Runtime dependency handling - migrate from none to no_symlink

Summary:
Removing `none` means that each enum option labels its own specific
behaviour. `no_symlink` replaces none.

Reviewed By: JakobDegen

Differential Revision: D96349347

fbshipit-source-id: cedcdfc7fada33306e043e0c304395139986782d

Author: r-barnes

prelude/cxx/cxx_executable.bzl

@@ -1004,7 +1004,11 @@ def _get_shared_library_symlink_deps(
             [d.shared_library_info for d in link_deps] +
             [d.shared_library_info for d in impl_params.extra_link_roots]
         )
+    elif impl_params.runtime_dependency_handling == RuntimeDependencyHandling("no_symlink"):
+        # Do not create a shared library symlink tree alongside the executable.
+        pass
     elif impl_params.runtime_dependency_handling == RuntimeDependencyHandling("symlink"):
+        # Include all transitive runtime shared library deps in a symlink tree.
         for linkable_node in linkable_graph.nodes.traverse():
             if linkable_node.linkable == None:
                 continue
@@ -1013,6 +1017,7 @@ def _get_shared_library_symlink_deps(
             if output_style == LibOutputStyle("shared_lib") and not linkable_node.linkable.stub:
                 shlib_deps.append(merge_shared_libraries(ctx.actions, node = linkable_node.linkable.shared_libs))
     elif impl_params.runtime_dependency_handling == RuntimeDependencyHandling("symlink_single_level_only"):
+        # Include only first-level (direct) runtime shared library deps in a symlink tree.
         for d in link_deps + impl_params.extra_link_roots:
             if d.linkable_graph == None:
                 continue

prelude/cxx/cxx_toolchain_types.bzl

@@ -216,8 +216,6 @@ PicBehavior = enum(
 
 # Additional behavior for how to handle runtime dependencies
 RuntimeDependencyHandling = enum(
-    # Do no additional handling (alias for "no_symlink" - hopefully we can remove this one)
-    "none",
     # Do no additional handling
     "no_symlink",
     # Always include runtime dependencies in a symlink tree, regardless
@@ -338,7 +336,7 @@ def cxx_toolchain_infos(
         objc_compiler_info = None,
         objcxx_compiler_info = None,
         cxx_error_handler = None,
-        runtime_dependency_handling = RuntimeDependencyHandling("none")):
+        runtime_dependency_handling = RuntimeDependencyHandling("no_symlink")):
     """
     Creates the collection of cxx-toolchain Infos for a cxx toolchain.
 

prelude/decls/cxx_common.bzl

@@ -322,9 +322,8 @@ def _version_arg():
 def _runtime_dependency_handling_arg():
     return {
         "runtime_dependency_handling": attrs.option(attrs.enum(RuntimeDependencyHandling), default = None, doc = """
-    Controls how shared library dependencies are handled at runtime. By default the `none` behaviour
-    is used. In the future this behaviour will be named `no_symlink`. Both behaviours opt out of
-    symlink creation. If `symlink` is specified then shared library dependencies with
+    Controls how shared library dependencies are handled at runtime. By default the `no_symlink` behaviour
+    is used, which opts out of symlink creation. If `symlink` is specified then shared library dependencies with
     `preferred_linkage = "shared"` are automatically detected and included in a symlink tree
     alongside the executable. Set to `symlink_single_level_only` to only include first-level runtime
     dependencies in a symlink tree.

prelude/toolchains/cxx.bzl

@@ -225,7 +225,7 @@ def _cxx_toolchain_from_cxx_tools_info(ctx: AnalysisContext, cxx_tools_info: Cxx
             pic_behavior = pic_behavior,
             llvm_link = llvm_link,
             use_dep_files = True,
-            runtime_dependency_handling = RuntimeDependencyHandling("none"),
+            runtime_dependency_handling = RuntimeDependencyHandling("no_symlink"),
         ),
         CxxPlatformInfo(name = target_name),
     ]