Generate coverage with Rust nightly

Fixes solana-labs#177

Thanks @marco-c!

README.md

@@ -231,7 +231,7 @@ To generate code coverage statistics, run kcov via Docker:
 ```bash
 $ ./ci/coverage.sh
 ```
-The coverage report will be written to `./target/cov/index.html`
+The coverage report will be written to `./target/cov/report/index.html`
 
 
 Why coverage? While most see coverage as a code quality metric, we see it primarily as a developer

ci/buildkite.yml

@@ -3,9 +3,6 @@ steps:
     name: "stable [public]"
     timeout_in_minutes: 20
   - wait
-  - command: "ci/coverage.sh"
-    name: "coverage [public]"
-    timeout_in_minutes: 20
   - command: "ci/docker-run.sh rustlang/rust:nightly ci/test-nightly.sh || true"
     name: "nightly - FAILURES IGNORED [public]"
     timeout_in_minutes: 20

ci/coverage.sh

@@ -2,15 +2,11 @@
 
 cd "$(dirname "$0")/.."
 
-ci/docker-run.sh evilmachines/rust-cargo-kcov \
-  bash -exc "\
-    export RUST_BACKTRACE=1; \
-    cargo build --verbose; \
-    cargo kcov --lib --verbose; \
-  "
+cargo install cargo-cov
+cargo cov test
 
 echo Coverage report:
-ls -l target/cov/index.html
+ls -l target/cov/report/index.html
 
 if [[ -z "$CODECOV_TOKEN" ]]; then
   echo CODECOV_TOKEN undefined

ci/test-nightly.sh

@@ -10,5 +10,6 @@ rustup component add rustfmt-preview
 cargo build --verbose --features unstable
 cargo test --verbose --features unstable
 cargo bench --verbose --features unstable
+ci/coverage.sh
 
 exit 0