1 //! This module contains the fcuntaiontliy to convert from the wacky tcx data
2 //! structures into the HAIR. The `builder` is generally ignorant of the tcx,
3 //! etc., and instead goes through the `Cx` for most of its work.
6 use crate::hair::util::UserAnnotatedTyHelpers;
8 use rustc_data_structures::indexed_vec::Idx;
9 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
11 use rustc::middle::region;
12 use rustc::infer::InferCtxt;
13 use rustc::ty::subst::Subst;
14 use rustc::ty::{self, Ty, TyCtxt};
15 use rustc::ty::subst::{Kind, Substs};
16 use rustc::ty::layout::VariantIdx;
19 use syntax::symbol::Symbol;
21 use rustc_data_structures::sync::Lrc;
22 use crate::hair::constant::{lit_to_const, LitToConstError};
25 pub struct Cx<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
26 tcx: TyCtxt<'a, 'gcx, 'tcx>,
27 infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
29 pub root_lint_level: hir::HirId,
30 pub param_env: ty::ParamEnv<'gcx>,
32 /// Identity `Substs` for use with const-evaluation.
33 pub identity_substs: &'gcx Substs<'gcx>,
35 pub region_scope_tree: Lrc<region::ScopeTree>,
36 pub tables: &'a ty::TypeckTables<'gcx>,
38 /// This is `Constness::Const` if we are compiling a `static`,
39 /// `const`, or the body of a `const fn`.
40 constness: hir::Constness,
42 /// What kind of body is being compiled.
43 pub body_owner_kind: hir::BodyOwnerKind,
45 /// Whether this constant/function needs overflow checks.
48 /// See field with the same name on `Mir`.
49 control_flow_destroyed: Vec<(Span, String)>,
52 impl<'a, 'gcx, 'tcx> Cx<'a, 'gcx, 'tcx> {
53 pub fn new(infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
54 src_id: hir::HirId) -> Cx<'a, 'gcx, 'tcx> {
56 let src_def_id = tcx.hir().local_def_id_from_hir_id(src_id);
57 let body_owner_kind = tcx.hir().body_owner_kind_by_hir_id(src_id);
59 let constness = match body_owner_kind {
60 hir::BodyOwnerKind::Const |
61 hir::BodyOwnerKind::Static(_) => hir::Constness::Const,
62 hir::BodyOwnerKind::Closure |
63 hir::BodyOwnerKind::Fn => hir::Constness::NotConst,
66 let attrs = tcx.hir().attrs_by_hir_id(src_id);
68 // Some functions always have overflow checks enabled,
69 // however, they may not get codegen'd, depending on
70 // the settings for the crate they are codegened in.
71 let mut check_overflow = attr::contains_name(attrs, "rustc_inherit_overflow_checks");
73 // Respect -C overflow-checks.
74 check_overflow |= tcx.sess.overflow_checks();
76 // Constants always need overflow checks.
77 check_overflow |= constness == hir::Constness::Const;
79 let lint_level = lint_level_for_hir_id(tcx, src_id);
83 root_lint_level: lint_level,
84 param_env: tcx.param_env(src_def_id),
85 identity_substs: Substs::identity_for_item(tcx.global_tcx(), src_def_id),
86 region_scope_tree: tcx.region_scope_tree(src_def_id),
87 tables: tcx.typeck_tables_of(src_def_id),
91 control_flow_destroyed: Vec::new(),
95 pub fn control_flow_destroyed(self) -> Vec<(Span, String)> {
96 self.control_flow_destroyed
100 impl<'a, 'gcx, 'tcx> Cx<'a, 'gcx, 'tcx> {
101 /// Normalizes `ast` into the appropriate "mirror" type.
102 pub fn mirror<M: Mirror<'tcx>>(&mut self, ast: M) -> M::Output {
103 ast.make_mirror(self)
106 pub fn usize_ty(&mut self) -> Ty<'tcx> {
110 pub fn usize_literal(&mut self, value: u64) -> &'tcx ty::LazyConst<'tcx> {
111 self.tcx.mk_lazy_const(ty::LazyConst::Evaluated(ty::Const::from_usize(self.tcx, value)))
114 pub fn bool_ty(&mut self) -> Ty<'tcx> {
118 pub fn unit_ty(&mut self) -> Ty<'tcx> {
122 pub fn true_literal(&mut self) -> &'tcx ty::LazyConst<'tcx> {
123 self.tcx.mk_lazy_const(ty::LazyConst::Evaluated(ty::Const::from_bool(self.tcx, true)))
126 pub fn false_literal(&mut self) -> &'tcx ty::LazyConst<'tcx> {
127 self.tcx.mk_lazy_const(ty::LazyConst::Evaluated(ty::Const::from_bool(self.tcx, false)))
130 pub fn const_eval_literal(
132 lit: &'tcx ast::LitKind,
136 ) -> ty::Const<'tcx> {
137 trace!("const_eval_literal: {:#?}, {:?}, {:?}, {:?}", lit, ty, sp, neg);
139 match lit_to_const(lit, self.tcx, ty, neg) {
141 Err(LitToConstError::UnparseableFloat) => {
142 // FIXME(#31407) this is only necessary because float parsing is buggy
143 self.tcx.sess.span_err(sp, "could not evaluate float literal (see issue #31407)");
144 // create a dummy value and continue compiling
145 Const::from_bits(self.tcx, 0, self.param_env.and(ty))
147 Err(LitToConstError::Reported) => {
148 // create a dummy value and continue compiling
149 Const::from_bits(self.tcx, 0, self.param_env.and(ty))
154 pub fn pattern_from_hir(&mut self, p: &hir::Pat) -> Pattern<'tcx> {
155 let tcx = self.tcx.global_tcx();
156 let p = match tcx.hir().get(p.id) {
157 Node::Pat(p) | Node::Binding(p) => p,
158 node => bug!("pattern became {:?}", node)
160 Pattern::from_hir(tcx,
161 self.param_env.and(self.identity_substs),
166 pub fn trait_method(&mut self,
170 params: &[Kind<'tcx>])
171 -> (Ty<'tcx>, ty::Const<'tcx>) {
172 let method_name = Symbol::intern(method_name);
173 let substs = self.tcx.mk_substs_trait(self_ty, params);
174 for item in self.tcx.associated_items(trait_def_id) {
175 if item.kind == ty::AssociatedKind::Method && item.ident.name == method_name {
176 let method_ty = self.tcx.type_of(item.def_id);
177 let method_ty = method_ty.subst(self.tcx, substs);
178 return (method_ty, ty::Const::zero_sized(method_ty));
182 bug!("found no method `{}` in `{:?}`", method_name, trait_def_id);
185 pub fn all_fields(&mut self, adt_def: &ty::AdtDef, variant_index: VariantIdx) -> Vec<Field> {
186 (0..adt_def.variants[variant_index].fields.len())
191 pub fn needs_drop(&mut self, ty: Ty<'tcx>) -> bool {
192 let (ty, param_env) = self.tcx.lift_to_global(&(ty, self.param_env)).unwrap_or_else(|| {
193 bug!("MIR: Cx::needs_drop({:?}, {:?}) got \
194 type with inference types/regions",
197 ty.needs_drop(self.tcx.global_tcx(), param_env)
200 fn lint_level_of(&self, node_id: ast::NodeId) -> LintLevel {
201 let hir_id = self.tcx.hir().definitions().node_to_hir_id(node_id);
202 let has_lint_level = self.tcx.dep_graph.with_ignore(|| {
203 self.tcx.lint_levels(LOCAL_CRATE).lint_level_set(hir_id).is_some()
207 LintLevel::Explicit(hir_id)
213 pub fn tcx(&self) -> TyCtxt<'a, 'gcx, 'tcx> {
217 pub fn tables(&self) -> &'a ty::TypeckTables<'gcx> {
221 pub fn check_overflow(&self) -> bool {
225 pub fn type_is_copy_modulo_regions(&self, ty: Ty<'tcx>, span: Span) -> bool {
226 self.infcx.type_is_copy_modulo_regions(self.param_env, ty, span)
230 impl UserAnnotatedTyHelpers<'gcx, 'tcx> for Cx<'_, 'gcx, 'tcx> {
231 fn tcx(&self) -> TyCtxt<'_, 'gcx, 'tcx> {
235 fn tables(&self) -> &ty::TypeckTables<'tcx> {
240 fn lint_level_for_hir_id(tcx: TyCtxt<'_, '_, '_>, mut id: hir::HirId) -> hir::HirId {
241 // Right now we insert a `with_ignore` node in the dep graph here to
242 // ignore the fact that `lint_levels` below depends on the entire crate.
243 // For now this'll prevent false positives of recompiling too much when
246 // Once red/green incremental compilation lands we should be able to
247 // remove this because while the crate changes often the lint level map
248 // will change rarely.
249 tcx.dep_graph.with_ignore(|| {
250 let sets = tcx.lint_levels(LOCAL_CRATE);
252 if sets.lint_level_set(id).is_some() {
255 let next = tcx.hir().get_parent_node_by_hir_id(id);
257 bug!("lint traversal reached the root of the crate");