contrib: script to generate Clang coverage report

The script converts a raw Clang coverage profile to an HTML report.

contrib/clang-coverage-report.sh

@@ -0,0 +1,26 @@
+#!/bin/bash -eu
+#
+# Generates an HTML coverage report from a raw Clang coverage profile. See
+# https://clang.llvm.org/docs/SourceBasedCodeCoverage.html for more details.
+# 
+# Example usage to create full_channel.html from full_channel.profraw for the
+# run-full_channel unit test:
+#   ./contrib/clang-coverage-report.sh channeld/test/run-full_channel \
+#       full_channel.profraw full_channel.html
+
+if [[ "$#" -ne 3 ]]; then
+	echo "Usage: $0 BINARY RAW_PROFILE_FILE TARGET_HTML_FILE"
+	exit 1
+fi
+
+readonly BINARY="$1"
+readonly RAW_PROFILE_FILE="$2"
+readonly TARGET_HTML_FILE="$3"
+
+readonly MERGED_PROFILE_FILE=$(mktemp)
+
+llvm-profdata merge -sparse "${RAW_PROFILE_FILE}" -o "${MERGED_PROFILE_FILE}"
+llvm-cov show "${BINARY}" -instr-profile="${MERGED_PROFILE_FILE}" -format=html \
+	> "${TARGET_HTML_FILE}"
+
+rm "${MERGED_PROFILE_FILE}"