Panic when `unstable` + `use_std` feature is set

[virtualritz]

EDIT: Just checking out this repo and doing a:

cargo test --features unstable

already produces the below issue:

running 5 tests
test test_gt_f32 ... FAILED
test test_gt_f64 ... FAILED
test test_lt_f32 ... FAILED
test test_lt_f64 ... FAILED
test exphp_tests ... FAILED

failures:

---- test_gt_f32 stdout ----
thread 'test_gt_f32' panicked at /home/moritz/code/crates/is_sorted-orig/src/floats.rs:315:5:
assertion failed: i == n - 1 || s.as_ptr().offset(i as isize).align_offset(ALIGNMENT) == 0
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

---- test_gt_f64 stdout ----
thread 'test_gt_f64' panicked at /home/moritz/code/crates/is_sorted-orig/src/floats.rs:315:5:
assertion failed: i == n - 1 || s.as_ptr().offset(i as isize).align_offset(ALIGNMENT) == 0

---- test_lt_f32 stdout ----
thread 'test_lt_f32' panicked at /home/moritz/code/crates/is_sorted-orig/src/floats.rs:271:5:
assertion failed: i == n - 1 || s.as_ptr().offset(i as isize).align_offset(ALIGNMENT) == 0

---- test_lt_f64 stdout ----
thread 'test_lt_f64' panicked at /home/moritz/code/crates/is_sorted-orig/src/floats.rs:271:5:
assertion failed: i == n - 1 || s.as_ptr().offset(i as isize).align_offset(ALIGNMENT) == 0

---- exphp_tests stdout ----
thread 'exphp_tests' panicked at /home/moritz/code/crates/is_sorted-orig/src/floats.rs:249:5:
assertion failed: i == n - 1 || s.as_ptr().offset(i as isize).align_offset(ALIGNMENT) == 0

BEFORE (ignore):

I'm using this crate behind a feature gate in my uniform-cubic-splines crate.

Running

cargo test --all_features 

on my crate I get a panic (see below). Note that this only happens when both features unstable and use_std are set on is_sorted. Using only unstable everything works.

---- src/lib.rs - spline_inverse (line 187) stdout ----
Test executable failed (exit status: 101).

stderr:
thread 'main' panicked at /home/moritz/.cargo/registry/src/index.crates.io-6f17d22bba15001f/is_sorted-0.1.1/src/floats.rs:271:5:
assertion failed: i == n - 1 || s.as_ptr().offset(i as isize).align_offset(ALIGNMENT) == 0
stack backtrace:
   0:     0x555d3252091c - std::backtrace_rs::backtrace::libunwind::trace::h895decac6837a495
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x555d3252091c - std::backtrace_rs::backtrace::trace_unsynchronized::hcbdb001903b8da06
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x555d3252091c - std::sys_common::backtrace::_print_fmt::hbb4acc0429a0e855
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/sys_common/backtrace.rs:67:5
   3:     0x555d3252091c - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hb131321ae2a401dd
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x555d32544550 - core::fmt::rt::Argument::fmt::hd9aeb95c38745bc3
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/core/src/fmt/rt.rs:142:9
   5:     0x555d32544550 - core::fmt::write::hc405bb79f2ac8cb8
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/core/src/fmt/mod.rs:1117:17
   6:     0x555d3251ebff - std::io::Write::write_fmt::ha55bc380d2605627
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/io/mod.rs:1762:15
   7:     0x555d32520704 - std::sys_common::backtrace::_print::he5b4ffb2f8b9aae2
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x555d32520704 - std::sys_common::backtrace::print::h7dfa57d65fbc411a
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x555d32521c97 - std::panicking::default_hook::{{closure}}::h359697fee07a3691
  10:     0x555d325219da - std::panicking::default_hook::hbf7afbae604c2e97
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/panicking.rs:292:9
  11:     0x555d32522178 - std::panicking::rust_panic_with_hook::hd5cf40cf90f0da4f
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/panicking.rs:731:13
  12:     0x555d32522016 - std::panicking::begin_panic_handler::{{closure}}::h7a7594a015de3c11
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/panicking.rs:601:13
  13:     0x555d32520e36 - std::sys_common::backtrace::__rust_end_short_backtrace::h7bca82ae1dc2e605
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/sys_common/backtrace.rs:170:18
  14:     0x555d32521d92 - rust_begin_unwind
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/panicking.rs:597:5
  15:     0x555d32500265 - core::panicking::panic_fmt::h50936ad2e0c759a9
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/core/src/panicking.rs:72:14
  16:     0x555d32500303 - core::panicking::panic::h8d79140416ece116
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/core/src/panicking.rs:127:5
  17:     0x555d3250421b - is_sorted::floats::avx::is_sorted_lt_f64::h38592d1ff5e74d0a
  18:     0x555d32500f8f - <core::slice::iter::Iter<f64> as is_sorted::IsSortedBy<is_sorted::ord::types::Increasing>>::is_sorted_by::h40bf262d7b7c4e5c
  19:     0x555d32503d76 - is_sorted::is_sorted_by_impl::hf8d8e45986ba2579
  20:     0x555d32506026 - is_sorted::IsSorted::is_sorted_by::h05a4302c1b93a447
  21:     0x555d32506036 - is_sorted::IsSorted::is_sorted::hf5ddb051c4536238
  22:     0x555d32501083 - uniform_cubic_splines::spline_inverse::h5195130f16818a47
  23:     0x555d325060bb - rust_out::main::_doctest_main_src_lib_rs_187_0::hacfaea99b5d67fe0
  24:     0x555d32506046 - rust_out::main::hbdbaecddcf9d610c
  25:     0x555d325028f3 - core::ops::function::FnOnce::call_once::h07daadcc9a42a906
  26:     0x555d32502416 - std::sys_common::backtrace::__rust_begin_short_backtrace::hd892616f0cb29327
  27:     0x555d32502469 - std::rt::lang_start::{{closure}}::hac27b7c71c7d146a
  28:     0x555d3251ccd7 - core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once::hf49a447a50c1bd28
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/core/src/ops/function.rs:284:13
  29:     0x555d3251ccd7 - std::panicking::try::do_call::h98590e8abae72330
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/panicking.rs:504:40
  30:     0x555d3251ccd7 - std::panicking::try::h71c63625f42b207c
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/panicking.rs:468:19
  31:     0x555d3251ccd7 - std::panic::catch_unwind::h771c283950160ec8
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/panic.rs:142:14
  32:     0x555d3251ccd7 - std::rt::lang_start_internal::{{closure}}::h21612fab3a4cac96
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/rt.rs:148:48
  33:     0x555d3251ccd7 - std::panicking::try::do_call::ha15438754ab0311a
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/panicking.rs:504:40
  34:     0x555d3251ccd7 - std::panicking::try::h98e2cdaa52e3617a
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/panicking.rs:468:19
  35:     0x555d3251ccd7 - std::panic::catch_unwind::h39d9ee82e15c4984
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/panic.rs:142:14
  36:     0x555d3251ccd7 - std::rt::lang_start_internal::hcde5a668a935b8aa
                               at /rustc/fcab24817c72ffbd6ffb66d92b7ddc0d3ee4d2f0/library/std/src/rt.rs:148:20
  37:     0x555d32502447 - std::rt::lang_start::h2d122096cc3f94cb
  38:     0x555d32506145 - main
  39:     0x7fd2a0023a90 - __libc_start_call_main
                               at ./csu/../sysdeps/nptl/libc_start_call_main.h:58:16
  40:     0x7fd2a0023b49 - __libc_start_main_impl
                               at ./csu/../csu/libc-start.c:360:3
  41:     0x555d325009c5 - _start
  42:                0x0 - <unknown>