Remove the grammar.

[steveklabnik]

This is completely vestigial, and we have a grammar WG whose job it is to handle the grammar.

This is a revival of #50835; if accepted, I'll have to update the reference as well.

r? @rust-lang/lang i think? I forget who is the lead of wg-grammar. @nikomatsakis ?

[Centril]

@qmx is WG-grammar lead.

I use parser-lalr.y all the time when doing language design (it still is accurate to a certain extent) so I'd prefer not to see it go. I'd like these to remain until we have a more fully formed grammar or at least move this to a different location (but that would break some links in the interim so I'd rather not do that as well...).

[Centril]

Clarification: I'd like us to remove this eventually, but I think it's too soon.

[eddyb]

cc @rust-lang/wg-grammar

[rust-highfive]

The job x86_64-gnu-llvm-5.0 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.

travis_time:end:10273063:start=1541003248988526487,finish=1541003250107221169,duration=1118694682
$ git checkout -qf FETCH_HEAD
travis_fold:end:git.checkout

Encrypted environment variables have been removed for security reasons.
See https://docs.travis-ci.com/user/pull-requests/#Pull-Requests-and-Security-Restrictions
$ export SCCACHE_BUCKET=rust-lang-ci-sccache2
$ export SCCACHE_REGION=us-west-1
Setting environment variables from .travis.yml
$ export IMAGE=x86_64-gnu-llvm-5.0
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travis_time:start:test_codegen
Check compiletest suite=codegen mode=codegen (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
[01:11:06] 
[01:11:06] running 115 tests
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[01:11:09] .i....iiii.....
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[01:11:09]  finished in 3.950
[01:11:09] travis_fold:end:test_codegen

---
travis_time:start:test_debuginfo
Check compiletest suite=debuginfo mode=debuginfo-both (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
[01:11:26] 
[01:11:26] running 118 tests
[01:11:51] .iiiii...i.....i..i...i..i.i..i.i..i.....i..i....i..........iiii.........i.i....i...i.......ii.i.i.i 100/118
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[01:11:55]  finished in 29.373
[01:11:55] travis_fold:end:test_debuginfo

---
[01:42:50] travis_fold:end:stage0-linkchecker

[01:42:50] travis_time:end:stage0-linkchecker:start=1541009428260257864,finish=1541009430570420873,duration=2310163009

[01:45:22] reference/introduction.html:156: broken link - grammar.html
[01:45:22] reference/types.html:396: broken link - grammar.html
[01:45:23] reference/notation.html:150: broken link - grammar.html
[01:45:23] reference/index.html:155: broken link - grammar.html
[01:45:23] reference/print.html:156: broken link - grammar.html
[01:45:23] reference/print.html:267: broken link - grammar.html
[01:45:23] reference/print.html:7223: broken link - grammar.html
[01:45:54] thread 'main' panicked at 'found some broken links', tools/linkchecker/main.rs:49:9
[01:45:54] 
[01:45:54] 
[01:45:54] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/linkchecker" "/checkout/obj/build/x86_64-unknown-linux-gnu/doc"
[01:45:54] expected success, got: exit code: 101
[01:45:54] expected success, got: exit code: 101
[01:45:54] 
[01:45:54] 
[01:45:54] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
[01:45:54] Build completed unsuccessfully in 0:54:53
[01:45:54] make: *** [check] Error 1
[01:45:54] Makefile:58: recipe for target 'check' failed

The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:1ba9892e
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
---
travis_time:end:0ff31524:start=1541009617539885869,finish=1541009617545069777,duration=5183908
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:2880063c
$ ln -s . checkout && for CORE in obj/cores/core.*; do EXE=$(echo $CORE | sed 's|obj/cores/core\.[0-9]*\.!checkout!\(.*\)|\1|;y|!|/|'); if [ -f "$EXE" ]; then printf travis_fold":start:crashlog\n\033[31;1m%s\033[0m\n" "$CORE"; gdb --batch -q -c "$CORE" "$EXE" -iex 'set auto-load off' -iex 'dir src/' -iex 'set sysroot .' -ex bt -ex q; echo travis_fold":"end:crashlog; fi; done || true
travis_fold:end:after_failure.4
travis_fold:start:after_failure.5
travis_time:start:1f54089a
travis_time:start:1f54089a
$ cat ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers || true
cat: ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers: No such file or directory
travis_fold:end:after_failure.5
travis_fold:start:after_failure.6
travis_time:start:0168583e
$ dmesg | grep -i kill

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)

[qmx]

Added rust-lang/wg-grammar#9 to track this work lest we forget. Hopefully we'll be able to get to this soon!

[TimNN]

Ping from triage @qmx / @rust-lang/wg-grammar: Do I understand correctly, that this PR shouldn't be merged for now?

[qmx]

@TimNN yes, that is correct - feel free to close this PR and we'll get back to it later