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<'tcx>(
  22     tcx: TyCtxt<'tcx>,
  23     owner_def: ty::WithOptConstParam<LocalDefId>,
  24 ) -> Result<(&'tcx Steal<Thir<'tcx>>, 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>(
  56     tcx: TyCtxt<'tcx>,
  57     owner_def: ty::WithOptConstParam<LocalDefId>,
  58 ) -> String {
  59     match thir_body(tcx, owner_def) {
  60         Ok((thir, _)) => format!("{:#?}", thir.steal()),
  61         Err(_) => "error".into(),
  62     }
  63 }
  64
  65 struct Cx<'tcx> {
  66     tcx: TyCtxt<'tcx>,
  67     thir: Thir<'tcx>,
  68
  69     param_env: ty::ParamEnv<'tcx>,
  70
  71     region_scope_tree: &'tcx region::ScopeTree,
  72     typeck_results: &'tcx ty::TypeckResults<'tcx>,
  73     rvalue_scopes: &'tcx RvalueScopes,
  74
  75     /// When applying adjustments to the expression
  76     /// with the given `HirId`, use the given `Span`,
  77     /// instead of the usual span. This is used to
  78     /// assign the span of an overall method call
  79     /// (e.g. `my_val.foo()`) to the adjustment expressions
  80     /// for the receiver.
  81     adjustment_span: Option<(HirId, Span)>,
  82
  83     /// False to indicate that adjustments should not be applied. Only used for `custom_mir`
  84     apply_adjustments: bool,
  85
  86     /// The `DefId` of the owner of this body.
  87     body_owner: DefId,
  88 }
  89
  90 impl<'tcx> Cx<'tcx> {
  91     fn new(tcx: TyCtxt<'tcx>, def: ty::WithOptConstParam<LocalDefId>) -> Cx<'tcx> {
  92         let typeck_results = tcx.typeck_opt_const_arg(def);
  93         let did = def.did;
  94         let hir = tcx.hir();
  95         Cx {
  96             tcx,
  97             thir: Thir::new(),
  98             param_env: tcx.param_env(def.did),
  99             region_scope_tree: tcx.region_scope_tree(def.did),
 100             typeck_results,
 101             rvalue_scopes: &typeck_results.rvalue_scopes,
 102             body_owner: did.to_def_id(),
 103             adjustment_span: None,
 104             apply_adjustments: hir
 105                 .attrs(hir.local_def_id_to_hir_id(did))
 106                 .iter()
 107                 .all(|attr| attr.name_or_empty() != rustc_span::sym::custom_mir),
 108         }
 109     }
 110
 111     #[instrument(level = "debug", skip(self))]
 112     fn pattern_from_hir(&mut self, p: &hir::Pat<'_>) -> Box<Pat<'tcx>> {
 113         let p = match self.tcx.hir().get(p.hir_id) {
 114             Node::Pat(p) => p,
 115             node => bug!("pattern became {:?}", node),
 116         };
 117         pat_from_hir(self.tcx, self.param_env, self.typeck_results(), p)
 118     }
 119
 120     fn closure_env_param(&self, owner_def: LocalDefId, owner_id: HirId) -> Option<Param<'tcx>> {
 121         match self.tcx.def_kind(owner_def) {
 122             DefKind::Closure => {
 123                 let closure_ty = self.typeck_results.node_type(owner_id);
 124
 125                 let ty::Closure(closure_def_id, closure_substs) = *closure_ty.kind() else {
 126                     bug!("closure expr does not have closure type: {:?}", closure_ty);
 127                 };
 128
 129                 let bound_vars = self.tcx.mk_bound_variable_kinds(std::iter::once(
 130                     ty::BoundVariableKind::Region(ty::BrEnv),
 131                 ));
 132                 let br = ty::BoundRegion {
 133                     var: ty::BoundVar::from_usize(bound_vars.len() - 1),
 134                     kind: ty::BrEnv,
 135                 };
 136                 let env_region = ty::ReLateBound(ty::INNERMOST, br);
 137                 let closure_env_ty =
 138                     self.tcx.closure_env_ty(closure_def_id, closure_substs, env_region).unwrap();
 139                 let liberated_closure_env_ty = self.tcx.erase_late_bound_regions(
 140                     ty::Binder::bind_with_vars(closure_env_ty, bound_vars),
 141                 );
 142                 let env_param = Param {
 143                     ty: liberated_closure_env_ty,
 144                     pat: None,
 145                     ty_span: None,
 146                     self_kind: None,
 147                     hir_id: None,
 148                 };
 149
 150                 Some(env_param)
 151             }
 152             DefKind::Generator => {
 153                 let gen_ty = self.typeck_results.node_type(owner_id);
 154                 let gen_param =
 155                     Param { ty: gen_ty, pat: None, ty_span: None, self_kind: None, hir_id: None };
 156                 Some(gen_param)
 157             }
 158             _ => None,
 159         }
 160     }
 161
 162     fn explicit_params<'a>(
 163         &'a mut self,
 164         owner_id: HirId,
 165         fn_decl: &'tcx hir::FnDecl<'tcx>,
 166         body: &'tcx hir::Body<'tcx>,
 167     ) -> impl Iterator<Item = Param<'tcx>> + 'a {
 168         let fn_sig = self.typeck_results.liberated_fn_sigs()[owner_id];
 169
 170         body.params.iter().enumerate().map(move |(index, param)| {
 171             let ty_span = fn_decl
 172                 .inputs
 173                 .get(index)
 174                 // Make sure that inferred closure args have no type span
 175                 .and_then(|ty| if param.pat.span != ty.span { Some(ty.span) } else { None });
 176
 177             let self_kind = if index == 0 && fn_decl.implicit_self.has_implicit_self() {
 178                 Some(fn_decl.implicit_self)
 179             } else {
 180                 None
 181             };
 182
 183             // C-variadic fns also have a `VaList` input that's not listed in `fn_sig`
 184             // (as it's created inside the body itself, not passed in from outside).
 185             let ty = if fn_decl.c_variadic && index == fn_decl.inputs.len() {
 186                 let va_list_did = self.tcx.require_lang_item(LangItem::VaList, Some(param.span));
 187
 188                 self.tcx
 189                     .bound_type_of(va_list_did)
 190                     .subst(self.tcx, &[self.tcx.lifetimes.re_erased.into()])
 191             } else {
 192                 fn_sig.inputs()[index]
 193             };
 194
 195             let pat = self.pattern_from_hir(param.pat);
 196             Param { pat: Some(pat), ty, ty_span, self_kind, hir_id: Some(param.hir_id) }
 197         })
 198     }
 199 }
 200
 201 impl<'tcx> UserAnnotatedTyHelpers<'tcx> for Cx<'tcx> {
 202     fn tcx(&self) -> TyCtxt<'tcx> {
 203         self.tcx
 204     }
 205
 206     fn typeck_results(&self) -> &ty::TypeckResults<'tcx> {
 207         self.typeck_results
 208     }
 209 }
 210
 211 mod block;
 212 mod expr;