Remove use of expr_ty from coercions code

src/librustc_typeck/check/_match.rs

@@ -419,11 +419,14 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             }
             _ => result_ty
         };
+
+        let mut arm_tys = Vec::new();
         for (i, arm) in arms.iter().enumerate() {
             if let Some(ref e) = arm.guard {
                 self.check_expr_has_type(e, tcx.types.bool);
             }
             let arm_ty = self.check_expr_with_expectation(&arm.body, expected);
+            arm_tys.push(arm_ty);
 
             if result_ty.references_error() || arm_ty.references_error() {
                 result_ty = tcx.types.err;
@@ -453,10 +456,11 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                     })
             } else if i == 0 {
                 // Special-case the first arm, as it has no "previous expressions".
-                self.try_coerce(&arm.body, coerce_first)
+                self.try_coerce(&arm.body, arm_ty, coerce_first)
             } else {
-                let prev_arms = || arms[..i].iter().map(|arm| &*arm.body);
-                self.try_find_coercion_lub(origin, prev_arms, result_ty, &arm.body)
+                let prev_arms = || arms[..i].iter().map(|arm| &*arm.body)
+                                            .zip(arm_tys.iter().cloned());
+                self.try_find_coercion_lub(origin, prev_arms, result_ty, &arm.body, arm_ty)
             };
 
             result_ty = match result {

src/librustc_typeck/check/cast.rs

@@ -321,7 +321,7 @@ impl<'a, 'gcx, 'tcx> CastCheck<'tcx> {
             (None, Some(t_cast)) => {
                 if let ty::TyFnDef(.., f) = self.expr_ty.sty {
                     // Attempt a coercion to a fn pointer type.
-                    let res = fcx.try_coerce(self.expr, fcx.tcx.mk_fn_ptr(f));
+                    let res = fcx.try_coerce(self.expr, self.expr_ty, fcx.tcx.mk_fn_ptr(f));
                     if !res.is_ok() {
                         return Err(CastError::NonScalar);
                     }
@@ -471,7 +471,7 @@ impl<'a, 'gcx, 'tcx> CastCheck<'tcx> {
     }
 
     fn try_coercion_cast(&self, fcx: &FnCtxt<'a, 'gcx, 'tcx>) -> bool {
-        fcx.try_coerce(self.expr, self.cast_ty).is_ok()
+        fcx.try_coerce(self.expr, self.expr_ty, self.cast_ty).is_ok()
     }
 
 }

src/librustc_typeck/check/coercion.rs

@@ -630,9 +630,10 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
     /// The expressions *must not* have any pre-existing adjustments.
     pub fn try_coerce(&self,
                       expr: &hir::Expr,
+                      expr_ty: Ty<'tcx>,
                       target: Ty<'tcx>)
                       -> RelateResult<'tcx, Ty<'tcx>> {
-        let source = self.resolve_type_vars_with_obligations(self.expr_ty(expr));
+        let source = self.resolve_type_vars_with_obligations(expr_ty);
         debug!("coercion::try({:?}: {:?} -> {:?})", expr, source, target);
 
         let mut coerce = Coerce::new(self, TypeOrigin::ExprAssignable(expr.span));
@@ -658,14 +659,15 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                                            origin: TypeOrigin,
                                            exprs: E,
                                            prev_ty: Ty<'tcx>,
-                                           new: &'b hir::Expr)
+                                           new: &'b hir::Expr,
+                                           new_ty: Ty<'tcx>)
                                            -> RelateResult<'tcx, Ty<'tcx>>
         // FIXME(eddyb) use copyable iterators when that becomes ergonomic.
         where E: Fn() -> I,
-              I: IntoIterator<Item=&'b hir::Expr> {
+              I: IntoIterator<Item=(&'b hir::Expr, Ty<'tcx>)> {
 
         let prev_ty = self.resolve_type_vars_with_obligations(prev_ty);
-        let new_ty = self.resolve_type_vars_with_obligations(self.expr_ty(new));
+        let new_ty = self.resolve_type_vars_with_obligations(new_ty);
         debug!("coercion::try_find_lub({:?}, {:?})", prev_ty, new_ty);
 
         let trace = TypeTrace::types(origin, true, prev_ty, new_ty);
@@ -701,7 +703,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                 }
 
                 // Reify both sides and return the reified fn pointer type.
-                for expr in exprs().into_iter().chain(Some(new)) {
+                for (expr, _) in exprs().into_iter().chain(Some((new, new_ty))) {
                     // No adjustments can produce a fn item, so this should never trip.
                     assert!(!self.tables.borrow().adjustments.contains_key(&expr.id));
                     self.write_adjustment(expr.id, AdjustReifyFnPointer);
@@ -735,13 +737,13 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         // Then try to coerce the previous expressions to the type of the new one.
         // This requires ensuring there are no coercions applied to *any* of the
         // previous expressions, other than noop reborrows (ignoring lifetimes).
-        for expr in exprs() {
+        for (expr, expr_ty) in exprs() {
             let noop = match self.tables.borrow().adjustments.get(&expr.id) {
                 Some(&AdjustDerefRef(AutoDerefRef {
                     autoderefs: 1,
                     autoref: Some(AutoPtr(_, mutbl_adj)),
                     unsize: None
-                })) => match self.expr_ty(expr).sty {
+                })) => match expr_ty.sty {
                     ty::TyRef(_, mt_orig) => {
                         // Reborrow that we can safely ignore.
                         mutbl_adj == mt_orig.mutbl
@@ -765,7 +767,9 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             }
         }
 
-        match self.commit_if_ok(|_| apply(&mut coerce, &exprs, prev_ty, new_ty)) {
+        match self.commit_if_ok(|_| apply(&mut coerce,
+                                          &|| exprs().into_iter().map(|(e, _)| e),
+                                          prev_ty, new_ty)) {
             Err(_) => {
                 // Avoid giving strange errors on failed attempts.
                 if let Some(e) = first_error {
@@ -783,7 +787,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             }
             Ok((ty, adjustment)) => {
                 if !adjustment.is_identity() {
-                    for expr in exprs() {
+                    for (expr, _) in exprs() {
                         let previous = self.tables.borrow().adjustments.get(&expr.id).cloned();
                         if let Some(AdjustNeverToAny(_)) = previous {
                             self.write_adjustment(expr.id, AdjustNeverToAny(ty));

src/librustc_typeck/check/demand.rs

@@ -53,11 +53,11 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
     }
 
     // Checks that the type of `expr` can be coerced to `expected`.
-    pub fn demand_coerce(&self, expr: &hir::Expr, expected: Ty<'tcx>) {
+    pub fn demand_coerce(&self, expr: &hir::Expr, checked_ty: Ty<'tcx>, expected: Ty<'tcx>) {
         let expected = self.resolve_type_vars_with_obligations(expected);
-        if let Err(e) = self.try_coerce(expr, expected) {
+        if let Err(e) = self.try_coerce(expr, checked_ty, expected) {
             let origin = TypeOrigin::Misc(expr.span);
-            let expr_ty = self.resolve_type_vars_with_obligations(self.expr_ty(expr));
+            let expr_ty = self.resolve_type_vars_with_obligations(checked_ty);
             self.report_mismatched_types(origin, expected, expr_ty, e);
         }
     }

src/librustc_typeck/check/mod.rs

@@ -2567,13 +2567,13 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                         Expectation::rvalue_hint(self, ty)
                     });
 
-                    self.check_expr_with_expectation(&arg,
-                        expected.unwrap_or(ExpectHasType(formal_ty)));
+                    let checked_ty = self.check_expr_with_expectation(&arg,
+                                            expected.unwrap_or(ExpectHasType(formal_ty)));
                     // 2. Coerce to the most detailed type that could be coerced
                     //    to, which is `expected_ty` if `rvalue_hint` returns an
                     //    `ExpectHasType(expected_ty)`, or the `formal_ty` otherwise.
                     let coerce_ty = expected.and_then(|e| e.only_has_type(self));
-                    self.demand_coerce(&arg, coerce_ty.unwrap_or(formal_ty));
+                    self.demand_coerce(&arg, checked_ty, coerce_ty.unwrap_or(formal_ty));
 
                     // 3. Relate the expected type and the formal one,
                     //    if the expected type was used for the coercion.
@@ -2715,7 +2715,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                                     expr: &'gcx hir::Expr,
                                     expected: Ty<'tcx>) -> Ty<'tcx> {
         let ty = self.check_expr_with_hint(expr, expected);
-        self.demand_coerce(expr, expected);
+        self.demand_coerce(expr, ty, expected);
         ty
     }
 
@@ -2861,8 +2861,8 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             // Only try to coerce-unify if we have a then expression
             // to assign coercions to, otherwise it's () or diverging.
             let result = if let Some(ref then) = then_blk.expr {
-                let res = self.try_find_coercion_lub(origin, || Some(&**then),
-                                                     then_ty, else_expr);
+                let res = self.try_find_coercion_lub(origin, || Some((&**then, then_ty)),
+                                                     then_ty, else_expr, else_ty);
 
                 // In case we did perform an adjustment, we have to update
                 // the type of the block, because old trans still uses it.
@@ -3594,16 +3594,19 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             let mut unified = self.next_ty_var();
             let coerce_to = uty.unwrap_or(unified);
 
+            let mut arg_tys = Vec::new();
             for (i, e) in args.iter().enumerate() {
                 let e_ty = self.check_expr_with_hint(e, coerce_to);
+                arg_tys.push(e_ty);
                 let origin = TypeOrigin::Misc(e.span);
 
                 // Special-case the first element, as it has no "previous expressions".
                 let result = if i == 0 {
-                    self.try_coerce(e, coerce_to)
+                    self.try_coerce(e, e_ty, coerce_to)
                 } else {
-                    let prev_elems = || args[..i].iter().map(|e| &**e);
-                    self.try_find_coercion_lub(origin, prev_elems, unified, e)
+                    let prev_elems = || args[..i].iter().map(|e| &**e)
+                                                 .zip(arg_tys.iter().cloned());
+                    self.try_find_coercion_lub(origin, prev_elems, unified, e, e_ty)
                 };
 
                 match result {