1 use crate::middle
::codegen_fn_attrs
::CodegenFnAttrFlags
;
2 use crate::ty
::print
::{FmtPrinter, Printer}
;
3 use crate::ty
::subst
::{InternalSubsts, Subst}
;
4 use crate::ty
::{self, SubstsRef, Ty, TyCtxt, TypeFoldable}
;
5 use rustc_errors
::ErrorReported
;
6 use rustc_hir
::def
::Namespace
;
7 use rustc_hir
::def_id
::{CrateNum, DefId}
;
8 use rustc_hir
::lang_items
::LangItem
;
9 use rustc_macros
::HashStable
;
13 /// A monomorphized `InstanceDef`.
15 /// Monomorphization happens on-the-fly and no monomorphized MIR is ever created. Instead, this type
16 /// simply couples a potentially generic `InstanceDef` with some substs, and codegen and const eval
17 /// will do all required substitution as they run.
18 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
19 #[derive(HashStable, Lift)]
20 pub struct Instance
<'tcx
> {
21 pub def
: InstanceDef
<'tcx
>,
22 pub substs
: SubstsRef
<'tcx
>,
25 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
26 #[derive(TyEncodable, TyDecodable, HashStable, TypeFoldable)]
27 pub enum InstanceDef
<'tcx
> {
28 /// A user-defined callable item.
34 Item(ty
::WithOptConstParam
<DefId
>),
36 /// An intrinsic `fn` item (with `"rust-intrinsic"` or `"platform-intrinsic"` ABI).
38 /// Alongside `Virtual`, this is the only `InstanceDef` that does not have its own callable MIR.
39 /// Instead, codegen and const eval "magically" evaluate calls to intrinsics purely in the
43 /// `<T as Trait>::method` where `method` receives unsizeable `self: Self` (part of the
44 /// `unsized_locals` feature).
46 /// The generated shim will take `Self` via `*mut Self` - conceptually this is `&owned Self` -
47 /// and dereference the argument to call the original function.
50 /// `fn()` pointer where the function itself cannot be turned into a pointer.
52 /// One example is `<dyn Trait as Trait>::fn`, where the shim contains
53 /// a virtual call, which codegen supports only via a direct call to the
54 /// `<dyn Trait as Trait>::fn` instance (an `InstanceDef::Virtual`).
56 /// Another example is functions annotated with `#[track_caller]`, which
57 /// must have their implicit caller location argument populated for a call.
58 /// Because this is a required part of the function's ABI but can't be tracked
59 /// as a property of the function pointer, we use a single "caller location"
60 /// (the definition of the function itself).
63 /// `<fn() as FnTrait>::call_*` (generated `FnTrait` implementation for `fn()` pointers).
65 /// `DefId` is `FnTrait::call_*`.
66 FnPtrShim(DefId
, Ty
<'tcx
>),
68 /// Dynamic dispatch to `<dyn Trait as Trait>::fn`.
70 /// This `InstanceDef` does not have callable MIR. Calls to `Virtual` instances must be
71 /// codegen'd as virtual calls through the vtable.
73 /// If this is reified to a `fn` pointer, a `ReifyShim` is used (see `ReifyShim` above for more
75 Virtual(DefId
, usize),
77 /// `<[FnMut closure] as FnOnce>::call_once`.
79 /// The `DefId` is the ID of the `call_once` method in `FnOnce`.
80 ClosureOnceShim { call_once: DefId }
,
82 /// `core::ptr::drop_in_place::<T>`.
84 /// The `DefId` is for `core::ptr::drop_in_place`.
85 /// The `Option<Ty<'tcx>>` is either `Some(T)`, or `None` for empty drop
87 DropGlue(DefId
, Option
<Ty
<'tcx
>>),
89 /// Compiler-generated `<T as Clone>::clone` implementation.
91 /// For all types that automatically implement `Copy`, a trivial `Clone` impl is provided too.
92 /// Additionally, arrays, tuples, and closures get a `Clone` shim even if they aren't `Copy`.
94 /// The `DefId` is for `Clone::clone`, the `Ty` is the type `T` with the builtin `Clone` impl.
95 CloneShim(DefId
, Ty
<'tcx
>),
98 impl<'tcx
> Instance
<'tcx
> {
99 /// Returns the `Ty` corresponding to this `Instance`, with generic substitutions applied and
100 /// lifetimes erased, allowing a `ParamEnv` to be specified for use during normalization.
101 pub fn ty(&self, tcx
: TyCtxt
<'tcx
>, param_env
: ty
::ParamEnv
<'tcx
>) -> Ty
<'tcx
> {
102 let ty
= tcx
.type_of(self.def
.def_id());
103 tcx
.subst_and_normalize_erasing_regions(self.substs
, param_env
, &ty
)
106 /// Finds a crate that contains a monomorphization of this instance that
107 /// can be linked to from the local crate. A return value of `None` means
108 /// no upstream crate provides such an exported monomorphization.
110 /// This method already takes into account the global `-Zshare-generics`
111 /// setting, always returning `None` if `share-generics` is off.
112 pub fn upstream_monomorphization(&self, tcx
: TyCtxt
<'tcx
>) -> Option
<CrateNum
> {
113 // If we are not in share generics mode, we don't link to upstream
114 // monomorphizations but always instantiate our own internal versions
116 if !tcx
.sess
.opts
.share_generics() {
120 // If this is an item that is defined in the local crate, no upstream
121 // crate can know about it/provide a monomorphization.
122 if self.def_id().is_local() {
126 // If this a non-generic instance, it cannot be a shared monomorphization.
127 self.substs
.non_erasable_generics().next()?
;
130 InstanceDef
::Item(def
) => tcx
131 .upstream_monomorphizations_for(def
.did
)
132 .and_then(|monos
| monos
.get(&self.substs
).cloned()),
133 InstanceDef
::DropGlue(_
, Some(_
)) => tcx
.upstream_drop_glue_for(self.substs
),
139 impl<'tcx
> InstanceDef
<'tcx
> {
141 pub fn def_id(self) -> DefId
{
143 InstanceDef
::Item(def
) => def
.did
,
144 InstanceDef
::VtableShim(def_id
)
145 | InstanceDef
::ReifyShim(def_id
)
146 | InstanceDef
::FnPtrShim(def_id
, _
)
147 | InstanceDef
::Virtual(def_id
, _
)
148 | InstanceDef
::Intrinsic(def_id
)
149 | InstanceDef
::ClosureOnceShim { call_once: def_id }
150 | InstanceDef
::DropGlue(def_id
, _
)
151 | InstanceDef
::CloneShim(def_id
, _
) => def_id
,
156 pub fn with_opt_param(self) -> ty
::WithOptConstParam
<DefId
> {
158 InstanceDef
::Item(def
) => def
,
159 InstanceDef
::VtableShim(def_id
)
160 | InstanceDef
::ReifyShim(def_id
)
161 | InstanceDef
::FnPtrShim(def_id
, _
)
162 | InstanceDef
::Virtual(def_id
, _
)
163 | InstanceDef
::Intrinsic(def_id
)
164 | InstanceDef
::ClosureOnceShim { call_once: def_id }
165 | InstanceDef
::DropGlue(def_id
, _
)
166 | InstanceDef
::CloneShim(def_id
, _
) => ty
::WithOptConstParam
::unknown(def_id
),
171 pub fn attrs(&self, tcx
: TyCtxt
<'tcx
>) -> ty
::Attributes
<'tcx
> {
172 tcx
.get_attrs(self.def_id())
175 /// Returns `true` if the LLVM version of this instance is unconditionally
176 /// marked with `inline`. This implies that a copy of this instance is
177 /// generated in every codegen unit.
178 /// Note that this is only a hint. See the documentation for
179 /// `generates_cgu_internal_copy` for more information.
180 pub fn requires_inline(&self, tcx
: TyCtxt
<'tcx
>) -> bool
{
181 use rustc_hir
::definitions
::DefPathData
;
182 let def_id
= match *self {
183 ty
::InstanceDef
::Item(def
) => def
.did
,
184 ty
::InstanceDef
::DropGlue(_
, Some(_
)) => return false,
188 tcx
.def_key(def_id
).disambiguated_data
.data
,
189 DefPathData
::Ctor
| DefPathData
::ClosureExpr
193 /// Returns `true` if the machine code for this instance is instantiated in
194 /// each codegen unit that references it.
195 /// Note that this is only a hint! The compiler can globally decide to *not*
196 /// do this in order to speed up compilation. CGU-internal copies are
197 /// only exist to enable inlining. If inlining is not performed (e.g. at
198 /// `-Copt-level=0`) then the time for generating them is wasted and it's
199 /// better to create a single copy with external linkage.
200 pub fn generates_cgu_internal_copy(&self, tcx
: TyCtxt
<'tcx
>) -> bool
{
201 if self.requires_inline(tcx
) {
204 if let ty
::InstanceDef
::DropGlue(.., Some(ty
)) = *self {
205 // Drop glue generally wants to be instantiated at every codegen
206 // unit, but without an #[inline] hint. We should make this
207 // available to normal end-users.
208 if tcx
.sess
.opts
.incremental
.is_none() {
211 // When compiling with incremental, we can generate a *lot* of
212 // codegen units. Including drop glue into all of them has a
213 // considerable compile time cost.
215 // We include enums without destructors to allow, say, optimizing
216 // drops of `Option::None` before LTO. We also respect the intent of
217 // `#[inline]` on `Drop::drop` implementations.
218 return ty
.ty_adt_def().map_or(true, |adt_def
| {
219 adt_def
.destructor(tcx
).map_or_else(
220 || adt_def
.is_enum(),
221 |dtor
| tcx
.codegen_fn_attrs(dtor
.did
).requests_inline(),
225 tcx
.codegen_fn_attrs(self.def_id()).requests_inline()
228 pub fn requires_caller_location(&self, tcx
: TyCtxt
<'_
>) -> bool
{
230 InstanceDef
::Item(ty
::WithOptConstParam { did: def_id, .. }
)
231 | InstanceDef
::Virtual(def_id
, _
) => {
232 tcx
.codegen_fn_attrs(def_id
).flags
.contains(CodegenFnAttrFlags
::TRACK_CALLER
)
238 /// Returns `true` when the MIR body associated with this instance should be monomorphized
239 /// by its users (e.g. codegen or miri) by substituting the `substs` from `Instance` (see
240 /// `Instance::substs_for_mir_body`).
242 /// Otherwise, returns `false` only for some kinds of shims where the construction of the MIR
243 /// body should perform necessary substitutions.
244 pub fn has_polymorphic_mir_body(&self) -> bool
{
246 InstanceDef
::CloneShim(..)
247 | InstanceDef
::FnPtrShim(..)
248 | InstanceDef
::DropGlue(_
, Some(_
)) => false,
249 InstanceDef
::ClosureOnceShim { .. }
250 | InstanceDef
::DropGlue(..)
251 | InstanceDef
::Item(_
)
252 | InstanceDef
::Intrinsic(..)
253 | InstanceDef
::ReifyShim(..)
254 | InstanceDef
::Virtual(..)
255 | InstanceDef
::VtableShim(..) => true,
260 impl<'tcx
> fmt
::Display
for Instance
<'tcx
> {
261 fn fmt(&self, f
: &mut fmt
::Formatter
<'_
>) -> fmt
::Result
{
262 ty
::tls
::with(|tcx
| {
263 let substs
= tcx
.lift(self.substs
).expect("could not lift for printing");
264 FmtPrinter
::new(tcx
, &mut *f
, Namespace
::ValueNS
)
265 .print_def_path(self.def_id(), substs
)?
;
270 InstanceDef
::Item(_
) => Ok(()),
271 InstanceDef
::VtableShim(_
) => write
!(f
, " - shim(vtable)"),
272 InstanceDef
::ReifyShim(_
) => write
!(f
, " - shim(reify)"),
273 InstanceDef
::Intrinsic(_
) => write
!(f
, " - intrinsic"),
274 InstanceDef
::Virtual(_
, num
) => write
!(f
, " - virtual#{}", num
),
275 InstanceDef
::FnPtrShim(_
, ty
) => write
!(f
, " - shim({})", ty
),
276 InstanceDef
::ClosureOnceShim { .. }
=> write
!(f
, " - shim"),
277 InstanceDef
::DropGlue(_
, None
) => write
!(f
, " - shim(None)"),
278 InstanceDef
::DropGlue(_
, Some(ty
)) => write
!(f
, " - shim(Some({}))", ty
),
279 InstanceDef
::CloneShim(_
, ty
) => write
!(f
, " - shim({})", ty
),
284 impl<'tcx
> Instance
<'tcx
> {
285 pub fn new(def_id
: DefId
, substs
: SubstsRef
<'tcx
>) -> Instance
<'tcx
> {
287 !substs
.has_escaping_bound_vars(),
288 "substs of instance {:?} not normalized for codegen: {:?}",
292 Instance { def: InstanceDef::Item(ty::WithOptConstParam::unknown(def_id)), substs }
295 pub fn mono(tcx
: TyCtxt
<'tcx
>, def_id
: DefId
) -> Instance
<'tcx
> {
296 let substs
= InternalSubsts
::for_item(tcx
, def_id
, |param
, _
| match param
.kind
{
297 ty
::GenericParamDefKind
::Lifetime
=> tcx
.lifetimes
.re_erased
.into(),
298 ty
::GenericParamDefKind
::Type { .. }
=> {
299 bug
!("Instance::mono: {:?} has type parameters", def_id
)
301 ty
::GenericParamDefKind
::Const { .. }
=> {
302 bug
!("Instance::mono: {:?} has const parameters", def_id
)
306 Instance
::new(def_id
, substs
)
310 pub fn def_id(&self) -> DefId
{
314 /// Resolves a `(def_id, substs)` pair to an (optional) instance -- most commonly,
315 /// this is used to find the precise code that will run for a trait method invocation,
318 /// Returns `Ok(None)` if we cannot resolve `Instance` to a specific instance.
319 /// For example, in a context like this,
322 /// fn foo<T: Debug>(t: T) { ... }
325 /// trying to resolve `Debug::fmt` applied to `T` will yield `Ok(None)`, because we do not
326 /// know what code ought to run. (Note that this setting is also affected by the
327 /// `RevealMode` in the parameter environment.)
329 /// Presuming that coherence and type-check have succeeded, if this method is invoked
330 /// in a monomorphic context (i.e., like during codegen), then it is guaranteed to return
331 /// `Ok(Some(instance))`.
333 /// Returns `Err(ErrorReported)` when the `Instance` resolution process
334 /// couldn't complete due to errors elsewhere - this is distinct
335 /// from `Ok(None)` to avoid misleading diagnostics when an error
336 /// has already been/will be emitted, for the original cause
339 param_env
: ty
::ParamEnv
<'tcx
>,
341 substs
: SubstsRef
<'tcx
>,
342 ) -> Result
<Option
<Instance
<'tcx
>>, ErrorReported
> {
343 Instance
::resolve_opt_const_arg(
346 ty
::WithOptConstParam
::unknown(def_id
),
351 // This should be kept up to date with `resolve`.
352 #[instrument(level = "debug", skip(tcx))]
353 pub fn resolve_opt_const_arg(
355 param_env
: ty
::ParamEnv
<'tcx
>,
356 def
: ty
::WithOptConstParam
<DefId
>,
357 substs
: SubstsRef
<'tcx
>,
358 ) -> Result
<Option
<Instance
<'tcx
>>, ErrorReported
> {
359 // All regions in the result of this query are erased, so it's
360 // fine to erase all of the input regions.
362 // HACK(eddyb) erase regions in `substs` first, so that `param_env.and(...)`
363 // below is more likely to ignore the bounds in scope (e.g. if the only
364 // generic parameters mentioned by `substs` were lifetime ones).
365 let substs
= tcx
.erase_regions(substs
);
367 // FIXME(eddyb) should this always use `param_env.with_reveal_all()`?
368 if let Some((did
, param_did
)) = def
.as_const_arg() {
369 tcx
.resolve_instance_of_const_arg(
370 tcx
.erase_regions(param_env
.and((did
, param_did
, substs
))),
373 tcx
.resolve_instance(tcx
.erase_regions(param_env
.and((def
.did
, substs
))))
377 pub fn resolve_for_fn_ptr(
379 param_env
: ty
::ParamEnv
<'tcx
>,
381 substs
: SubstsRef
<'tcx
>,
382 ) -> Option
<Instance
<'tcx
>> {
383 debug
!("resolve(def_id={:?}, substs={:?})", def_id
, substs
);
384 Instance
::resolve(tcx
, param_env
, def_id
, substs
).ok().flatten().map(|mut resolved
| {
386 InstanceDef
::Item(def
) if resolved
.def
.requires_caller_location(tcx
) => {
387 debug
!(" => fn pointer created for function with #[track_caller]");
388 resolved
.def
= InstanceDef
::ReifyShim(def
.did
);
390 InstanceDef
::Virtual(def_id
, _
) => {
391 debug
!(" => fn pointer created for virtual call");
392 resolved
.def
= InstanceDef
::ReifyShim(def_id
);
401 pub fn resolve_for_vtable(
403 param_env
: ty
::ParamEnv
<'tcx
>,
405 substs
: SubstsRef
<'tcx
>,
406 ) -> Option
<Instance
<'tcx
>> {
407 debug
!("resolve_for_vtable(def_id={:?}, substs={:?})", def_id
, substs
);
408 let fn_sig
= tcx
.fn_sig(def_id
);
409 let is_vtable_shim
= !fn_sig
.inputs().skip_binder().is_empty()
410 && fn_sig
.input(0).skip_binder().is_param(0)
411 && tcx
.generics_of(def_id
).has_self
;
413 debug
!(" => associated item with unsizeable self: Self");
414 Some(Instance { def: InstanceDef::VtableShim(def_id), substs }
)
416 Instance
::resolve(tcx
, param_env
, def_id
, substs
).ok().flatten().map(|mut resolved
| {
418 InstanceDef
::Item(def
) => {
419 // We need to generate a shim when we cannot guarantee that
420 // the caller of a trait object method will be aware of
421 // `#[track_caller]` - this ensures that the caller
422 // and callee ABI will always match.
424 // The shim is generated when all of these conditions are met:
426 // 1) The underlying method expects a caller location parameter
428 if resolved
.def
.requires_caller_location(tcx
)
429 // 2) The caller location parameter comes from having `#[track_caller]`
430 // on the implementation, and *not* on the trait method.
431 && !tcx
.should_inherit_track_caller(def
.did
)
432 // If the method implementation comes from the trait definition itself
433 // (e.g. `trait Foo { #[track_caller] my_fn() { /* impl */ } }`),
434 // then we don't need to generate a shim. This check is needed because
435 // `should_inherit_track_caller` returns `false` if our method
436 // implementation comes from the trait block, and not an impl block
438 tcx
.opt_associated_item(def
.did
),
440 container
: ty
::AssocItemContainer
::TraitContainer(_
),
446 " => vtable fn pointer created for function with #[track_caller]"
448 resolved
.def
= InstanceDef
::ReifyShim(def
.did
);
451 InstanceDef
::Virtual(def_id
, _
) => {
452 debug
!(" => vtable fn pointer created for virtual call");
453 resolved
.def
= InstanceDef
::ReifyShim(def_id
);
463 pub fn resolve_closure(
466 substs
: ty
::SubstsRef
<'tcx
>,
467 requested_kind
: ty
::ClosureKind
,
468 ) -> Instance
<'tcx
> {
469 let actual_kind
= substs
.as_closure().kind();
471 match needs_fn_once_adapter_shim(actual_kind
, requested_kind
) {
472 Ok(true) => Instance
::fn_once_adapter_instance(tcx
, def_id
, substs
),
473 _
=> Instance
::new(def_id
, substs
),
477 pub fn resolve_drop_in_place(tcx
: TyCtxt
<'tcx
>, ty
: Ty
<'tcx
>) -> ty
::Instance
<'tcx
> {
478 let def_id
= tcx
.require_lang_item(LangItem
::DropInPlace
, None
);
479 let substs
= tcx
.intern_substs(&[ty
.into()]);
480 Instance
::resolve(tcx
, ty
::ParamEnv
::reveal_all(), def_id
, substs
).unwrap().unwrap()
483 pub fn fn_once_adapter_instance(
486 substs
: ty
::SubstsRef
<'tcx
>,
487 ) -> Instance
<'tcx
> {
488 debug
!("fn_once_adapter_shim({:?}, {:?})", closure_did
, substs
);
489 let fn_once
= tcx
.require_lang_item(LangItem
::FnOnce
, None
);
491 .associated_items(fn_once
)
492 .in_definition_order()
493 .find(|it
| it
.kind
== ty
::AssocKind
::Fn
)
496 let def
= ty
::InstanceDef
::ClosureOnceShim { call_once }
;
498 let self_ty
= tcx
.mk_closure(closure_did
, substs
);
500 let sig
= substs
.as_closure().sig();
501 let sig
= tcx
.normalize_erasing_late_bound_regions(ty
::ParamEnv
::reveal_all(), sig
);
502 assert_eq
!(sig
.inputs().len(), 1);
503 let substs
= tcx
.mk_substs_trait(self_ty
, &[sig
.inputs()[0].into()]);
505 debug
!("fn_once_adapter_shim: self_ty={:?} sig={:?}", self_ty
, sig
);
506 Instance { def, substs }
509 /// Depending on the kind of `InstanceDef`, the MIR body associated with an
510 /// instance is expressed in terms of the generic parameters of `self.def_id()`, and in other
511 /// cases the MIR body is expressed in terms of the types found in the substitution array.
512 /// In the former case, we want to substitute those generic types and replace them with the
513 /// values from the substs when monomorphizing the function body. But in the latter case, we
514 /// don't want to do that substitution, since it has already been done effectively.
516 /// This function returns `Some(substs)` in the former case and `None` otherwise -- i.e., if
517 /// this function returns `None`, then the MIR body does not require substitution during
519 fn substs_for_mir_body(&self) -> Option
<SubstsRef
<'tcx
>> {
520 if self.def
.has_polymorphic_mir_body() { Some(self.substs) }
else { None }
523 pub fn subst_mir
<T
>(&self, tcx
: TyCtxt
<'tcx
>, v
: &T
) -> T
525 T
: TypeFoldable
<'tcx
> + Copy
,
527 if let Some(substs
) = self.substs_for_mir_body() { v.subst(tcx, substs) }
else { *v }
531 pub fn subst_mir_and_normalize_erasing_regions
<T
>(
534 param_env
: ty
::ParamEnv
<'tcx
>,
538 T
: TypeFoldable
<'tcx
> + Clone
,
540 if let Some(substs
) = self.substs_for_mir_body() {
541 tcx
.subst_and_normalize_erasing_regions(substs
, param_env
, v
)
543 tcx
.normalize_erasing_regions(param_env
, v
)
547 /// Returns a new `Instance` where generic parameters in `instance.substs` are replaced by
548 /// identity parameters if they are determined to be unused in `instance.def`.
549 pub fn polymorphize(self, tcx
: TyCtxt
<'tcx
>) -> Self {
550 debug
!("polymorphize: running polymorphization analysis");
551 if !tcx
.sess
.opts
.debugging_opts
.polymorphize
{
555 if let InstanceDef
::Item(def
) = self.def
{
556 let polymorphized_substs
= polymorphize(tcx
, def
.did
, self.substs
);
557 debug
!("polymorphize: self={:?} polymorphized_substs={:?}", self, polymorphized_substs
);
558 Self { def: self.def, substs: polymorphized_substs }
565 fn polymorphize
<'tcx
>(
568 substs
: SubstsRef
<'tcx
>,
569 ) -> SubstsRef
<'tcx
> {
570 debug
!("polymorphize({:?}, {:?})", def_id
, substs
);
571 let unused
= tcx
.unused_generic_params(def_id
);
572 debug
!("polymorphize: unused={:?}", unused
);
574 // If this is a closure or generator then we need to handle the case where another closure
575 // from the function is captured as an upvar and hasn't been polymorphized. In this case,
576 // the unpolymorphized upvar closure would result in a polymorphized closure producing
577 // multiple mono items (and eventually symbol clashes).
578 let upvars_ty
= if tcx
.is_closure(def_id
) {
579 Some(substs
.as_closure().tupled_upvars_ty())
580 } else if tcx
.type_of(def_id
).is_generator() {
581 Some(substs
.as_generator().tupled_upvars_ty())
585 let has_upvars
= upvars_ty
.map_or(false, |ty
| ty
.tuple_fields().count() > 0);
586 debug
!("polymorphize: upvars_ty={:?} has_upvars={:?}", upvars_ty
, has_upvars
);
588 struct PolymorphizationFolder
<'tcx
> {
592 impl ty
::TypeFolder
<'tcx
> for PolymorphizationFolder
<'tcx
> {
593 fn tcx
<'a
>(&'a
self) -> TyCtxt
<'tcx
> {
597 fn fold_ty(&mut self, ty
: Ty
<'tcx
>) -> Ty
<'tcx
> {
598 debug
!("fold_ty: ty={:?}", ty
);
600 ty
::Closure(def_id
, substs
) => {
601 let polymorphized_substs
= polymorphize(self.tcx
, def_id
, substs
);
602 if substs
== polymorphized_substs
{
605 self.tcx
.mk_closure(def_id
, polymorphized_substs
)
608 ty
::Generator(def_id
, substs
, movability
) => {
609 let polymorphized_substs
= polymorphize(self.tcx
, def_id
, substs
);
610 if substs
== polymorphized_substs
{
613 self.tcx
.mk_generator(def_id
, polymorphized_substs
, movability
)
616 _
=> ty
.super_fold_with(self),
621 InternalSubsts
::for_item(tcx
, def_id
, |param
, _
| {
622 let is_unused
= unused
.contains(param
.index
).unwrap_or(false);
623 debug
!("polymorphize: param={:?} is_unused={:?}", param
, is_unused
);
625 // Upvar case: If parameter is a type parameter..
626 ty
::GenericParamDefKind
::Type { .. }
if
627 // ..and has upvars..
629 // ..and this param has the same type as the tupled upvars..
630 upvars_ty
== Some(substs
[param
.index
as usize].expect_ty()) => {
631 // ..then double-check that polymorphization marked it used..
632 debug_assert
!(!is_unused
);
633 // ..and polymorphize any closures/generators captured as upvars.
634 let upvars_ty
= upvars_ty
.unwrap();
635 let polymorphized_upvars_ty
= upvars_ty
.fold_with(
636 &mut PolymorphizationFolder { tcx }
);
637 debug
!("polymorphize: polymorphized_upvars_ty={:?}", polymorphized_upvars_ty
);
638 ty
::GenericArg
::from(polymorphized_upvars_ty
)
641 // Simple case: If parameter is a const or type parameter..
642 ty
::GenericParamDefKind
::Const { .. }
| ty
::GenericParamDefKind
::Type { .. }
if
643 // ..and is within range and unused..
644 unused
.contains(param
.index
).unwrap_or(false) =>
645 // ..then use the identity for this parameter.
646 tcx
.mk_param_from_def(param
),
648 // Otherwise, use the parameter as before.
649 _
=> substs
[param
.index
as usize],
654 fn needs_fn_once_adapter_shim(
655 actual_closure_kind
: ty
::ClosureKind
,
656 trait_closure_kind
: ty
::ClosureKind
,
657 ) -> Result
<bool
, ()> {
658 match (actual_closure_kind
, trait_closure_kind
) {
659 (ty
::ClosureKind
::Fn
, ty
::ClosureKind
::Fn
)
660 | (ty
::ClosureKind
::FnMut
, ty
::ClosureKind
::FnMut
)
661 | (ty
::ClosureKind
::FnOnce
, ty
::ClosureKind
::FnOnce
) => {
662 // No adapter needed.
665 (ty
::ClosureKind
::Fn
, ty
::ClosureKind
::FnMut
) => {
666 // The closure fn `llfn` is a `fn(&self, ...)`. We want a
667 // `fn(&mut self, ...)`. In fact, at codegen time, these are
668 // basically the same thing, so we can just return llfn.
671 (ty
::ClosureKind
::Fn
| ty
::ClosureKind
::FnMut
, ty
::ClosureKind
::FnOnce
) => {
672 // The closure fn `llfn` is a `fn(&self, ...)` or `fn(&mut
673 // self, ...)`. We want a `fn(self, ...)`. We can produce
674 // this by doing something like:
676 // fn call_once(self, ...) { call_mut(&self, ...) }
677 // fn call_once(mut self, ...) { call_mut(&mut self, ...) }
679 // These are both the same at codegen time.
682 (ty
::ClosureKind
::FnMut
| ty
::ClosureKind
::FnOnce
, _
) => Err(()),