run Miri on CI

[RalfJung]

After discussions like #7, I figured running Miri to check the test suite for UB might be a good idea. However, I am not sure how extensive the test suite is so far. Miri can only find UB if the test suite actually hits the problematic code paths (think of it like ubsan or other sanitizers).

It seems like cargo test is not even run on CI?

[maciejhirsz]

Cheers! Tests are being run for stable, beta, and nightly.

There are two additional builds that don't run tests:

• Making sure const_fn feature compiles on nightly (this can probably be a full test).
• Check if no_std compiles for thumbv6m-none-eabi.

Adding more tests, in particular longer tests that do allocations and deallocations multiple times, is definitely on the agenda.

[RalfJung]

Oh d'oh, there's a default script that Travis uses when you give no script: yourself...

I was looking for the cargo test and didn't see it.^^ Sorry.

[RalfJung]

I didn't do any further investigation for why Miri sees a memory leak.
This might or might not be rust-lang/miri#940.

[RalfJung]

One of the leaked allocations is allocated here:

note: inside call to `std::string::String::push_str` at src/lean.rs:87:13
   --> src/lean.rs:87:13
    |
87  |             owned.push_str("Hello?.. ");
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: inside call to `lean::tests::stress_test_owned` at src/lean.rs:75:5
   --> src/lean.rs:75:5
    |
75  | /     fn stress_test_owned() {
76  | |         let mut expected = String::from("Hello... ");
77  | |         let mut cow: Cow<str> = Cow::borrowed("Hello... ");
78  | |
...   |
92  | |         assert_eq!(expected, cow.into_owned());
93  | |     }
    | |_____^

Doesn't look like there is anything being put in a static here, so this is likely a genuine leak?