compiler/rustc_mir_build/src/thir/cx/mod.rs

   1 //! This module contains the functionality to convert from the wacky tcx data
   2 //! structures into the THIR. The `builder` is generally ignorant of the tcx,
   3 //! etc., and instead goes through the `Cx` for most of its work.
   4
   5 use crate::thir::pattern::pat_from_hir;
   6 use crate::thir::util::UserAnnotatedTyHelpers;
   7
   8 use rustc_data_structures::steal::Steal;
   9 use rustc_errors::ErrorGuaranteed;
  10 use rustc_hir as hir;
  11 use rustc_hir::def::DefKind;
  12 use rustc_hir::def_id::{DefId, LocalDefId};
  13 use rustc_hir::lang_items::LangItem;
  14 use rustc_hir::HirId;
  15 use rustc_hir::Node;
  16 use rustc_middle::middle::region;
  17 use rustc_middle::thir::*;
  18 use rustc_middle::ty::{self, RvalueScopes, TyCtxt};
  19 use rustc_span::Span;
  20
  21 pub(crate) fn thir_body(
  22     tcx: TyCtxt<'_>,
  23     owner_def: ty::WithOptConstParam<LocalDefId>,
  24 ) -> Result<(&Steal<Thir<'_>>, ExprId), ErrorGuaranteed> {
  25     let hir = tcx.hir();
  26     let body = hir.body(hir.body_owned_by(owner_def.did));
  27     let mut cx = Cx::new(tcx, owner_def);
  28     if let Some(reported) = cx.typeck_results.tainted_by_errors {
  29         return Err(reported);
  30     }
  31     let expr = cx.mirror_expr(&body.value);
  32
  33     let owner_id = hir.local_def_id_to_hir_id(owner_def.did);
  34     if let Some(ref fn_decl) = hir.fn_decl_by_hir_id(owner_id) {
  35         let closure_env_param = cx.closure_env_param(owner_def.did, owner_id);
  36         let explicit_params = cx.explicit_params(owner_id, fn_decl, body);
  37         cx.thir.params = closure_env_param.into_iter().chain(explicit_params).collect();
  38
  39         // The resume argument may be missing, in that case we need to provide it here.
  40         // It will always be `()` in this case.
  41         if tcx.def_kind(owner_def.did) == DefKind::Generator && body.params.is_empty() {
  42             cx.thir.params.push(Param {
  43                 ty: tcx.mk_unit(),
  44                 pat: None,
  45                 ty_span: None,
  46                 self_kind: None,
  47                 hir_id: None,
  48             });
  49         }
  50     }
  51
  52     Ok((tcx.alloc_steal_thir(cx.thir), expr))
  53 }
  54
  55 pub(crate) fn thir_tree(tcx: TyCtxt<'_>, owner_def: ty::WithOptConstParam<LocalDefId>) -> String {
  56     match thir_body(tcx, owner_def) {
  57         Ok((thir, _)) => format!("{:#?}", thir.steal()),
  58         Err(_) => "error".into(),
  59     }
  60 }
  61
  62 struct Cx<'tcx> {
  63     tcx: TyCtxt<'tcx>,
  64     thir: Thir<'tcx>,
  65
  66     param_env: ty::ParamEnv<'tcx>,
  67
  68     region_scope_tree: &'tcx region::ScopeTree,
  69     typeck_results: &'tcx ty::TypeckResults<'tcx>,
  70     rvalue_scopes: &'tcx RvalueScopes,
  71
  72     /// When applying adjustments to the expression
  73     /// with the given `HirId`, use the given `Span`,
  74     /// instead of the usual span. This is used to
  75     /// assign the span of an overall method call
  76     /// (e.g. `my_val.foo()`) to the adjustment expressions
  77     /// for the receiver.
  78     adjustment_span: Option<(HirId, Span)>,
  79
  80     /// False to indicate that adjustments should not be applied. Only used for `custom_mir`
  81     apply_adjustments: bool,
  82
  83     /// The `DefId` of the owner of this body.
  84     body_owner: DefId,
  85 }
  86
  87 impl<'tcx> Cx<'tcx> {
  88     fn new(tcx: TyCtxt<'tcx>, def: ty::WithOptConstParam<LocalDefId>) -> Cx<'tcx> {
  89         let typeck_results = tcx.typeck_opt_const_arg(def);
  90         let did = def.did;
  91         let hir = tcx.hir();
  92         Cx {
  93             tcx,
  94             thir: Thir::new(),
  95             param_env: tcx.param_env(def.did),
  96             region_scope_tree: tcx.region_scope_tree(def.did),
  97             typeck_results,
  98             rvalue_scopes: &typeck_results.rvalue_scopes,
  99             body_owner: did.to_def_id(),
 100             adjustment_span: None,
 101             apply_adjustments: hir
 102                 .attrs(hir.local_def_id_to_hir_id(did))
 103                 .iter()
 104                 .all(|attr| attr.name_or_empty() != rustc_span::sym::custom_mir),
 105         }
 106     }
 107
 108     #[instrument(level = "debug", skip(self))]
 109     fn pattern_from_hir(&mut self, p: &hir::Pat<'_>) -> Box<Pat<'tcx>> {
 110         let p = match self.tcx.hir().get(p.hir_id) {
 111             Node::Pat(p) => p,
 112             node => bug!("pattern became {:?}", node),
 113         };
 114         pat_from_hir(self.tcx, self.param_env, self.typeck_results(), p)
 115     }
 116
 117     fn closure_env_param(&self, owner_def: LocalDefId, owner_id: HirId) -> Option<Param<'tcx>> {
 118         match self.tcx.def_kind(owner_def) {
 119             DefKind::Closure => {
 120                 let closure_ty = self.typeck_results.node_type(owner_id);
 121
 122                 let ty::Closure(closure_def_id, closure_substs) = *closure_ty.kind() else {
 123                     bug!("closure expr does not have closure type: {:?}", closure_ty);
 124                 };
 125
 126                 let bound_vars = self.tcx.mk_bound_variable_kinds(std::iter::once(
 127                     ty::BoundVariableKind::Region(ty::BrEnv),
 128                 ));
 129                 let br = ty::BoundRegion {
 130                     var: ty::BoundVar::from_usize(bound_vars.len() - 1),
 131                     kind: ty::BrEnv,
 132                 };
 133                 let env_region = ty::ReLateBound(ty::INNERMOST, br);
 134                 let closure_env_ty =
 135                     self.tcx.closure_env_ty(closure_def_id, closure_substs, env_region).unwrap();
 136                 let liberated_closure_env_ty = self.tcx.erase_late_bound_regions(
 137                     ty::Binder::bind_with_vars(closure_env_ty, bound_vars),
 138                 );
 139                 let env_param = Param {
 140                     ty: liberated_closure_env_ty,
 141                     pat: None,
 142                     ty_span: None,
 143                     self_kind: None,
 144                     hir_id: None,
 145                 };
 146
 147                 Some(env_param)
 148             }
 149             DefKind::Generator => {
 150                 let gen_ty = self.typeck_results.node_type(owner_id);
 151                 let gen_param =
 152                     Param { ty: gen_ty, pat: None, ty_span: None, self_kind: None, hir_id: None };
 153                 Some(gen_param)
 154             }
 155             _ => None,
 156         }
 157     }
 158
 159     fn explicit_params<'a>(
 160         &'a mut self,
 161         owner_id: HirId,
 162         fn_decl: &'tcx hir::FnDecl<'tcx>,
 163         body: &'tcx hir::Body<'tcx>,
 164     ) -> impl Iterator<Item = Param<'tcx>> + 'a {
 165         let fn_sig = self.typeck_results.liberated_fn_sigs()[owner_id];
 166
 167         body.params.iter().enumerate().map(move |(index, param)| {
 168             let ty_span = fn_decl
 169                 .inputs
 170                 .get(index)
 171                 // Make sure that inferred closure args have no type span
 172                 .and_then(|ty| if param.pat.span != ty.span { Some(ty.span) } else { None });
 173
 174             let self_kind = if index == 0 && fn_decl.implicit_self.has_implicit_self() {
 175                 Some(fn_decl.implicit_self)
 176             } else {
 177                 None
 178             };
 179
 180             // C-variadic fns also have a `VaList` input that's not listed in `fn_sig`
 181             // (as it's created inside the body itself, not passed in from outside).
 182             let ty = if fn_decl.c_variadic && index == fn_decl.inputs.len() {
 183                 let va_list_did = self.tcx.require_lang_item(LangItem::VaList, Some(param.span));
 184
 185                 self.tcx
 186                     .bound_type_of(va_list_did)
 187                     .subst(self.tcx, &[self.tcx.lifetimes.re_erased.into()])
 188             } else {
 189                 fn_sig.inputs()[index]
 190             };
 191
 192             let pat = self.pattern_from_hir(param.pat);
 193             Param { pat: Some(pat), ty, ty_span, self_kind, hir_id: Some(param.hir_id) }
 194         })
 195     }
 196 }
 197
 198 impl<'tcx> UserAnnotatedTyHelpers<'tcx> for Cx<'tcx> {
 199     fn tcx(&self) -> TyCtxt<'tcx> {
 200         self.tcx
 201     }
 202
 203     fn typeck_results(&self) -> &ty::TypeckResults<'tcx> {
 204         self.typeck_results
 205     }
 206 }
 207
 208 mod block;
 209 mod expr;