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

kjellahl · kjellahl · commit 504c2eca7272 · 2023-07-28T15:41:49.000+02:00
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 #98
diff --git a/configure.ac b/configure.ac
@@ -74,6 +74,8 @@ AS_IF([test "x$enable_benchmark" = xyes],[
 ])
 
 AC_SUBST(MSVC_STATIC_CXXFLAG, '')
+AC_SUBST(DOXYGEN_HAVE_DOT, [YES])
+AM_SUBST_NOTMAKE(DOXYGEN_HAVE_DOT)
 
 AC_CONFIG_FILES([Makefile
                  ${SIGCXX_MODULE_NAME}.pc:sigc++.pc.in
diff --git a/docs/docs/reference/Doxyfile.in b/docs/docs/reference/Doxyfile.in
@@ -296,7 +296,7 @@ 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/docs/reference/meson.build b/docs/docs/reference/meson.build
@@ -3,7 +3,7 @@
 # Input: project_build_root, project_source_root, sigcxx_pcname,
 #        sigcxx_api_version, build_documentation, source_h_files,
 #        hg_ccg_basenames, install_datadir, python3, doc_reference,
-#        can_add_dist_script
+#        can_add_dist_script, dot
 # Output: install_docdir, install_devhelpdir, book_name,
 #         if build_documentation: tag_file
 
@@ -60,6 +60,7 @@ doc_conf_data.set('abs_top_builddir', project_build_root)
 doc_conf_data.set('abs_top_srcdir', project_source_root)
 doc_conf_data.set('SIGCXX_API_VERSION', sigcxx_api_version)
 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
@@ -134,9 +134,14 @@ if maintainer_mode and not mm_common_get.found()
 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_dir = project_source_root / 'untracked' / 'build_scripts'
 doc_reference = script_dir / 'doc-reference.py'
 dist_changelog = script_dir / 'dist-changelog.py'
