Collect code coverage.

.gitignore

@@ -1,2 +1,4 @@
 target
 Cargo.lock
+*.gcno
+*.gcda

Cargo.toml

@@ -17,3 +17,7 @@ alloc = []
 default = ["std"]
 # Unstable features
 map = []
+
+[profile.test]
+opt-level = 1
+codegen-units = 1

coverage.sh

@@ -0,0 +1,17 @@
+#!/bin/bash -e
+
+cargo rustc -- --test -C link-dead-code -Z profile -Z no-landing-pads
+
+LCOVOPTS=(
+  --gcov-tool llvm-gcov
+  --rc lcov_branch_coverage=1
+  --rc lcov_excl_line=assert
+)
+lcov "${LCOVOPTS[@]}" --capture --directory . --base-directory . \
+  -o target/coverage/raw.lcov
+lcov "${LCOVOPTS[@]}" --extract target/coverage/raw.lcov "$(pwd)/*" \
+  -o target/coverage/raw_crate.lcov
+
+genhtml --branch-coverage --demangle-cpp --legend \
+  -o target/coverage/ \
+  target/coverage/raw_crate.lcov