Use a single lifetime for MIR construction

src/librustc/infer/mod.rs

@@ -465,7 +465,7 @@ impl<'tcx> fmt::Display for FixupError<'tcx> {
 /// Helper type of a temporary returned by `tcx.infer_ctxt()`.
 /// Necessary because we can't write the following bound:
 /// `F: for<'b, 'tcx> where 'gcx: 'tcx FnOnce(InferCtxt<'b, 'gcx, 'tcx>)`.
-pub struct InferCtxtBuilder<'gcx, 'tcx> {
+pub struct InferCtxtBuilder<'gcx: 'tcx, 'tcx> {
     global_tcx: TyCtxt<'gcx, 'gcx>,
     fresh_tables: Option<RefCell<ty::TypeckTables<'tcx>>>,
 }
@@ -510,7 +510,7 @@ impl<'gcx, 'tcx> InferCtxtBuilder<'gcx, 'tcx> {
         })
     }
 
-    pub fn enter<R>(&'tcx mut self, f: impl for<'a> FnOnce(InferCtxt<'a, 'gcx, 'tcx>) -> R) -> R {
+    pub fn enter<R>(&mut self, f: impl for<'a> FnOnce(InferCtxt<'a, 'gcx, 'tcx>) -> R) -> R {
         let InferCtxtBuilder {
             global_tcx,
             ref fresh_tables,

src/librustc_mir/build/block.rs

@@ -6,7 +6,7 @@ use rustc::mir::*;
 use rustc::hir;
 use syntax_pos::Span;
 
-impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> Builder<'a, 'tcx> {
     pub fn ast_block(&mut self,
                      destination: &Place<'tcx>,
                      block: BasicBlock,

src/librustc_mir/build/expr/as_constant.rs

@@ -5,7 +5,7 @@ use crate::hair::*;
 use rustc::mir::*;
 use rustc::ty::CanonicalUserTypeAnnotation;
 
-impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Compile `expr`, yielding a compile-time constant. Assumes that
     /// `expr` is a valid compile-time constant!
     pub fn as_constant<M>(&mut self, expr: M) -> Constant<'tcx>

src/librustc_mir/build/expr/as_operand.rs

@@ -6,7 +6,7 @@ use crate::hair::*;
 use rustc::middle::region;
 use rustc::mir::*;
 
-impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Returns an operand suitable for use until the end of the current
     /// scope expression.
     ///

src/librustc_mir/build/expr/as_place.rs

@@ -10,7 +10,7 @@ use rustc::ty::{CanonicalUserTypeAnnotation, Variance};
 
 use rustc_data_structures::indexed_vec::Idx;
 
-impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Compile `expr`, yielding a place that we can move from etc.
     pub fn as_place<M>(&mut self, block: BasicBlock, expr: M) -> BlockAnd<Place<'tcx>>
     where

src/librustc_mir/build/expr/as_rvalue.rs

@@ -12,7 +12,7 @@ use rustc::mir::*;
 use rustc::ty::{self, CanonicalUserTypeAnnotation, Ty, UpvarSubsts};
 use syntax_pos::Span;
 
-impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// See comment on `as_local_operand`
     pub fn as_local_rvalue<M>(&mut self, block: BasicBlock, expr: M) -> BlockAnd<Rvalue<'tcx>>
     where

src/librustc_mir/build/expr/as_temp.rs

@@ -6,7 +6,7 @@ use crate::hair::*;
 use rustc::middle::region;
 use rustc::mir::*;
 
-impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Compile `expr` into a fresh temporary. This is used when building
     /// up rvalues so as to freeze the value that will be consumed.
     pub fn as_temp<M>(

src/librustc_mir/build/expr/into.rs

@@ -8,7 +8,7 @@ use rustc::ty;
 
 use rustc_target::spec::abi::Abi;
 
-impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Compile `expr`, storing the result into `destination`, which
     /// is assumed to be uninitialized.
     pub fn into_expr(

src/librustc_mir/build/expr/stmt.rs

@@ -3,7 +3,7 @@ use crate::build::{BlockAnd, BlockAndExtension, BlockFrame, Builder};
 use crate::hair::*;
 use rustc::mir::*;
 
-impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Builds a block of MIR statements to evaluate the HAIR `expr`.
     /// If the original expression was an AST statement,
     /// (e.g., `some().code(&here());`) then `opt_stmt_span` is the

src/librustc_mir/build/into.rs

@@ -9,14 +9,15 @@ use crate::hair::*;
 use rustc::mir::*;
 
 pub(in crate::build) trait EvalInto<'tcx> {
-    fn eval_into<'a, 'gcx>(self,
-                           builder: &mut Builder<'a, 'gcx, 'tcx>,
-                           destination: &Place<'tcx>,
-                           block: BasicBlock)
-                           -> BlockAnd<()>;
+    fn eval_into(
+        self,
+        builder: &mut Builder<'_, 'tcx>,
+        destination: &Place<'tcx>,
+        block: BasicBlock,
+    ) -> BlockAnd<()>;
 }
 
-impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> Builder<'a, 'tcx> {
     pub fn into<E>(&mut self,
                    destination: &Place<'tcx>,
                    block: BasicBlock,
@@ -29,22 +30,24 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
 }
 
 impl<'tcx> EvalInto<'tcx> for ExprRef<'tcx> {
-    fn eval_into<'a, 'gcx>(self,
-                           builder: &mut Builder<'a, 'gcx, 'tcx>,
-                           destination: &Place<'tcx>,
-                           block: BasicBlock)
-                           -> BlockAnd<()> {
+    fn eval_into(
+        self,
+        builder: &mut Builder<'_, 'tcx>,
+        destination: &Place<'tcx>,
+        block: BasicBlock,
+    ) -> BlockAnd<()> {
         let expr = builder.hir.mirror(self);
         builder.into_expr(destination, block, expr)
     }
 }
 
 impl<'tcx> EvalInto<'tcx> for Expr<'tcx> {
-    fn eval_into<'a, 'gcx>(self,
-                           builder: &mut Builder<'a, 'gcx, 'tcx>,
-                           destination: &Place<'tcx>,
-                           block: BasicBlock)
-                           -> BlockAnd<()> {
+    fn eval_into(
+        self,
+        builder: &mut Builder<'_, 'tcx>,
+        destination: &Place<'tcx>,
+        block: BasicBlock,
+    ) -> BlockAnd<()> {
         builder.into_expr(destination, block, self)
     }
 }

src/librustc_mir/build/matches/mod.rs

@@ -27,7 +27,7 @@ mod util;
 
 use std::convert::TryFrom;
 
-impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Generates MIR for a `match` expression.
     ///
     /// The MIR that we generate for a match looks like this.
@@ -768,7 +768,7 @@ pub(crate) struct ArmHasGuard(pub bool);
 ///////////////////////////////////////////////////////////////////////////
 // Main matching algorithm
 
-impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// The main match algorithm. It begins with a set of candidates
     /// `candidates` and has the job of generating code to determine
     /// which of these candidates, if any, is the correct one. The
@@ -1296,7 +1296,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
 ///////////////////////////////////////////////////////////////////////////
 // Pattern binding - used for `let` and function parameters as well.
 
-impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Initializes each of the bindings from the candidate by
     /// moving/copying/ref'ing the source as appropriate. Tests the guard, if
     /// any, and then branches to the arm. Returns the block for the case where

src/librustc_mir/build/matches/simplify.rs

@@ -23,7 +23,7 @@ use rustc::mir::interpret::truncate;
 
 use std::mem;
 
-impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> Builder<'a, 'tcx> {
     pub fn simplify_candidate<'pat>(&mut self,
                                     candidate: &mut Candidate<'pat, 'tcx>) {
         // repeatedly simplify match pairs until fixed point is reached

src/librustc_mir/build/matches/test.rs

@@ -19,7 +19,7 @@ use rustc::hir::{RangeEnd, Mutability};
 use syntax_pos::Span;
 use std::cmp::Ordering;
 
-impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Identifies what test is needed to decide if `match_pair` is applicable.
     ///
     /// It is a bug to call this with a simplifiable pattern.

src/librustc_mir/build/matches/util.rs

@@ -5,7 +5,7 @@ use rustc::mir::*;
 use std::u32;
 use std::convert::TryInto;
 
-impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> Builder<'a, 'tcx> {
     pub fn field_match_pairs<'pat>(&mut self,
                                    place: Place<'tcx>,
                                    subpatterns: &'pat [FieldPattern<'tcx>])

src/librustc_mir/build/misc.rs

@@ -8,7 +8,7 @@ use rustc::ty::{self, Ty};
 use rustc::mir::*;
 use syntax_pos::{Span, DUMMY_SP};
 
-impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
+impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Adds a new temporary value of type `ty` storing the result of
     /// evaluating `expr`.
     ///