Allocate HIR on an arena 2/4 -- Expr & Pat

[cjgillot]

This is the second PR in the series started by #66931

This time, commits don't really make sense on their own.
They are mostly split by type of compile error.

The additional diff is here: cjgillot/rust@hirene-preamble...hirene-expr

[davidtwco]

r? @eddyb
cc @Zoxc

[rust-highfive]

The job x86_64-gnu-llvm-6.0 of your PR failed (pretty log, 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.

2019-12-02T19:49:52.0883694Z ##[command]git remote add origin https://github.com/rust-lang/rust
2019-12-02T19:49:52.1073113Z ##[command]git config gc.auto 0
2019-12-02T19:49:52.1134435Z ##[command]git config --get-all http.https://github.com/rust-lang/rust.extraheader
2019-12-02T19:49:52.1198558Z ##[command]git config --get-all http.proxy
2019-12-02T19:49:52.1323834Z ##[command]git -c http.extraheader="AUTHORIZATION: basic ***" fetch --force --tags --prune --progress --no-recurse-submodules --depth=2 origin +refs/heads/*:refs/remotes/origin/* +refs/pull/66936/merge:refs/remotes/pull/66936/merge
---
2019-12-02T20:15:55.0260053Z fatal runtime error: stack overflow
2019-12-02T20:15:55.3125594Z error: could not compile `core`.
2019-12-02T20:15:55.3125719Z 2019-12-02T20:15:55.3125762Z Caused by:
2019-12-02T20:15:55.3136067Z process didn't exit successfully: `/checkout/obj/build/bootstrap/debug/rustc --edition=2018 --crate-name core src/libcore/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts --crate-type lib --emit=dep-info,metadata,link -C opt-level=2 -C codegen-units=1 -C debuginfo=0 -C metadata=8dab76f6898d904f -C extra-filename=-8dab76f6898d904f --out-dir /checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps --target x86_64-unknown-linux-gnu -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/release/deps -Zexternal-macro-backtrace '-Clink-args=-Wl,-rpath,$ORIGIN/../lib' -Wrust_2018_idioms -Wunused_lifetimes -Dwarnings -Cprefer-dynamic -Zbinary-dep-depinfo` (signal: 6, SIGABRT: process abort signal)
2019-12-02T20:15:56.9123561Z error: build failed
2019-12-02T20:15:56.9140676Z command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "build" "-Zconfig-profile" "--target" "x86_64-unknown-linux-gnu" "-Zbinary-dep-depinfo" "-j" "2" "--release" "--locked" "--color" "always" "--features" "panic-unwind backtrace compiler-builtins-c" "--manifest-path" "/checkout/src/libtest/Cargo.toml" "--message-format" "json-render-diagnostics"
2019-12-02T20:15:56.9140809Z expected success, got: exit code: 101
2019-12-02T20:15:56.9153845Z failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
2019-12-02T20:15:56.9153845Z failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
2019-12-02T20:15:56.9153943Z Build completed unsuccessfully in 0:20:35
2019-12-02T20:15:56.9202769Z == clock drift check ==
2019-12-02T20:15:56.9218274Z local time: Mon Dec 2 20:15:56 UTC 2019
2019-12-02T20:15:57.1877585Z network time: Mon, 02 Dec 2019 20:15:57 GMT
2019-12-02T20:15:57.1881821Z == end clock drift check ==
2019-12-02T20:15:57.8993319Z 2019-12-02T20:15:57.9091492Z ##[error]Bash exited with code '1'.
2019-12-02T20:15:57.9126620Z ##[section]Starting: Checkout
2019-12-02T20:15:57.9128281Z ==============================================================================
2019-12-02T20:15:57.9128330Z Task : Get sources
2019-12-02T20:15:57.9128372Z Description : Get sources from a repository. Supports Git, TfsVC, and SVN repositories.

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)

[cjgillot]

I seem to be constructing some sort of infinite loop in the HIR graph. The stack overflow happens when hashing everything. The loop consists of a ExprKind::Call(ExprKind::Path(QPath::TypeRelative(...)), &[ExprKind::Binary(..., loop, ...)).

[Zoxc]

Did you ensure that the Fewer calls to arena.alloc commit didn't result in allocations which wouldn't get used?

And did you resolve the infinite loop?

[cjgillot]

Rebased.

Did you ensure that the Fewer calls to arena.alloc commit didn't result in allocations which wouldn't get used?

I did as much as I could. There are no unused allocation of HIR nodes, because of typing. However, typing does not guarantee against unused allocation of a pointer.

And did you resolve the infinite loop?

Yes. It was in the arena allocation code. Bug #67001

[Centril]

We can probably elide the intermediate allocations here by converting the code above into more functional style code, but we can leave this for another time.

[cjgillot]

Rebased.

[Centril]

@bors r=Zoxc p=5

[bors]

📌 Commit fb100e5 has been approved by Zoxc

[bors]

⌛ Testing commit fb100e5 with merge a04c789...

[bors]

☀️ Test successful - checks-azure
Approved by: Zoxc
Pushing a04c789 to master...