| //! Check the bodies of `const`s, `static`s and `const fn`s for illegal operations. |
| //! |
| //! This module will eventually replace the parts of `qualify_consts.rs` that check whether a local |
| //! has interior mutability or needs to be dropped, as well as the visitor that emits errors when |
| //! it finds operations that are invalid in a certain context. |
| |
| use rustc_attr as attr; |
| use rustc_hir as hir; |
| use rustc_hir::def_id::{DefId, LocalDefId}; |
| use rustc_middle::mir; |
| use rustc_middle::ty::{self, TyCtxt}; |
| use rustc_span::Symbol; |
| |
| pub use self::qualifs::Qualif; |
| |
| mod ops; |
| pub mod post_drop_elaboration; |
| pub mod qualifs; |
| mod resolver; |
| pub mod validation; |
| |
| /// Information about the item currently being const-checked, as well as a reference to the global |
| /// context. |
| pub struct ConstCx<'mir, 'tcx> { |
| pub body: &'mir mir::Body<'tcx>, |
| pub tcx: TyCtxt<'tcx>, |
| pub def_id: LocalDefId, |
| pub param_env: ty::ParamEnv<'tcx>, |
| pub const_kind: Option<hir::ConstContext>, |
| } |
| |
| impl ConstCx<'mir, 'tcx> { |
| pub fn new(tcx: TyCtxt<'tcx>, def_id: LocalDefId, body: &'mir mir::Body<'tcx>) -> Self { |
| let param_env = tcx.param_env(def_id); |
| Self::new_with_param_env(tcx, def_id, body, param_env) |
| } |
| |
| pub fn new_with_param_env( |
| tcx: TyCtxt<'tcx>, |
| def_id: LocalDefId, |
| body: &'mir mir::Body<'tcx>, |
| param_env: ty::ParamEnv<'tcx>, |
| ) -> Self { |
| let const_kind = tcx.hir().body_const_context(def_id); |
| ConstCx { body, tcx, def_id: def_id, param_env, const_kind } |
| } |
| |
| /// Returns the kind of const context this `Item` represents (`const`, `static`, etc.). |
| /// |
| /// Panics if this `Item` is not const. |
| pub fn const_kind(&self) -> hir::ConstContext { |
| self.const_kind.expect("`const_kind` must not be called on a non-const fn") |
| } |
| |
| pub fn is_const_stable_const_fn(&self) -> bool { |
| self.const_kind == Some(hir::ConstContext::ConstFn) |
| && self.tcx.features().staged_api |
| && is_const_stable_const_fn(self.tcx, self.def_id.to_def_id()) |
| } |
| } |
| |
| /// Returns `true` if this `DefId` points to one of the official `panic` lang items. |
| pub fn is_lang_panic_fn(tcx: TyCtxt<'tcx>, def_id: DefId) -> bool { |
| Some(def_id) == tcx.lang_items().panic_fn() || Some(def_id) == tcx.lang_items().begin_panic_fn() |
| } |
| |
| pub fn allow_internal_unstable(tcx: TyCtxt<'tcx>, def_id: DefId, feature_gate: Symbol) -> bool { |
| let attrs = tcx.get_attrs(def_id); |
| attr::allow_internal_unstable(&tcx.sess, attrs) |
| .map_or(false, |mut features| features.any(|name| name == feature_gate)) |
| } |
| |
| // Returns `true` if the given `const fn` is "const-stable". |
| // |
| // Panics if the given `DefId` does not refer to a `const fn`. |
| // |
| // Const-stability is only relevant for `const fn` within a `staged_api` crate. Only "const-stable" |
| // functions can be called in a const-context by users of the stable compiler. "const-stable" |
| // functions are subject to more stringent restrictions than "const-unstable" functions: They |
| // cannot use unstable features and can only call other "const-stable" functions. |
| pub fn is_const_stable_const_fn(tcx: TyCtxt<'tcx>, def_id: DefId) -> bool { |
| use attr::{ConstStability, Stability, StabilityLevel}; |
| |
| // Const-stability is only relevant for `const fn`. |
| assert!(tcx.is_const_fn_raw(def_id)); |
| |
| // Functions with `#[rustc_const_unstable]` are const-unstable. |
| match tcx.lookup_const_stability(def_id) { |
| Some(ConstStability { level: StabilityLevel::Unstable { .. }, .. }) => return false, |
| Some(ConstStability { level: StabilityLevel::Stable { .. }, .. }) => return true, |
| None => {} |
| } |
| |
| // Functions with `#[unstable]` are const-unstable. |
| // |
| // FIXME(ecstaticmorse): We should keep const-stability attributes wholly separate from normal stability |
| // attributes. `#[unstable]` should be irrelevant. |
| if let Some(Stability { level: StabilityLevel::Unstable { .. }, .. }) = |
| tcx.lookup_stability(def_id) |
| { |
| return false; |
| } |
| |
| true |
| } |