pw_toolchain: Emit an error when using the default
This change updates the default (dummy) toolchain to emit an error if it
is used to build any source code.
Change-Id: I4bcca9aef1f657c0a5acc367db1b2721d1bac200
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/13683
Reviewed-by: Wyatt Hepler <hepler@google.com>
Reviewed-by: Armando Montanez <amontanez@google.com>
Commit-Queue: Alexei Frolov <frolv@google.com>
diff --git a/pw_toolchain/dummy/BUILD.gn b/pw_toolchain/dummy/BUILD.gn
index f7e6d81..5d4cf74 100644
--- a/pw_toolchain/dummy/BUILD.gn
+++ b/pw_toolchain/dummy/BUILD.gn
@@ -23,4 +23,41 @@
}
description = "stamp {{output}}"
}
+
+ # If the user tries to build a target with the default toolchain, run a script
+ # printing out the error.
+ _bad_toolchain_command = "python " + rebase_path("bad_toolchain.py")
+
+ tool("asm") {
+ command = _bad_toolchain_command
+ outputs =
+ [ "{{source_out_dir}}/{{target_output_name}}.{{source_file_part}}.o" ]
+ }
+
+ tool("cc") {
+ command = _bad_toolchain_command
+ outputs =
+ [ "{{source_out_dir}}/{{target_output_name}}.{{source_file_part}}.o" ]
+ }
+
+ tool("cxx") {
+ command = _bad_toolchain_command
+ outputs =
+ [ "{{source_out_dir}}/{{target_output_name}}.{{source_file_part}}.o" ]
+ }
+
+ tool("link") {
+ command = _bad_toolchain_command
+ outputs = [ "{{output_dir}}/{{target_output_name}}{{output_extension}}" ]
+ }
+
+ tool("alink") {
+ command = _bad_toolchain_command
+ outputs = [ "{{output_dir}}/{{target_output_name}}{{output_extension}}" ]
+ }
+
+ tool("solink") {
+ command = _bad_toolchain_command
+ outputs = [ "{{output_dir}}/{{target_output_name}}{{output_extension}}" ]
+ }
}
diff --git a/pw_toolchain/dummy/bad_toolchain.py b/pw_toolchain/dummy/bad_toolchain.py
new file mode 100644
index 0000000..c87150d
--- /dev/null
+++ b/pw_toolchain/dummy/bad_toolchain.py
@@ -0,0 +1,92 @@
+# Copyright 2020 The Pigweed Authors
+#
+# 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
+#
+# https://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.
+"""Emits an error telling the user not to use the default toolchain."""
+
+import sys
+
+_ERROR_MESSAGE = """
+Error: trying to build a target with the default toolchain
+
+ This occurs when a GN target is listed as a dependency outside of a toolchain
+ group (such as host_clang or stm32f429i) in the root BUILD.gn file.
+
+ Make sure that your top-level targets are always instantiated with a toolchain
+ and that no dependencies are pulled in through the default toolchain.
+
+ group("my_target_wrapper") {
+ deps = [ ":my_target(//path/to/my/toolchain)" ]
+ }
+
+ group("my_target") {
+ deps = []
+ if (current_toolchain != default_toolchain) {
+ deps += [ "//my_application:image" ]
+ }
+ }
+
+ If you are developing in Pigweed itself, list your build target under one of
+ the predefined groups in //BUILD.gn. For example,
+
+ # apps is an existing group intended for building application images.
+ group("apps") {
+ deps = [
+ ...
+ "your_target:here",
+ ]
+ }
+
+ Other predefined groups include host_tools, pw_modules, and pw_module_tests.
+
+ If you want to add a custom group instead of using an existing one, it must be
+ defined alongside the predefined groups, within the toolchain condition block:
+
+ if (current_toolchain != default_toolchain) {
+ group("apps") {
+ ...
+ }
+
+ # Other predefined groups...
+
+ group("my_custom_group") {
+ deps = [ "//path/to:my_target" ]
+ }
+ }
+
+ To include your custom group in the build, add it to the pigweed_default group
+ to have it compile for every supported Pigweed target.
+
+ group("pigweed_default") {
+ deps = []
+
+ if (current_toolchain != default_toolchain) {
+ # Standard Pigweed dependencies...
+
+ # Add your group here.
+ deps += [ ":my_custom_group" ]
+ }
+ }
+
+ For more details on the Pigweed build structure and how to configure custom
+ build targets or toolchains, please refer to "Build system" in the Pigweed
+ documentation.
+"""
+
+
+def main() -> int:
+ print(_ERROR_MESSAGE, file=sys.stderr)
+ return 1
+
+
+if __name__ == '__main__':
+ sys.exit(main())
