Use the Rust tracing crate for C++ logging
This PR swaps in the `tracing` crate (via FFI) for logging to either standard
output or `debug.log`. It transparently maps all existing `LogPrintf` and
`LogPrint` invocations to info-level `tracing` events, and passes through
correct file and line information. `error` invocations are mapped to error-level
`tracing` events, currently without line information (due to the way that
`error` is used in the codebase; swapping individual callsites to the new
`LogError` macro will provide that information).
The end-goal for this change is that we don't need to make any disruptive
changes to the codebase, but we can start to leverage `tracing`-specific
functionality where we want to, such as providing extra fields on certain log
lines (that can be filtered for), adding spans to record the flow of execution
through `zcashd`, and logging within C++ and Rust simultaneously. Support
for extra fields on spans and events will be added in a subsequent PR.
The `-debug` config options are converted at launch into their corresponding
directives for tracing's `EnvFilter`. The new `setlogfilter` RPC method allows
this filter to be reloaded dynamically. The syntax is documented in the
`setlogfilter` help text, as well as here:
https://docs.rs/tracing-subscriber/0.2.7/tracing_subscriber/filter/struct.EnvFilter.html#directives
When `-printtoconsole` is specified, the output now includes timestamps and
ANSI encoding :)
A new safe_depends() checker is added, which allows the '.' character on
top of the existing safe() characters.
The time crate is postponed to 2021-02-01, by which time hopefully the
chrono crate will have figured out what it is doing with that dependency.
The previous version of full_test_suite.py directly called the test
binary, which was being compiled at the same time as the static library.
However, by passing the --tests argument to cargo, rustc was ignoring
several important release-profile configurations, and was also
attempting to link the test binary, which was breaking cross-compilation
builds.
This commit alters src/Makefile.am to only build the static library, and
leaves test compilation to the test runner itself. This ensures that the
tests are only compiled for native builds, when the tests will be run on
the same platform.
Additional librustzcash integration
This adds librustzcash tests to the full test suite, and brings in the release profile configurations that are currently present in the librustzcash workspace on the other repository. It's very important that we build librustzcash with panic=abort because otherwise the unwinding panics across FFI boundaries could cause undefined behavior.