Meson build: Don't require the 'dot' command

kjellahl · kjellahl · commit 771ad1bbd120 · 2024-01-09T10:45:27.000+01:00
Make it possible to build documentation without the dot command. Set the HAVE_DOT option in Doxyfile during configuration. In Autotools builds it's still unconditionally YES. The inheritance diagrams don't look as nice without the dot command from the GraphViz package. See libsigcplusplus/libsigcplusplus#98
diff --git a/configure.ac b/configure.ac
@@ -37,6 +37,8 @@ LT_INIT([dlopen win32-dll disable-static])
 AC_SUBST([LIBXMLXX_MODULES], ['libxml-2.0 >= 2.7.7 glibmm-2.4 >= 2.32.0'])
 AC_SUBST([LIBXML2_LIB_NO_PKGCONFIG], [''])
 AC_SUBST([MSVC_TOOLSET_VER], [''])
+AC_SUBST(DOXYGEN_HAVE_DOT, [YES])
+AM_SUBST_NOTMAKE(DOXYGEN_HAVE_DOT)
 PKG_CHECK_MODULES([LIBXMLXX], [$LIBXMLXX_MODULES])
 
 AC_LANG([C++])
diff --git a/docs/reference/Doxyfile.in b/docs/reference/Doxyfile.in
@@ -313,7 +313,7 @@ EXTERNAL_PAGES         = YES
 #---------------------------------------------------------------------------
 DIA_PATH               =
 HIDE_UNDOC_RELATIONS   = NO
-HAVE_DOT               = YES
+HAVE_DOT               = @DOXYGEN_HAVE_DOT@
 DOT_NUM_THREADS        = 0
 DOT_FONTNAME           = Sans
 DOT_FONTSIZE           = 10
diff --git a/docs/reference/meson.build b/docs/reference/meson.build
@@ -2,7 +2,7 @@
 
 # Input: project_build_root, project_source_root, xmlxx_pcname,
 #        xmlxx_api_version, build_documentation, source_h_files,
-#        install_datadir, python3, doc_reference_py, can_add_dist_script
+#        install_datadir, python3, doc_reference_py, can_add_dist_script, dot
 # Output: install_docdir, install_devhelpdir, book_name,
 #         if build_documentation: tag_file
 
@@ -61,6 +61,7 @@ doc_conf_data.set('abs_top_builddir', project_build_root)
 doc_conf_data.set('abs_top_srcdir', project_source_root)
 doc_conf_data.set('LIBXMLXX_MODULE_NAME', book_name)
 doc_conf_data.set('DOXYGEN_TAGFILES', doxygen_tagfiles)
+doc_conf_data.set('DOXYGEN_HAVE_DOT', dot.found() ? 'YES' : 'NO')
 
 doxyfile = configure_file(
   input: 'Doxyfile.in',
diff --git a/meson.build b/meson.build
@@ -225,9 +225,14 @@ if maintainer_mode and not mm_common_get.found()
   mm_common_get = find_program('mm-common-get', required: true)
 endif
 doxygen = find_program('doxygen', required: build_documentation)
-dot = find_program('dot', required: build_documentation) # Used by Doxygen
+dot = find_program('dot', required: false) # Used by Doxygen, if found
 xsltproc = find_program('xsltproc', required: build_documentation)
 
+if build_documentation and not dot.found()
+  message('The \'dot\' command is not found.\n  ' + \
+          'This will affect the look of the inheritance diagrams in the documentation.')
+endif
+
 # Script files copied to 'untracked/' by mm-common-get.
 script_dir = project_source_root / 'untracked' / 'build_scripts'
 doc_reference_py = script_dir / 'doc-reference.py'
