Add BUILD_DOCS option to enable/disable building documentation.

CMakeLists.txt

@@ -17,6 +17,7 @@ option(DISABLE_DOWNLOADS "Disable downloads of dependencies during build." OFF)
 option(DOWNLOAD_ENSMALLEN "If ensmallen is not found, download it." ON)
 option(DOWNLOAD_STB_IMAGE "Download stb_image for image loading." ON)
 option(BUILD_GO_SHLIB "Build Go shared library." OFF)
+option(BUILD_DOCS "Build doxygen documentation (if doxygen is available)." ON)
 
 # Set minimum library version required by mlpack.
 set(ARMADILLO_VERSION "8.400.0")
@@ -617,43 +618,45 @@ add_dependencies(mlpack_headers mlpack_arma_config)
 
 # Make a target to generate the documentation.  If Doxygen isn't installed, then
 # I guess this option will just be unavailable.
-find_package(Doxygen)
-if (DOXYGEN_FOUND)
-  if (MATHJAX)
-    find_package(MathJax)
-    if (NOT MATHJAX_FOUND)
-      message(STATUS "Using MathJax at the MathJax Content Delivery Network. "
-          "Be careful, formulas will not be shown without the internet.")
+if (BUILD_DOCS)
+  find_package(Doxygen)
+  if (DOXYGEN_FOUND)
+    if (MATHJAX)
+      find_package(MathJax)
+      if (NOT MATHJAX_FOUND)
+        message(STATUS "Using MathJax at the MathJax Content Delivery Network. "
+            "Be careful, formulas will not be shown without the internet.")
+      endif ()
     endif ()
+    # Preprocess the Doxyfile.  This is done before 'make doc'.
+    add_custom_command(OUTPUT ${CMAKE_BINARY_DIR}/Doxyfile
+        PRE_BUILD
+        COMMAND ${CMAKE_COMMAND}
+            -D DESTDIR=${CMAKE_BINARY_DIR}
+            -D MATHJAX="${MATHJAX}"
+            -D MATHJAX_FOUND="${MATHJAX_FOUND}"
+            -D MATHJAX_PATH="${MATHJAX_PATH}"
+            -P "${CMAKE_CURRENT_SOURCE_DIR}/CMake/GenerateDoxyfile.cmake"
+        WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
+        DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile"
+        COMMENT "Creating Doxyfile to generate Doxygen documentation"
+    )
+
+    # Generate documentation.
+    add_custom_target(doc
+        COMMAND "${DOXYGEN_EXECUTABLE}" "${CMAKE_BINARY_DIR}/Doxyfile"
+        DEPENDS "${CMAKE_BINARY_DIR}/Doxyfile"
+        WORKING_DIRECTORY "${CMAKE_BINARY_DIR}"
+        COMMENT "Generating API documentation with Doxygen"
+    )
+
+    install(DIRECTORY "${CMAKE_BINARY_DIR}/doc/html"
+        DESTINATION "${CMAKE_INSTALL_DOCDIR}"
+        COMPONENT doc
+        OPTIONAL
+    )
   endif ()
-  # Preprocess the Doxyfile.  This is done before 'make doc'.
-  add_custom_command(OUTPUT ${CMAKE_BINARY_DIR}/Doxyfile
-      PRE_BUILD
-      COMMAND ${CMAKE_COMMAND}
-          -D DESTDIR=${CMAKE_BINARY_DIR}
-          -D MATHJAX="${MATHJAX}"
-          -D MATHJAX_FOUND="${MATHJAX_FOUND}"
-          -D MATHJAX_PATH="${MATHJAX_PATH}"
-          -P "${CMAKE_CURRENT_SOURCE_DIR}/CMake/GenerateDoxyfile.cmake"
-      WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
-      DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile"
-      COMMENT "Creating Doxyfile to generate Doxygen documentation"
-  )
-
-  # Generate documentation.
-  add_custom_target(doc
-      COMMAND "${DOXYGEN_EXECUTABLE}" "${CMAKE_BINARY_DIR}/Doxyfile"
-      DEPENDS "${CMAKE_BINARY_DIR}/Doxyfile"
-      WORKING_DIRECTORY "${CMAKE_BINARY_DIR}"
-      COMMENT "Generating API documentation with Doxygen"
-  )
-
-  install(DIRECTORY "${CMAKE_BINARY_DIR}/doc/html"
-      DESTINATION "${CMAKE_INSTALL_DOCDIR}"
-      COMPONENT doc
-      OPTIONAL
-  )
-endif ()
+endif()
 
 # Create the pkg-config file, if we have pkg-config.
 find_package(PkgConfig)

Doxyfile

@@ -75,7 +75,8 @@ FILE_VERSION_FILTER    =
 #---------------------------------------------------------------------------
 QUIET                  = NO
 WARNINGS               = YES
-WARN_AS_ERROR          = YES
+# This will be set to YES for the Jenkins doxygen check build.
+WARN_AS_ERROR          = NO
 WARN_IF_UNDOCUMENTED   = YES
 WARN_IF_DOC_ERROR      = YES
 WARN_NO_PARAMDOC       = YES

HISTORY.md

@@ -2,6 +2,9 @@
 ###### ????-??-??
   * Added an implementation to Stratify Data (#2671).
 
+  * Add `BUILD_DOCS` CMake option to control whether Doxygen documentation is
+    built (default ON) (#2730).
+
 ### mlpack 3.4.2
 ###### 2020-10-26
   * Added Mean Absolute Percentage Error.

README.md

@@ -217,6 +217,8 @@ Options are specified with the -D flag.  The allowed options include:
     STB_IMAGE_INCLUDE_DIR=(/path/to/stb/include): path to include directory for
        STB image library
     USE_OPENMP=(ON/OFF): whether or not to use OpenMP if available
+    BUILD_DOCS=(ON/OFF): build Doxygen documentation, if Doxygen is available
+       (default ON)
 
 Other tools can also be used to configure CMake, but those are not documented
 here.  See [this section of the build guide](https://www.mlpack.org/doc/mlpack-git/doxygen/build.html#build_config)

doc/guide/build.hpp

@@ -179,6 +179,8 @@ The full list of options mlpack allows:
  - JULIA_EXECUTABLE=(/path/to/julia): Path to specific Julia executable
  - BUILD_MARKDOWN_BINDINGS=(ON/OFF): Build Markdown bindings for website
        documentation (default OFF)
+ - BUILD_DOCS=(ON/OFF): build Doxygen documentation, if Doxygen is available
+       (default ON)
  - MATHJAX=(ON/OFF): use MathJax for generated Doxygen documentation (default
        OFF)
  - FORCE_CXX11=(ON/OFF): assume that the compiler supports C++11 instead of