diff options
Diffstat (limited to 'compiler/rustc_typeck/src/check/fn_ctxt/mod.rs')
| -rw-r--r-- | compiler/rustc_typeck/src/check/fn_ctxt/mod.rs | 296 |
1 files changed, 296 insertions, 0 deletions
diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/mod.rs b/compiler/rustc_typeck/src/check/fn_ctxt/mod.rs new file mode 100644 index 000000000..05bcc710e --- /dev/null +++ b/compiler/rustc_typeck/src/check/fn_ctxt/mod.rs @@ -0,0 +1,296 @@ +mod _impl; +mod arg_matrix; +mod checks; +mod suggestions; + +pub use _impl::*; +pub use suggestions::*; + +use crate::astconv::AstConv; +use crate::check::coercion::DynamicCoerceMany; +use crate::check::{Diverges, EnclosingBreakables, Inherited, UnsafetyState}; + +use rustc_hir as hir; +use rustc_hir::def_id::DefId; +use rustc_infer::infer; +use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; +use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind}; +use rustc_middle::ty::subst::GenericArgKind; +use rustc_middle::ty::visit::TypeVisitable; +use rustc_middle::ty::{self, Const, Ty, TyCtxt}; +use rustc_session::Session; +use rustc_span::symbol::Ident; +use rustc_span::{self, Span}; +use rustc_trait_selection::traits::{ObligationCause, ObligationCauseCode}; + +use std::cell::{Cell, RefCell}; +use std::ops::Deref; + +pub struct FnCtxt<'a, 'tcx> { + pub(super) body_id: hir::HirId, + + /// The parameter environment used for proving trait obligations + /// in this function. This can change when we descend into + /// closures (as they bring new things into scope), hence it is + /// not part of `Inherited` (as of the time of this writing, + /// closures do not yet change the environment, but they will + /// eventually). + pub(super) param_env: ty::ParamEnv<'tcx>, + + /// Number of errors that had been reported when we started + /// checking this function. On exit, if we find that *more* errors + /// have been reported, we will skip regionck and other work that + /// expects the types within the function to be consistent. + // FIXME(matthewjasper) This should not exist, and it's not correct + // if type checking is run in parallel. + err_count_on_creation: usize, + + /// If `Some`, this stores coercion information for returned + /// expressions. If `None`, this is in a context where return is + /// inappropriate, such as a const expression. + /// + /// This is a `RefCell<DynamicCoerceMany>`, which means that we + /// can track all the return expressions and then use them to + /// compute a useful coercion from the set, similar to a match + /// expression or other branching context. You can use methods + /// like `expected_ty` to access the declared return type (if + /// any). + pub(super) ret_coercion: Option<RefCell<DynamicCoerceMany<'tcx>>>, + + pub(super) ret_type_span: Option<Span>, + + /// Used exclusively to reduce cost of advanced evaluation used for + /// more helpful diagnostics. + pub(super) in_tail_expr: bool, + + /// First span of a return site that we find. Used in error messages. + pub(super) ret_coercion_span: Cell<Option<Span>>, + + pub(super) resume_yield_tys: Option<(Ty<'tcx>, Ty<'tcx>)>, + + pub(super) ps: Cell<UnsafetyState>, + + /// Whether the last checked node generates a divergence (e.g., + /// `return` will set this to `Always`). In general, when entering + /// an expression or other node in the tree, the initial value + /// indicates whether prior parts of the containing expression may + /// have diverged. It is then typically set to `Maybe` (and the + /// old value remembered) for processing the subparts of the + /// current expression. As each subpart is processed, they may set + /// the flag to `Always`, etc. Finally, at the end, we take the + /// result and "union" it with the original value, so that when we + /// return the flag indicates if any subpart of the parent + /// expression (up to and including this part) has diverged. So, + /// if you read it after evaluating a subexpression `X`, the value + /// you get indicates whether any subexpression that was + /// evaluating up to and including `X` diverged. + /// + /// We currently use this flag only for diagnostic purposes: + /// + /// - To warn about unreachable code: if, after processing a + /// sub-expression but before we have applied the effects of the + /// current node, we see that the flag is set to `Always`, we + /// can issue a warning. This corresponds to something like + /// `foo(return)`; we warn on the `foo()` expression. (We then + /// update the flag to `WarnedAlways` to suppress duplicate + /// reports.) Similarly, if we traverse to a fresh statement (or + /// tail expression) from an `Always` setting, we will issue a + /// warning. This corresponds to something like `{return; + /// foo();}` or `{return; 22}`, where we would warn on the + /// `foo()` or `22`. + /// + /// An expression represents dead code if, after checking it, + /// the diverges flag is set to something other than `Maybe`. + pub(super) diverges: Cell<Diverges>, + + /// Whether any child nodes have any type errors. + pub(super) has_errors: Cell<bool>, + + pub(super) enclosing_breakables: RefCell<EnclosingBreakables<'tcx>>, + + pub(super) inh: &'a Inherited<'a, 'tcx>, + + /// True if the function or closure's return type is known before + /// entering the function/closure, i.e. if the return type is + /// either given explicitly or inferred from, say, an `Fn*` trait + /// bound. Used for diagnostic purposes only. + pub(super) return_type_pre_known: bool, + + /// True if the return type has an Opaque type + pub(super) return_type_has_opaque: bool, +} + +impl<'a, 'tcx> FnCtxt<'a, 'tcx> { + pub fn new( + inh: &'a Inherited<'a, 'tcx>, + param_env: ty::ParamEnv<'tcx>, + body_id: hir::HirId, + ) -> FnCtxt<'a, 'tcx> { + FnCtxt { + body_id, + param_env, + err_count_on_creation: inh.tcx.sess.err_count(), + ret_coercion: None, + ret_type_span: None, + in_tail_expr: false, + ret_coercion_span: Cell::new(None), + resume_yield_tys: None, + ps: Cell::new(UnsafetyState::function(hir::Unsafety::Normal, hir::CRATE_HIR_ID)), + diverges: Cell::new(Diverges::Maybe), + has_errors: Cell::new(false), + enclosing_breakables: RefCell::new(EnclosingBreakables { + stack: Vec::new(), + by_id: Default::default(), + }), + inh, + return_type_pre_known: true, + return_type_has_opaque: false, + } + } + + pub fn cause(&self, span: Span, code: ObligationCauseCode<'tcx>) -> ObligationCause<'tcx> { + ObligationCause::new(span, self.body_id, code) + } + + pub fn misc(&self, span: Span) -> ObligationCause<'tcx> { + self.cause(span, ObligationCauseCode::MiscObligation) + } + + pub fn sess(&self) -> &Session { + &self.tcx.sess + } + + pub fn errors_reported_since_creation(&self) -> bool { + self.tcx.sess.err_count() > self.err_count_on_creation + } +} + +impl<'a, 'tcx> Deref for FnCtxt<'a, 'tcx> { + type Target = Inherited<'a, 'tcx>; + fn deref(&self) -> &Self::Target { + &self.inh + } +} + +impl<'a, 'tcx> AstConv<'tcx> for FnCtxt<'a, 'tcx> { + fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { + self.tcx + } + + fn item_def_id(&self) -> Option<DefId> { + None + } + + fn get_type_parameter_bounds( + &self, + _: Span, + def_id: DefId, + _: Ident, + ) -> ty::GenericPredicates<'tcx> { + let tcx = self.tcx; + let item_def_id = tcx.hir().ty_param_owner(def_id.expect_local()); + let generics = tcx.generics_of(item_def_id); + let index = generics.param_def_id_to_index[&def_id]; + ty::GenericPredicates { + parent: None, + predicates: tcx.arena.alloc_from_iter( + self.param_env.caller_bounds().iter().filter_map(|predicate| { + match predicate.kind().skip_binder() { + ty::PredicateKind::Trait(data) if data.self_ty().is_param(index) => { + // HACK(eddyb) should get the original `Span`. + let span = tcx.def_span(def_id); + Some((predicate, span)) + } + _ => None, + } + }), + ), + } + } + + fn re_infer(&self, def: Option<&ty::GenericParamDef>, span: Span) -> Option<ty::Region<'tcx>> { + let v = match def { + Some(def) => infer::EarlyBoundRegion(span, def.name), + None => infer::MiscVariable(span), + }; + Some(self.next_region_var(v)) + } + + fn allow_ty_infer(&self) -> bool { + true + } + + fn ty_infer(&self, param: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> { + if let Some(param) = param { + if let GenericArgKind::Type(ty) = self.var_for_def(span, param).unpack() { + return ty; + } + unreachable!() + } else { + self.next_ty_var(TypeVariableOrigin { + kind: TypeVariableOriginKind::TypeInference, + span, + }) + } + } + + fn ct_infer( + &self, + ty: Ty<'tcx>, + param: Option<&ty::GenericParamDef>, + span: Span, + ) -> Const<'tcx> { + if let Some(param) = param { + if let GenericArgKind::Const(ct) = self.var_for_def(span, param).unpack() { + return ct; + } + unreachable!() + } else { + self.next_const_var( + ty, + ConstVariableOrigin { kind: ConstVariableOriginKind::ConstInference, span }, + ) + } + } + + fn projected_ty_from_poly_trait_ref( + &self, + span: Span, + item_def_id: DefId, + item_segment: &hir::PathSegment<'_>, + poly_trait_ref: ty::PolyTraitRef<'tcx>, + ) -> Ty<'tcx> { + let trait_ref = self.replace_bound_vars_with_fresh_vars( + span, + infer::LateBoundRegionConversionTime::AssocTypeProjection(item_def_id), + poly_trait_ref, + ); + + let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item( + self, + self.tcx, + span, + item_def_id, + item_segment, + trait_ref.substs, + ); + + self.tcx().mk_projection(item_def_id, item_substs) + } + + fn normalize_ty(&self, span: Span, ty: Ty<'tcx>) -> Ty<'tcx> { + if ty.has_escaping_bound_vars() { + ty // FIXME: normalization and escaping regions + } else { + self.normalize_associated_types_in(span, ty) + } + } + + fn set_tainted_by_errors(&self) { + self.infcx.set_tainted_by_errors() + } + + fn record_ty(&self, hir_id: hir::HirId, ty: Ty<'tcx>, _span: Span) { + self.write_ty(hir_id, ty) + } +} |