meson: sphinx-build

For now, sphinx is run on every invocation of make.  The previous mechanism
using $(wildcard) is not reproducible in Meson and was also brittle; for
example some .rst.inc files were left out.  The next patch will introduce
a Sphinx extension to emit a depfile.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

docs/meson.build

@@ -0,0 +1,68 @@
+SPHINX_ARGS = [config_host['SPHINX_BUILD'],
+               '-Dversion=' + meson.project_version(),
+               '-Drelease=' + config_host['PKGVERSION']]
+
+if get_option('werror')
+  SPHINX_ARGS += [ '-W' ]
+endif
+
+if build_docs
+  configure_file(output: 'index.html',
+                 input: files('index.html.in'),
+                 configuration: {'VERSION': meson.project_version()},
+                 install_dir: config_host['qemu_docdir'])
+  manuals = [ 'devel', 'interop', 'tools', 'specs', 'system', 'user' ]
+  man_pages = {
+    'interop' : {
+        'qemu-ga.8': (have_tools ? 'man8' : ''),
+    },
+    'tools': {
+        'qemu-img.1': (have_tools ? 'man1' : ''),
+        'qemu-nbd.8': (have_tools ? 'man8' : ''),
+        'qemu-trace-stap.1': (config_host.has_key('CONFIG_TRACE_SYSTEMTAP') ? 'man1' : ''),
+        'virtfs-proxy-helper.1': (have_virtfs_proxy_helper ? 'man1' : ''),
+        'virtiofsd.1': (have_virtiofsd ? 'man1' : ''),
+    },
+    'system': {
+        'qemu.1': 'man1',
+        'qemu-block-drivers.7': 'man7',
+        'qemu-cpu-models.7': 'man7'
+    },
+  }
+
+  sphinxdocs = []
+  sphinxmans = []
+  foreach manual : manuals
+    private_dir = meson.current_build_dir() / (manual + '.p')
+    input_dir = meson.current_source_dir() / manual
+    sphinxdocs += custom_target(manual + ' manual',
+                build_always_stale: true,
+                build_by_default: build_docs,
+                output: manual,
+                command: [SPHINX_ARGS, '-b', 'html', '-d', private_dir,
+                          input_dir, meson.current_build_dir() / manual])
+    if build_docs and manual != 'devel'
+      install_subdir(meson.current_build_dir() / manual,
+                     install_dir: config_host['qemu_docdir'])
+    endif
+
+    these_man_pages = []
+    install_dirs = []
+    foreach page, section : man_pages.get(manual, {})
+      these_man_pages += page
+      install_dirs += section == '' ? false : get_option('mandir') / section
+    endforeach
+    if these_man_pages.length() > 0
+      sphinxmans += custom_target(manual + ' man pages',
+                         build_always_stale: true,
+                         build_by_default: build_docs,
+                         output: these_man_pages,
+                         install: build_docs,
+                         install_dir: install_dirs,
+                         command: [SPHINX_ARGS, '-b', 'man', '-d', private_dir,
+                                   input_dir, meson.current_build_dir()])
+    endif
+  endforeach
+  alias_target('sphinxdocs', sphinxdocs)
+  alias_target('man', sphinxmans)
+endif