### Integration Tests
This commit introduces some new fixtures to the `run-make-fulldeps`
test suite.
* c-unwind-abi-catch-panic: Exercise unwinding a panic. This
catches a panic across an FFI boundary and downcasts it into
an integer.
* c-unwind-abi-catch-lib-panic: This is similar to the previous
`*catch-panic` test, however in this case the Rust code that
panics resides in a separate crate.
### Add `rust_eh_personality` to `#[no_std]` alloc tests
This commit addresses some test failures that now occur in the
following two tests:
* no_std-alloc-error-handler-custom.rs
* no_std-alloc-error-handler-default.rs
Each test now defines a `rust_eh_personality` extern function, in
the same manner as shown in the "Writing an executable without
stdlib" section of the `lang_items` documentation here:
https://doc.rust-lang.org/unstable-book/language-features/lang-items.html#writing-an-executable-without-stdlib
Without this change, these tests would fail to compile due to a
linking error explaining that there was an "undefined reference
to `rust_eh_personality'."
### Updated hash
* update 32-bit hash in `impl1` test
### Panics
This commit uses `panic!` macro invocations that return a string,
rather than using an integer as a panic payload.
Doing so avoids the following warnings that were observed during
rollup for the `*-msvc-1` targets:
```
warning: panic message is not a string literal
--> panic.rs:10:16
|
10 | panic!(x); // That is too big!
| ^
|
= note: `#[warn(non_fmt_panic)]` on by default
= note: this is no longer accepted in Rust 2021
help: add a "{}" format string to Display the message
|
10 | panic!("{}", x); // That is too big!
| ^^^^^
help: or use std::panic::panic_any instead
|
10 | std::panic::panic_any(x); // That is too big!
| ^^^^^^^^^^^^^^^^^^^^^
warning: 1 warning emitted
```
See: https://github.com/rust-lang-ci/rust/runs/1992118428
As these errors imply, panicking without a format string will be
disallowed in Rust 2021, per #78500.
