twister: add an option to force a toolchain variant for a platform

Using --force-platform-toolchain native_sim/native:llvm will force
building native_sim tests with llvm while everything else is built with
whatever variant was set in the environment.

This option can be provided multiple times for multiple platforms and
toolchain variants.

Signed-off-by: Anas Nashif <[email protected]>

Author: nashif

scripts/pylib/twister/twisterlib/environment.py

@@ -421,6 +421,10 @@ def add_parse_arguments(parser = None) -> argparse.ArgumentParser:
                         help="Do not filter based on toolchain, use the set "
                              " toolchain unconditionally")
 
+    parser.add_argument("--force-platform-toolchain", action="append",
+                        help="Force a toolchain variant for a platform in the form of <platform>:<toolchain variant>. "
+                             "(Can be specified multiple time)")
+
     parser.add_argument("--gcov-tool", type=Path, default=None,
                         help="Path to the gcov tool to use for code coverage "
                              "reports")

scripts/pylib/twister/twisterlib/runner.py

@@ -616,8 +616,13 @@ def run_cmake(self, args="", filter_stages=[]):
             f'-D{warning_command}={warnings_as_errors}',
             f'-DEXTRA_GEN_EDT_ARGS={gen_edt_args}',
             f'-G{self.env.generator}',
-            f'-DPython3_EXECUTABLE={pathlib.Path(sys.executable).as_posix()}'
+            f'-DPython3_EXECUTABLE={pathlib.Path(sys.executable).as_posix()}',
         ]
+        if self.env.options.force_platform_toolchain:
+            for e in self.env.options.force_platform_toolchain:
+                platform, variant = e.split(":")
+                if platform and variant and self.platform.name == platform:
+                    cmake_args.append(f'-DZEPHYR_TOOLCHAIN_VARIANT={variant}')
 
         # If needed, run CMake using the package_helper script first, to only run
         # a subset of all cmake modules. This output will be used to filter