-DWITH_DOC has no effect

[fvalenduc]

According to the website, -DWITH_DOC_ON build the documentation, so I suppose -DWITH_DOC_OFF disable that.
But no matter which argument you use, it has no effect:

11:05 francois@pc-francois /usr/src/pgrouting/build% cmake -DWITH_DOC=OFF ..
-- CMAKE_BUILD_TYPE Release
-- DOXYGEN_MINIMUM_VERSION=1.7
-- SPHINX_MINIMUM_VERSION=4.0
-- POSTGRESQL_MINIMUM_VERSION=13
-- BOOST_MINIMUM_VERSION=1.56.0
-- POSTGIS_MINIMUM_VERSION=3.0.0
-- pgRouting: Require C++17
-- POSTGRESQL_PG_CONFIG is /usr/sbin/pg_config
-- POSTGRESQL_EXECUTABLE is /usr/lib64/postgresql-18/bin/postgres
-- POSTGRESQL_VERSION_STRING in FindPostgreSQL.cmake is PostgreSQL 18.3
-- POSTGRESQL_INCLUDE_DIR: /usr/include/postgresql-18/server
-- POSTGRESQL_LIBRARIES: /usr/lib64/postgresql-18/lib64
-- POSTGRESQL_VERSION_STRING=PostgreSQL 18.3
-- POSTGRESQL_VERSION=18.3
-- PGSQL_VERSION=18003
-- PGSQL_VERSION=18003
-- LIBRARY_INSTALL_PATH /usr/lib64/postgresql-18/lib64
-- DOXYGEN_VERSION=1.13.2
-- PROJECT_BUILD_LANGUAGES = en;es;sv;zh_Hans
-- PGR_DOCUMENTATION_BUILD_DIR = /usr/src/pgrouting/build/doc/_build
-- PGR_DOCUMENTATION_SOURCE_DIR = /usr/src/pgrouting/build/doc
-- format=html
-- Configuring done (0.1s)
-- Generating done (0.2s)
CMake Warning:
Manually-specified variables were not used by the project:

WITH_DOC

-- Build files have been written to: /usr/src/pgrouting/build