103 lines
4.0 KiB
Rust
103 lines
4.0 KiB
Rust
//! Detecting lang items.
|
|
//!
|
|
//! Language items are items that represent concepts intrinsic to the language
|
|
//! itself. Examples are:
|
|
//!
|
|
//! * Traits that specify "kinds"; e.g., `Sync`, `Send`.
|
|
//! * Traits that represent operators; e.g., `Add`, `Sub`, `Index`.
|
|
//! * Functions called by the compiler itself.
|
|
|
|
use rustc_hir::LangItem;
|
|
use rustc_hir::def_id::DefId;
|
|
use rustc_span::Span;
|
|
use rustc_target::spec::PanicStrategy;
|
|
|
|
use crate::ty::{self, TyCtxt};
|
|
|
|
impl<'tcx> TyCtxt<'tcx> {
|
|
/// Returns the `DefId` for a given `LangItem`.
|
|
/// If not found, fatally aborts compilation.
|
|
pub fn require_lang_item(self, lang_item: LangItem, span: Span) -> DefId {
|
|
self.lang_items().get(lang_item).unwrap_or_else(|| {
|
|
self.dcx().emit_fatal(crate::error::RequiresLangItem { span, name: lang_item.name() });
|
|
})
|
|
}
|
|
|
|
pub fn is_lang_item(self, def_id: DefId, lang_item: LangItem) -> bool {
|
|
self.lang_items().get(lang_item) == Some(def_id)
|
|
}
|
|
|
|
pub fn as_lang_item(self, def_id: DefId) -> Option<LangItem> {
|
|
self.lang_items().from_def_id(def_id)
|
|
}
|
|
|
|
/// Given a [`DefId`] of one of the [`Fn`], [`FnMut`] or [`FnOnce`] traits,
|
|
/// returns a corresponding [`ty::ClosureKind`].
|
|
/// For any other [`DefId`] return `None`.
|
|
pub fn fn_trait_kind_from_def_id(self, id: DefId) -> Option<ty::ClosureKind> {
|
|
match self.as_lang_item(id)? {
|
|
LangItem::Fn => Some(ty::ClosureKind::Fn),
|
|
LangItem::FnMut => Some(ty::ClosureKind::FnMut),
|
|
LangItem::FnOnce => Some(ty::ClosureKind::FnOnce),
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
/// Given a [`DefId`] of one of the `AsyncFn`, `AsyncFnMut` or `AsyncFnOnce` traits,
|
|
/// returns a corresponding [`ty::ClosureKind`].
|
|
/// For any other [`DefId`] return `None`.
|
|
pub fn async_fn_trait_kind_from_def_id(self, id: DefId) -> Option<ty::ClosureKind> {
|
|
match self.as_lang_item(id)? {
|
|
LangItem::AsyncFn => Some(ty::ClosureKind::Fn),
|
|
LangItem::AsyncFnMut => Some(ty::ClosureKind::FnMut),
|
|
LangItem::AsyncFnOnce => Some(ty::ClosureKind::FnOnce),
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
/// Given a [`ty::ClosureKind`], get the [`DefId`] of its corresponding `Fn`-family
|
|
/// trait, if it is defined.
|
|
pub fn fn_trait_kind_to_def_id(self, kind: ty::ClosureKind) -> Option<DefId> {
|
|
let items = self.lang_items();
|
|
match kind {
|
|
ty::ClosureKind::Fn => items.fn_trait(),
|
|
ty::ClosureKind::FnMut => items.fn_mut_trait(),
|
|
ty::ClosureKind::FnOnce => items.fn_once_trait(),
|
|
}
|
|
}
|
|
|
|
/// Given a [`ty::ClosureKind`], get the [`DefId`] of its corresponding `Fn`-family
|
|
/// trait, if it is defined.
|
|
pub fn async_fn_trait_kind_to_def_id(self, kind: ty::ClosureKind) -> Option<DefId> {
|
|
let items = self.lang_items();
|
|
match kind {
|
|
ty::ClosureKind::Fn => items.async_fn_trait(),
|
|
ty::ClosureKind::FnMut => items.async_fn_mut_trait(),
|
|
ty::ClosureKind::FnOnce => items.async_fn_once_trait(),
|
|
}
|
|
}
|
|
|
|
/// Returns `true` if `id` is a `DefId` of [`Fn`], [`FnMut`] or [`FnOnce`] traits.
|
|
pub fn is_fn_trait(self, id: DefId) -> bool {
|
|
self.fn_trait_kind_from_def_id(id).is_some()
|
|
}
|
|
}
|
|
|
|
/// Returns `true` if the specified `lang_item` must be present for this
|
|
/// compilation.
|
|
///
|
|
/// Not all lang items are always required for each compilation, particularly in
|
|
/// the case of panic=abort. In these situations some lang items are injected by
|
|
/// crates and don't actually need to be defined in libstd.
|
|
pub fn required(tcx: TyCtxt<'_>, lang_item: LangItem) -> bool {
|
|
// If we're not compiling with unwinding, we won't actually need these
|
|
// symbols. Other panic runtimes ensure that the relevant symbols are
|
|
// available to link things together, but they're never exercised.
|
|
match tcx.sess.panic_strategy() {
|
|
PanicStrategy::Abort => {
|
|
lang_item != LangItem::EhPersonality && lang_item != LangItem::EhCatchTypeinfo
|
|
}
|
|
PanicStrategy::Unwind => true,
|
|
}
|
|
}
|