Auto merge of #39877 - estebank:remove-params, r=petrochenkov

Remove noop method `Substs::params()`

Re: 48b3dd1 & 7a8d482

Author: bors

Diff for: src/librustc/traits/select.rs

@@ -2547,7 +2547,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
                 // TyError and ensure they do not affect any other fields.
                 // This could be checked after type collection for any struct
                 // with a potentially unsized trailing field.
-                let params = substs_a.params().iter().enumerate().map(|(i, &k)| {
+                let params = substs_a.iter().enumerate().map(|(i, &k)| {
                     if ty_params.contains(i) {
                         Kind::from(tcx.types.err)
                     } else {
@@ -2567,7 +2567,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
 
                 // Check that the source structure with the target's
                 // type parameters is a subtype of the target.
-                let params = substs_a.params().iter().enumerate().map(|(i, &k)| {
+                let params = substs_a.iter().enumerate().map(|(i, &k)| {
                     if ty_params.contains(i) {
                         Kind::from(substs_b.type_at(i))
                     } else {

Diff for: src/librustc/ty/relate.rs

@@ -143,7 +143,7 @@ pub fn relate_substs<'a, 'gcx, 'tcx, R>(relation: &mut R,
 {
     let tcx = relation.tcx();
 
-    let params = a_subst.params().iter().zip(b_subst.params()).enumerate().map(|(i, (a, b))| {
+    let params = a_subst.iter().zip(b_subst).enumerate().map(|(i, (a, b))| {
         let variance = variances.map_or(ty::Invariant, |v| v[i]);
         if let (Some(a_ty), Some(b_ty)) = (a.as_type(), b.as_type()) {
             Ok(Kind::from(relation.relate_with_variance(variance, &a_ty, &b_ty)?))

Diff for: src/librustc/ty/subst.rs

@@ -254,12 +254,6 @@ impl<'a, 'gcx, 'tcx> Substs<'tcx> {
         self.is_empty()
     }
 
-    #[inline]
-    pub fn params(&self) -> &[Kind<'tcx>] {
-        // FIXME (dikaiosune) this should be removed, and corresponding compilation errors fixed
-        self
-    }
-
     #[inline]
     pub fn types(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
         self.iter().filter_map(|k| k.as_type())

Diff for: src/librustc_typeck/check/method/confirm.rs

@@ -309,17 +309,17 @@ impl<'a, 'gcx, 'tcx> ConfirmContext<'a, 'gcx, 'tcx> {
         // parameters from the type and those from the method.
         //
         // FIXME -- permit users to manually specify lifetimes
-        let supplied_start = substs.params().len() + method_generics.regions.len();
+        let supplied_start = substs.len() + method_generics.regions.len();
         Substs::for_item(self.tcx, pick.item.def_id, |def, _| {
             let i = def.index as usize;
-            if i < substs.params().len() {
+            if i < substs.len() {
                 substs.region_at(i)
             } else {
                 self.region_var_for_def(self.span, def)
             }
         }, |def, cur_substs| {
             let i = def.index as usize;
-            if i < substs.params().len() {
+            if i < substs.len() {
                 substs.type_at(i)
             } else if supplied_method_types.is_empty() {
                 self.type_var_for_def(self.span, def, cur_substs)

Diff for: src/librustc_typeck/check/method/probe.rs

@@ -1326,7 +1326,7 @@ impl<'a, 'gcx, 'tcx> ProbeContext<'a, 'gcx, 'tcx> {
         } else {
             let substs = Substs::for_item(self.tcx, method, |def, _| {
                 let i = def.index as usize;
-                if i < substs.params().len() {
+                if i < substs.len() {
                     substs.region_at(i)
                 } else {
                     // In general, during probe we erase regions. See
@@ -1335,7 +1335,7 @@ impl<'a, 'gcx, 'tcx> ProbeContext<'a, 'gcx, 'tcx> {
                 }
             }, |def, cur_substs| {
                 let i = def.index as usize;
-                if i < substs.params().len() {
+                if i < substs.len() {
                     substs.type_at(i)
                 } else {
                     self.type_var_for_def(self.span, def, cur_substs)

Diff for: src/librustc_typeck/check/writeback.rs

@@ -100,7 +100,7 @@ impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
 
         let gcx = fcx.tcx.global_tcx();
         let free_substs = fcx.parameter_environment.free_substs;
-        for (i, k) in free_substs.params().iter().enumerate() {
+        for (i, k) in free_substs.iter().enumerate() {
             let r = if let Some(r) = k.as_region() {
                 r
             } else {