Fix various issues with control-flow statements inside anonymous constants

[varkor]

Fixes#51761.
Fixes#51963 (and the host of other reported issues there).
(Might be easiest to review per commit, as they should be standalone.)

r? @estebank

[estebank]

Minor nitpicks, after that r=me.

[estebank]

Add Issue Number

[estebank]

Use an enum instead of a boolean? That way you can communicate the meaning of the different states, not only in the method signature, but also at the return point and when being checked.

[estebank]

Merge with the ty::TyParam(_) branch above, as they return the same thing.

[estebank]

Expand the bug description a little with something like "literal integer with bad type".

[estebank]

I don't really like the wording here, but that is the current wording, so don't bother coming up with better wording if you can't think of one immediately (I can't).

[varkor]

Yeah, I thought the same thing. It's hard to think of something snappy. Perhaps simply:

`return` found outside a function

?

[estebank]

Maybe "outside of function scope"? It'd be good to also expand the diagnostic to include an explanation that it is in a const scope, presenting a terse explanation that whatever is in such a scope will be evaluated at compile time, as well as a link to the documentation (https://doc.rust-lang.org/book/second-edition/ch03-01-variables-and-mutability.html#differences-between-variables-and-constants seems like the appropriate place, but it doesn't go into detail about this case).

Regardless, out of scope for this PR.

[estebank]

@bors r+

[bors]

📌 Commit 9132e8510337bdee76562e6e594016ac9e530c12 has been approved by estebank

[bors]

☔ The latest upstream changes (presumably #51321) made this pull request unmergeable. Please resolve the merge conflicts.

[varkor]

I'm just going to keep trying to talk to @bors until they listen to me...
@bors r=estebank

[bors]

@varkor: 🔑 Insufficient privileges: Not in reviewers

[estebank]

@bors r+

[bors]

📌 Commit adf4ef7 has been approved by estebank

[rust-highfive]

The job mingw-check 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.

[00:03:50] Downloading lazycell v0.6.0
[00:03:50] error: unable to get packages from source
[00:03:50] [00:03:50] Caused by:
[00:03:50] [18] Transferred a partial file (transfer closed with outstanding read data remaining)
[00:03:50] thread 'main' panicked at 'command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "metadata" "--format-version" "1" "--features" "panic-unwind jemalloc backtrace" "--manifest-path" "/checkout/src/libstd/Cargo.toml"
[00:03:50] expected success, got: exit code: 101', build_helper/lib.rs:122:9
[00:03:50] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap check
[00:03:50] Build completed unsuccessfully in 0:02:18
travis_time:end:1444d154:start=1530557188789423760,finish=1530557419939705166,duration=231150281406
---
travis_time:end:1283bc83:start=1530557420286968071,finish=1530557420298180853,duration=11212782
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:051f0388
$ head -30 ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers || true
head: cannot open ‘./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers��� for reading: No such file or directory
travis_fold:end:after_failure.4
travis_fold:start:after_failure.5
travis_time:start:2f1619bf
$ 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)

[varkor]

Looks like a spurious failure to me.

[estebank]

@bors retry

[bors]

⌛ Testing commit adf4ef7 with merge 69b9e1e...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: estebank
Pushing 69b9e1e to master...