| use crate::{FnCtxt, LocalTy}; |
| use rustc_hir as hir; |
| use rustc_hir::intravisit::{self, Visitor}; |
| use rustc_hir::PatKind; |
| use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; |
| use rustc_middle::ty::Ty; |
| use rustc_middle::ty::UserType; |
| use rustc_span::Span; |
| use rustc_trait_selection::traits; |
| |
| /// A declaration is an abstraction of [hir::Local] and [hir::Let]. |
| /// |
| /// It must have a hir_id, as this is how we connect gather_locals to the check functions. |
| pub(super) struct Declaration<'a> { |
| pub hir_id: hir::HirId, |
| pub pat: &'a hir::Pat<'a>, |
| pub ty: Option<&'a hir::Ty<'a>>, |
| pub span: Span, |
| pub init: Option<&'a hir::Expr<'a>>, |
| pub els: Option<&'a hir::Block<'a>>, |
| } |
| |
| impl<'a> From<&'a hir::Local<'a>> for Declaration<'a> { |
| fn from(local: &'a hir::Local<'a>) -> Self { |
| let hir::Local { hir_id, pat, ty, span, init, els, source: _ } = *local; |
| Declaration { hir_id, pat, ty, span, init, els } |
| } |
| } |
| |
| impl<'a> From<&'a hir::Let<'a>> for Declaration<'a> { |
| fn from(let_expr: &'a hir::Let<'a>) -> Self { |
| let hir::Let { hir_id, pat, ty, span, init } = *let_expr; |
| Declaration { hir_id, pat, ty, span, init: Some(init), els: None } |
| } |
| } |
| |
| pub(super) struct GatherLocalsVisitor<'a, 'tcx> { |
| fcx: &'a FnCtxt<'a, 'tcx>, |
| // parameters are special cases of patterns, but we want to handle them as |
| // *distinct* cases. so track when we are hitting a pattern *within* an fn |
| // parameter. |
| outermost_fn_param_pat: Option<Span>, |
| } |
| |
| impl<'a, 'tcx> GatherLocalsVisitor<'a, 'tcx> { |
| pub(super) fn new(fcx: &'a FnCtxt<'a, 'tcx>) -> Self { |
| Self { fcx, outermost_fn_param_pat: None } |
| } |
| |
| fn assign(&mut self, span: Span, nid: hir::HirId, ty_opt: Option<LocalTy<'tcx>>) -> Ty<'tcx> { |
| match ty_opt { |
| None => { |
| // Infer the variable's type. |
| let var_ty = self.fcx.next_ty_var(TypeVariableOrigin { |
| kind: TypeVariableOriginKind::TypeInference, |
| span, |
| }); |
| self.fcx |
| .locals |
| .borrow_mut() |
| .insert(nid, LocalTy { decl_ty: var_ty, revealed_ty: var_ty }); |
| var_ty |
| } |
| Some(typ) => { |
| // Take type that the user specified. |
| self.fcx.locals.borrow_mut().insert(nid, typ); |
| typ.revealed_ty |
| } |
| } |
| } |
| |
| /// Allocates a [LocalTy] for a declaration, which may have a type annotation. If it does have |
| /// a type annotation, then the LocalTy stored will be the resolved type. This may be found |
| /// again during type checking by querying [FnCtxt::local_ty] for the same hir_id. |
| fn declare(&mut self, decl: Declaration<'tcx>) { |
| let local_ty = match decl.ty { |
| Some(ref ty) => { |
| let o_ty = self.fcx.to_ty(&ty); |
| |
| let c_ty = self.fcx.inh.infcx.canonicalize_user_type_annotation(UserType::Ty(o_ty)); |
| debug!("visit_local: ty.hir_id={:?} o_ty={:?} c_ty={:?}", ty.hir_id, o_ty, c_ty); |
| self.fcx |
| .typeck_results |
| .borrow_mut() |
| .user_provided_types_mut() |
| .insert(ty.hir_id, c_ty); |
| |
| Some(LocalTy { decl_ty: o_ty, revealed_ty: o_ty }) |
| } |
| None => None, |
| }; |
| self.assign(decl.span, decl.hir_id, local_ty); |
| |
| debug!( |
| "local variable {:?} is assigned type {}", |
| decl.pat, |
| self.fcx.ty_to_string(self.fcx.locals.borrow().get(&decl.hir_id).unwrap().decl_ty) |
| ); |
| } |
| } |
| |
| impl<'a, 'tcx> Visitor<'tcx> for GatherLocalsVisitor<'a, 'tcx> { |
| // Add explicitly-declared locals. |
| fn visit_local(&mut self, local: &'tcx hir::Local<'tcx>) { |
| self.declare(local.into()); |
| intravisit::walk_local(self, local) |
| } |
| |
| fn visit_let_expr(&mut self, let_expr: &'tcx hir::Let<'tcx>) { |
| self.declare(let_expr.into()); |
| intravisit::walk_let_expr(self, let_expr); |
| } |
| |
| fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) { |
| let old_outermost_fn_param_pat = self.outermost_fn_param_pat.replace(param.ty_span); |
| intravisit::walk_param(self, param); |
| self.outermost_fn_param_pat = old_outermost_fn_param_pat; |
| } |
| |
| // Add pattern bindings. |
| fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) { |
| if let PatKind::Binding(_, _, ident, _) = p.kind { |
| let var_ty = self.assign(p.span, p.hir_id, None); |
| |
| if let Some(ty_span) = self.outermost_fn_param_pat { |
| if !self.fcx.tcx.features().unsized_fn_params { |
| self.fcx.require_type_is_sized( |
| var_ty, |
| p.span, |
| traits::SizedArgumentType(Some(ty_span)), |
| ); |
| } |
| } else { |
| if !self.fcx.tcx.features().unsized_locals { |
| self.fcx.require_type_is_sized(var_ty, p.span, traits::VariableType(p.hir_id)); |
| } |
| } |
| |
| debug!( |
| "pattern binding {} is assigned to {} with type {:?}", |
| ident, |
| self.fcx.ty_to_string(self.fcx.locals.borrow().get(&p.hir_id).unwrap().decl_ty), |
| var_ty |
| ); |
| } |
| let old_outermost_fn_param_pat = self.outermost_fn_param_pat.take(); |
| intravisit::walk_pat(self, p); |
| self.outermost_fn_param_pat = old_outermost_fn_param_pat; |
| } |
| |
| // Don't descend into the bodies of nested closures. |
| fn visit_fn( |
| &mut self, |
| _: intravisit::FnKind<'tcx>, |
| _: &'tcx hir::FnDecl<'tcx>, |
| _: hir::BodyId, |
| _: Span, |
| _: hir::HirId, |
| ) { |
| } |
| } |