use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags; use crate::ty::print::{FmtPrinter, Printer}; use crate::ty::subst::{InternalSubsts, Subst}; use crate::ty::{ self, EarlyBinder, SubstsRef, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable, TypeVisitable, }; use rustc_errors::ErrorGuaranteed; use rustc_hir::def::Namespace; use rustc_hir::def_id::{CrateNum, DefId}; use rustc_hir::lang_items::LangItem; use rustc_macros::HashStable; use rustc_middle::ty::normalize_erasing_regions::NormalizationError; use rustc_span::Symbol; use std::fmt; /// A monomorphized `InstanceDef`. /// /// Monomorphization happens on-the-fly and no monomorphized MIR is ever created. Instead, this type /// simply couples a potentially generic `InstanceDef` with some substs, and codegen and const eval /// will do all required substitution as they run. #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)] #[derive(HashStable, Lift)] pub struct Instance<'tcx> { pub def: InstanceDef<'tcx>, pub substs: SubstsRef<'tcx>, } #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)] #[derive(TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)] pub enum InstanceDef<'tcx> { /// A user-defined callable item. /// /// This includes: /// - `fn` items /// - closures /// - generators Item(ty::WithOptConstParam), /// An intrinsic `fn` item (with `"rust-intrinsic"` or `"platform-intrinsic"` ABI). /// /// Alongside `Virtual`, this is the only `InstanceDef` that does not have its own callable MIR. /// Instead, codegen and const eval "magically" evaluate calls to intrinsics purely in the /// caller. Intrinsic(DefId), /// `::method` where `method` receives unsizeable `self: Self` (part of the /// `unsized_locals` feature). /// /// The generated shim will take `Self` via `*mut Self` - conceptually this is `&owned Self` - /// and dereference the argument to call the original function. VTableShim(DefId), /// `fn()` pointer where the function itself cannot be turned into a pointer. /// /// One example is `::fn`, where the shim contains /// a virtual call, which codegen supports only via a direct call to the /// `::fn` instance (an `InstanceDef::Virtual`). /// /// Another example is functions annotated with `#[track_caller]`, which /// must have their implicit caller location argument populated for a call. /// Because this is a required part of the function's ABI but can't be tracked /// as a property of the function pointer, we use a single "caller location" /// (the definition of the function itself). ReifyShim(DefId), /// `::call_*` (generated `FnTrait` implementation for `fn()` pointers). /// /// `DefId` is `FnTrait::call_*`. FnPtrShim(DefId, Ty<'tcx>), /// Dynamic dispatch to `::fn`. /// /// This `InstanceDef` does not have callable MIR. Calls to `Virtual` instances must be /// codegen'd as virtual calls through the vtable. /// /// If this is reified to a `fn` pointer, a `ReifyShim` is used (see `ReifyShim` above for more /// details on that). Virtual(DefId, usize), /// `<[FnMut closure] as FnOnce>::call_once`. /// /// The `DefId` is the ID of the `call_once` method in `FnOnce`. ClosureOnceShim { call_once: DefId, track_caller: bool }, /// `core::ptr::drop_in_place::`. /// /// The `DefId` is for `core::ptr::drop_in_place`. /// The `Option>` is either `Some(T)`, or `None` for empty drop /// glue. DropGlue(DefId, Option>), /// Compiler-generated `::clone` implementation. /// /// For all types that automatically implement `Copy`, a trivial `Clone` impl is provided too. /// Additionally, arrays, tuples, and closures get a `Clone` shim even if they aren't `Copy`. /// /// The `DefId` is for `Clone::clone`, the `Ty` is the type `T` with the builtin `Clone` impl. CloneShim(DefId, Ty<'tcx>), } impl<'tcx> Instance<'tcx> { /// Returns the `Ty` corresponding to this `Instance`, with generic substitutions applied and /// lifetimes erased, allowing a `ParamEnv` to be specified for use during normalization. pub fn ty(&self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Ty<'tcx> { let ty = tcx.type_of(self.def.def_id()); tcx.subst_and_normalize_erasing_regions(self.substs, param_env, ty) } /// Finds a crate that contains a monomorphization of this instance that /// can be linked to from the local crate. A return value of `None` means /// no upstream crate provides such an exported monomorphization. /// /// This method already takes into account the global `-Zshare-generics` /// setting, always returning `None` if `share-generics` is off. pub fn upstream_monomorphization(&self, tcx: TyCtxt<'tcx>) -> Option { // If we are not in share generics mode, we don't link to upstream // monomorphizations but always instantiate our own internal versions // instead. if !tcx.sess.opts.share_generics() { return None; } // If this is an item that is defined in the local crate, no upstream // crate can know about it/provide a monomorphization. if self.def_id().is_local() { return None; } // If this a non-generic instance, it cannot be a shared monomorphization. self.substs.non_erasable_generics().next()?; match self.def { InstanceDef::Item(def) => tcx .upstream_monomorphizations_for(def.did) .and_then(|monos| monos.get(&self.substs).cloned()), InstanceDef::DropGlue(_, Some(_)) => tcx.upstream_drop_glue_for(self.substs), _ => None, } } } impl<'tcx> InstanceDef<'tcx> { #[inline] pub fn def_id(self) -> DefId { match self { InstanceDef::Item(def) => def.did, InstanceDef::VTableShim(def_id) | InstanceDef::ReifyShim(def_id) | InstanceDef::FnPtrShim(def_id, _) | InstanceDef::Virtual(def_id, _) | InstanceDef::Intrinsic(def_id) | InstanceDef::ClosureOnceShim { call_once: def_id, track_caller: _ } | InstanceDef::DropGlue(def_id, _) | InstanceDef::CloneShim(def_id, _) => def_id, } } /// Returns the `DefId` of instances which might not require codegen locally. pub fn def_id_if_not_guaranteed_local_codegen(self) -> Option { match self { ty::InstanceDef::Item(def) => Some(def.did), ty::InstanceDef::DropGlue(def_id, Some(_)) => Some(def_id), InstanceDef::VTableShim(..) | InstanceDef::ReifyShim(..) | InstanceDef::FnPtrShim(..) | InstanceDef::Virtual(..) | InstanceDef::Intrinsic(..) | InstanceDef::ClosureOnceShim { .. } | InstanceDef::DropGlue(..) | InstanceDef::CloneShim(..) => None, } } #[inline] pub fn with_opt_param(self) -> ty::WithOptConstParam { match self { InstanceDef::Item(def) => def, InstanceDef::VTableShim(def_id) | InstanceDef::ReifyShim(def_id) | InstanceDef::FnPtrShim(def_id, _) | InstanceDef::Virtual(def_id, _) | InstanceDef::Intrinsic(def_id) | InstanceDef::ClosureOnceShim { call_once: def_id, track_caller: _ } | InstanceDef::DropGlue(def_id, _) | InstanceDef::CloneShim(def_id, _) => ty::WithOptConstParam::unknown(def_id), } } #[inline] pub fn get_attrs(&self, tcx: TyCtxt<'tcx>, attr: Symbol) -> ty::Attributes<'tcx> { tcx.get_attrs(self.def_id(), attr) } /// Returns `true` if the LLVM version of this instance is unconditionally /// marked with `inline`. This implies that a copy of this instance is /// generated in every codegen unit. /// Note that this is only a hint. See the documentation for /// `generates_cgu_internal_copy` for more information. pub fn requires_inline(&self, tcx: TyCtxt<'tcx>) -> bool { use rustc_hir::definitions::DefPathData; let def_id = match *self { ty::InstanceDef::Item(def) => def.did, ty::InstanceDef::DropGlue(_, Some(_)) => return false, _ => return true, }; matches!( tcx.def_key(def_id).disambiguated_data.data, DefPathData::Ctor | DefPathData::ClosureExpr ) } /// Returns `true` if the machine code for this instance is instantiated in /// each codegen unit that references it. /// Note that this is only a hint! The compiler can globally decide to *not* /// do this in order to speed up compilation. CGU-internal copies are /// only exist to enable inlining. If inlining is not performed (e.g. at /// `-Copt-level=0`) then the time for generating them is wasted and it's /// better to create a single copy with external linkage. pub fn generates_cgu_internal_copy(&self, tcx: TyCtxt<'tcx>) -> bool { if self.requires_inline(tcx) { return true; } if let ty::InstanceDef::DropGlue(.., Some(ty)) = *self { // Drop glue generally wants to be instantiated at every codegen // unit, but without an #[inline] hint. We should make this // available to normal end-users. if tcx.sess.opts.incremental.is_none() { return true; } // When compiling with incremental, we can generate a *lot* of // codegen units. Including drop glue into all of them has a // considerable compile time cost. // // We include enums without destructors to allow, say, optimizing // drops of `Option::None` before LTO. We also respect the intent of // `#[inline]` on `Drop::drop` implementations. return ty.ty_adt_def().map_or(true, |adt_def| { adt_def.destructor(tcx).map_or_else( || adt_def.is_enum(), |dtor| tcx.codegen_fn_attrs(dtor.did).requests_inline(), ) }); } tcx.codegen_fn_attrs(self.def_id()).requests_inline() } pub fn requires_caller_location(&self, tcx: TyCtxt<'_>) -> bool { match *self { InstanceDef::Item(ty::WithOptConstParam { did: def_id, .. }) | InstanceDef::Virtual(def_id, _) => { tcx.body_codegen_attrs(def_id).flags.contains(CodegenFnAttrFlags::TRACK_CALLER) } InstanceDef::ClosureOnceShim { call_once: _, track_caller } => track_caller, _ => false, } } /// Returns `true` when the MIR body associated with this instance should be monomorphized /// by its users (e.g. codegen or miri) by substituting the `substs` from `Instance` (see /// `Instance::substs_for_mir_body`). /// /// Otherwise, returns `false` only for some kinds of shims where the construction of the MIR /// body should perform necessary substitutions. pub fn has_polymorphic_mir_body(&self) -> bool { match *self { InstanceDef::CloneShim(..) | InstanceDef::FnPtrShim(..) | InstanceDef::DropGlue(_, Some(_)) => false, InstanceDef::ClosureOnceShim { .. } | InstanceDef::DropGlue(..) | InstanceDef::Item(_) | InstanceDef::Intrinsic(..) | InstanceDef::ReifyShim(..) | InstanceDef::Virtual(..) | InstanceDef::VTableShim(..) => true, } } } impl<'tcx> fmt::Display for Instance<'tcx> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { ty::tls::with(|tcx| { let substs = tcx.lift(self.substs).expect("could not lift for printing"); let s = FmtPrinter::new(tcx, Namespace::ValueNS) .print_def_path(self.def_id(), substs)? .into_buffer(); f.write_str(&s) })?; match self.def { InstanceDef::Item(_) => Ok(()), InstanceDef::VTableShim(_) => write!(f, " - shim(vtable)"), InstanceDef::ReifyShim(_) => write!(f, " - shim(reify)"), InstanceDef::Intrinsic(_) => write!(f, " - intrinsic"), InstanceDef::Virtual(_, num) => write!(f, " - virtual#{}", num), InstanceDef::FnPtrShim(_, ty) => write!(f, " - shim({})", ty), InstanceDef::ClosureOnceShim { .. } => write!(f, " - shim"), InstanceDef::DropGlue(_, None) => write!(f, " - shim(None)"), InstanceDef::DropGlue(_, Some(ty)) => write!(f, " - shim(Some({}))", ty), InstanceDef::CloneShim(_, ty) => write!(f, " - shim({})", ty), } } } impl<'tcx> Instance<'tcx> { pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> Instance<'tcx> { assert!( !substs.has_escaping_bound_vars(), "substs of instance {:?} not normalized for codegen: {:?}", def_id, substs ); Instance { def: InstanceDef::Item(ty::WithOptConstParam::unknown(def_id)), substs } } pub fn mono(tcx: TyCtxt<'tcx>, def_id: DefId) -> Instance<'tcx> { let substs = InternalSubsts::for_item(tcx, def_id, |param, _| match param.kind { ty::GenericParamDefKind::Lifetime => tcx.lifetimes.re_erased.into(), ty::GenericParamDefKind::Type { .. } => { bug!("Instance::mono: {:?} has type parameters", def_id) } ty::GenericParamDefKind::Const { .. } => { bug!("Instance::mono: {:?} has const parameters", def_id) } }); Instance::new(def_id, substs) } #[inline] pub fn def_id(&self) -> DefId { self.def.def_id() } /// Resolves a `(def_id, substs)` pair to an (optional) instance -- most commonly, /// this is used to find the precise code that will run for a trait method invocation, /// if known. /// /// Returns `Ok(None)` if we cannot resolve `Instance` to a specific instance. /// For example, in a context like this, /// /// ```ignore (illustrative) /// fn foo(t: T) { ... } /// ``` /// /// trying to resolve `Debug::fmt` applied to `T` will yield `Ok(None)`, because we do not /// know what code ought to run. (Note that this setting is also affected by the /// `RevealMode` in the parameter environment.) /// /// Presuming that coherence and type-check have succeeded, if this method is invoked /// in a monomorphic context (i.e., like during codegen), then it is guaranteed to return /// `Ok(Some(instance))`. /// /// Returns `Err(ErrorGuaranteed)` when the `Instance` resolution process /// couldn't complete due to errors elsewhere - this is distinct /// from `Ok(None)` to avoid misleading diagnostics when an error /// has already been/will be emitted, for the original cause pub fn resolve( tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, def_id: DefId, substs: SubstsRef<'tcx>, ) -> Result>, ErrorGuaranteed> { Instance::resolve_opt_const_arg( tcx, param_env, ty::WithOptConstParam::unknown(def_id), substs, ) } // This should be kept up to date with `resolve`. pub fn resolve_opt_const_arg( tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, def: ty::WithOptConstParam, substs: SubstsRef<'tcx>, ) -> Result>, ErrorGuaranteed> { // All regions in the result of this query are erased, so it's // fine to erase all of the input regions. // HACK(eddyb) erase regions in `substs` first, so that `param_env.and(...)` // below is more likely to ignore the bounds in scope (e.g. if the only // generic parameters mentioned by `substs` were lifetime ones). let substs = tcx.erase_regions(substs); // FIXME(eddyb) should this always use `param_env.with_reveal_all()`? if let Some((did, param_did)) = def.as_const_arg() { tcx.resolve_instance_of_const_arg( tcx.erase_regions(param_env.and((did, param_did, substs))), ) } else { tcx.resolve_instance(tcx.erase_regions(param_env.and((def.did, substs)))) } } pub fn resolve_for_fn_ptr( tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, def_id: DefId, substs: SubstsRef<'tcx>, ) -> Option> { debug!("resolve(def_id={:?}, substs={:?})", def_id, substs); // Use either `resolve_closure` or `resolve_for_vtable` assert!(!tcx.is_closure(def_id), "Called `resolve_for_fn_ptr` on closure: {:?}", def_id); Instance::resolve(tcx, param_env, def_id, substs).ok().flatten().map(|mut resolved| { match resolved.def { InstanceDef::Item(def) if resolved.def.requires_caller_location(tcx) => { debug!(" => fn pointer created for function with #[track_caller]"); resolved.def = InstanceDef::ReifyShim(def.did); } InstanceDef::Virtual(def_id, _) => { debug!(" => fn pointer created for virtual call"); resolved.def = InstanceDef::ReifyShim(def_id); } _ => {} } resolved }) } pub fn resolve_for_vtable( tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, def_id: DefId, substs: SubstsRef<'tcx>, ) -> Option> { debug!("resolve_for_vtable(def_id={:?}, substs={:?})", def_id, substs); let fn_sig = tcx.fn_sig(def_id); let is_vtable_shim = !fn_sig.inputs().skip_binder().is_empty() && fn_sig.input(0).skip_binder().is_param(0) && tcx.generics_of(def_id).has_self; if is_vtable_shim { debug!(" => associated item with unsizeable self: Self"); Some(Instance { def: InstanceDef::VTableShim(def_id), substs }) } else { Instance::resolve(tcx, param_env, def_id, substs).ok().flatten().map(|mut resolved| { match resolved.def { InstanceDef::Item(def) => { // We need to generate a shim when we cannot guarantee that // the caller of a trait object method will be aware of // `#[track_caller]` - this ensures that the caller // and callee ABI will always match. // // The shim is generated when all of these conditions are met: // // 1) The underlying method expects a caller location parameter // in the ABI if resolved.def.requires_caller_location(tcx) // 2) The caller location parameter comes from having `#[track_caller]` // on the implementation, and *not* on the trait method. && !tcx.should_inherit_track_caller(def.did) // If the method implementation comes from the trait definition itself // (e.g. `trait Foo { #[track_caller] my_fn() { /* impl */ } }`), // then we don't need to generate a shim. This check is needed because // `should_inherit_track_caller` returns `false` if our method // implementation comes from the trait block, and not an impl block && !matches!( tcx.opt_associated_item(def.did), Some(ty::AssocItem { container: ty::AssocItemContainer::TraitContainer, .. }) ) { if tcx.is_closure(def.did) { debug!(" => vtable fn pointer created for closure with #[track_caller]: {:?} for method {:?} {:?}", def.did, def_id, substs); // Create a shim for the `FnOnce/FnMut/Fn` method we are calling // - unlike functions, invoking a closure always goes through a // trait. resolved = Instance { def: InstanceDef::ReifyShim(def_id), substs }; } else { debug!( " => vtable fn pointer created for function with #[track_caller]: {:?}", def.did ); resolved.def = InstanceDef::ReifyShim(def.did); } } } InstanceDef::Virtual(def_id, _) => { debug!(" => vtable fn pointer created for virtual call"); resolved.def = InstanceDef::ReifyShim(def_id); } _ => {} } resolved }) } } pub fn resolve_closure( tcx: TyCtxt<'tcx>, def_id: DefId, substs: ty::SubstsRef<'tcx>, requested_kind: ty::ClosureKind, ) -> Option> { let actual_kind = substs.as_closure().kind(); match needs_fn_once_adapter_shim(actual_kind, requested_kind) { Ok(true) => Instance::fn_once_adapter_instance(tcx, def_id, substs), _ => Some(Instance::new(def_id, substs)), } } pub fn resolve_drop_in_place(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> ty::Instance<'tcx> { let def_id = tcx.require_lang_item(LangItem::DropInPlace, None); let substs = tcx.intern_substs(&[ty.into()]); Instance::resolve(tcx, ty::ParamEnv::reveal_all(), def_id, substs).unwrap().unwrap() } pub fn fn_once_adapter_instance( tcx: TyCtxt<'tcx>, closure_did: DefId, substs: ty::SubstsRef<'tcx>, ) -> Option> { debug!("fn_once_adapter_shim({:?}, {:?})", closure_did, substs); let fn_once = tcx.require_lang_item(LangItem::FnOnce, None); let call_once = tcx .associated_items(fn_once) .in_definition_order() .find(|it| it.kind == ty::AssocKind::Fn) .unwrap() .def_id; let track_caller = tcx.codegen_fn_attrs(closure_did).flags.contains(CodegenFnAttrFlags::TRACK_CALLER); let def = ty::InstanceDef::ClosureOnceShim { call_once, track_caller }; let self_ty = tcx.mk_closure(closure_did, substs); let sig = substs.as_closure().sig(); let sig = tcx.try_normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), sig).ok()?; assert_eq!(sig.inputs().len(), 1); let substs = tcx.mk_substs_trait(self_ty, &[sig.inputs()[0].into()]); debug!("fn_once_adapter_shim: self_ty={:?} sig={:?}", self_ty, sig); Some(Instance { def, substs }) } /// Depending on the kind of `InstanceDef`, the MIR body associated with an /// instance is expressed in terms of the generic parameters of `self.def_id()`, and in other /// cases the MIR body is expressed in terms of the types found in the substitution array. /// In the former case, we want to substitute those generic types and replace them with the /// values from the substs when monomorphizing the function body. But in the latter case, we /// don't want to do that substitution, since it has already been done effectively. /// /// This function returns `Some(substs)` in the former case and `None` otherwise -- i.e., if /// this function returns `None`, then the MIR body does not require substitution during /// codegen. fn substs_for_mir_body(&self) -> Option> { if self.def.has_polymorphic_mir_body() { Some(self.substs) } else { None } } pub fn subst_mir(&self, tcx: TyCtxt<'tcx>, v: &T) -> T where T: TypeFoldable<'tcx> + Copy, { if let Some(substs) = self.substs_for_mir_body() { EarlyBinder(*v).subst(tcx, substs) } else { *v } } #[inline(always)] pub fn subst_mir_and_normalize_erasing_regions( &self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, v: T, ) -> T where T: TypeFoldable<'tcx> + Clone, { if let Some(substs) = self.substs_for_mir_body() { tcx.subst_and_normalize_erasing_regions(substs, param_env, v) } else { tcx.normalize_erasing_regions(param_env, v) } } #[inline(always)] pub fn try_subst_mir_and_normalize_erasing_regions( &self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, v: T, ) -> Result> where T: TypeFoldable<'tcx> + Clone, { if let Some(substs) = self.substs_for_mir_body() { tcx.try_subst_and_normalize_erasing_regions(substs, param_env, v) } else { tcx.try_normalize_erasing_regions(param_env, v) } } /// Returns a new `Instance` where generic parameters in `instance.substs` are replaced by /// identity parameters if they are determined to be unused in `instance.def`. pub fn polymorphize(self, tcx: TyCtxt<'tcx>) -> Self { debug!("polymorphize: running polymorphization analysis"); if !tcx.sess.opts.unstable_opts.polymorphize { return self; } let polymorphized_substs = polymorphize(tcx, self.def, self.substs); debug!("polymorphize: self={:?} polymorphized_substs={:?}", self, polymorphized_substs); Self { def: self.def, substs: polymorphized_substs } } } fn polymorphize<'tcx>( tcx: TyCtxt<'tcx>, instance: ty::InstanceDef<'tcx>, substs: SubstsRef<'tcx>, ) -> SubstsRef<'tcx> { debug!("polymorphize({:?}, {:?})", instance, substs); let unused = tcx.unused_generic_params(instance); debug!("polymorphize: unused={:?}", unused); // If this is a closure or generator then we need to handle the case where another closure // from the function is captured as an upvar and hasn't been polymorphized. In this case, // the unpolymorphized upvar closure would result in a polymorphized closure producing // multiple mono items (and eventually symbol clashes). let def_id = instance.def_id(); let upvars_ty = if tcx.is_closure(def_id) { Some(substs.as_closure().tupled_upvars_ty()) } else if tcx.type_of(def_id).is_generator() { Some(substs.as_generator().tupled_upvars_ty()) } else { None }; let has_upvars = upvars_ty.map_or(false, |ty| !ty.tuple_fields().is_empty()); debug!("polymorphize: upvars_ty={:?} has_upvars={:?}", upvars_ty, has_upvars); struct PolymorphizationFolder<'tcx> { tcx: TyCtxt<'tcx>, } impl<'tcx> ty::TypeFolder<'tcx> for PolymorphizationFolder<'tcx> { fn tcx<'a>(&'a self) -> TyCtxt<'tcx> { self.tcx } fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> { debug!("fold_ty: ty={:?}", ty); match *ty.kind() { ty::Closure(def_id, substs) => { let polymorphized_substs = polymorphize( self.tcx, ty::InstanceDef::Item(ty::WithOptConstParam::unknown(def_id)), substs, ); if substs == polymorphized_substs { ty } else { self.tcx.mk_closure(def_id, polymorphized_substs) } } ty::Generator(def_id, substs, movability) => { let polymorphized_substs = polymorphize( self.tcx, ty::InstanceDef::Item(ty::WithOptConstParam::unknown(def_id)), substs, ); if substs == polymorphized_substs { ty } else { self.tcx.mk_generator(def_id, polymorphized_substs, movability) } } _ => ty.super_fold_with(self), } } } InternalSubsts::for_item(tcx, def_id, |param, _| { let is_unused = unused.contains(param.index).unwrap_or(false); debug!("polymorphize: param={:?} is_unused={:?}", param, is_unused); match param.kind { // Upvar case: If parameter is a type parameter.. ty::GenericParamDefKind::Type { .. } if // ..and has upvars.. has_upvars && // ..and this param has the same type as the tupled upvars.. upvars_ty == Some(substs[param.index as usize].expect_ty()) => { // ..then double-check that polymorphization marked it used.. debug_assert!(!is_unused); // ..and polymorphize any closures/generators captured as upvars. let upvars_ty = upvars_ty.unwrap(); let polymorphized_upvars_ty = upvars_ty.fold_with( &mut PolymorphizationFolder { tcx }); debug!("polymorphize: polymorphized_upvars_ty={:?}", polymorphized_upvars_ty); ty::GenericArg::from(polymorphized_upvars_ty) }, // Simple case: If parameter is a const or type parameter.. ty::GenericParamDefKind::Const { .. } | ty::GenericParamDefKind::Type { .. } if // ..and is within range and unused.. unused.contains(param.index).unwrap_or(false) => // ..then use the identity for this parameter. tcx.mk_param_from_def(param), // Otherwise, use the parameter as before. _ => substs[param.index as usize], } }) } fn needs_fn_once_adapter_shim( actual_closure_kind: ty::ClosureKind, trait_closure_kind: ty::ClosureKind, ) -> Result { match (actual_closure_kind, trait_closure_kind) { (ty::ClosureKind::Fn, ty::ClosureKind::Fn) | (ty::ClosureKind::FnMut, ty::ClosureKind::FnMut) | (ty::ClosureKind::FnOnce, ty::ClosureKind::FnOnce) => { // No adapter needed. Ok(false) } (ty::ClosureKind::Fn, ty::ClosureKind::FnMut) => { // The closure fn `llfn` is a `fn(&self, ...)`. We want a // `fn(&mut self, ...)`. In fact, at codegen time, these are // basically the same thing, so we can just return llfn. Ok(false) } (ty::ClosureKind::Fn | ty::ClosureKind::FnMut, ty::ClosureKind::FnOnce) => { // The closure fn `llfn` is a `fn(&self, ...)` or `fn(&mut // self, ...)`. We want a `fn(self, ...)`. We can produce // this by doing something like: // // fn call_once(self, ...) { call_mut(&self, ...) } // fn call_once(mut self, ...) { call_mut(&mut self, ...) } // // These are both the same at codegen time. Ok(true) } (ty::ClosureKind::FnMut | ty::ClosureKind::FnOnce, _) => Err(()), } }