Print theories that are not part of session as part of the CI build.

.woodpecker/build.yml

@@ -2,6 +2,7 @@ pipeline:
   build:
     image: docker.io/logicalhacking/isabelle2022
     commands:
+      - ./.woodpecker/unchecked-theories
       - ./.woodpecker/check_external_file_refs
       - export ARTIFACT_DIR=$CI_WORKSPACE/.artifacts/$CI_REPO/$CI_BRANCH/$CI_BUILD_NUMBER/$LATEX
       - mkdir -p $ARTIFACT_DIR

.woodpecker/unchecked-theories

@@ -0,0 +1,8 @@
+#!/bin/bash
+PWD=`pwd`
+TMPDIR=`mktemp -d`
+isabelle build  -D . -l -n | grep $PWD | sed -e "s| *${PWD}/||" | sort -u | grep thy$ > ${TMPDIR}/sessions-thy-files.txt
+find * -type f | sort -u | grep thy$ > ${TMPDIR}/actual-thy-files.txt
+echo "Theories that are not part of a Isabelle session:"
+echo "================================================="
+comm -13 ${TMPDIR}/sessions-thy-files.txt ${TMPDIR}/actual-thy-files.txt