vs: Fix link_whole usage with the vs backend

/WHOLEARCHIVE must go to AdditionalOptions, not AdditionalDependencies
and we must add a project reference to trick msbuild/visual studio into
building a target that is built from only libraries linked in via
/WHOLEARCHIVE.

mesonbuild/backend/backends.py

@@ -155,6 +155,12 @@ class Backend:
             dirname = 'meson-out'
         return dirname
 
+    def get_target_dir_relative_to(self, t, o):
+        '''Get a target dir relative to another target's directory'''
+        target_dir = os.path.join(self.environment.get_build_dir(), self.get_target_dir(t))
+        othert_dir = os.path.join(self.environment.get_build_dir(), self.get_target_dir(o))
+        return os.path.relpath(target_dir, othert_dir)
+
     def get_target_source_dir(self, target):
         dirname = os.path.join(self.build_to_src, self.get_target_dir(target))
         return dirname

mesonbuild/backend/vs2010backend.py

@@ -904,20 +904,26 @@ class Vs2010Backend(backends.Backend):
         # *_winlibs that we want to link to are static mingw64 libraries.
         extra_link_args += compiler.get_option_link_args(self.environment.coredata.compiler_options)
         (additional_libpaths, additional_links, extra_link_args) = self.split_link_args(extra_link_args.to_native())
-        if len(extra_link_args) > 0:
-            extra_link_args.append('%(AdditionalOptions)')
-            ET.SubElement(link, "AdditionalOptions").text = ' '.join(extra_link_args)
-        if len(additional_libpaths) > 0:
-            additional_libpaths.insert(0, '%(AdditionalLibraryDirectories)')
-            ET.SubElement(link, 'AdditionalLibraryDirectories').text = ';'.join(additional_libpaths)
 
         # Add more libraries to be linked if needed
         for t in target.get_dependencies():
             lobj = self.build.targets[t.get_id()]
             linkname = os.path.join(down, self.get_target_filename_for_linking(lobj))
             if t in target.link_whole_targets:
-                linkname = compiler.get_link_whole_for(linkname)[0]
-            additional_links.append(linkname)
+                # /WHOLEARCHIVE:foo must go into AdditionalOptions
+                extra_link_args += compiler.get_link_whole_for(linkname)
+                # To force Visual Studio to build this project even though it
+                # has no sources, we include a reference to the vcxproj file
+                # that builds this target. Technically we should add this only
+                # if the current target has no sources, but it doesn't hurt to
+                # have 'extra' references.
+                trelpath = self.get_target_dir_relative_to(t, target)
+                tvcxproj = os.path.join(trelpath, t.get_id() + '.vcxproj')
+                tid = self.environment.coredata.target_guids[t.get_id()]
+                self.add_project_reference(root, tvcxproj, tid)
+            else:
+                # Other libraries go into AdditionalDependencies
+                additional_links.append(linkname)
         for lib in self.get_custom_target_provided_libraries(target):
             additional_links.append(self.relpath(lib, self.get_target_dir(target)))
         additional_objects = []
@@ -926,6 +932,13 @@ class Vs2010Backend(backends.Backend):
             additional_objects.append(o)
         for o in custom_objs:
             additional_objects.append(o)
+
+        if len(extra_link_args) > 0:
+            extra_link_args.append('%(AdditionalOptions)')
+            ET.SubElement(link, "AdditionalOptions").text = ' '.join(extra_link_args)
+        if len(additional_libpaths) > 0:
+            additional_libpaths.insert(0, '%(AdditionalLibraryDirectories)')
+            ET.SubElement(link, 'AdditionalLibraryDirectories').text = ';'.join(additional_libpaths)
         if len(additional_links) > 0:
             additional_links.append('%(AdditionalDependencies)')
             ET.SubElement(link, 'AdditionalDependencies').text = ';'.join(additional_links)