Add support for C++20 modules

CMakeLists.txt

@@ -11,7 +11,7 @@
 # Documents produced by Doxygen are derivative works derived from the
 # input used in their production; they are not affected by this license.
 
-cmake_minimum_required(VERSION 3.3)
+cmake_minimum_required(VERSION 3.12)
 project(doxygen)
 
 option(build_wizard    "Build the GUI frontend for doxygen." OFF)
@@ -148,7 +148,7 @@ else ()
 endif ()
 
 find_program(DOT NAMES dot)
-find_package(PythonInterp REQUIRED)
+find_package(Python REQUIRED)
 find_package(FLEX REQUIRED)
 if (FLEX_VERSION VERSION_LESS 2.5.37)
   message(SEND_ERROR "Doxygen requires at least flex version 2.5.37 (installed: ${FLEX_VERSION})")

doc/CMakeLists.txt

@@ -15,7 +15,7 @@ include (${TOP}/cmake/version.cmake)
 string(TIMESTAMP DATE "%d-%m-%Y")
 string(TIMESTAMP YEAR "%Y")
 
-find_package(PythonInterp REQUIRED)
+find_package(Python REQUIRED)
 find_program(EPSTOPDF NAMES epstopdf )
 find_program(PDFLATEX NAMES pdflatex )
 find_program(MAKEINDEX NAMES makeindex )

doc/commands.doc

@@ -145,6 +145,7 @@ documentation:
 \refitem cmdmaninclude \\maninclude
 \refitem cmdmanonly \\manonly
 \refitem cmdmemberof \\memberof
+\refitem cmdmodule \\module
 \refitem cmdmsc \\msc
 \refitem cmdmscfile \\mscfile
 \refitem cmdn \\n
@@ -509,9 +510,9 @@ Structural indicators
 
   \addindex \\defgroup
   Indicates that a comment block contains documentation for a
-  \ref modules "group" of classes, files or namespaces. This can be used to
-  categorize classes, files or namespaces, and document those
-  categories. You can also use groups as members of other groups,
+  \ref topics "topics" of classes, modules, concepts, files or namespaces. This can be used to
+  categorize symbols, and document those categories.
+  You can also use groups as members of other groups,
   thus building a hierarchy of groups.
 
   The \<name\> argument should be a single-word identifier.
@@ -917,6 +918,13 @@ Structural indicators
       \ref cmdpublic "\\public", \ref cmdprotected "\\protected" and
       \ref cmdprivate "\\private".
 
+<hr>
+\section cmdmodule \\module <name>
+
+  \addindex \\module
+  Indicates that a comment block contains documentation for a
+  C++20 module with name \<name\>.
+
 <hr>
 \section cmdname \\name [(header)]
 

doc/doxygen_manual.tex

@@ -205,7 +205,7 @@ \chapter{Resolving Typedef Example}\label{restypedef_example}\hypertarget{restyp
   \subinputfrom{examples/diagrams/latex/}{refman_doc}
 }{}
 
-\chapter{Modules Example}\label{modules_example}\hypertarget{modules_example}{}
+\chapter{Grouping Example}\label{modules_example}\hypertarget{grouping_example}{}
 \subinputfrom{examples/group/latex/}{refman_doc}
 \chapter{Member Groups Example}\label{memgrp_example}\hypertarget{memgrp_example}{}
 \subinputfrom{examples/memgrp/latex/}{refman_doc}

doc/grouping.doc

@@ -1,12 +1,12 @@
 /******************************************************************************
  *
- * 
+ *
  *
  * Copyright (C) 1997-2015 by Dimitri van Heesch.
  *
  * Permission to use, copy, modify, and distribute this software and its
- * documentation under the terms of the GNU General Public License is hereby 
- * granted. No representations are made about the suitability of this software 
+ * documentation under the terms of the GNU General Public License is hereby
+ * granted. No representations are made about the suitability of this software
  * for any purpose. It is provided "as is" without express or implied warranty.
  * See the GNU General Public License for more details.
  *
@@ -16,49 +16,49 @@
  */
 /*! \page grouping Grouping
 
-Doxygen has three mechanisms to group things together. 
+Doxygen has three mechanisms to group things together.
 One mechanism works at a global level, creating a new page
-for each group. These groups are called \ref modules "'modules'" in the documentation.
+for each group. These groups are called \ref topics "'topics'" in the documentation.
 The second mechanism works within a member list of some compound entity,
-and is referred to as a \ref memgroup "'member groups'". 
-For \ref cmdpage "pages" there is a third grouping mechanism referred to 
+and is referred to as a \ref memgroup "'member groups'".
+For \ref cmdpage "pages" there is a third grouping mechanism referred to
 as \ref subpaging "subpaging".
 
-\section modules Modules
+\section topics Topics
 
-Modules are a way to group things together on a separate page. You
-can document a group as a whole, as well as all individual members.
-Members of a group can be files, namespaces, classes, functions,
+Grouping is a way to group things together on a separate page, called a topic.
+You can document a group as a whole, as well as all individual members.
+Members of a group can be files, namespaces, classes, concepts, modules, functions,
 variables, enums, typedefs, and defines, but also other groups.
 
 To define a group, you should put the \ref cmddefgroup "\\defgroup"
-command in a special comment block. The first argument of the command 
-is a label that should uniquely identify the group.  
-The second argument is the name or title of the group as it should appear 
+command in a special comment block. The first argument of the command
+is a label that should uniquely identify the group.
+The second argument is the name or title of the group as it should appear
 in the documentation.
 
-You can make an entity a member of a specific group by putting 
+You can make an entity a member of a specific group by putting
 a \ref cmdingroup "\\ingroup" command inside its documentation block.
 
 To avoid putting \ref cmdingroup "\\ingroup" commands in the documentation
-for each member you can also group members together by the 
-open marker <code>\@{</code> before the group and the 
-closing marker <code>\@}</code> after the group. The markers can 
-be put in the documentation of the group definition or in a separate 
-documentation block. 
+for each member you can also group members together by the
+open marker <code>\@{</code> before the group and the
+closing marker <code>\@}</code> after the group. The markers can
+be put in the documentation of the group definition or in a separate
+documentation block.
 
 Groups themselves can also be nested using these grouping markers.
 
 You will get an error message when you use the same group label more than once.
-If you don't want doxygen to enforce unique labels, then you can 
+If you don't want doxygen to enforce unique labels, then you can
 use \ref cmdaddtogroup "\\addtogroup" instead of
-\ref cmddefgroup "\\defgroup". 
+\ref cmddefgroup "\\defgroup".
 It can be used exactly like \ref cmddefgroup "\\defgroup",
-but when the group has been defined already, then it silently merges the 
+but when the group has been defined already, then it silently merges the
 existing documentation with the new one.
 The title of the group is optional for this command, so you can use
 \verbatim
-/** \addtogroup <label> 
+/** \addtogroup <label>
  *  @{
  */
 ...
@@ -69,19 +69,19 @@ to add additional members to a group that is defined in more detail elsewhere.
 
 Note that compound entities (like classes, files and namespaces) can
 be put into multiple groups, but members (like variable, functions, typedefs
-and enums) can only be a member of one group 
-(this restriction is in place to avoid ambiguous linking targets in case 
+and enums) can only be a member of one group
+(this restriction is in place to avoid ambiguous linking targets in case
 a member is not documented in the context of its class, namespace
 or file, but only visible as part of a group).
 
 Doxygen will put members into the group whose definition has
-the highest "priority": e.g. An explicit \ref cmdingroup "\\ingroup" overrides 
-an implicit grouping definition via <code>\@{</code> <code>\@}</code>. 
-Conflicting grouping definitions with the same priority trigger a warning, 
-unless one definition was for a member without any explicit documentation. 
+the highest "priority": e.g. An explicit \ref cmdingroup "\\ingroup" overrides
+an implicit grouping definition via <code>\@{</code> <code>\@}</code>.
+Conflicting grouping definitions with the same priority trigger a warning,
+unless one definition was for a member without any explicit documentation.
 
-The following example puts VarInA into group A and silently resolves 
-the conflict for IntegerVariable by putting it into group IntVariables, 
+The following example puts VarInA into group A and silently resolves
+the conflict for IntegerVariable by putting it into group IntVariables,
 because the second instance of IntegerVariable
 is undocumented:
 
@@ -119,7 +119,7 @@ int IntegerVariable;
 
 The \ref cmdref "\\ref" command can be used to refer to a group.
 The first argument of the \\ref command should be group's label.
-To use a custom link name, you can put the name of the links in 
+To use a custom link name, you can put the name of the links in
 double quotes after the label, as shown by the following example
 \verbatim
 This is the \ref group_label "link" to this group.
@@ -138,64 +138,64 @@ in .c files without having to duplicate the hierarchy exactly.
 \include group.cpp
 
 \htmlonly
-Click <a href="examples/group/html/modules.html">here</a> 
+Click <a href="examples/group/html/topics.html">here</a>
 for the corresponding HTML documentation that is generated by doxygen.
 \endhtmlonly
 \latexonly
-See \hyperlink{modules_example}{Modules example}
+See \hyperlink{grouping_example}{Grouping example}
 for the corresponding \mbox{\LaTeX} documentation that is generated by doxygen.
 \endlatexonly
 
 \section memgroup Member Groups
 
-If a compound (e.g. a class or file) has many members, it is often 
-desired to group them together. Doxygen already automatically groups 
-things together on type and protection level, but maybe you feel that 
-this is not enough or that that default grouping is wrong. 
-For instance, because you feel that members of different (syntactic) 
+If a compound (e.g. a class or file) has many members, it is often
+desired to group them together. Doxygen already automatically groups
+things together on type and protection level, but maybe you feel that
+this is not enough or that that default grouping is wrong.
+For instance, because you feel that members of different (syntactic)
 types belong to the same (semantic) group.
 
-A member group is defined by 
-a 
+A member group is defined by
+a
 \verbatim
-///@{ 
+///@{
   ...
 ///@}
-\endverbatim 
-block or a 
+\endverbatim
+block or a
 \verbatim
-/**@{*/ 
-  ... 
-/**@}*/ 
-\endverbatim 
-block if you prefer C style 
-comments. Note that the members of the group should be 
+/**@{*/
+  ...
+/**@}*/
+\endverbatim
+block if you prefer C style
+comments. Note that the members of the group should be
 physically inside the member group's body.
 
-Before the opening marker of a block a separate comment block may be 
-placed. This block should contain the \ref cmdname "@@name" 
-(or \ref cmdname "\\name") command and is used to specify the header 
+Before the opening marker of a block a separate comment block may be
+placed. This block should contain the \ref cmdname "@@name"
+(or \ref cmdname "\\name") command and is used to specify the header
 of the group. Optionally, the comment block may also contain more
 detailed information about the group.
 
-Nesting of member groups is not allowed. 
+Nesting of member groups is not allowed.
 
-If all members of a member group inside a class have the same type 
-and protection level (for instance all are static public members), 
-then the whole member group is displayed as a subgroup of 
-the type/protection level group (the group is displayed as a 
-subsection of the "Static Public Members" section for instance). 
-If two or more members have different types, then the group is put 
+If all members of a member group inside a class have the same type
+and protection level (for instance all are static public members),
+then the whole member group is displayed as a subgroup of
+the type/protection level group (the group is displayed as a
+subsection of the "Static Public Members" section for instance).
+If two or more members have different types, then the group is put
 at the same level as the automatically generated groups.
-If you want to force all member-groups of a class to be at the top level, 
+If you want to force all member-groups of a class to be at the top level,
 you should put a \ref cmdnosubgrouping "\\nosubgrouping" command inside the
-documentation of the class. 
+documentation of the class.
 
 \par Example:
 \include memgrp.cpp
 
 \htmlonly
-Click <a href="examples/memgrp/html/class_memgrp___test.html">here</a> 
+Click <a href="examples/memgrp/html/class_memgrp___test.html">here</a>
 for the corresponding HTML documentation that is generated by doxygen.
 \endhtmlonly
 \latexonly
@@ -211,16 +211,16 @@ different protection levels (i.e. public and protected).
 
 Information can be grouped into pages using the \ref cmdpage "\\page" and
 \ref cmdsubpage "\\mainpage" commands. Normally, this results in a
-flat list of pages, where the "main" page is the first in the list. 
+flat list of pages, where the "main" page is the first in the list.
 
 Instead of adding structure using the approach described in section
-\ref modules "modules" it is often more natural and convenient to add 
-additional structure to the pages using the \ref cmdsubpage "\\subpage" 
-command. 
+\ref topics "topics" it is often more natural and convenient to add
+additional structure to the pages using the \ref cmdsubpage "\\subpage"
+command.
 
-For a page A the \\subpage command adds a link to another page B and at 
+For a page A the \\subpage command adds a link to another page B and at
 the same time makes page B a subpage of A. This has the effect of making
-two groups GA and GB, where GB is part of GA, page A is put in group GA, 
+two groups GA and GB, where GB is part of GA, page A is put in group GA,
 and page B is put in group GB.
 
 \htmlonly

src/CMakeLists.txt

@@ -295,6 +295,7 @@ add_library(doxymain STATIC
     memberdef.cpp
     membergroup.cpp
     memberlist.cpp
+    moduledef.cpp
     msc.cpp
     namespacedef.cpp
     outputgen.cpp