Merge changes from topic "ci-coverage"

* changes:
  CI: compare code coverage changes
  CI: start building with coverage profiling
  CI: only build docs once
diff --git a/.zuul.yaml b/.zuul.yaml
index 6f09b90..07833bf 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -1,10 +1,19 @@
 - project:
     check:
+      fail-fast: true
       jobs:
         - clang-format:
             voting: false
-        - f29-gcc:
+        - f29-gcc-cover:
             requires: CzechLight-deps-f29-gcc
+            provides: coverage-f29-gcc
+        - f29-gcc-cover-diff:
+            voting: false
+            requires:
+              - CzechLight-deps-f29-gcc
+              - coverage-f29-gcc
+            dependencies:
+              - f29-gcc-cover
         - f29-gcc-asan-ubsan:
             requires: CzechLight-deps-f29-gcc-asan-ubsan
         - f29-clang-asan:
diff --git a/ci/build.sh b/ci/build.sh
index ba8db7b..8b08c3b 100755
--- a/ci/build.sh
+++ b/ci/build.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 
 set -eux -o pipefail
-shopt -s failglob
+shopt -s failglob extglob
 
 ZUUL_JOB_NAME=$(jq < ~/zuul-env.json -r '.job')
 ZUUL_TENANT=$(jq < ~/zuul-env.json -r '.tenant')
@@ -50,6 +50,12 @@
     CMAKE_OPTIONS="${CMAKE_OPTIONS} -DWITH_PYTHON_BINDINGS=ON"
 fi
 
+if [[ $ZUUL_JOB_NAME =~ .*-cover.* ]]; then
+    export CFLAGS="${CFLAGS} --coverage"
+    export CXXFLAGS="${CXXFLAGS} --coverage"
+    export LDFLAGS="${LDFLAGS} --coverage"
+fi
+
 PREFIX=~/target
 mkdir ${PREFIX}
 BUILD_DIR=~/build
@@ -69,7 +75,7 @@
 
 if [[ -z "${ARTIFACT_URL}" ]]; then
     # fallback to a promoted artifact
-    ARTIFACT_URL="https://object-store.cloud.muni.cz/swift/v1/ci-artifacts-${ZUUL_TENANT}/${ZUUL_GERRIT_HOSTNAME}/CzechLight/dependencies/${ZUUL_JOB_NAME}/${DEP_SUBMODULE_COMMIT}.tar.xz"
+    ARTIFACT_URL="https://object-store.cloud.muni.cz/swift/v1/ci-artifacts-${ZUUL_TENANT}/${ZUUL_GERRIT_HOSTNAME}/CzechLight/dependencies/${ZUUL_JOB_NAME%%-cover?(-diff)}/${DEP_SUBMODULE_COMMIT}.tar.xz"
 fi
 
 ARTIFACT_FILE=$(basename ${ARTIFACT_URL})
@@ -82,14 +88,18 @@
 tar -C ${PREFIX} -xf ${ARTIFACT_FILE}
 rm ${ARTIFACT_FILE}
 
-# TODO: move this to CzechLight/dependencies
-mkdir -p /home/ci/target/var-run
-
 cd ${BUILD_DIR}
 cmake -GNinja -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE:-Debug} -DCMAKE_INSTALL_PREFIX=${PREFIX} ${CMAKE_OPTIONS} ${ZUUL_PROJECT_SRC_DIR}
 ninja-build
 ctest -j${CI_PARALLEL_JOBS} --output-on-failure
-ninja-build doc
-pushd html
-zip -r ~/zuul-output/docs/html.zip .
-popd
+
+if [[ $JOB_PERFORM_EXTRA_WORK == 1 ]]; then
+    ninja-build doc
+    pushd html
+    zip -r ~/zuul-output/docs/html.zip .
+    popd
+fi
+
+if [[ $LDFLAGS =~ .*--coverage.* ]]; then
+    gcovr -j ${CI_PARALLEL_JOBS} --object-directory ${BUILD_DIR} --root ${ZUUL_PROJECT_SRC_DIR} --xml --output ${BUILD_DIR}/coverage.xml
+fi