Fix bug in integer range matching

[varkor]

Fixes #57894.

[rust-highfive]

r? @michaelwoerister

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[varkor]

r? @oli-obk

[oli-obk]

So this basically makes sure that unsigned comparison of signed numbers still works out?

[varkor]

Yeah. I'll add a comment.

[rust-highfive]

The job x86_64-gnu-llvm-6.0 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:0d7d7338:start=1548894141300430345,finish=1548894246135799271,duration=104835368926
$ 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-6.0
---

[00:04:03] travis_fold:start:tidy
travis_time:start:tidy
tidy check
[00:04:03] tidy error: /checkout/src/librustc_mir/build/matches/simplify.rs:131: line longer than 100 chars
[00:04:03] tidy error: /checkout/src/librustc_mir/build/matches/simplify.rs:132: line longer than 100 chars
[00:04:03] tidy error: /checkout/src/librustc_mir/build/matches/simplify.rs:133: line longer than 100 chars
[00:04:04] some tidy checks failed
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[00:04:04] 
[00:04:04] 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"
[00:04:04] 
[00:04:04] 
[00:04:04] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test src/tools/tidy
[00:04:04] Build completed unsuccessfully in 0:00:49
[00:04:04] Build completed unsuccessfully in 0:00:49
[00:04:04] Makefile:68: recipe for target 'tidy' failed
[00:04:04] make: *** [tidy] Error 1
The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:05ee4d34
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
Thu Jan 31 00:28:19 UTC 2019
---
travis_time:end:00e0f77c:start=1548894500722019038,finish=1548894500727289008,duration=5269970
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travis_time:start:101b966b
$ 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
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travis_time:start:0125cf82
travis_time:start:0125cf82
$ 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
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$ 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)

[oli-obk]

@bors r+

[matthewjasper]

Signed integers

[bors]

📌 Commit 441355d7c2fe99b1e666d3c30ee9b6c7996547bf has been approved by oli-obk

[oli-obk]

@bors r-

r=me with the comment nit addressed

[pnkfelix]

@varkor your update to the comment (890198445cde6603ea58c67a3177d38c36da4ede) continues to refer to floating-point numbers rather than signed integers (which is what I had interpreted @matthewjasper 's comment nit as referring to).

So now I am inferring that you did in fact mean to reference floating-point numbers in your comment.

I haven't attempted to validate the reasoning in the comment/code when applied to floating-point numbers.

• (I would be somewhat surprised if such a simple expression actually did suffice for comparing the binary representations of arbitrary floating-point values, but it has been a while since I've been in the depths of software FP implementation...)

But, both your own code here and the referenced code in pattern/_match.rs, is only going to look at ranges constructed from one of the types {char, iN, uN} ... nothing with floating-point type.

... so ... is there some way that floating point values can arise in these code paths? Even the underlying representation in the MIR interpreter, as far as I can tell, avoids using floating-point values...

[pnkfelix]

(If in fact floating-point values can arise ... I guess I'd expect to see a unit test illustrating that scenario...)

[varkor]

Sorry, I must have been distracted when editing the comment; it should not refer to floating-point numbers at all. I think I was conflating it with another problem I've been thinking about recently. Floating-point range patterns are not permitted in this location and do not need to be handled. I shall update the comment (and squash all of the edits) once I get back to my computer. Sorry for the confusion.

[varkor]

@bors r=oli-obk

[bors]

📌 Commit cd1047e has been approved by oli-obk

[bors]

⌛ Testing commit cd1047e with merge 852701a...

[bors]

☀️ Test successful - checks-travis, status-appveyor
Approved by: oli-obk
Pushing 852701a to master...