This provides a clear and consistent interface for selecting TLS-related
features on both (xmpp and tokio-xmpp) crates. All feature checks have
been revamped. All working combinations have been tested (including a
connectivity test + --all-features docs build) using:
```
set -xeuo pipefail
features=(aws_lc_rs ring ktls,aws_lc_rs ktls,ring aws_lc_rs,ring aws_lc_rs,ring,ktls native-tls rustls-any-backend)
export RUSTFLAGS=" -D warnings"
cargo test --no-default-features
cargo test
for feature in ${features[@]}; do
echo ">>> BUILDING with $feature" 2>&1
# Running code or building examples cannot succeed with rustls-any-backend.
features="starttls,$feature"
if [ "$feature" != 'rustls-any-backend' ]; then
if ! cargo test --no-default-features --features="$features"; then
echo ">>> BUILD FAILED for tls feature set: $features" >&2
exit 1
fi
set +e
timeout -sINT -p -k 2 3 cargo run --no-default-features --features="$features" --example keep_connection -- test@hub.sotecware.net "$(pass xmpp/test@hub.sotecware.net)"
status="$?"
set -e
if [ $status -ne 0 ]; then
echo ">>> keep_connection did not shut down cleanly! (status: $status)" >&2
exit 1
fi
else
if ! cargo build --no-default-features --features="$feature"; then
echo ">>> BUILD FAILED for tls feature set: $features" >&2
exit 1
fi
fi
done
RUSTDOCFLAGS="--cfg docsrs" RUSTFLAGS="--cfg xmpprs_doc_build" cargo +nightly doc -Zrustdoc-map --all-features
```