Auto merge of #42927 - brson:beta-next, r=alexcrichton

[beta] backports

Reopening #42841 as a new PR due to bors flakiness.

- #42785
- #42740
- #42735
- #42728
- #42695
- #42659
- #42634
- #42566

I just unilaterally accepted all the non-accepted nominations. Everything picked cleanly.

src/bootstrap/bin/main.rs

@@ -26,12 +26,6 @@ use bootstrap::{Flags, Config, Build};
 fn main() {
     let args = env::args().skip(1).collect::<Vec<_>>();
     let flags = Flags::parse(&args);
-    let mut config = Config::parse(&flags.build, flags.config.clone());
-
-    // compat with `./configure` while we're still using that
-    if std::fs::metadata("config.mk").is_ok() {
-        config.update_with_config_mk();
-    }
-
+    let config = Config::parse(&flags.build, flags.config.clone());
     Build::new(flags, config).build();
 }

src/bootstrap/config.rs

@@ -15,7 +15,7 @@
 
 use std::collections::HashMap;
 use std::env;
-use std::fs::File;
+use std::fs::{self, File};
 use std::io::prelude::*;
 use std::path::PathBuf;
 use std::process;
@@ -404,6 +404,12 @@ impl Config {
             set(&mut config.rust_dist_src, t.src_tarball);
         }
 
+
+        // compat with `./configure` while we're still using that
+        if fs::metadata("config.mk").is_ok() {
+            config.update_with_config_mk();
+        }
+
         return config
     }
 
@@ -412,7 +418,7 @@ impl Config {
     /// While we still have `./configure` this implements the ability to decode
     /// that configuration into this. This isn't exactly a full-blown makefile
     /// parser, but hey it gets the job done!
-    pub fn update_with_config_mk(&mut self) {
+    fn update_with_config_mk(&mut self) {
         let mut config = String::new();
         File::open("config.mk").unwrap().read_to_string(&mut config).unwrap();
         for line in config.lines() {

src/bootstrap/flags.rs

@@ -237,11 +237,18 @@ Arguments:
         let cwd = t!(env::current_dir());
         let paths = matches.free[1..].iter().map(|p| cwd.join(p)).collect::<Vec<_>>();
 
+        let cfg_file = matches.opt_str("config").map(PathBuf::from).or_else(|| {
+            if fs::metadata("config.toml").is_ok() {
+                Some(PathBuf::from("config.toml"))
+            } else {
+                None
+            }
+        });
 
         // All subcommands can have an optional "Available paths" section
         if matches.opt_present("verbose") {
             let flags = Flags::parse(&["build".to_string()]);
-            let mut config = Config::default();
+            let mut config = Config::parse(&flags.build, cfg_file.clone());
             config.build = flags.build.clone();
             let mut build = Build::new(flags, config);
             metadata::build(&mut build);
@@ -302,14 +309,6 @@ Arguments:
         };
 
 
-        let cfg_file = matches.opt_str("config").map(PathBuf::from).or_else(|| {
-            if fs::metadata("config.toml").is_ok() {
-                Some(PathBuf::from("config.toml"))
-            } else {
-                None
-            }
-        });
-
         let mut stage = matches.opt_str("stage").map(|j| j.parse().unwrap());
 
         if matches.opt_present("incremental") {

src/liballoc_jemalloc/build.rs

@@ -93,7 +93,29 @@ fn main() {
        .env("AR", &ar)
        .env("RANLIB", format!("{} s", ar.display()));
 
-    if target.contains("ios") {
+    if target.contains("windows") {
+        // A bit of history here, this used to be --enable-lazy-lock added in
+        // #14006 which was filed with jemalloc in jemalloc/jemalloc#83 which
+        // was also reported to MinGW:
+        //
+        //  http://sourceforge.net/p/mingw-w64/bugs/395/
+        //
+        // When updating jemalloc to 4.0, however, it was found that binaries
+        // would exit with the status code STATUS_RESOURCE_NOT_OWNED indicating
+        // that a thread was unlocking a mutex it never locked. Disabling this
+        // "lazy lock" option seems to fix the issue, but it was enabled by
+        // default for MinGW targets in 13473c7 for jemalloc.
+        //
+        // As a result of all that, force disabling lazy lock on Windows, and
+        // after reading some code it at least *appears* that the initialization
+        // of mutexes is otherwise ok in jemalloc, so shouldn't cause problems
+        // hopefully...
+        //
+        // tl;dr: make windows behave like other platforms by disabling lazy
+        //        locking, but requires passing an option due to a historical
+        //        default with jemalloc.
+        cmd.arg("--disable-lazy-lock");
+    } else if target.contains("ios") {
         cmd.arg("--disable-tls");
     } else if target.contains("android") {
         // We force android to have prefixed symbols because apparently

src/libcore/iter/mod.rs

@@ -191,10 +191,12 @@
 //! {
 //!     let result = match IntoIterator::into_iter(values) {
 //!         mut iter => loop {
-//!             let x = match iter.next() {
-//!                 Some(val) => val,
+//!             let next;
+//!             match iter.next() {
+//!                 Some(val) => next = val,
 //!                 None => break,
 //!             };
+//!             let x = next;
 //!             let () = { println!("{}", x); };
 //!         },
 //!     };

src/librustc/hir/lowering.rs

@@ -2168,11 +2168,13 @@ impl<'a> LoweringContext<'a> {
                 //     let result = match ::std::iter::IntoIterator::into_iter(<head>) {
                 //       mut iter => {
                 //         [opt_ident]: loop {
-                //           let <pat> = match ::std::iter::Iterator::next(&mut iter) {
-                //             ::std::option::Option::Some(val) => val,
+                //           let mut _next;
+                //           match ::std::iter::Iterator::next(&mut iter) {
+                //             ::std::option::Option::Some(val) => _next = val,
                 //             ::std::option::Option::None => break
                 //           };
-                //           SemiExpr(<body>);
+                //           let <pat> = _next;
+                //           StmtExpr(<body>);
                 //         }
                 //       }
                 //     };
@@ -2184,13 +2186,22 @@ impl<'a> LoweringContext<'a> {
 
                 let iter = self.str_to_ident("iter");
 
-                // `::std::option::Option::Some(val) => val`
+                let next_ident = self.str_to_ident("_next");
+                let next_pat = self.pat_ident_binding_mode(e.span,
+                                                           next_ident,
+                                                           hir::BindByValue(hir::MutMutable));
+
+                // `::std::option::Option::Some(val) => next = val`
                 let pat_arm = {
                     let val_ident = self.str_to_ident("val");
                     let val_pat = self.pat_ident(e.span, val_ident);
                     let val_expr = P(self.expr_ident(e.span, val_ident, val_pat.id));
+                    let next_expr = P(self.expr_ident(e.span, next_ident, next_pat.id));
+                    let assign = P(self.expr(e.span,
+                                             hir::ExprAssign(next_expr, val_expr),
+                                             ThinVec::new()));
                     let some_pat = self.pat_some(e.span, val_pat);
-                    self.arm(hir_vec![some_pat], val_expr)
+                    self.arm(hir_vec![some_pat], assign)
                 };
 
                 // `::std::option::Option::None => break`
@@ -2220,10 +2231,20 @@ impl<'a> LoweringContext<'a> {
                                                hir::MatchSource::ForLoopDesugar),
                                 ThinVec::new()))
                 };
+                let match_stmt = respan(e.span, hir::StmtExpr(match_expr, self.next_id()));
+
+                let next_expr = P(self.expr_ident(e.span, next_ident, next_pat.id));
+
+                // `let mut _next`
+                let next_let = self.stmt_let_pat(e.span,
+                    None,
+                    next_pat,
+                    hir::LocalSource::ForLoopDesugar);
 
+                // `let <pat> = _next`
                 let pat = self.lower_pat(pat);
                 let pat_let = self.stmt_let_pat(e.span,
-                    match_expr,
+                    Some(next_expr),
                     pat,
                     hir::LocalSource::ForLoopDesugar);
 
@@ -2232,7 +2253,12 @@ impl<'a> LoweringContext<'a> {
                 let body_expr = P(self.expr_block(body_block, ThinVec::new()));
                 let body_stmt = respan(e.span, hir::StmtExpr(body_expr, self.next_id()));
 
-                let loop_block = P(self.block_all(e.span, hir_vec![pat_let, body_stmt], None));
+                let loop_block = P(self.block_all(e.span,
+                                                  hir_vec![next_let,
+                                                           match_stmt,
+                                                           pat_let,
+                                                           body_stmt],
+                                                  None));
 
                 // `[opt_ident]: loop { ... }`
                 let loop_expr = hir::ExprLoop(loop_block, self.lower_opt_sp_ident(opt_ident),
@@ -2599,14 +2625,14 @@ impl<'a> LoweringContext<'a> {
 
     fn stmt_let_pat(&mut self,
                     sp: Span,
-                    ex: P<hir::Expr>,
+                    ex: Option<P<hir::Expr>>,
                     pat: P<hir::Pat>,
                     source: hir::LocalSource)
                     -> hir::Stmt {
         let local = P(hir::Local {
             pat: pat,
             ty: None,
-            init: Some(ex),
+            init: ex,
             id: self.next_id(),
             span: sp,
             attrs: ThinVec::new(),
@@ -2624,7 +2650,7 @@ impl<'a> LoweringContext<'a> {
             self.pat_ident(sp, ident)
         };
         let pat_id = pat.id;
-        (self.stmt_let_pat(sp, ex, pat, hir::LocalSource::Normal), pat_id)
+        (self.stmt_let_pat(sp, Some(ex), pat, hir::LocalSource::Normal), pat_id)
     }
 
     fn block_expr(&mut self, expr: P<hir::Expr>) -> hir::Block {

src/librustc/middle/free_region.rs

@@ -18,7 +18,6 @@
 use hir::def_id::DefId;
 use middle::region::RegionMaps;
 use ty::{self, Lift, TyCtxt, Region};
-use ty::wf::ImpliedBound;
 use rustc_data_structures::transitive_relation::TransitiveRelation;
 
 /// Combines a `RegionMaps` (which governs relationships between
@@ -136,23 +135,6 @@ impl<'tcx> FreeRegionMap<'tcx> {
         self.relation.is_empty()
     }
 
-    pub fn relate_free_regions_from_implied_bounds(&mut self,
-                                                   implied_bounds: &[ImpliedBound<'tcx>])
-    {
-        debug!("relate_free_regions_from_implied_bounds()");
-        for implied_bound in implied_bounds {
-            debug!("implied bound: {:?}", implied_bound);
-            match *implied_bound {
-                ImpliedBound::RegionSubRegion(a, b) => {
-                    self.relate_regions(a, b);
-                }
-                ImpliedBound::RegionSubParam(..) |
-                ImpliedBound::RegionSubProjection(..) => {
-                }
-            }
-        }
-    }
-
     pub fn relate_free_regions_from_predicates(&mut self,
                                                predicates: &[ty::Predicate<'tcx>]) {
         debug!("relate_free_regions_from_predicates(predicates={:?})", predicates);
@@ -177,7 +159,7 @@ impl<'tcx> FreeRegionMap<'tcx> {
 
     // Record that `'sup:'sub`. Or, put another way, `'sub <= 'sup`.
     // (with the exception that `'static: 'x` is not notable)
-    fn relate_regions(&mut self, sub: Region<'tcx>, sup: Region<'tcx>) {
+    pub fn relate_regions(&mut self, sub: Region<'tcx>, sup: Region<'tcx>) {
         if (is_free(sub) || *sub == ty::ReStatic) && is_free(sup) {
             self.relation.add(sub, sup)
         }