Point to the current box syntax tracking issue

[est31]

The issue was used for both box syntax as well as placement new.
It got closed due to placement new being unapproved.
So a new one got created for box syntax, yet neither
the unstable book nor feature_gate.rs got updated.
We are doing this now.

r? @aidanhs

[sfackler]

@bors r+

[bors]

📌 Commit 93b2958 has been approved by sfackler

[kennytm]

@bors rollup

[rust-highfive]

The job x86_64-gnu-llvm-3.9 of your PR failed on Travis (raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

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[00:46:34] 
[00:46:34] ---- [ui] ui/feature-gate-box-expr.rs stdout ----
[00:46:34] diff of stderr:
[00:46:34] 
[00:46:34] 
[00:46:34] - error[E0658]: box expression syntax is experimental; you can call `Box::new` instead. (see issue #27779)
[00:46:34] + error[E0658]: box expression syntax is experimental; you can call `Box::new` instead. (see issue #49733)
[00:46:34] 2   --> $DIR/feature-gate-box-expr.rs:22:13
[00:46:34] 3    |
[00:46:34] 4 LL |     let x = box 'c'; //~ ERROR box expression syntax is experimental
[00:46:34] 
[00:46:34] The actual stderr differed from the expected stderr.
[00:46:34] The actual stderr differed from the expected stderr.
[00:46:34] Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/feature-gate-box-expr/feature-gate-box-expr.stderr
[00:46:34] To update references, rerun the tests and pass the `--bless` flag
[00:46:34] To only update this specific test, also pass `--test-args feature-gate-box-expr.rs`
[00:46:34] error: 1 errors occurred comparing output.
[00:46:34] status: exit code: 101
[00:46:34] status: exit code: 101
[00:46:34] command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui/feature-gate-box-expr.rs" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "-Zui-testing" "-C" "prefer-dynamic" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/feature-gate-box-expr/a" "-Crpath" "-O" "-Zunstable-options" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/feature-gate-box-expr/auxiliary" "-A" "unused"
[00:46:34] ------------------------------------------
[00:46:34] 
[00:46:34] ------------------------------------------
[00:46:34] stderr:
[00:46:34] stderr:
[00:46:34] ------------------------------------------
[00:46:34] {"message":"box expression syntax is experimental; you can call `Box::new` instead. (see issue #49733)","code":{"code":"E0658","explanation":"\nAn unstable feature was used.\n\nErroneous code example:\n\n```compile_fail,E658\n#[repr(u128)] // error: use of unstable library feature 'repr128'\nenum Foo {\n    Bar(u64),\n}\n```\n\nIf you're using a stable or a beta version of rustc, you won't be able to use\nany unstable features. In order to do so, please switch to a nightly version of\nrustc (by using rustup).\n\nIf you're using a nightly version of rustc, just add the corresponding feature\nto be able to use it:\n\n```\n#![feature(repr128)]\n\n#[repr(u128)] // ok!\nenum Foo {\n    Bar(u64),\] ui/feature-gate-box_syntax.rs stdout ----
[00:46:34] 
[00:46:34] 
[00:46:34] - error[E0658]: box expression syntax is experimental; you can call `Box::new` instead. (see issue #27779)
[00:46:34] + error[E0658]: box expression syntax is experimental; you can call `Box::new` instead. (see issue #49733)
[00:46:34] 2   --> $DIR/feature-gate-box_syntax.rs:14:13
[00:46:34] 3    |
[00:46:34] 4 LL |     let x = box 3;
[00:46:34] 
[00:46:34] The actual stderr differed from the expected stderr.
[00:46:34] The actual stderr differed from the expected stderr.
[00:46:34] Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/feature-gate-box_syntax/feature-gate-box_syntax.stderr
[00:46:34] To update references, rerun the tests and pass the `--bless` flag
[00:46:34] To only update this specific test, also pass `--test-args feature-gate-box_syntax.rs`
[00:46:34] error: 1 errors occurred comparing output.
[00:46:34] status: exit code: 101
[00:46:34] status: exit code: 101
[00:46:34] command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui/feature-gate-box_syntax.rs" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "-Zui-testing" "-C" "prefer-dynamic" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/feature-gate-box_syntax/a" "-Crpath" "-O" "-Zunstable-options" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/feature-gate-box_syntax/auxiliary" "-A" "unused"
[00:46:34] ------------------------------------------
[00:46:34] 
[00:46:34] ------------------------------------------
[00:46:34] stderr:
[00:46:34] stderr:
[00:46:34] ------------------------------------------
[00:46:34] {"message":"box expression syntax is experimental; you can call `Box::new` instead. (see issue #49733)","code":{"code":"E0658","explanation":"\nAn unstable feature was used.\n\nErroneous code example:\n\n```compile_fail,E658\n#[repr(u128)] // error: use of unstable library feature 'repr128'\nenum Foo {\n    Bar(u64),\n}\n```\n\nIf you're using a stable or a beta version of rustc, you won't be able to use\nany unstable features. In order to do so, please switch to a nightly version of\nrustc (by using rustup).\n\nIf you're using a nightly version of rustc, just add the corresponding feature\nto be able to use it:\n\n```\n#![feature(repr128)]\n\n#[repr(u128)] // ok!\nenum Foo {\n    Bar(u64),\n}\n```\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/feature-gate-box_syntax.rs","byte_start":570,"byte_end":575,"line_start":14,"line_end":14,"column_start":13,"column_end":18,"is_primary":true,"text":[{"text":"    let x = box 3;","highlight_start":13,"highlight_end":18}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"add #![feature(box_syntax)] to the crate attributes to enable","code":null,"level":"help","spans":[],"children":[],"rendered":null}],"rendered":"error[E0658]: box expression syntax is experimental; you can call `Box::new` instead. (see issue #49733)\n  --> /checkout/src/test/ui/feature-gate-box_syntax.rs:14:13\n   |\nLL |     let x = box 3;\n   |             ^^^^^\n   |\n   = help: add #![feature(box_syntax)] to the crate attributes to enable\n\n"}
[00:46:34] {"message":"aborting due to previous error","code":null,"level":"error","spans":[],"children":[],"rendered":"error: aborting due to previous error\n\n"}
[00:46:34] {"message":"For more information about this error, try `rustc --explain E0658`.","code":null,"level":"","spans":[],"children":[],"rendered":"For more information about this error, try `rustc --explain E0658`.\n"}
[00:46:34] ------------------------------------------
[00:46:34] 
[00:46:34] thread '[ui] ui/feature-gate-box_syntax.rs' panicked at 'explicit panic', tools/compiletest/src/runtest.rs:3053:9
[00:46:34] 
---
[00:46:34] 
[00:46:34] thread 'main' panicked at 'Some tests failed', tools/compiletest/src/main.rs:498:22
[00:46:34] 
[00:46:34] 
[00:46:34] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/compiletest" "--compile-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib" "--run-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "--rustc-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "--src-base" "/checkout/src/test/ui" "--build-base" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui" "--stage-id" "stage2-x86_64-unknown-linux-gnu" "--mode" "ui" "--target" "x86_64-unknown-linux-gnu" "--host" "x86_64-unknown-linux-gnu" "--llvm-filecheck" "/usr/lib/llvm-3.9/bin/FileCheck" "--host-rustcflags" "-Crpath -O -Zunstable-options " "--target-rustcflags" "-Crpath -O -Zunstable-options  -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--docck-python" "/usr/bin/python2.7" "--lldb-python" "/usr/bin/python2.7" "--gdb" "/usr/bin/gdb" "--quiet" "--llvm-version" "3.9.1\n" "--system-llvm" "--cc" "" "--cxx" "" "--cflags" "" "--llvm-components" "" "--llvm-cxxflags" "" "--adb-path" "adb" "--adb-test-dir" "/data/tmp/work" "--android-cross-path" "" "--color" "always"
[00:46:34] 
[00:46:34] 
[00:46:34] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
[00:46:34] Build completed unsuccessfully in 0:02:36
[00:46:34] Build completed unsuccessfully in 0:02:36
[00:46:34] make: *** [check] Error 1
[00:46:34] Makefile:58: recipe for target 'check' failed

The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:1c730bcc
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

[hanna-kruppe]

@bors r=sfackler

[bors]

📌 Commit 20ab884 has been approved by sfackler

[bors]

⌛ Testing commit 20ab884 with merge f0805a4...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: sfackler
Pushing f0805a4 to master...