ci: generate annotation reports

These will render links in the sidebar for each job.

See: https://docs.gitlab.com/ee/ci/yaml/artifacts_reports.html#artifactsreportsannotations
diff --git a/.gitlab/ci/ctest_annotation.cmake b/.gitlab/ci/ctest_annotation.cmake
new file mode 100644
index 0000000..a219753
--- /dev/null
+++ b/.gitlab/ci/ctest_annotation.cmake
@@ -0,0 +1,32 @@
+function (ctest_annotation_report file)
+  set(label "")
+
+  if (EXISTS "${file}")
+    file(READ "${file}" json)
+  else ()
+    set(json "{\"CDash\": []}")
+  endif ()
+
+  foreach (arg IN LISTS ARGN)
+    if (NOT label)
+      set(label "${arg}")
+      continue ()
+    endif ()
+
+    set(item "{\"external_link\":{\"label\":\"${label}\",\"url\":\"${arg}\"}}")
+    set(label "")
+
+    string(JSON length LENGTH "${json}" "CDash")
+    string(JSON json SET "${json}" "CDash" "${length}" "${item}")
+  endforeach ()
+
+  file(WRITE "${file}" "${json}")
+endfunction ()
+
+if (NOT DEFINED build_id)
+  include("${CTEST_BINARY_DIRECTORY}/cdash-build-id" OPTIONAL)
+endif ()
+function (store_build_id build_id)
+  file(WRITE "${CTEST_BINARY_DIRECTORY}/cdash-build-id"
+    "set(build_id \"${build_id}\")\n")
+endfunction ()
diff --git a/.gitlab/ci/ctest_build.cmake b/.gitlab/ci/ctest_build.cmake
index e874a62..b1b9830 100644
--- a/.gitlab/ci/ctest_build.cmake
+++ b/.gitlab/ci/ctest_build.cmake
@@ -45,11 +45,17 @@
 endif ()
 
 ctest_build(
+  NUMBER_ERRORS num_errors
   NUMBER_WARNINGS num_warnings
   RETURN_VALUE build_result
   ${ctest_build_args})
 ctest_submit(PARTS Build)
 
+include("${CMAKE_CURRENT_LIST_DIR}/ctest_annotation.cmake")
+ctest_annotation_report("${CTEST_BINARY_DIRECTORY}/annotations.json"
+  "Build Errors (${num_errors})"      "https://open.cdash.org/viewBuildError.php?buildid=${build_id}"
+  "Build Warnings (${num_warnings})"  "https://open.cdash.org/viewBuildError.php?type=1&buildid=${build_id}")
+
 if (build_result)
   message(FATAL_ERROR
     "Failed to build")
diff --git a/.gitlab/ci/ctest_configure.cmake b/.gitlab/ci/ctest_configure.cmake
index 2682055..04285fd 100644
--- a/.gitlab/ci/ctest_configure.cmake
+++ b/.gitlab/ci/ctest_configure.cmake
@@ -22,10 +22,18 @@
 # Read the files from the build directory.
 ctest_read_custom_files("${CTEST_BINARY_DIRECTORY}")
 
-# We can now submit because we've configured. This is a cmb-superbuild-ism.
-ctest_submit(PARTS Update)
+# We can now submit because we've configured.
+ctest_submit(PARTS Update
+  BUILD_ID build_id)
 ctest_submit(PARTS Configure)
 
+include("${CMAKE_CURRENT_LIST_DIR}/ctest_annotation.cmake")
+ctest_annotation_report("${CTEST_BINARY_DIRECTORY}/annotations.json"
+  "Build Summary" "https://open.cdash.org/build/${build_id}"
+  "Update"        "https://open.cdash.org/build/${build_id}/update"
+  "Configure"     "https://open.cdash.org/build/${build_id}/configure")
+store_build_id("${build_id}")
+
 if (configure_result)
   message(FATAL_ERROR
     "Failed to configure")
diff --git a/.gitlab/ci/ctest_memcheck.cmake b/.gitlab/ci/ctest_memcheck.cmake
index dac907c..c650681 100644
--- a/.gitlab/ci/ctest_memcheck.cmake
+++ b/.gitlab/ci/ctest_memcheck.cmake
@@ -34,6 +34,15 @@
 ctest_submit(PARTS Test)
 ctest_submit(PARTS Memcheck)
 
+include("${CMAKE_CURRENT_LIST_DIR}/ctest_annotation.cmake")
+ctest_annotation_report("${CTEST_BINARY_DIRECTORY}/annotations.json"
+  "Build Summary"     "https://open.cdash.org/build/${build_id}"
+  "All Tests"         "https://open.cdash.org/viewTest.php?buildid=${build_id}"
+  "Dynamic Analysis"  "https://open.cdash.org/viewDynamicAnalysis.php?buildid=${build_id}"
+  "Test Failures"     "https://open.cdash.org/viewTest.php?onlyfailed&buildid=${build_id}"
+  "Tests Not Run"     "https://open.cdash.org/viewTest.php?onlynotrun&buildid=${build_id}"
+  "Test Passes"       "https://open.cdash.org/viewTest.php?onlypassed&buildid=${build_id}")
+
 if (test_result)
   message(FATAL_ERROR
     "Failed to test")
diff --git a/.gitlab/ci/ctest_standalone.cmake b/.gitlab/ci/ctest_standalone.cmake
index 36ba71c..2e67793 100644
--- a/.gitlab/ci/ctest_standalone.cmake
+++ b/.gitlab/ci/ctest_standalone.cmake
@@ -38,9 +38,16 @@
 ctest_read_custom_files("${CTEST_BINARY_DIRECTORY}")
 
 # We can now submit because we've configured. This is a cmb-superbuild-ism.
-ctest_submit(PARTS Update)
+ctest_submit(PARTS Update
+  BUILD_ID build_id)
 ctest_submit(PARTS Configure)
 
+include("${CMAKE_CURRENT_LIST_DIR}/ctest_annotation.cmake")
+ctest_annotation_report("${CTEST_BINARY_DIRECTORY}/annotations.json"
+  "Build Summary" "https://open.cdash.org/build/${build_id}"
+  "Update"        "https://open.cdash.org/build/${build_id}/update"
+  "Configure"     "https://open.cdash.org/build/${build_id}/configure")
+
 if (configure_result)
   ctest_submit(PARTS Done)
   message(FATAL_ERROR
@@ -54,10 +61,15 @@
 endif ()
 
 ctest_build(
+  NUMBER_ERRORS num_errors
   NUMBER_WARNINGS num_warnings
   RETURN_VALUE build_result)
 ctest_submit(PARTS Build)
 
+ctest_annotation_report("${CTEST_BINARY_DIRECTORY}/annotations.json"
+  "Build Errors (${num_errors})"      "https://open.cdash.org/viewBuildError.php?buildid=${build_id}"
+  "Build Warnings (${num_warnings})"  "https://open.cdash.org/viewBuildError.php?type=1&buildid=${build_id}")
+
 if (build_result)
   ctest_submit(PARTS Done)
   message(FATAL_ERROR
@@ -86,6 +98,12 @@
   EXCLUDE "${test_exclusions}")
 ctest_submit(PARTS Test)
 
+ctest_annotation_report("${CTEST_BINARY_DIRECTORY}/annotations.json"
+  "All Tests"     "https://open.cdash.org/viewTest.php?buildid=${build_id}"
+  "Test Failures" "https://open.cdash.org/viewTest.php?onlyfailed&buildid=${build_id}"
+  "Tests Not Run" "https://open.cdash.org/viewTest.php?onlynotrun&buildid=${build_id}"
+  "Test Passes"   "https://open.cdash.org/viewTest.php?onlypassed&buildid=${build_id}")
+
 if (test_result)
   ctest_submit(PARTS Done)
   message(FATAL_ERROR
diff --git a/.gitlab/ci/ctest_test.cmake b/.gitlab/ci/ctest_test.cmake
index b02d032..c155ab3 100644
--- a/.gitlab/ci/ctest_test.cmake
+++ b/.gitlab/ci/ctest_test.cmake
@@ -25,6 +25,14 @@
   EXCLUDE "${test_exclusions}")
 ctest_submit(PARTS Test)
 
+include("${CMAKE_CURRENT_LIST_DIR}/ctest_annotation.cmake")
+ctest_annotation_report("${CTEST_BINARY_DIRECTORY}/annotations.json"
+  "Build Summary" "https://open.cdash.org/build/${build_id}"
+  "All Tests"     "https://open.cdash.org/viewTest.php?buildid=${build_id}"
+  "Test Failures" "https://open.cdash.org/viewTest.php?onlyfailed&buildid=${build_id}"
+  "Tests Not Run" "https://open.cdash.org/viewTest.php?onlynotrun&buildid=${build_id}"
+  "Test Passes"   "https://open.cdash.org/viewTest.php?onlypassed&buildid=${build_id}")
+
 if (test_result)
   message(FATAL_ERROR
     "Failed to test")