Update Cargo and its dependencies

This'll probably have a bunch of build errors, so let's try and head those off
and find them sooner rather than later!

src/Cargo.toml

@@ -55,8 +55,18 @@ debug-assertions = false
 debug = false
 debug-assertions = false
 
+# We want the RLS to use the version of Cargo that we've got vendored in this
+# repository to ensure that the same exact version of Cargo is used by both the
+# RLS and the Cargo binary itself. The RLS depends on Cargo as a git repository
+# so we use a `[patch]` here to override the github repository with our local
+# vendored copy.
 [patch."https://github.com/rust-lang/cargo"]
 cargo = { path = "tools/cargo" }
 
 [patch.crates-io]
+# Similar to Cargo above we want the RLS to use a vendored version of `rustfmt`
+# that we're shipping as well (to ensure that the rustfmt in RLS and the
+# `rustfmt` executable are the same exact vesion). Unlike Cargo, however, the
+# RLS depends on `rustfmt` from crates.io, so we put this in a `[patch]` section
+# for crates.io
 rustfmt-nightly = { path = "tools/rustfmt" }

src/bootstrap/bootstrap.py

@@ -351,11 +351,6 @@ class RustBuild(object):
             with open(self.rustc_stamp(), 'w') as rust_stamp:
                 rust_stamp.write(self.date)
 
-            if "pc-windows-gnu" in self.build:
-                filename = "rust-mingw-{}-{}.tar.gz".format(
-                    rustc_channel, self.build)
-                self._download_stage0_helper(filename, "rust-mingw")
-
         if self.cargo().startswith(self.bin_root()) and \
                 (not os.path.exists(self.cargo()) or
                  self.program_out_of_date(self.cargo_stamp())):

src/bootstrap/builder.rs

@@ -620,6 +620,39 @@ impl<'a> Builder<'a> {
         // Set this for all builds to make sure doc builds also get it.
         cargo.env("CFG_RELEASE_CHANNEL", &self.build.config.channel);
 
+        // This one's a bit tricky. As of the time of this writing the compiler
+        // links to the `winapi` crate on crates.io. This crate provides raw
+        // bindings to Windows system functions, sort of like libc does for
+        // Unix. This crate also, however, provides "import libraries" for the
+        // MinGW targets. There's an import library per dll in the windows
+        // distribution which is what's linked to. These custom import libraries
+        // are used because the winapi crate can reference Windows functions not
+        // present in the MinGW import libraries.
+        //
+        // For example MinGW may ship libdbghelp.a, but it may not have
+        // references to all the functions in the dbghelp dll. Instead the
+        // custom import library for dbghelp in the winapi crates has all this
+        // information.
+        //
+        // Unfortunately for us though the import libraries are linked by
+        // default via `-ldylib=winapi_foo`. That is, they're linked with the
+        // `dylib` type with a `winapi_` prefix (so the winapi ones don't
+        // conflict with the system MinGW ones). This consequently means that
+        // the binaries we ship of things like rustc_trans (aka the rustc_trans
+        // DLL) when linked against *again*, for example with procedural macros
+        // or plugins, will trigger the propagation logic of `-ldylib`, passing
+        // `-lwinapi_foo` to the linker again. This isn't actually available in
+        // our distribution, however, so the link fails.
+        //
+        // To solve this problem we tell winapi to not use its bundled import
+        // libraries. This means that it will link to the system MinGW import
+        // libraries by default, and the `-ldylib=foo` directives will still get
+        // passed to the final linker, but they'll look like `-lfoo` which can
+        // be resolved because MinGW has the import library. The downside is we
+        // don't get newer functions from Windows, but we don't use any of them
+        // anyway.
+        cargo.env("WINAPI_NO_BUNDLED_LIBRARIES", "1");
+
         if self.is_very_verbose() {
             cargo.arg("-v");
         }

src/bootstrap/dist.rs

@@ -224,6 +224,8 @@ fn make_win_dist(
         "libwinspool.a",
         "libws2_32.a",
         "libwsock32.a",
+        "libdbghelp.a",
+        "libmsimg32.a",
     ];
 
     //Find mingw artifacts we want to bundle

src/bootstrap/doc.rs

@@ -160,7 +160,7 @@ impl Step for CargoBook {
 
         let target = self.target;
         let name = self.name;
-        let src = build.src.join("src/tools/cargo/src/doc/book");
+        let src = build.src.join("src/tools/cargo/src/doc");
 
         let out = build.doc_out(target);
         t!(fs::create_dir_all(&out));

src/tools/cargo

@@ -1 +1 @@
-Subproject commit a88fbace48ac42ab21e1d8609012480d0aeab982
+Subproject commit 6a8eb71f6d226f9ac869dbacd5ff6aa76deef1c4