Don't count MIR locals as borrowed after StorageDead when finding locals live across a yield terminator

[Zoxc]

This should fix #52792.

r? @eddyb

[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.

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[00:03:50] travis_fold:start:tidy
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tidy check
[00:03:51] tidy error: /checkout/src/test/run-pass/generator/yield-in-initializer.rs: missing trailing newline
[00:03:52] some tidy checks failed
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[00:03:52] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/tidy" "/checkout/src" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "--no-vendor" "--quiet"
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[00:03:52] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test src/tools/tidy
[00:03:52] Build completed unsuccessfully in 0:00:46
[00:03:52] Build completed unsuccessfully in 0:00:46
[00:03:52] Makefile:79: recipe for target 'tidy' failed
[00:03:52] make: *** [tidy] Error 1

The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
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$ 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 -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
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cat: ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers: No such file or directory
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[eddyb]

r=me after fixing tidy

This explains why @cramertj and I couldn't find anything to toggle, we didn't realize this was about borrows outliving the StorageDead. Also cc @RalfJung (whom we discussed this with on IRC).

[RalfJung]

Not sure what you mean by "toggle", but yes -- StorageDead is like "free" for a local, nothing can refer to it any more.

[Zoxc]

@bors r=eddyb

[bors]

📌 Commit 0babbf1 has been approved by eddyb

[eddyb]

Not sure what you mean by "toggle"

Specifically, something to change in the liveness computation that would make a difference.