Replace the use of dicts.add(...) with the native operator to union dictionaries (#496)

Cherry-pick:
a849ab4
+ more changes to remove references to `dicts.add`

---------

Co-authored-by: Nicholas Levin <nglevin@google.com>

Author: luispadron

doc/apple_support.md

@@ -46,7 +46,7 @@ maintainers to use:
    Bazel flag. The most common way to retrieve this provider is:
    `ctx.attr._xcode_config[apple_common.XcodeVersionConfig]`.
 
-The returned `dict` can be added to the rule's attributes using Skylib's `dicts.add()` method.
+The returned `dict` can be added to the rule's attributes using a [Starlark dictionary union expression: `|`](https://bazel.build/rules/lib/core/dict).
 
 
 
@@ -140,7 +140,7 @@ apple_support.platform_constraint_attrs()
 
 Returns a dictionary of all known Apple platform constraints that can be resolved.
 
-The returned `dict` can be added to the rule's attributes using Skylib's `dicts.add()` method.
+The returned `dict` can be added to the rule's attributes using a [Starlark dictionary union expression: `|`](https://bazel.build/rules/lib/core/dict).
 
 
 
@@ -166,7 +166,7 @@ following:
 
   * `fragments = ["apple"]`
   * Add the `apple_support.action_required_attrs()` attributes to the `attrs` dictionary. This
-    can be done using the `dicts.add()` method from Skylib.
+    can be done using a [Starlark dictionary union expression: `|`](https://bazel.build/rules/lib/core/dict)
 
 This method registers an action to run on an Apple machine, configuring it to ensure that the
 `DEVELOPER_DIR` and `SDKROOT` environment variables are set.
@@ -226,7 +226,7 @@ the following:
 
   * `fragments = ["apple"]`
   * Add the `apple_support.action_required_attrs()` attributes to the `attrs` dictionary. This
-    can be done using the `dicts.add()` method from Skylib.
+    can be done using a [Starlark dictionary union expression: `|`](https://bazel.build/rules/lib/core/dict).
 
 This method registers an action to run on an Apple machine, configuring it to ensure that the
 `DEVELOPER_DIR` and `SDKROOT` environment variables are set.
@@ -264,7 +264,7 @@ In order to use `apple_support.target_arch_from_rule_ctx()`, you'll need to modi
 definition to add the following:
 
   * Add the `apple_support.platform_constraint_attrs()` attributes to the `attrs` dictionary.
-    This can be done using the `dicts.add()` method from Skylib.
+    This can be done using a [Starlark dictionary union expression: `|`](https://bazel.build/rules/lib/core/dict).
 
 
 **PARAMETERS**
@@ -301,7 +301,7 @@ In order to use `apple_support.target_environment_from_rule_ctx()`, you'll need
 rule definition to add the following:
 
   * Add the `apple_support.platform_constraint_attrs()` attributes to the `attrs` dictionary.
-    This can be done using the `dicts.add()` method from Skylib.
+    This can be done using a [Starlark dictionary union expression: `|`](https://bazel.build/rules/lib/core/dict).
 
 
 **PARAMETERS**
@@ -337,7 +337,7 @@ In order to use `apple_support.target_os_from_rule_ctx()`, you'll need to modify
 definition to add the following:
 
   * Add the `apple_support.platform_constraint_attrs()` attributes to the `attrs` dictionary.
-    This can be done using the `dicts.add()` method from Skylib.
+    This can be done using a [Starlark dictionary union expression: `|`](https://bazel.build/rules/lib/core/dict).
 
 
 **PARAMETERS**

lib/apple_support.bzl

@@ -224,7 +224,8 @@ def _action_required_attrs():
        Bazel flag. The most common way to retrieve this provider is:
        `ctx.attr._xcode_config[apple_common.XcodeVersionConfig]`.
 
-    The returned `dict` can be added to the rule's attributes using Skylib's `dicts.add()` method.
+    The returned `dict` can be added to the rule's attributes using a \
+[Starlark dictionary union expression: `|`](https://bazel.build/rules/lib/core/dict).
 
     Returns:
         A `dict` object containing attributes to be added to rule implementations.
@@ -241,7 +242,8 @@ def _action_required_attrs():
 def _platform_constraint_attrs():
     """Returns a dictionary of all known Apple platform constraints that can be resolved.
 
-    The returned `dict` can be added to the rule's attributes using Skylib's `dicts.add()` method.
+    The returned `dict` can be added to the rule's attributes using a \
+[Starlark dictionary union expression: `|`](https://bazel.build/rules/lib/core/dict).
 
     Returns:
         A `dict` object containing attributes to be added to rule implementations.
@@ -299,7 +301,8 @@ def _run(
 
       * `fragments = ["apple"]`
       * Add the `apple_support.action_required_attrs()` attributes to the `attrs` dictionary. This
-        can be done using the `dicts.add()` method from Skylib.
+        can be done using a \
+[Starlark dictionary union expression: `|`](https://bazel.build/rules/lib/core/dict)
 
     This method registers an action to run on an Apple machine, configuring it to ensure that the
     `DEVELOPER_DIR` and `SDKROOT` environment variables are set.
@@ -426,7 +429,8 @@ def _run_shell(
 
       * `fragments = ["apple"]`
       * Add the `apple_support.action_required_attrs()` attributes to the `attrs` dictionary. This
-        can be done using the `dicts.add()` method from Skylib.
+        can be done using a \
+[Starlark dictionary union expression: `|`](https://bazel.build/rules/lib/core/dict).
 
     This method registers an action to run on an Apple machine, configuring it to ensure that the
     `DEVELOPER_DIR` and `SDKROOT` environment variables are set.
@@ -460,7 +464,8 @@ def _target_arch_from_rule_ctx(
     definition to add the following:
 
       * Add the `apple_support.platform_constraint_attrs()` attributes to the `attrs` dictionary.
-        This can be done using the `dicts.add()` method from Skylib.
+        This can be done using a \
+[Starlark dictionary union expression: `|`](https://bazel.build/rules/lib/core/dict).
 
     Args:
         ctx: The context of the rule that has Apple platform constraint attributes.
@@ -504,7 +509,8 @@ def _target_environment_from_rule_ctx(
     rule definition to add the following:
 
       * Add the `apple_support.platform_constraint_attrs()` attributes to the `attrs` dictionary.
-        This can be done using the `dicts.add()` method from Skylib.
+        This can be done using a \
+[Starlark dictionary union expression: `|`](https://bazel.build/rules/lib/core/dict).
 
     Args:
         ctx: The context of the rule that has Apple platform constraint attributes.
@@ -539,7 +545,8 @@ def _target_os_from_rule_ctx(
     definition to add the following:
 
       * Add the `apple_support.platform_constraint_attrs()` attributes to the `attrs` dictionary.
-        This can be done using the `dicts.add()` method from Skylib.
+        This can be done using a \
+[Starlark dictionary union expression: `|`](https://bazel.build/rules/lib/core/dict).
 
     Args:
         ctx: The context of the rule that has Apple platform constraint attributes.

rules/BUILD

@@ -29,7 +29,6 @@ bzl_library(
         "//lib:apple_support",
         "//lib:lipo",
         "//lib:transitions",
-        "@bazel_skylib//lib:dicts",
     ],
 )
 

rules/private/BUILD

@@ -11,7 +11,6 @@ bzl_library(
     ],
     deps = [
         "//lib:apple_support",
-        "@bazel_skylib//lib:dicts",
     ],
 )
 

rules/private/apple_genrule.bzl

@@ -14,7 +14,6 @@
 
 """Genrule which provides Apple's Xcode environment."""
 
-load("@bazel_skylib//lib:dicts.bzl", "dicts")
 load("//lib:apple_support.bzl", "apple_support")
 
 def _compute_make_variables(
@@ -102,7 +101,7 @@ def _apple_genrule_impl(ctx):
 
 apple_genrule = rule(
     implementation = _apple_genrule_impl,
-    attrs = dicts.add(apple_support.action_required_attrs(), {
+    attrs = apple_support.action_required_attrs() | {
         "cmd": attr.string(
             mandatory = True,
             doc = "The command to run. Subject the variable substitution.",
@@ -141,7 +140,7 @@ action is run.
         "no_sandbox": attr.bool(
             doc = "If the sandbox should be disabled when the action is run.",
         ),
-    }),
+    },
     doc = """\
 Genrule which provides Apple specific environment and make variables.
 

rules/universal_binary.bzl

@@ -14,7 +14,6 @@
 
 """Implementation for macOS universal binary rule."""
 
-load("@bazel_skylib//lib:dicts.bzl", "dicts")
 load("//lib:apple_support.bzl", "apple_support")
 load("//lib:lipo.bzl", "lipo")
 load("//lib:transitions.bzl", "macos_universal_transition")
@@ -61,19 +60,17 @@ def _universal_binary_impl(ctx):
     ]
 
 universal_binary = rule(
-    attrs = dicts.add(
-        apple_support.action_required_attrs(),
-        {
-            "binary": attr.label(
-                cfg = macos_universal_transition,
-                doc = "Target to generate a 'fat' binary from.",
-                mandatory = True,
-            ),
-            "_allowlist_function_transition": attr.label(
-                default = "@bazel_tools//tools/allowlists/function_transition_allowlist",
-            ),
-        },
-    ),
+    attrs = apple_support.action_required_attrs() |
+            {
+                "binary": attr.label(
+                    cfg = macos_universal_transition,
+                    doc = "Target to generate a 'fat' binary from.",
+                    mandatory = True,
+                ),
+                "_allowlist_function_transition": attr.label(
+                    default = "@bazel_tools//tools/allowlists/function_transition_allowlist",
+                ),
+            },
     doc = """
 This rule produces a multi-architecture ("fat") binary targeting Apple macOS
 platforms *regardless* of the architecture of the macOS host platform. The

test/rules/apple_verification_test.bzl

@@ -14,8 +14,6 @@
 
 """Test rule to perform generic bundle verification tests."""
 
-load("@bazel_skylib//lib:dicts.bzl", "dicts")
-
 _supports_visionos = hasattr(apple_common.platform_type, "visionos")
 
 def _transition_impl(_, attr):
@@ -97,10 +95,10 @@ def _apple_verification_test_impl(ctx):
 
     return [
         testing.ExecutionInfo(xcode_config.execution_info()),
-        testing.TestEnvironment(dicts.add(
-            apple_common.apple_host_system_env(xcode_config),
+        testing.TestEnvironment(
+            apple_common.apple_host_system_env(xcode_config) |
             test_env,
-        )),
+        ),
         DefaultInfo(
             executable = output_script,
             runfiles = ctx.runfiles(