Add malloc attribute to swift_binary.

RELNOTES: Like `cc_{binary,test}`, `swift_{binary,test}` now supports a `malloc` attribute that lets the user substitute an alternate `malloc` implementation to be linked into the binary.
PiperOrigin-RevId: 244659591

swift/internal/deps.bzl

@@ -39,6 +39,16 @@ def collect_link_libraries(target):
 
     if SwiftCcLibsInfo in target:
         depsets.append(target[SwiftCcLibsInfo].libraries)
+    elif CcInfo in target:
+        # TODO(b/124371696): This edge case occurs for the "malloc" target of binaries, which is
+        # passed directly to the link action and does not pass through swift_cc_libs_aspect. This
+        # can be removed when all linking logic is consolidated into `CcInfo`.
+        linking_context = target[CcInfo].linking_context
+        for library in linking_context.libraries_to_link:
+            if library.pic_static_library:
+                depsets.append(depset(direct = [library.pic_static_library]))
+            elif library.static_library:
+                depsets.append(depset(direct = [library.static_library]))
 
     return [depset(transitive = depsets, order = "topological")]
 

swift/internal/swift_binary_test.bzl

@@ -25,6 +25,34 @@ load(":providers.bzl", "SwiftToolchainInfo")
 load(":swift_c_module_aspect.bzl", "swift_c_module_aspect")
 load(":utils.bzl", "expand_locations")
 
+# Attributes common to both `swift_binary` and `swift_test`.
+_BINARY_RULE_ATTRS = dicts.add(
+    swift_common.compilation_attrs(additional_deps_aspects = [swift_c_module_aspect]),
+    {
+        "linkopts": attr.string_list(
+            doc = """
+Additional linker options that should be passed to `clang`. These strings are subject to
+`$(location ...)` expansion.
+""",
+            mandatory = False,
+        ),
+        "malloc": attr.label(
+            default = Label("@bazel_tools//tools/cpp:malloc"),
+            doc = """
+Override the default dependency on `malloc`.
+
+By default, Swift binaries are linked against `@bazel_tools//tools/cpp:malloc"`, which is an empty
+library and the resulting binary will use libc's `malloc`. This label must refer to a `cc_library`
+rule.
+""",
+            mandatory = False,
+            providers = [[CcInfo]],
+        ),
+        # Do not add references; temporary attribute for C++ toolchain Skylark migration.
+        "_cc_toolchain": attr.label(default = Label("@bazel_tools//tools/cpp:current_cc_toolchain")),
+    },
+)
+
 def _configure_features_for_binary(ctx, requested_features = [], unsupported_features = []):
     """Creates and returns the feature configuration for binary linking.
 
@@ -151,11 +179,15 @@ def _swift_linking_rule_impl(
     )
     link_args.add_all(link_cpp_toolchain_flags)
 
+    deps_to_link = ctx.attr.deps + toolchain.implicit_deps
+    if ctx.attr.malloc:
+        deps_to_link.append(ctx.attr.malloc)
+
     register_link_action(
         actions = ctx.actions,
         action_environment = toolchain.action_environment,
         clang_executable = toolchain.clang_executable,
-        deps = ctx.attr.deps + toolchain.implicit_deps,
+        deps = deps_to_link,
         expanded_linkopts = linkopts,
         inputs = additional_inputs_to_linker,
         mnemonic = "SwiftLinkExecutable",
@@ -295,20 +327,7 @@ def _swift_test_impl(ctx):
     ]
 
 swift_binary = rule(
-    attrs = dicts.add(
-        swift_common.compilation_attrs(additional_deps_aspects = [swift_c_module_aspect]),
-        {
-            "linkopts": attr.string_list(
-                doc = """
-Additional linker options that should be passed to `clang`. These strings are subject to
-`$(location ...)` expansion.
-""",
-                mandatory = False,
-            ),
-            # Do not add references; temporary attribute for C++ toolchain Skylark migration.
-            "_cc_toolchain": attr.label(default = Label("@bazel_tools//tools/cpp:current_cc_toolchain")),
-        },
-    ),
+    attrs = _BINARY_RULE_ATTRS,
     doc = """
 Compiles and links Swift code into an executable binary.
 
@@ -335,21 +354,12 @@ instead of `swift_binary`.
 
 swift_test = rule(
     attrs = dicts.add(
-        swift_common.compilation_attrs(additional_deps_aspects = [swift_c_module_aspect]),
+        _BINARY_RULE_ATTRS,
         {
-            "linkopts": attr.string_list(
-                doc = """
-Additional linker options that should be passed to `clang`. These strings are subject to
-`$(location ...)` expansion.
-""",
-                mandatory = False,
-            ),
             "_apple_coverage_support": attr.label(
                 cfg = "host",
                 default = Label("@build_bazel_apple_support//tools:coverage_support"),
             ),
-            # Do not add references; temporary attribute for C++ toolchain Skylark migration.
-            "_cc_toolchain": attr.label(default = Label("@bazel_tools//tools/cpp:current_cc_toolchain")),
             "_xctest_runner_template": attr.label(
                 allow_single_file = True,
                 default = Label(