mk: Switch rustbuild to the default build system

This commit switches the default build system for Rust from the makefiles to
rustbuild. The rustbuild build system has been in development for almost a year
now and has become quite mature over time. This commit is an implementation of
the proposal on [internals] which slates deletion of the makefiles on
2016-01-02.

[internals]: https://internals.rust-lang.org/t/proposal-for-promoting-rustbuild-to-official-status/4368

This commit also updates various documentation in `README.md`,
`CONTRIBUTING.md`, `src/bootstrap/README.md`, and throughout the source code of
rustbuild itself.

Closes #37858

1 files changed, 28 insertions, 11 deletions

diff --git a/configure b/configure
index 483471604cb..a287291c280 100755
--- a/configure
+++ b/configure
@@ -631,7 +631,7 @@ opt stage0-landing-pads 1 "enable landing pads during bootstrap with stage0"
 opt dist-host-only 0 "only install bins for the host architecture"
 opt inject-std-version 1 "inject the current compiler version of libstd into programs"
 opt llvm-version-check 1 "check if the LLVM version is supported, build anyway"
-opt rustbuild 0 "use the rust and cargo based build system"
+opt rustbuild 1 "use the rust and cargo based build system"
 opt codegen-tests 1 "run the src/test/codegen tests"
 opt option-checking 1 "complain about unrecognized options in this configure script"
 opt ninja 0 "build LLVM using the Ninja generator (for MSVC, requires building in the correct environment)"
@@ -664,11 +664,11 @@ valopt armv7-linux-androideabi-ndk "" "armv7-linux-androideabi NDK standalone pa
 valopt aarch64-linux-android-ndk "" "aarch64-linux-android NDK standalone path"
 valopt nacl-cross-path  "" "NaCl SDK path (Pepper Canary is recommended). Must be absolute!"
 valopt musl-root "/usr/local" "MUSL root installation directory (deprecated)"
-valopt musl-root-x86_64 "/usr/local" "x86_64-unknown-linux-musl install directory"
-valopt musl-root-i686 "/usr/local" "i686-unknown-linux-musl install directory"
-valopt musl-root-arm "/usr/local" "arm-unknown-linux-musleabi install directory"
-valopt musl-root-armhf "/usr/local" "arm-unknown-linux-musleabihf install directory"
-valopt musl-root-armv7 "/usr/local" "armv7-unknown-linux-musleabihf install directory"
+valopt musl-root-x86_64 "" "x86_64-unknown-linux-musl install directory"
+valopt musl-root-i686 "" "i686-unknown-linux-musl install directory"
+valopt musl-root-arm "" "arm-unknown-linux-musleabi install directory"
+valopt musl-root-armhf "" "arm-unknown-linux-musleabihf install directory"
+valopt musl-root-armv7 "" "armv7-unknown-linux-musleabihf install directory"
 valopt extra-filename "" "Additional data that is hashed and passed to the -C extra-filename flag"
 
 if [ -e ${CFG_SRC_DIR}.git ]
@@ -1374,7 +1374,7 @@ then
     fi
 fi
 
-if [ -z "$CFG_ENABLE_RUSTBUILD" ]; then
+if [ -n "$CFG_DISABLE_RUSTBUILD" ]; then
 
   step_msg "making directories"
 
@@ -1474,7 +1474,7 @@ fi
 step_msg "configuring submodules"
 
 # Have to be in the top of src directory for this
-if [ -z "$CFG_DISABLE_MANAGE_SUBMODULES" ] && [ -z "$CFG_ENABLE_RUSTBUILD" ]
+if [ -z "$CFG_DISABLE_MANAGE_SUBMODULES" ] && [ -n "$CFG_DISABLE_RUSTBUILD" ]
 then
     cd ${CFG_SRC_DIR}
 
@@ -1546,7 +1546,7 @@ do
         ;;
     esac
 
-    if [ -n "$CFG_ENABLE_RUSTBUILD" ]
+    if [ -z "$CFG_DISABLE_RUSTBUILD" ]
     then
         msg "not configuring LLVM, rustbuild in use"
         do_reconfigure=0
@@ -1871,7 +1871,7 @@ do
     putvar $CFG_LLVM_INST_DIR
 done
 
-if [ -n "$CFG_ENABLE_RUSTBUILD" ]
+if [ -z "$CFG_DISABLE_RUSTBUILD" ]
 then
     INPUT_MAKEFILE=src/bootstrap/mk/Makefile.in
 else
@@ -1890,5 +1890,22 @@ else
     step_msg "complete"
 fi
 
-msg "run \`make help\`"
+if [ -z "$CFG_DISABLE_RUSTBUILD" ]; then
+    msg "NOTE you have now configured rust to use a rewritten build system"
+    msg "     called rustbuild, and as a result this may have bugs that "
+    msg "     you did not see before. If you experience any issues you can"
+    msg "     go back to the old build system with --disable-rustbuild and"
+    msg "     please feel free to report any bugs!"
+    msg ""
+    msg "run \`python x.py --help\`"
+else
+    warn "the makefile-based build system is deprecated in favor of rustbuild"
+    msg ""
+    msg "It is recommended you avoid passing --disable-rustbuild to get your"
+    msg "build working as the makefiles will be deleted on 2017-02-02. If you"
+    msg "encounter bugs with rustbuild please file issues against rust-lang/rust"
+    msg ""
+    msg "run \`make help\`"
+fi
+
 msg