Replace uses of cfg = "host" with cfg = "exec" (bazelbuild#15922)

This increases the compatibility for builds where host and exec platform
are different (e.g., with remote execution).

Closes bazelbuild#15785.

PiperOrigin-RevId: 461897893
Change-Id: I734ccdd1ae13e7c625cc22c894bc482fe080d70b

Co-authored-by: Yannic Bonenberger <yannic@engflow.com>

site/docs/creating-workers.md

@@ -167,12 +167,13 @@ level of the build, this might be the attribute definition:
 "worker": attr.label(
     default = Label("//work:worker"),
     executable = True,
-    cfg = "host",
+    cfg = "exec",
 )
 ```
 
-`cfg = "host"` indicates that the worker should be built to run on your host
-platform.
+`cfg = "exec"` indicates that the worker should be built to run on your
+execution platform rather than on the target platform (i.e., the worker is used
+as tool during the build).
 
 ### Work action requirements
 

site/docs/skylark/aspects.md

@@ -281,7 +281,7 @@ demonstrates how you could pass in a tool to an aspect:
         '_protoc' : attr.label(
             default = Label('//tools:protoc'),
             executable = True,
-            cfg = "host"
+            cfg = "exec"
         )
     }
 ...

src/embedded_tools.bzl

@@ -35,7 +35,7 @@ embedded_tools = rule(
         "out": attr.output(mandatory = True),
         "tool": attr.label(
             executable = True,
-            cfg = "host",
+            cfg = "exec",
             allow_files = True,
             default = Label("//src:create_embedded_tools_sh"),
         ),

src/main/res/winsdk_toolchain.bzl

@@ -62,7 +62,7 @@ windows_resource_compiler_toolchain = rule(
         "rc_exe": attr.label(
             allow_files = True,
             executable = True,
-            cfg = "host",
+            cfg = "exec",
             doc = "Label of the resource compiler (or a wrapper script)",
         ),
     },

src/test/java/com/google/devtools/build/skydoc/testdata/function_wrap_multiple_lines_test/input.bzl

@@ -47,7 +47,7 @@ dependencies here.
         "Xwatchconversion": attr.bool(default = False, doc = "Don't delete temporary lexers generated from combined grammars."),
         "_tool": attr.label(
             executable = True,
-            cfg = "host",
+            cfg = "exec",
         ),
     },
 )

src/test/java/com/google/devtools/build/skydoc/testdata/misc_apis_test/input.bzl

@@ -44,7 +44,7 @@ A list of dependencies.
             doc = "The location of the tool to use.",
             allow_files = True,
             default = Label("//foo/bar/baz:target"),
-            cfg = "host",
+            cfg = "exec",
             executable = True,
         ),
         "out": attr.output(

src/test/py/bazel/bazel_windows_cpp_test.py

@@ -861,7 +861,7 @@ def testCcCompileWithTreeArtifactAsSource(self):
         '  attrs = {',
         '    "_tool": attr.label(',
         '      executable = True,',
-        '      cfg = "host",',
+        '      cfg = "exec",',
         '      allow_files = True,',
         '      default = Label("//:genccs"),',
         '    )',

src/test/py/bazel/bazel_windows_test.py

@@ -177,7 +177,7 @@ def testRunPowershellInAction(self):
         '        "out": attr.output(mandatory = True),',
         '        "tool": attr.label(',
         '            executable = True,',
-        '            cfg = "host",',
+        '            cfg = "exec",',
         '            allow_files = True,',
         '            default = Label("//:write.bat"),',
         '        ),',

src/test/py/bazel/native_test.bzl

@@ -68,7 +68,7 @@ exe_test = rule(
     attrs = {
         "src": attr.label(
             allow_single_file = True,
-            cfg = "host",
+            cfg = "exec",
             executable = True,
         ),
     },

src/test/shell/bazel/apple/apple_common.sh

@@ -0,0 +1,203 @@
+#!/bin/bash
+#
+# Copyright 2022 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# Common Bash functions to test Apple rules in Bazel.
+#
+
+function make_starlark_apple_binary_rule_in() {
+  local dir="$1"; shift
+
+  # All of the attributes below, except for `stamp`, are required as part of the
+  # implied contract of `apple_common.link_multi_arch_binary` since it asks for
+  # attributes directly from the rule context. As these requirements are changed
+  # from implied attributes to function arguments, they can be removed.
+  cat >> "${dir}/starlark_apple_binary.bzl" <<EOF
+def _starlark_apple_binary_impl(ctx):
+    link_result = apple_common.link_multi_arch_binary(
+        ctx = ctx,
+        stamp = ctx.attr.stamp,
+    )
+    processed_binary = ctx.actions.declare_file(
+        '{}_lipobin'.format(ctx.label.name)
+    )
+    lipo_inputs = [output.binary for output in link_result.outputs]
+    if len(lipo_inputs) > 1:
+        apple_env = {}
+        xcode_config = ctx.attr._xcode_config[apple_common.XcodeVersionConfig]
+        apple_env.update(apple_common.apple_host_system_env(xcode_config))
+        apple_env.update(
+            apple_common.target_apple_env(
+                xcode_config,
+                ctx.fragments.apple.single_arch_platform,
+            ),
+        )
+        args = ctx.actions.args()
+        args.add('-create')
+        args.add_all(lipo_inputs)
+        args.add('-output', processed_binary)
+        ctx.actions.run(
+            arguments = [args],
+            env = apple_env,
+            executable = '/usr/bin/lipo',
+            execution_requirements = xcode_config.execution_info(),
+            inputs = lipo_inputs,
+            outputs = [processed_binary],
+        )
+    else:
+        ctx.actions.symlink(
+            target_file = lipo_inputs[0],
+            output = processed_binary,
+        )
+    return [
+        DefaultInfo(files = depset([processed_binary])),
+        OutputGroupInfo(**link_result.output_groups),
+        link_result.debug_outputs_provider,
+    ]
+
+starlark_apple_binary = rule(
+    attrs = {
+        "_child_configuration_dummy": attr.label(
+            cfg = apple_common.multi_arch_split,
+            default = Label("@bazel_tools//tools/cpp:current_cc_toolchain"),
+        ),
+        "_xcode_config": attr.label(
+            default = configuration_field(
+                fragment = "apple",
+                name = "xcode_config_label",
+            ),
+        ),
+        "_xcrunwrapper": attr.label(
+            cfg = "exec",
+            default = Label("@bazel_tools//tools/objc:xcrunwrapper"),
+            executable = True,
+        ),
+        "binary_type": attr.string(default = "executable"),
+        "bundle_loader": attr.label(),
+        "deps": attr.label_list(
+            cfg = apple_common.multi_arch_split,
+        ),
+        "dylibs": attr.label_list(),
+        "linkopts": attr.string_list(),
+        "minimum_os_version": attr.string(),
+        "platform_type": attr.string(),
+        "stamp": attr.int(default = -1, values = [-1, 0, 1]),
+    },
+    fragments = ["apple", "objc", "cpp"],
+    implementation = _starlark_apple_binary_impl,
+    outputs = {
+        # Provided for compatibility with apple_binary tests only.
+        "lipobin": "%{name}_lipobin",
+    },
+)
+EOF
+}
+
+function make_starlark_apple_static_library_rule_in() {
+  local dir="$1"; shift
+
+  # All of the attributes below are required as part of the implied contract of
+  # `apple_common.link_multi_arch_static_library` since it asks for attributes
+  # directly from the rule context. As these requirements are changed from
+  # implied attributes to function arguments, they can be removed.
+  cat >> "${dir}/starlark_apple_static_library.bzl" <<EOF
+def _starlark_apple_static_library_impl(ctx):
+    if not hasattr(apple_common.platform_type, ctx.attr.platform_type):
+        fail('Unsupported platform type \"{}\"'.format(ctx.attr.platform_type))
+    link_result = apple_common.link_multi_arch_static_library(ctx = ctx)
+    processed_library = ctx.actions.declare_file(
+        '{}_lipo.a'.format(ctx.label.name)
+    )
+    files_to_build = [processed_library]
+    runfiles = ctx.runfiles(
+        files = files_to_build,
+        collect_default = True,
+        collect_data = True,
+    )
+    lipo_inputs = [output.library for output in link_result.outputs]
+    if len(lipo_inputs) > 1:
+        apple_env = {}
+        xcode_config = ctx.attr._xcode_config[apple_common.XcodeVersionConfig]
+        apple_env.update(apple_common.apple_host_system_env(xcode_config))
+        apple_env.update(
+            apple_common.target_apple_env(
+                xcode_config,
+                ctx.fragments.apple.single_arch_platform,
+            ),
+        )
+        args = ctx.actions.args()
+        args.add('-create')
+        args.add_all(lipo_inputs)
+        args.add('-output', processed_library)
+        ctx.actions.run(
+            arguments = [args],
+            env = apple_env,
+            executable = '/usr/bin/lipo',
+            execution_requirements = xcode_config.execution_info(),
+            inputs = lipo_inputs,
+            outputs = [processed_library],
+        )
+    else:
+        ctx.actions.symlink(
+            target_file = lipo_inputs[0],
+            output = processed_library,
+        )
+    providers = [
+        DefaultInfo(files = depset(files_to_build), runfiles = runfiles),
+        link_result.objc,
+        link_result.output_groups,
+    ]
+    return providers
+
+starlark_apple_static_library = rule(
+    _starlark_apple_static_library_impl,
+    attrs = {
+        '_child_configuration_dummy': attr.label(
+            cfg = apple_common.multi_arch_split,
+            default = Label("@bazel_tools//tools/cpp:current_cc_toolchain"),
+        ),
+        '_xcode_config': attr.label(
+            default = configuration_field(
+                fragment = "apple",
+                name = "xcode_config_label",
+            ),
+        ),
+        '_xcrunwrapper': attr.label(
+            executable = True,
+            cfg = 'exec',
+            default = Label("@bazel_tools//tools/objc:xcrunwrapper"),
+        ),
+        'additional_linker_inputs': attr.label_list(
+            allow_files = True,
+        ),
+        'avoid_deps': attr.label_list(
+            cfg = apple_common.multi_arch_split,
+            default = [],
+        ),
+        'deps': attr.label_list(
+            cfg = apple_common.multi_arch_split,
+        ),
+        'linkopts': attr.string_list(),
+        'platform_type': attr.string(),
+        'minimum_os_version': attr.string(),
+    },
+    outputs = {
+        'lipo_archive': '%{name}_lipo.a',
+    },
+    cfg = apple_common.apple_crosstool_transition,
+    fragments = ['apple', 'objc', 'cpp',],
+)
+EOF
+}

src/test/shell/bazel/bazel_rules_test.sh

@@ -583,7 +583,7 @@ out_rule = rule(_out_rule, attrs = {
     "_hello_bin": attr.label(
         default = ":hello_bin",
         executable = True,
-        cfg = "host",
+        cfg = "exec",
     ),
 })
 EOF

src/test/shell/bazel/cc_integration_test.sh

@@ -700,11 +700,11 @@ def _tree_art_impl(ctx):
 tree_art_rule = rule(implementation = _tree_art_impl,
     attrs = {
         "_makes_tree" : attr.label(allow_single_file = True,
-            cfg = "host",
+            cfg = "exec",
             executable = True,
             default = "//${package}:makes_tree_artifacts.sh"),
         "_write" : attr.label(allow_single_file = True,
-            cfg = "host",
+            cfg = "exec",
             executable = True,
             default = "//${package}:write.sh")})