Add better tests for hidden lifetimes in impl trait #60756

matthewjasper · 2019-05-12T11:31:27Z

rust-highfive · 2019-05-12T11:31:37Z

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nikomatsakis

Good idea to add a test! But since this test is kind of testing for a tricky scenario, it'd be good to explain the scenario in more detail, so when we trip over it, we can understand what happened. =)

nikomatsakis · 2019-05-17T20:26:24Z

src/test/ui/impl-trait/hidden-lifetimes.rs

@@ -0,0 +1,53 @@
+// Test to show actual unsound behaviour that occurs when the hidden lifetime
+// check is removed from impl trait types.


Can you cc the relevant issues/PRs here in the test, to help us track down more info later?

Or else expand this comment a bit?

Or both? :)

Something like:

Test to show what would happen if we were not careful and permitted lifetimes to escape through an impl trait. In this case, we are returning a &'a mut &'b T, but the 'b does not appear in the impl trait type. We can use this to engineer an unsoundness. (XXX perhaps a more detailed explanation)

rust-highfive · 2019-05-17T23:22:34Z

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:05399439:start=1558130585300147390,finish=1558130672456236753,duration=87156089363
$ 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
$ export GCP_CACHE_BUCKET=rust-lang-ci-cache
$ export AWS_ACCESS_KEY_ID=AKIA46X5W6CZEJZ6XT55
---
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---
[01:17:47] 
[01:17:47] ---- [ui] ui/impl-trait/hidden-lifetimes.rs stdout ----
[01:17:47] diff of stderr:
[01:17:47] 
[01:17:47] 1 error[E0700]: hidden type for `impl Trait` captures lifetime that does not appear in bounds
[01:17:47] -   --> $DIR/hidden-lifetimes.rs:23:54
[01:17:47] +   --> $DIR/hidden-lifetimes.rs:28:54
[01:17:47] 3    |
[01:17:47] 4 LL | fn hide_ref<'a, 'b, T: 'static>(x: &'a mut &'b T) -> impl Swap + 'a {
[01:17:47] 
[01:17:47] 6    |
[01:17:47] 6    |
[01:17:47] - note: hidden type `&'a mut &'b T` captures the lifetime 'b as defined on the function body at 23:17
[01:17:47] -   --> $DIR/hidden-lifetimes.rs:23:17
[01:17:47] + note: hidden type `&'a mut &'b T` captures the lifetime 'b as defined on the function body at 28:17
[01:17:47] +   --> $DIR/hidden-lifetimes.rs:28:17
[01:17:47] 9    |
[01:17:47] 10 LL | fn hide_ref<'a, 'b, T: 'static>(x: &'a mut &'b T) -> impl Swap + 'a {
[01:17:47] 
[01:17:47] 12 
[01:17:47] 12 
[01:17:47] 13 error[E0700]: hidden type for `impl Trait` captures lifetime that does not appear in bounds
[01:17:47] -   --> $DIR/hidden-lifetimes.rs:35:70
[01:17:47] +   --> $DIR/hidden-lifetimes.rs:45:70
[01:17:47] 15    |
[01:17:47] 16 LL | fn hide_rc_refcell<'a, 'b: 'a, T: 'static>(x: Rc<RefCell<&'b T>>) -> impl Swap + 'a {
[01:17:47] 
[01:17:47] 18    |
[01:17:47] 18    |
[01:17:47] - note: hidden type `std::rc::Rc<std::cell::RefCell<&'b T>>` captures the lifetime 'b as defined on the function body at 35:24
[01:17:47] -   --> $DIR/hidden-lifetimes.rs:35:24
[01:17:47] + note: hidden type `std::rc::Rc<std::cell::RefCell<&'b T>>` captures the lifetime 'b as defined on the function body at 45:24
[01:17:47] +   --> $DIR/hidden-lifetimes.rs:45:24
[01:17:47] 21    |
[01:17:47] 22 LL | fn hide_rc_refcell<'a, 'b: 'a, T: 'static>(x: Rc<RefCell<&'b T>>) -> impl Swap + 'a {
[01:17:47] 
[01:17:47] 
[01:17:47] The actual stderr differed from the expected stderr.
[01:17:47] Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/impl-trait/hidden-lifetimes/hidden-lifetimes.stderr
[01:17:47] Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/impl-trait/hidden-lifetimes/hidden-lifetimes.stderr
[01:17:47] To update references, rerun the tests and pass the `--bless` flag
[01:17:47] To only update this specific test, also pass `--test-args impl-trait/hidden-lifetimes.rs`
[01:17:47] error: 1 errors occurred comparing output.
[01:17:47] status: exit code: 1
[01:17:47] status: exit code: 1
[01:17:47] command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui/impl-trait/hidden-lifetimes.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "-Zui-testing" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/impl-trait/hidden-lifetimes" "-Crpath" "-O" "-Zunstable-options" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/impl-trait/hidden-lifetimes/auxiliary" "-A" "unused"
[01:17:47] ------------------------------------------
[01:17:47] 
[01:17:47] ------------------------------------------
[01:17:47] stderr:
[01:17:47] stderr:
[01:17:47] ------------------------------------------
[01:17:47] error[E0700]: hidden type for `impl Trait` captures lifetime that does not appear in bounds
[01:17:47]   --> /checkout/src/test/ui/impl-trait/hidden-lifetimes.rs:28:54
[01:17:47]    |
[01:17:47] LL | fn hide_ref<'a, 'b, T: 'static>(x: &'a mut &'b T) -> impl Swap + 'a {
[01:17:47]    |
[01:17:47]    |
[01:17:47] note: hidden type `&'a mut &'b T` captures the lifetime 'b as defined on the function body at 28:17
[01:17:47]   --> /checkout/src/test/ui/impl-trait/hidden-lifetimes.rs:28:17
[01:17:47]    |
[01:17:47] LL | fn hide_ref<'a, 'b, T: 'static>(x: &'a mut &'b T) -> impl Swap + 'a {
[01:17:47] 
[01:17:47] 
[01:17:47] error[E0700]: hidden type for `impl Trait` captures lifetime that does not appear in bounds
[01:17:47]   --> /checkout/src/test/ui/impl-trait/hidden-lifetimes.rs:45:70
[01:17:47]    |
[01:17:47] LL | fn hide_rc_refcell<'a, 'b: 'a, T: 'static>(x: Rc<RefCell<&'b T>>) -> impl Swap + 'a {
[01:17:47]    |
[01:17:47]    |
[01:17:47] note: hidden type `std::rc::Rc<std::cell::RefCell<&'b T>>` captures the lifetime 'b as defined on the function body at 45:24
[01:17:47]   --> /checkout/src/test/ui/impl-trait/hidden-lifetimes.rs:45:24
[01:17:47]    |
[01:17:47] LL | fn hide_rc_refcell<'a, 'b: 'a, T: 'static>(x: Rc<RefCell<&'b T>>) -> impl Swap + 'a {
[01:17:47] 
[01:17:47] error: aborting due to 2 previous errors
[01:17:47] 
[01:17:47] For more information about this error, try `rustc --explain E0700`.
---
[01:17:47] thread 'main' panicked at 'Some tests failed', src/tools/compiletest/src/main.rs:512:22
[01:17:47] note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
[01:17:47] 
[01:17:47] 
[01:17:47] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/compiletest" "--compile-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib" "--run-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "--rustc-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "--src-base" "/checkout/src/test/ui" "--build-base" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui" "--stage-id" "stage2-x86_64-unknown-linux-gnu" "--mode" "ui" "--target" "x86_64-unknown-linux-gnu" "--host" "x86_64-unknown-linux-gnu" "--llvm-filecheck" "/usr/lib/llvm-6.0/bin/FileCheck" "--host-rustcflags" "-Crpath -O -Zunstable-options  -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--target-rustcflags" "-Crpath -O -Zunstable-options  -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--docck-python" "/usr/bin/python2.7" "--lldb-python" "/usr/bin/python2.7" "--gdb" "/usr/bin/gdb" "--quiet" "--llvm-version" "6.0.0\n" "--system-llvm" "--cc" "" "--cxx" "" "--cflags" "" "--llvm-components" "" "--llvm-cxxflags" "" "--adb-path" "adb" "--adb-test-dir" "/data/tmp/work" "--android-cross-path" "" "--color" "always"
[01:17:47] 
[01:17:47] 
[01:17:47] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
[01:17:47] Build completed unsuccessfully in 0:04:52
[01:17:47] Build completed unsuccessfully in 0:04:52
[01:17:47] make: *** [check] Error 1
[01:17:47] Makefile:48: recipe for target 'check' failed
The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:05b0cb48
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
Fri May 17 23:22:29 UTC 2019
---
travis_time:end:0e03ab1c:start=1558135350289765692,finish=1558135350294189820,duration=4424128
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:0b2ab3d0
$ 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:037c34c7
travis_time:start:037c34c7
$ 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:00f50919
$ dmesg | grep -i kill

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nikomatsakis

Thanks!

nikomatsakis · 2019-05-28T20:12:22Z

@bors r+

bors · 2019-05-28T20:12:24Z

📌 Commit 53e0474 has been approved by nikomatsakis

nikomatsakis · 2019-05-28T20:12:38Z

@bors rollup

…s, r=nikomatsakis Add better tests for hidden lifetimes in impl trait cc rust-lang#60670

@ghost

Rollup of 9 pull requests Successful merges: - #60742 (Allow const parameters in array sizes to be unified) - #60756 (Add better tests for hidden lifetimes in impl trait) - #60928 (Changes the type `mir::Mir` into `mir::Body`) - #61024 (tests: Centralize proc macros commonly used for testing) - #61157 (BufReader: In Seek impl, remove extra discard_buffer call) - #61195 (Special-case `.llvm` in mangler) - #61202 (Print PermissionExt::mode() in octal in Documentation Examples) - #61259 (Mailmap fixes) - #61273 (mention that MaybeUninit is a bit like Option) Failed merges: r? @ghost

rust-highfive assigned nikomatsakis May 12, 2019

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nikomatsakis approved these changes May 17, 2019

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nikomatsakis requested changes May 17, 2019

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nikomatsakis added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels May 17, 2019

matthewjasper force-pushed the extra-impl-trait-tests branch from 05ebc79 to 32c790c Compare May 17, 2019 22:02

Add better tests for hidden lifetimes in impl trait

53e0474

matthewjasper force-pushed the extra-impl-trait-tests branch from 32c790c to 53e0474 Compare May 18, 2019 12:17

nikomatsakis approved these changes May 28, 2019

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bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels May 28, 2019

Centril added a commit to Centril/rust that referenced this pull request May 28, 2019

Rollup merge of rust-lang#60756 - matthewjasper:extra-impl-trait-test…

031ecf4

…s, r=nikomatsakis Add better tests for hidden lifetimes in impl trait cc rust-lang#60670

Centril mentioned this pull request May 28, 2019

Rollup of 6 pull requests #61289

Closed

Centril added a commit to Centril/rust that referenced this pull request May 28, 2019

Rollup merge of rust-lang#60756 - matthewjasper:extra-impl-trait-test…

1004d20

…s, r=nikomatsakis Add better tests for hidden lifetimes in impl trait cc rust-lang#60670

Centril mentioned this pull request May 28, 2019

Rollup of 6 pull requests #61290

Closed

Centril added a commit to Centril/rust that referenced this pull request May 28, 2019

Rollup merge of rust-lang#60756 - matthewjasper:extra-impl-trait-test…

e19a229

…s, r=nikomatsakis Add better tests for hidden lifetimes in impl trait cc rust-lang#60670

Centril mentioned this pull request May 28, 2019

Rollup of 9 pull requests #61296

Merged

bors merged commit 53e0474 into rust-lang:master May 29, 2019

matthewjasper deleted the extra-impl-trait-tests branch May 31, 2019 11:24

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		@@ -0,0 +1,53 @@
		// Test to show actual unsound behaviour that occurs when the hidden lifetime
		// check is removed from impl trait types.

Add better tests for hidden lifetimes in impl trait #60756

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