SERVER-49761 Added libdeps rule for leaf node no dependencies

Author: dmoody256

site_scons/libdeps.py

@@ -179,15 +179,19 @@ def _raise_libdep_lint_exception(self, message):
         else:
             raise LibdepLinterError(message)
 
-    def _check_for_lint_tags(self, lint_tag, env=None):
+    def _check_for_lint_tags(self, lint_tag, env=None, inclusive_tag=False):
         """
         Used to get the lint tag from the environment,
         and if printing instead of raising exceptions,
         will ignore the tags.
         """
 
-        # ignore LIBDEP_TAGS if printing was selected
-        if self.__class__.print_linter_errors:
+        # If print mode is on, we want to make sure to bypass checking
+        # exclusive tags so we can make sure the exceptions are not excluded
+        # and are printed. If it's an inclusive tag, we want to ignore this
+        # early return completely, because we want to make sure the node
+        # gets included for checking, and the exception gets printed.
+        if not inclusive_tag and self.__class__.print_linter_errors:
             return False
 
         target_env = env if env else self.env
@@ -202,6 +206,29 @@ def _get_deps_dependents(self, env=None):
         deps_dependents += target_env.get(Constants.ProgdepsDependents, [])
         return deps_dependents
 
+    @linter_rule
+    def linter_rule_leaf_node_no_deps(self, libdep):
+        """
+        LIBDEP RULE:
+            Nodes marked explicitly as a leaf node should not have any dependencies,
+            unless those dependencies are explicitly marked as allowed as leaf node
+            dependencies.
+        """
+        if not self._check_for_lint_tags('lint-leaf-node-no-deps', inclusive_tag=True):
+            return
+
+        # Ignore dependencies that explicitly exempt themselves.
+        if self._check_for_lint_tags('lint-leaf-node-allowed-dep', libdep.target_node.env):
+            return
+
+        target_type = self.target[0].builder.get_name(self.env)
+        lib = os.path.basename(str(libdep))
+        self._raise_libdep_lint_exception(
+            textwrap.dedent(f"""\
+                {target_type} '{self.target[0]}' has dependency '{lib}' and is marked explicitly as a leaf node,
+                and '{lib}' does not exempt itself as an exception to the rule."""
+            ))
+
     @linter_rule
     def linter_rule_no_dups(self, libdep):
         """

src/mongo/util/SConscript

@@ -71,8 +71,10 @@ env.Library(
     source=[
         'boost_assert_shim.cpp'
     ],
-    # NOTE: This library *must not* depend on any mongodb code
-    LIBDEPS=[],
+    LIBDEPS_TAGS=[
+        # NOTE: This library *must not* depend on any mongodb code
+        'lint-leaf-node-no-deps',
+    ],
 )
 
 env.SConscript(

src/third_party/SConscript

@@ -543,6 +543,13 @@ gperftoolsEnv.Library(
         "shim_allocator.cpp",
     ],
     DISABLE_ALLOCATOR_SHIM_INJECTION=True,
+    LIBDEPS_TAGS=[
+        # The shim allocator must be linked to every node, including what would
+        # be considered a leaf node to ensure the system allocator
+        # is not linked in before tcmalloc. This tag allows nodes tagged as
+        # leaf nodes to still get the correct allocator.
+        'lint-leaf-node-allowed-dep'
+    ],
 )