assert_size!(Expr<'_>, 64);
static_assert_size!(ExprKind<'_>, 40);
static_assert_size!(Pat<'_>, 64);
static_assert_size!(PatKind<'_>, 48);
static_assert_size!(Stmt<'_>, 56);
static_assert_size!(StmtKind<'_>, 48);
// tidy-alphabetical-end
}