cargo clippy with clippy-preview crash on x86 Linux

[therealbstern]

$ rustc --version
rustc 1.29.2 (17a9dc751 2018-10-05)
$ cargo clippy -V
0.0.212

Line-wrapped output (for viewing convenience; irrelevant path specs replaced with ...). [In real life, the "Caused by" lines are one long line all the way through the end of the SIGSEGV.]

error: Could not compile `byte-tools`.
Caused by:
  process didn't exit successfully: `/usr/local/bin/clippy-driver rustc --crate-name
    byte_tools .../.cargo/registry/src/github.com-1ecc6299db9ec823/byte-tools-0.2.0/src/lib.rs
    --crate-type lib --emit=dep-info,metadata -C debuginfo=2 -C metadata=5da25c9bb6e69df5 -C
    extra-filename=-5da25c9bb6e69df5 --out-dir .../target/debug/deps -L
    dependency=.../target/debug/deps --cap-lints allow`
(signal: 11, SIGSEGV: invalid memory reference)

error: Could not compile `byteorder`.
Caused by:
  process didn't exit successfully: `/usr/local/bin/clippy-driver rustc --crate-name
    byteorder .../.cargo/registry/src/github.com-1ecc6299db9ec823/byteorder-1.2.4/src/lib.rs
    --crate-type lib --emit=dep-info,metadata -C debuginfo=2 --cfg 'feature="default"' --cfg
    'feature="std"' -C metadata=9166e152500d52e7 -C extra-filename=-9166e152500d52e7 --out-dir
    .../target/debug/deps -L dependency=.../target/debug/deps --cap-lints allow`
(signal: 11, SIGSEGV: invalid memory reference)

This is reproducible. It happens regardless of the status of cargo clean; i.e., if I do issue cargo clean; cargo clippy it happens, and if I do cargo build; cargo clippy it happens. (Note that my build succeeds).

Please let me know if you need any additional information.

[matthiaskrgr]

Hmm. I tried checking the bytetools https://github.com/RustCrypto/utils/tree/master/byte-tools crate with clippy on nightly, beta and stable but could not repro any crash.

[therealbstern]

Hmm. I'm on Linux 32-bit. Are you? I did forget that from my original report - I apologize. (In the title, my mistake.)

I'll test with byte-tools directly and report back.

[therealbstern]

This seems to happen to me with byte-tools 0.2.0. I'll see whether my project can trivially upgrade to 0.3.0, but clippy probably shouldn't segfault anyway.

Line-wrapped for clarity:

~/.cargo/registry/src/github.com-1ecc6299db9ec823/byte-tools-0.2.0$ cargo clippy --verbose
    Checking byte-tools v0.2.0 (file://[...]/byte-tools-0.2.0)                         
     Running `/usr/local/bin/clippy-driver rustc --crate-name byte_tools src/lib.rs
       --crate-type lib --emit=dep-info,metadata -C debuginfo=2 -C
       metadata=32680534df867787 -C extra-filename=-32680534df867787 --out-dir
       [...]/target/debug/deps -C incremental=[...]/target/debug/incremental -L
       dependency=[...]/target/debug/deps`
error: Could not compile `byte-tools`.

Caused by:
  process didn't exit successfully: `[all the same stuff just above]`
    (signal: 11, SIGSEGV: invalid memory reference)

~/.cargo/registry/src/github.com-1ecc6299db9ec823/byte-tools-0.2.0$ uname -imprvs
Linux 4.4.153-smp #2 SMP [...] i686 Intel(R) Core(TM) i7-4770K CPU @ 3.50GHz GenuineIntel

Is there any additional information that I can provide?

[hcpl]

From what I've seen, clippy for 32-bit targets are either not tested enough to run without fail or not supported at all, because clippy does not work on i686-pc-windows-{gnu,msvc} and quoting myself from that comment:

32-bit tests are broken in general. Travis never runs these so the failures don't matter there.

AIUI, this means that 32-bit clippy shipped via rustup is only built, but has never run (any tests) at all.

EDIT: or this means that 32-bit clippy cannot be run on 64-bit Windows (and vice versa) which sounds more plausible to me.

This is all pure speculation and I haven't tested my claim for 32-bit Unixes, so take my words with a grain of salt.

EDIT: also SIGSEGV on Linux is likely to be the equivalent of exit code 3221225477 == 0xC0000005 == access violation on Windows.

[therealbstern]

Re: "Access Violation": yes, I believe they are the same thing.

If clippy is broken on 32-bit and that's okay,

• I understand, and closing this issue is a reasonable reaction,
• but perhaps it should not be included in 32-bit releases of Rust, or on any platforms that it is expected to fail upon,
• though on the gripping hand, if the intent is to shake out these failures on other platforms, then chasing this further might be of benefit.

[therealbstern]

I kicked clippy a little more and got a backtrace:

byte-tools-0.2.0$ gdb cargo
GNU gdb (GDB) 7.11.1
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i586-slackware-linux".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from cargo...done.
(gdb) set follow-exec-mode new
(gdb) set detach-on-fork off
(gdb) show follow-fork-mode
Debugger response to a program call of fork or vfork is "parent".
(gdb) set follow-fork-mode child
(gdb) run clippy --verbose
Starting program: /usr/local/bin/cargo clippy --verbose
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/libthread_db.so.1".
process 12125 is executing new program: /usr/local/bin/cargo-clippy
[New process 12125]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/libthread_db.so.1".
[New process 12129]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/libthread_db.so.1".
process 12129 is executing new program: /usr/local/bin/cargo
[New process 12129]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/libthread_db.so.1".
[New Thread 0xb77ffb40 (LWP 12130)]
[New Thread 0xb73ffb40 (LWP 12131)]
    Checking byte-tools v0.2.0 ([...].byte-tools-0.2.0)
     Running `/usr/local/bin/clippy-driver rustc --crate-name byte_tools src/lib.rs
       --crate-type lib --emit=dep-info,metadata -C debuginfo=2 -C
      metadata=32680534df867787 -C extra-filename=-32680534df867787 --out-dir
      [...]/target/debug/deps -C incremental=[...]/target/debug/incremental -L
      dependency=[...]/target/debug/deps`
[New process 12132]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/libthread_db.so.1".
process 12132 is executing new program: /usr/local/bin/clippy-driver
[New process 12132]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/libthread_db.so.1".
[New process 12133]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/libthread_db.so.1".
process 12133 is executing new program: /usr/local/bin/rustc
Reading symbols from /usr/local/bin/../lib/librustc_driver-7347af2c9cdaca0e.so...done.
Reading symbols from /usr/local/bin/../lib/librustc-803d08957e6359cf.so...done.
Reading symbols from /usr/local/bin/../lib/librustc_data_structures-64688dc184c72a76.so...done.
Reading symbols from /usr/local/bin/../lib/libstd-2f004764056eda78.so...done.
Reading symbols from /usr/local/bin/../lib/../lib/librustc_codegen_utils-5f869f8aed6a721d.so...done.
Reading symbols from /usr/local/bin/../lib/../lib/librustc_save_analysis-611e72632f2e7117.so...done.
Reading symbols from /usr/local/bin/../lib/../lib/librustc_incremental-947417a5241cc107.so...done.
Reading symbols from /usr/local/bin/../lib/../lib/librustc_mir-f72f626c19579c1d.so...done.
Reading symbols from /usr/local/bin/../lib/../lib/libtest-37d49a8ff37bb238.so...done.
Reading symbols from /usr/local/bin/../lib/../lib/libserialize-55417a241a47e1db.so...done.
Reading symbols from /usr/local/bin/../lib/../lib/../lib/libterm-3b72c6a6d17b52fc.so...done.
[New process 12133]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/libthread_db.so.1".
[Inferior 8 (process 12133) exited normally]
(gdb) info inferiors
  Num  Description       Executable
  1    <null>            /usr/local/bin/cargo
  2    process 12125     /usr/local/bin/cargo-clippy
  4    process 12129     /usr/local/bin/cargo
  6    process 12132     /usr/local/bin/clippy-driver
* 8    <null>            /usr/local/bin/rustc
(gdb) inf
inferior  info
(gdb) inferior 6
[Switching to inferior 6 [process 12132] (/usr/local/bin/clippy-driver)]
[Switching to thread 6.1 (Thread 0xb4f35900 (LWP 12132))]
#0  0xb6217f51 in fork () from /lib/libc.so.6
(gdb) continue
Continuing.
[New Thread 0xb1817b40 (LWP 12162)]
[Thread 0xb1817b40 (LWP 12162) exited]
[New process 12163]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/libthread_db.so.1".
process 12163 is executing new program: /usr/local/bin/cargo
Reading symbols from /usr/local/bin/../lib/librustc_driver-7347af2c9cdaca0e.so...done.
Reading symbols from /usr/local/bin/../lib/librustc-803d08957e6359cf.so...done.
Reading symbols from /usr/local/bin/../lib/librustc_data_structures-64688dc184c72a76.so...done.
Reading symbols from /usr/local/bin/../lib/libstd-2f004764056eda78.so...done.
Reading symbols from /usr/local/bin/../lib/../lib/librustc_codegen_utils-5f869f8aed6a721d.so...done.
Reading symbols from /usr/local/bin/../lib/../lib/librustc_save_analysis-611e72632f2e7117.so...done.
Reading symbols from /usr/local/bin/../lib/../lib/librustc_incremental-947417a5241cc107.so...done.
Reading symbols from /usr/local/bin/../lib/../lib/librustc_mir-f72f626c19579c1d.so...done.
Reading symbols from /usr/local/bin/../lib/../lib/libtest-37d49a8ff37bb238.so...done.
Reading symbols from /usr/local/bin/../lib/../lib/libserialize-55417a241a47e1db.so...done.
Reading symbols from /usr/local/bin/../lib/../lib/../lib/libterm-3b72c6a6d17b52fc.so...done.
Reading symbols from /usr/local/lib/rustlib/i686-unknown-linux-gnu/codegen-backends/librustc_codegen_llvm-llvm.so...done.
[New process 12163]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/libthread_db.so.1".
[Inferior 10 (process 12163) exited normally]
(gdb) info inferiors
  Num  Description       Executable
  1    <null>            /usr/local/bin/cargo
  2    process 12125     /usr/local/bin/cargo-clippy
  4    process 12129     /usr/local/bin/cargo
  6    process 12132     /usr/local/bin/clippy-driver
  8    <null>            /usr/local/bin/rustc
* 10   <null>            /usr/local/bin/cargo
(gdb) inferior 6
[Switching to inferior 6 [process 12132] (/usr/local/bin/clippy-driver)]
[Switching to thread 6.1 (Thread 0xb4f35900 (LWP 12132))]
#0  0xb6217f51 in fork () from /lib/libc.so.6
(gdb)
[Switching to inferior 6 [process 12132] (/usr/local/bin/clippy-driver)]
[Switching to thread 6.1 (Thread 0xb4f35900 (LWP 12132))]
#0  0xb6217f51 in fork () from /lib/libc.so.6
(gdb) continue
Continuing.

Thread 6.1 "clippy-driver" received signal SIGSEGV, Segmentation fault.
0x00590adf in _$LT$clippy_lints..returns..ReturnPass$u20$as$u20$rustc..lint..EarlyLintPass$GT$::check_block::ha6aa870b73fc15d6 ()
(gdb) bt
#0  0x00590adf in _$LT$clippy_lints..returns..ReturnPass$u20$as$u20$rustc..lint..EarlyLintPass$GT$::check_block::ha6aa870b73fc15d6 ()
#1  0xb74e8a3f in _$LT$rustc..lint..context..EarlyContext$LT$$u27$a$GT$$u20$as$u20$syntax..visit..Visitor$LT$$u27$a$GT$$GT$::visit_block::hb2436b252d4dc7b0 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#2  0xb6e7eede in syntax::visit::walk_expr::h7bc7ae2cbcb8be07 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#3  0xb74e6d64 in _$LT$rustc..lint..context..EarlyContext$LT$$u27$a$GT$$u20$as$u20$syntax..visit..Visitor$LT$$u27$a$GT$$GT$::visit_expr::h1c6ae7dbe521c414 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#4  0xb6e82ab8 in syntax::visit::walk_stmt::hb125825f5119f593 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#5  0xb74e8b3d in _$LT$rustc..lint..context..EarlyContext$LT$$u27$a$GT$$u20$as$u20$syntax..visit..Visitor$LT$$u27$a$GT$$GT$::visit_block::hb2436b252d4dc7b0 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#6  0xb6e7edd1 in syntax::visit::walk_expr::h7bc7ae2cbcb8be07 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#7  0xb74e6d64 in _$LT$rustc..lint..context..EarlyContext$LT$$u27$a$GT$$u20$as$u20$syntax..visit..Visitor$LT$$u27$a$GT$$GT$::visit_expr::h1c6ae7dbe521c414 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#8  0xb6e82ab8 in syntax::visit::walk_stmt::hb125825f5119f593 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#9  0xb74e8b3d in _$LT$rustc..lint..context..EarlyContext$LT$$u27$a$GT$$u20$as$u20$syntax..visit..Visitor$LT$$u27$a$GT$$GT$::visit_block::hb2436b252d4dc7b0 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#10 0xb6e7eede in syntax::visit::walk_expr::h7bc7ae2cbcb8be07 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#11 0xb74e6d64 in _$LT$rustc..lint..context..EarlyContext$LT$$u27$a$GT$$u20$as$u20$syntax..visit..Visitor$LT$$u27$a$GT$$GT$::visit_expr::h1c6ae7dbe521c414 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#12 0xb6e82ab8 in syntax::visit::walk_stmt::hb125825f5119f593 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#13 0xb74e8b3d in _$LT$rustc..lint..context..EarlyContext$LT$$u27$a$GT$$u20$as$u20$syntax..visit..Visitor$LT$$u27$a$GT$$GT$::visit_block::hb2436b252d4dc7b0 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#14 0xb6e7a359 in syntax::visit::walk_fn::h4960770f1541328c () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#15 0xb74e7209 in _$LT$rustc..lint..context..EarlyContext$LT$$u27$a$GT$$u20$as$u20$syntax..visit..Visitor$LT$$u27$a$GT$$GT$::visit_fn::h95af3b5ab98fd0c8 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#16 0xb6e8240d in syntax::visit::walk_item::hdc16ab0c6bc30763 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#17 0xb74e641e in _$LT$rustc..lint..context..EarlyContext$LT$$u27$a$GT$$u20$as$u20$syntax..visit..Visitor$LT$$u27$a$GT$$GT$::visit_item::hd51921034e3befb4 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#18 0xb74e84fe in _$LT$rustc..lint..context..EarlyContext$LT$$u27$a$GT$$u20$as$u20$syntax..visit..Visitor$LT$$u27$a$GT$$GT$::visit_mod::h9a3d834787d83c51 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#19 0xb6e82437 in syntax::visit::walk_item::hdc16ab0c6bc30763 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#20 0xb74e641e in _$LT$rustc..lint..context..EarlyContext$LT$$u27$a$GT$$u20$as$u20$syntax..visit..Visitor$LT$$u27$a$GT$$GT$::visit_item::hd51921034e3befb4 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#21 0xb74e84fe in _$LT$rustc..lint..context..EarlyContext$LT$$u27$a$GT$$u20$as$u20$syntax..visit..Visitor$LT$$u27$a$GT$$GT$::visit_mod::h9a3d834787d83c51 () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#22 0xb74eb798 in rustc::lint::context::check_ast_crate::h09a610a2cc4f561c () from /usr/local/bin/../lib/librustc-803d08957e6359cf.so
#23 0xb7df0387 in rustc::util::common::time::h597b59de9d0dd1c6 () from /usr/local/bin/../lib/librustc_driver-7347af2c9cdaca0e.so
#24 0xb7de1c72 in rustc_driver::driver::phase_2_configure_and_expand::hb03d160f49ecf55e ()
   from /usr/local/bin/../lib/librustc_driver-7347af2c9cdaca0e.so
#25 0xb7ddc088 in rustc_driver::driver::compile_input::h309fce5a01e61835 () from /usr/local/bin/../lib/librustc_driver-7347af2c9cdaca0e.so
#26 0xb7e917a2 in rustc_driver::run_compiler_with_pool::hd9ecd1282f1ae6db () from /usr/local/bin/../lib/librustc_driver-7347af2c9cdaca0e.so
#27 0xb7da099a in _$LT$scoped_tls..ScopedKey$LT$T$GT$$GT$::set::h7903e06ad2cd8b6d () from /usr/local/bin/../lib/librustc_driver-7347af2c9cdaca0e.so
#28 0xb7da0669 in _$LT$scoped_tls..ScopedKey$LT$T$GT$$GT$::set::h6ce628e67dc9eb8d () from /usr/local/bin/../lib/librustc_driver-7347af2c9cdaca0e.so
#29 0xb7e42f8f in syntax::with_globals::h0ecbf7da16de1b06 () from /usr/local/bin/../lib/librustc_driver-7347af2c9cdaca0e.so
#30 0xb7e907a8 in rustc_driver::run_compiler::hf2535f8905c2e2de () from /usr/local/bin/../lib/librustc_driver-7347af2c9cdaca0e.so                       
#31 0x0044e980 in clippy_driver::main::h7d2ad413b1815726 ()
#32 0x0043a146 in std::rt::lang_start::_$u7b$$u7b$closure$u7d$$u7d$::h948d4b5b2bb6bda8 ()
#33 0xb63d80be in std::rt::lang_start_internal::_$u7b$$u7b$closure$u7d$$u7d$::_$u7b$$u7b$closure$u7d$$u7d$::h02a833680b7f2e42 () at libstd/rt.rs:59
#34 std::sys_common::backtrace::__rust_begin_short_backtrace::ha0d8ae30e78f33e6 () at libstd/sys_common/backtrace.rs:136
#35 0xb63d0ca2 in std::rt::lang_start_internal::_$u7b$$u7b$closure$u7d$$u7d$::hc407efd21fbbb227 () at libstd/rt.rs:59
#36 std::panicking::try::do_call::hadd24133eee93c2a () at libstd/panicking.rs:310
#37 0xb6415528 in __rust_maybe_catch_panic () at libpanic_unwind/lib.rs:105
#38 0xb63d0c06 in std::panicking::try::ha5043ce4d03a4ab3 () at libstd/panicking.rs:289
#39 0xb63d6385 in std::panic::catch_unwind::h1cf979638beb9551 () at libstd/panic.rs:392
#40 std::rt::lang_start_internal::h6bbe1a2cc9111404 () at libstd/rt.rs:58`
#41 0x0044fb71 in main ()
(gdb) cont
Continuing.

Thread 6.1 "clippy-driver" received signal SIGSEGV, Segmentation fault.
0x00590adf in _$LT$clippy_lints..returns..ReturnPass$u20$as$u20$rustc..lint..EarlyLintPass$GT$::check_block::ha6aa870b73fc15d6 ()
(gdb) cont
Continuing.

Program terminated with signal SIGSEGV, Segmentation fault.
The program no longer exists.

[therealbstern]

As predicted, I can cargo clippy byte-tools 0.2.0 all day long on 64-bit.

[hcpl]

So from this stacktrace (thanks @therealbstern!) this method segfaults:

https://github.com/rust-lang-nursery/rust-clippy/blob/48cb6e273ea49e85b6baa209e0123a2bbd6d15c2/clippy_lints/src/returns.rs#L146-L148

That was the latest commit to this file which precedes the release of clippy 0.0.212 (2018-07-07 according to crates.io). Git blame of the check_let_return method shows that it wasn't modified at all except some cosmetic changes since the release. So probably check_let_return is the one that needs a fix.

[phansch]

Thanks for the investigation!
I'm going to try and reproduce this on a 32bit Docker image and see if that can be integrated into CI.

[phansch]

I managed to set up a 32bit docker container to run Clippy on byte-tools:
https://gist.github.com/phansch/39baf111d6f5fa4c4c44b3ba8ab4f559

It's currently set to check RustCrypto/utils@12b85f9#diff-680d0fd529aaf10e64df6cd0feb785ea but doesn't cause a crash. I ran out of time for today and will check the other commits tomorrow.

[phansch]

I can't reproduce the crash with the docker container. Maybe because my host system is 64 bit? I'm going to try it with a Vagrant VM next.

[hcpl]

Maybe because my host system is 64 bit?

I think the answer is yes --- I tried to reproduce with qemu-i386 on my 64-bit laptop but couldn't as well.

[phansch]

I also can't seem to reproduce it with a Vagrant VM.
This is the Vagrantfile I used: https://gist.github.com/phansch/39baf111d6f5fa4c4c44b3ba8ab4f559#file-vagrantfile

@therealbstern Could you also provide the output of lscpu or cat /proc/cpuinfo?