rustc: make InferCtxt optional in MemCategorizationContext.

eddyb · eddyb · commit 63481a57dcb4 · 2017-06-10T15:29:18.000+03:00
diff --git a/src/librustc/infer/mod.rs b/src/librustc/infer/mod.rs
@@ -393,27 +393,6 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'gcx> {
             fresh_tables: env.fresh_tables().map(RefCell::new),
         }
     }
-
-    /// Fake InferCtxt with the global tcx. Used by pre-MIR borrowck
-    /// for MemCategorizationContext/ExprUseVisitor.
-    /// If any inference functionality is used, ICEs will occur.
-    pub fn borrowck_fake_infer_ctxt(self) -> InferCtxt<'a, 'gcx, 'gcx> {
-        InferCtxt {
-            tcx: self,
-            tables: InferTables::Missing,
-            type_variables: RefCell::new(type_variable::TypeVariableTable::new()),
-            int_unification_table: RefCell::new(UnificationTable::new()),
-            float_unification_table: RefCell::new(UnificationTable::new()),
-            region_vars: RegionVarBindings::new(self),
-            selection_cache: traits::SelectionCache::new(),
-            evaluation_cache: traits::EvaluationCache::new(),
-            projection_cache: RefCell::new(traits::ProjectionCache::new()),
-            reported_trait_errors: RefCell::new(FxHashSet()),
-            tainted_by_errors_flag: Cell::new(false),
-            err_count_on_creation: self.sess.err_count(),
-            in_snapshot: Cell::new(false),
-        }
-    }
 }
 
 impl<'a, 'gcx, 'tcx> InferCtxtBuilder<'a, 'gcx, 'tcx> {
diff --git a/src/librustc/middle/expr_use_visitor.rs b/src/librustc/middle/expr_use_visitor.rs
@@ -261,16 +261,32 @@ macro_rules! return_if_err {
     )
 }
 
-impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx, 'tcx> {
     pub fn new(delegate: &'a mut (Delegate<'tcx>+'a),
-               infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
+               tcx: TyCtxt<'a, 'tcx, 'tcx>,
                param_env: ty::ParamEnv<'tcx>,
                region_maps: &'a RegionMaps,
                tables: &'a ty::TypeckTables<'tcx>)
                -> Self
     {
         ExprUseVisitor {
-            mc: mc::MemCategorizationContext::new(infcx, region_maps, tables),
+            mc: mc::MemCategorizationContext::new(tcx, region_maps, tables),
+            delegate,
+            param_env,
+        }
+    }
+}
+
+impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
+    pub fn with_infer(delegate: &'a mut (Delegate<'tcx>+'a),
+                      infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
+                      param_env: ty::ParamEnv<'tcx>,
+                      region_maps: &'a RegionMaps,
+                      tables: &'a ty::TypeckTables<'tcx>)
+                      -> Self
+    {
+        ExprUseVisitor {
+            mc: mc::MemCategorizationContext::with_infer(infcx, region_maps, tables),
             delegate,
             param_env,
         }
@@ -296,7 +312,7 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
     }
 
     fn tcx(&self) -> TyCtxt<'a, 'gcx, 'tcx> {
-        self.mc.infcx.tcx
+        self.mc.tcx
     }
 
     fn delegate_consume(&mut self,
@@ -306,7 +322,7 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
         debug!("delegate_consume(consume_id={}, cmt={:?})",
                consume_id, cmt);
 
-        let mode = copy_or_move(self.mc.infcx, self.param_env, &cmt, DirectRefMove);
+        let mode = copy_or_move(&self.mc, self.param_env, &cmt, DirectRefMove);
         self.delegate.consume(consume_id, consume_span, cmt, mode);
     }
 
@@ -784,7 +800,7 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
                 PatKind::Binding(hir::BindByRef(..), ..) =>
                     mode.lub(BorrowingMatch),
                 PatKind::Binding(hir::BindByValue(..), ..) => {
-                    match copy_or_move(self.mc.infcx, self.param_env, &cmt_pat, PatBindingMove) {
+                    match copy_or_move(&self.mc, self.param_env, &cmt_pat, PatBindingMove) {
                         Copy => mode.lub(CopyingMatch),
                         Move(..) => mode.lub(MovingMatch),
                     }
@@ -801,7 +817,6 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
         debug!("walk_pat cmt_discr={:?} pat={:?}", cmt_discr, pat);
 
         let tcx = self.tcx();
-        let infcx = self.mc.infcx;
         let ExprUseVisitor { ref mc, ref mut delegate, param_env } = *self;
         return_if_err!(mc.cat_pattern(cmt_discr.clone(), pat, |cmt_pat, pat| {
             if let PatKind::Binding(bmode, def_id, ..) = pat.node {
@@ -826,7 +841,7 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
                         }
                     }
                     hir::BindByValue(..) => {
-                        let mode = copy_or_move(infcx, param_env, &cmt_pat, PatBindingMove);
+                        let mode = copy_or_move(mc, param_env, &cmt_pat, PatBindingMove);
                         debug!("walk_pat binding consuming pat");
                         delegate.consume_pat(pat, cmt_pat, mode);
                     }
@@ -885,7 +900,7 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
                                                                    freevar.def));
                 match upvar_capture {
                     ty::UpvarCapture::ByValue => {
-                        let mode = copy_or_move(self.mc.infcx,
+                        let mode = copy_or_move(&self.mc,
                                                 self.param_env,
                                                 &cmt_var,
                                                 CaptureMove);
@@ -917,13 +932,13 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
     }
 }
 
-fn copy_or_move<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
+fn copy_or_move<'a, 'gcx, 'tcx>(mc: &mc::MemCategorizationContext<'a, 'gcx, 'tcx>,
                                 param_env: ty::ParamEnv<'tcx>,
                                 cmt: &mc::cmt<'tcx>,
                                 move_reason: MoveReason)
                                 -> ConsumeMode
 {
-    if infcx.type_moves_by_default(param_env, cmt.ty, cmt.span) {
+    if mc.type_moves_by_default(param_env, cmt.ty, cmt.span) {
         Move(move_reason)
     } else {
         Copy
diff --git a/src/librustc/middle/mem_categorization.rs b/src/librustc/middle/mem_categorization.rs
@@ -282,9 +282,10 @@ impl ast_node for hir::Pat {
 
 #[derive(Clone)]
 pub struct MemCategorizationContext<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
-    pub infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
+    pub tcx: TyCtxt<'a, 'gcx, 'tcx>,
     pub region_maps: &'a RegionMaps,
     pub tables: &'a ty::TypeckTables<'tcx>,
+    infcx: Option<&'a InferCtxt<'a, 'gcx, 'tcx>>,
 }
 
 pub type McResult<T> = Result<T, ()>;
@@ -385,27 +386,51 @@ impl MutabilityCategory {
     }
 }
 
-impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
-    /// Context should be the `DefId` we use to fetch region-maps.
-    pub fn new(infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
+impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx, 'tcx> {
+    pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                region_maps: &'a RegionMaps,
                tables: &'a ty::TypeckTables<'tcx>)
-               -> MemCategorizationContext<'a, 'gcx, 'tcx> {
-        MemCategorizationContext { infcx, region_maps, tables }
+               -> MemCategorizationContext<'a, 'tcx, 'tcx> {
+        MemCategorizationContext { tcx, region_maps, tables, infcx: None }
     }
+}
 
-    fn tcx(&self) -> TyCtxt<'a, 'gcx, 'tcx> {
-        self.infcx.tcx
+impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
+    pub fn with_infer(infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
+                      region_maps: &'a RegionMaps,
+                      tables: &'a ty::TypeckTables<'tcx>)
+                      -> MemCategorizationContext<'a, 'gcx, 'tcx> {
+        MemCategorizationContext {
+            tcx: infcx.tcx,
+            region_maps,
+            tables,
+            infcx: Some(infcx),
+        }
+    }
+
+    pub fn type_moves_by_default(&self,
+                                 param_env: ty::ParamEnv<'tcx>,
+                                 ty: Ty<'tcx>,
+                                 span: Span)
+                                 -> bool {
+        self.infcx.map(|infcx| infcx.type_moves_by_default(param_env, ty, span))
+            .or_else(|| {
+                self.tcx.lift_to_global(&(param_env, ty)).map(|(param_env, ty)| {
+                    ty.moves_by_default(self.tcx.global_tcx(), param_env, span)
+                })
+            })
+            .unwrap_or(true)
     }
 
     fn resolve_type_vars_if_possible<T>(&self, value: &T) -> T
         where T: TypeFoldable<'tcx>
     {
-        self.infcx.resolve_type_vars_if_possible(value)
+        self.infcx.map(|infcx| infcx.resolve_type_vars_if_possible(value))
+            .unwrap_or_else(|| value.clone())
     }
 
     fn is_tainted_by_errors(&self) -> bool {
-        self.infcx.is_tainted_by_errors()
+        self.infcx.map_or(false, |infcx| infcx.is_tainted_by_errors())
     }
 
     fn resolve_type_vars_or_error(&self,
@@ -426,7 +451,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
             None if self.is_tainted_by_errors() => Err(()),
             None => {
                 bug!("no type for node {}: {} in mem_categorization",
-                     id, self.tcx().hir.node_to_string(id));
+                     id, self.tcx.hir.node_to_string(id));
             }
         }
     }
@@ -506,7 +531,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
             adjustment::Adjust::Deref(overloaded) => {
                 // Equivalent to *expr or something similar.
                 let base = if let Some(deref) = overloaded {
-                    let ref_ty = self.tcx().mk_ref(deref.region, ty::TypeAndMut {
+                    let ref_ty = self.tcx.mk_ref(deref.region, ty::TypeAndMut {
                         ty: target,
                         mutbl: deref.mutbl,
                     });
@@ -624,17 +649,17 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
           }
 
           Def::Upvar(def_id, _, fn_node_id) => {
-              let var_id = self.tcx().hir.as_local_node_id(def_id).unwrap();
+              let var_id = self.tcx.hir.as_local_node_id(def_id).unwrap();
               self.cat_upvar(id, span, var_id, fn_node_id)
           }
 
           Def::Local(def_id) => {
-            let vid = self.tcx().hir.as_local_node_id(def_id).unwrap();
+            let vid = self.tcx.hir.as_local_node_id(def_id).unwrap();
             Ok(Rc::new(cmt_ {
                 id: id,
                 span: span,
                 cat: Categorization::Local(vid),
-                mutbl: MutabilityCategory::from_local(self.tcx(), vid),
+                mutbl: MutabilityCategory::from_local(self.tcx, vid),
                 ty: expr_ty,
                 note: NoteNone
             }))
@@ -686,7 +711,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
         let var_ty = self.node_ty(var_id)?;
 
         // Mutability of original variable itself
-        let var_mutbl = MutabilityCategory::from_local(self.tcx(), var_id);
+        let var_mutbl = MutabilityCategory::from_local(self.tcx, var_id);
 
         // Construct the upvar. This represents access to the field
         // from the environment (perhaps we should eventually desugar
@@ -753,11 +778,11 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
                  -> cmt_<'tcx>
     {
         // Region of environment pointer
-        let env_region = self.tcx().mk_region(ty::ReFree(ty::FreeRegion {
+        let env_region = self.tcx.mk_region(ty::ReFree(ty::FreeRegion {
             // The environment of a closure is guaranteed to
             // outlive any bindings introduced in the body of the
             // closure itself.
-            scope: self.tcx().hir.local_def_id(upvar_id.closure_expr_id),
+            scope: self.tcx.hir.local_def_id(upvar_id.closure_expr_id),
             bound_region: ty::BrEnv
         }));
 
@@ -774,7 +799,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
         // one.
         let cmt_result = cmt_ {
             mutbl: McImmutable,
-            ty: self.tcx().types.err,
+            ty: self.tcx.types.err,
             ..cmt_result
         };
 
@@ -806,7 +831,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
     pub fn temporary_scope(&self, id: ast::NodeId) -> ty::Region<'tcx>
     {
         let scope = self.region_maps.temporary_scope(id);
-        self.tcx().mk_region(match scope {
+        self.tcx.mk_region(match scope {
             Some(scope) => ty::ReScope(scope),
             None => ty::ReStatic
         })
@@ -817,20 +842,20 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
                            span: Span,
                            expr_ty: Ty<'tcx>)
                            -> cmt<'tcx> {
-        let promotable = self.tcx().rvalue_promotable_to_static.borrow().get(&id).cloned()
+        let promotable = self.tcx.rvalue_promotable_to_static.borrow().get(&id).cloned()
                                    .unwrap_or(false);
 
         // When the corresponding feature isn't toggled, only promote `[T; 0]`.
         let promotable = match expr_ty.sty {
             ty::TyArray(_, 0) => true,
-            _ => promotable && self.tcx().sess.features.borrow().rvalue_static_promotion,
+            _ => promotable && self.tcx.sess.features.borrow().rvalue_static_promotion,
         };
 
         // Compute maximum lifetime of this rvalue. This is 'static if
         // we can promote to a constant, otherwise equal to enclosing temp
         // lifetime.
         let re = if promotable {
-            self.tcx().types.re_static
+            self.tcx.types.re_static
         } else {
             self.temporary_scope(id)
         };
@@ -911,7 +936,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
                 span_bug!(expr.span, "cat_overloaded_lvalue: base is not a reference")
             }
         };
-        let ref_ty = self.tcx().mk_ref(region, ty::TypeAndMut {
+        let ref_ty = self.tcx.mk_ref(region, ty::TypeAndMut {
             ty: lvalue_ty,
             mutbl,
         });
@@ -1098,8 +1123,8 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
                     Def::Variant(variant_did) |
                     Def::VariantCtor(variant_did, ..) => {
                         // univariant enums do not need downcasts
-                        let enum_did = self.tcx().parent_def_id(variant_did).unwrap();
-                        if !self.tcx().adt_def(enum_did).is_univariant() {
+                        let enum_did = self.tcx.parent_def_id(variant_did).unwrap();
+                        if !self.tcx.adt_def(enum_did).is_univariant() {
                             self.cat_downcast(pat, cmt.clone(), cmt.ty, variant_did)
                         } else {
                             cmt
@@ -1116,8 +1141,8 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
             let def = self.tables.qpath_def(qpath, pat.id);
             let expected_len = match def {
                 Def::VariantCtor(def_id, CtorKind::Fn) => {
-                    let enum_def = self.tcx().parent_def_id(def_id).unwrap();
-                    self.tcx().adt_def(enum_def).variant_with_id(def_id).fields.len()
+                    let enum_def = self.tcx.parent_def_id(def_id).unwrap();
+                    self.tcx.adt_def(enum_def).variant_with_id(def_id).fields.len()
                 }
                 Def::StructCtor(_, CtorKind::Fn) => {
                     match self.pat_ty(&pat)?.sty {
diff --git a/src/librustc_borrowck/borrowck/check_loans.rs b/src/librustc_borrowck/borrowck/check_loans.rs
@@ -200,8 +200,7 @@ pub fn check_loans<'a, 'b, 'c, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
         all_loans: all_loans,
         param_env,
     };
-    let infcx = bccx.tcx.borrowck_fake_infer_ctxt();
-    euv::ExprUseVisitor::new(&mut clcx, &infcx, param_env, &bccx.region_maps, bccx.tables)
+    euv::ExprUseVisitor::new(&mut clcx, bccx.tcx, param_env, &bccx.region_maps, bccx.tables)
         .consume_body(body);
 }
 
diff --git a/src/librustc_borrowck/borrowck/gather_loans/mod.rs b/src/librustc_borrowck/borrowck/gather_loans/mod.rs
@@ -49,8 +49,7 @@ pub fn gather_loans_in_fn<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
     };
 
     let body = glcx.bccx.tcx.hir.body(body);
-    let infcx = bccx.tcx.borrowck_fake_infer_ctxt();
-    euv::ExprUseVisitor::new(&mut glcx, &infcx, param_env, &bccx.region_maps, bccx.tables)
+    euv::ExprUseVisitor::new(&mut glcx, bccx.tcx, param_env, &bccx.region_maps, bccx.tables)
         .consume_body(body);
 
     glcx.report_potential_errors();
diff --git a/src/librustc_const_eval/check_match.rs b/src/librustc_const_eval/check_match.rs
@@ -493,20 +493,18 @@ fn check_legality_of_move_bindings(cx: &MatchVisitor,
 ///
 /// FIXME: this should be done by borrowck.
 fn check_for_mutation_in_guard(cx: &MatchVisitor, guard: &hir::Expr) {
-    cx.tcx.infer_ctxt(()).enter(|infcx| {
-        let mut checker = MutationChecker {
-            cx: cx,
-        };
-        ExprUseVisitor::new(&mut checker, &infcx, cx.param_env, cx.region_maps, cx.tables)
-            .walk_expr(guard);
-    });
+    let mut checker = MutationChecker {
+        cx: cx,
+    };
+    ExprUseVisitor::new(&mut checker, cx.tcx, cx.param_env, cx.region_maps, cx.tables)
+        .walk_expr(guard);
 }
 
-struct MutationChecker<'a, 'gcx: 'a> {
-    cx: &'a MatchVisitor<'a, 'gcx>,
+struct MutationChecker<'a, 'tcx: 'a> {
+    cx: &'a MatchVisitor<'a, 'tcx>,
 }
 
-impl<'a, 'gcx, 'tcx> Delegate<'tcx> for MutationChecker<'a, 'gcx> {
+impl<'a, 'tcx> Delegate<'tcx> for MutationChecker<'a, 'tcx> {
     fn matched_pat(&mut self, _: &Pat, _: cmt, _: euv::MatchMode) {}
     fn consume(&mut self, _: ast::NodeId, _: Span, _: cmt, _: ConsumeMode) {}
     fn consume_pat(&mut self, _: &Pat, _: cmt, _: ConsumeMode) {}
diff --git a/src/librustc_passes/consts.rs b/src/librustc_passes/consts.rs
diff --git a/src/librustc_typeck/check/regionck.rs b/src/librustc_typeck/check/regionck.rs
diff --git a/src/librustc_typeck/check/upvar.rs b/src/librustc_typeck/check/upvar.rs

Original file line number	Diff line number	Diff line change
`@@ -200,8 +200,7 @@ pub fn check_loans<'a, 'b, 'c, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,`
`200`	`200`	`all_loans: all_loans,`
`201`	`201`	`param_env,`
`202`	`202`	`};`
`203`		`- let infcx = bccx.tcx.borrowck_fake_infer_ctxt();`
`204`		`- euv::ExprUseVisitor::new(&mut clcx, &infcx, param_env, &bccx.region_maps, bccx.tables)`
	`203`	`+ euv::ExprUseVisitor::new(&mut clcx, bccx.tcx, param_env, &bccx.region_maps, bccx.tables)`
`205`	`204`	`.consume_body(body);`
`206`	`205`	`}`
`207`	`206`