compiler: unnest rustc_const_eval::check_consts
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10 changed files with 3 additions and 4 deletions
141
compiler/rustc_const_eval/src/check_consts/mod.rs
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141
compiler/rustc_const_eval/src/check_consts/mod.rs
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//! Check the bodies of `const`s, `static`s and `const fn`s for illegal operations.
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//!
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//! This module will eventually replace the parts of `qualify_consts.rs` that check whether a local
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//! has interior mutability or needs to be dropped, as well as the visitor that emits errors when
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//! it finds operations that are invalid in a certain context.
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use rustc_attr as attr;
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use rustc_errors::DiagCtxt;
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use rustc_hir as hir;
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use rustc_hir::def_id::{DefId, LocalDefId};
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use rustc_middle::bug;
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use rustc_middle::mir;
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use rustc_middle::ty::{self, PolyFnSig, TyCtxt};
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use rustc_span::Symbol;
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pub use self::qualifs::Qualif;
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pub mod check;
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mod ops;
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pub mod post_drop_elaboration;
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pub mod qualifs;
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mod resolver;
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/// Information about the item currently being const-checked, as well as a reference to the global
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/// context.
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pub struct ConstCx<'mir, 'tcx> {
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pub body: &'mir mir::Body<'tcx>,
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pub tcx: TyCtxt<'tcx>,
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pub param_env: ty::ParamEnv<'tcx>,
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pub const_kind: Option<hir::ConstContext>,
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}
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impl<'mir, 'tcx> ConstCx<'mir, 'tcx> {
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pub fn new(tcx: TyCtxt<'tcx>, body: &'mir mir::Body<'tcx>) -> Self {
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let def_id = body.source.def_id().expect_local();
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let param_env = tcx.param_env(def_id);
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Self::new_with_param_env(tcx, body, param_env)
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}
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pub fn new_with_param_env(
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tcx: TyCtxt<'tcx>,
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body: &'mir mir::Body<'tcx>,
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param_env: ty::ParamEnv<'tcx>,
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) -> Self {
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let const_kind = tcx.hir().body_const_context(body.source.def_id().expect_local());
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ConstCx { body, tcx, param_env, const_kind }
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}
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pub(crate) fn dcx(&self) -> &'tcx DiagCtxt {
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self.tcx.dcx()
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}
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pub fn def_id(&self) -> LocalDefId {
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self.body.source.def_id().expect_local()
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}
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/// Returns the kind of const context this `Item` represents (`const`, `static`, etc.).
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///
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/// Panics if this `Item` is not const.
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pub fn const_kind(&self) -> hir::ConstContext {
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self.const_kind.expect("`const_kind` must not be called on a non-const fn")
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}
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pub fn is_const_stable_const_fn(&self) -> bool {
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self.const_kind == Some(hir::ConstContext::ConstFn)
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&& self.tcx.features().staged_api
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&& is_const_stable_const_fn(self.tcx, self.def_id().to_def_id())
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}
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fn is_async(&self) -> bool {
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self.tcx.asyncness(self.def_id()).is_async()
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}
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pub fn fn_sig(&self) -> PolyFnSig<'tcx> {
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let did = self.def_id().to_def_id();
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if self.tcx.is_closure_like(did) {
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let ty = self.tcx.type_of(did).instantiate_identity();
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let ty::Closure(_, args) = ty.kind() else { bug!("type_of closure not ty::Closure") };
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args.as_closure().sig()
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} else {
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self.tcx.fn_sig(did).instantiate_identity()
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}
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}
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}
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pub fn rustc_allow_const_fn_unstable(
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tcx: TyCtxt<'_>,
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def_id: LocalDefId,
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feature_gate: Symbol,
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) -> bool {
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let attrs = tcx.hir().attrs(tcx.local_def_id_to_hir_id(def_id));
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attr::rustc_allow_const_fn_unstable(tcx.sess, attrs).any(|name| name == feature_gate)
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}
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/// Returns `true` if the given `const fn` is "const-stable".
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///
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/// Panics if the given `DefId` does not refer to a `const fn`.
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///
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/// Const-stability is only relevant for `const fn` within a `staged_api` crate. Only "const-stable"
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/// functions can be called in a const-context by users of the stable compiler. "const-stable"
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/// functions are subject to more stringent restrictions than "const-unstable" functions: They
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/// cannot use unstable features and can only call other "const-stable" functions.
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pub fn is_const_stable_const_fn(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
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// A default body in a `#[const_trait]` is not const-stable because const
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// trait fns currently cannot be const-stable. We shouldn't
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// restrict default bodies to only call const-stable functions.
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if tcx.is_const_default_method(def_id) {
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return false;
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}
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// Const-stability is only relevant for `const fn`.
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assert!(tcx.is_const_fn_raw(def_id));
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// A function is only const-stable if it has `#[rustc_const_stable]` or it the trait it belongs
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// to is const-stable.
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match tcx.lookup_const_stability(def_id) {
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Some(stab) => stab.is_const_stable(),
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None if is_parent_const_stable_trait(tcx, def_id) => {
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// Remove this when `#![feature(const_trait_impl)]` is stabilized,
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// returning `true` unconditionally.
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tcx.dcx().span_delayed_bug(
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tcx.def_span(def_id),
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"trait implementations cannot be const stable yet",
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);
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true
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}
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None => false, // By default, items are not const stable.
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}
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}
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fn is_parent_const_stable_trait(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
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let local_def_id = def_id.expect_local();
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let hir_id = tcx.local_def_id_to_hir_id(local_def_id);
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let parent_owner_id = tcx.parent_hir_id(hir_id).owner;
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if !tcx.is_const_trait_impl_raw(parent_owner_id.to_def_id()) {
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return false;
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}
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tcx.lookup_const_stability(parent_owner_id).is_some_and(|stab| stab.is_const_stable())
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}
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