setup the unsupported directory structure.

The unsupported module documentation is automatically generated in:
  build/doc/unsupported/
with bidirectional cross references.
I leave a class Foo in AdolcForward module to illustrate the
cross-reference behavior. I will remove it in the next commit.

doc/CMakeLists.txt

@@ -7,6 +7,11 @@ if(CMAKE_COMPILER_IS_GNUCXX)
   endif(CMAKE_SYSTEM_NAME MATCHES Linux)
 endif(CMAKE_COMPILER_IS_GNUCXX)
 
+configure_file(
+  ${Eigen_SOURCE_DIR}/unsupported/doc/Doxyfile.in
+  ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile-unsupported
+)
+
 configure_file(
   ${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile.in
   ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile
@@ -31,7 +36,7 @@ add_subdirectory(examples)
 add_subdirectory(snippets)
 
 add_custom_target(
-  doc
+  doc-eigen
   ALL
   COMMAND ${CMAKE_COMMAND} -E make_directory ${CMAKE_CURRENT_BINARY_DIR}/html/
   COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_CURRENT_SOURCE_DIR}/eigendoxy_tabs.css
@@ -42,4 +47,20 @@ add_custom_target(
   WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
 )
 
-add_dependencies(doc all_snippets all_examples)
+add_custom_target(
+  doc-unsupported
+  ALL
+  COMMAND ${CMAKE_COMMAND} -E make_directory ${Eigen_BINARY_DIR}/doc/html/unsupported
+  COMMAND ${CMAKE_COMMAND} -E copy ${Eigen_SOURCE_DIR}/doc/eigendoxy_tabs.css
+                                   ${Eigen_BINARY_DIR}/doc/html/unsupported/
+  COMMAND ${CMAKE_COMMAND} -E copy ${Eigen_SOURCE_DIR}/doc/Eigen_Silly_Professor_64x64.png
+                                   ${Eigen_BINARY_DIR}/doc/html/unsupported/
+  COMMAND doxygen Doxyfile-unsupported
+  WORKING_DIRECTORY ${Eigen_BINARY_DIR}/doc
+)
+
+add_dependencies(doc-eigen all_snippets all_examples)
+add_dependencies(doc-unsupported doc-eigen)
+# rerun doxygen to get eigen => unsupported cross references
+add_custom_target(doc ALL COMMAND doxygen WORKING_DIRECTORY ${Eigen_BINARY_DIR}/doc)
+add_dependencies(doc doc-eigen doc-unsupported)

doc/Doxyfile.in

@@ -564,9 +564,7 @@ WARN_LOGFILE           =
 
 INPUT                  = "${Eigen_SOURCE_DIR}/Eigen" \
                          "${Eigen_SOURCE_DIR}/doc" \
-                         "${Eigen_BINARY_DIR}/doc" \
-                         "${Eigen_SOURCE_DIR}/unsupported/Eigen" \
-                         "${Eigen_SOURCE_DIR}/unsupported/doc"
+                         "${Eigen_BINARY_DIR}/doc"
 
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding, which is
@@ -1242,12 +1240,12 @@ SKIP_FUNCTION_MACROS   = YES
 # If a tag file is not located in the directory in which doxygen
 # is run, you must also specify the path to the tagfile here.
 
-TAGFILES               =
+TAGFILES               = "${Eigen_BINARY_DIR}/doc/eigen-unsupported.doxytags"=unsupported
 
 # When a file name is specified after GENERATE_TAGFILE, doxygen will create
 # a tag file that is based on the input files it reads.
 
-GENERATE_TAGFILE       =
+GENERATE_TAGFILE       = "${Eigen_BINARY_DIR}/doc/eigen.doxytags"
 
 # If the ALLEXTERNALS tag is set to YES all external classes will be listed
 # in the class index. If set to NO only the inherited external classes

doc/Overview.dox

@@ -19,6 +19,8 @@ In fact, except for advanced use, the only class that you'll have to explicitly
 
 Most of the other classes are just return types for MatrixBase methods.
 
+Want more? Checkout the \ref Unsupported_modules "unsupported modules" <a href="unsupported/index.html">documentation</a>.
+
 */
 
 }

doc/unsupported_modules.dox

@@ -0,0 +1,16 @@
+
+namespace Eigen {
+
+/** \defgroup Unsupported_modules Unsupported modules
+  *
+  * The unsupported modules are contributions from various users. They are
+  * provided "as is", without any support. Nevertheless, they are subject to be
+  * included in Eigen in the future.
+  */
+
+// please list here all unsupported modules
+
+/** \ingroup Unsupported_modules
+  * \defgroup AdolcForward_Module Adolc forward module */
+
+} // namespace Eigen