switch to postorder ordering to first process the external deps

Author: aignas

python/private/attributes.bzl

@@ -260,7 +260,7 @@ The order of this list can matter because it affects the order that information
 from dependencies is merged in, which can be relevant depending on the ordering
 mode of depsets that are merged.
 
-* {obj}`PyInfo.venv_symlinks` uses topological ordering.
+* {obj}`PyInfo.venv_symlinks` uses postorder ordering.
 
 See {obj}`PyInfo` for more information about the ordering of its depsets and
 how its fields are merged.

python/private/py_executable.bzl

@@ -653,7 +653,7 @@ def _create_venv_symlinks(ctx, venv_dir_map):
         # NOTE: Topological ordering is used so that dependencies closer to the
         # binary have precedence in creating their symlinks. This allows the
         # binary a modicum of control over the result.
-        order = "topological",
+        order = "postorder",
         transitive = [
             dep[PyInfo].venv_symlinks
             for dep in ctx.attr.deps
@@ -688,7 +688,7 @@ def _build_link_map(entries):
 
     for entry in entries:
         # We overwrite duplicates by design. The dependency closer to the
-        # binary gets precedence due to the topological ordering.
+        # binary gets precedence due to the postorder ordering.
 
         if entry.package and version_by_pkg.get(entry.package) != entry.version:
             # If we detect that we are adding a different package version, clear the
@@ -704,13 +704,13 @@ def _build_link_map(entries):
 
         if entry.venv_path in kind_map:
             # We ignore duplicates by design. The dependency closer to the
-            # binary gets precedence due to the topological ordering.
+            # binary gets precedence due to the postorder ordering.
             continue
         else:
             kind_map[entry.venv_path] = entry.link_to_path
 
     # An empty link_to value means to not create the site package symlink.
-    # Because of the topological ordering, this allows binaries to remove
+    # Because of the postorder ordering, this allows binaries to remove
     # entries by having an earlier dependency produce empty link_to values.
     for link_map in pkg_link_map.values():
         for kind, kind_map in link_map.items():

python/private/py_info.bzl

@@ -309,13 +309,13 @@ This field is currently unused in Bazel and may go away in the future.
         "venv_symlinks": """
 :type: depset[VenvSymlinkEntry]
 
-A depset with `topological` ordering.
+A depset with `postorder` ordering.
 
 :::{include} /_includes/experimental_api.md
 :::
 
 :::{tip}
-The topological ordering means dependencies earlier and closer to the consumer
+The postorder ordering means dependencies earlier and closer to the consumer
 have precedence. This allows e.g. a binary to add dependencies that override
 values from further way dependencies, such as forcing symlinks to point to
 specific paths or preventing symlinks from being created.
@@ -378,7 +378,7 @@ def _PyInfoBuilder_typedef():
     :::{field} venv_symlinks
     :type: DepsetBuilder[tuple[str | None, str]]
 
-    NOTE: This depset has `topological` order
+    NOTE: This depset has `postorder` order
     :::
     """
 
@@ -419,7 +419,7 @@ def _PyInfoBuilder_new():
         transitive_pyc_files = builders.DepsetBuilder(),
         transitive_pyi_files = builders.DepsetBuilder(),
         transitive_sources = builders.DepsetBuilder(),
-        venv_symlinks = builders.DepsetBuilder(order = "topological"),
+        venv_symlinks = builders.DepsetBuilder(order = "postorder"),
     )
     return self
 

python/private/py_library.bzl

@@ -93,7 +93,7 @@ likely lead to conflicts with other targets that contribute to the namespace.
 
 :::{tip}
 This attributes populates {obj}`PyInfo.venv_symlinks`, which is
-a topologically ordered depset. This means dependencies closer and earlier
+a `postorder` ordered depset. This means dependencies closer and earlier
 to a consumer have precedence. See {obj}`PyInfo.venv_symlinks` for
 more information.
 :::