Don't leak -g0 to the MSVC compiler on Windows

Workaround #24545

RELNOTES: None
PiperOrigin-RevId: 702651276
Change-Id: Ic2e6f8f215798d202603e1771bd228bcd6b21bed

src/main/starlark/builtins_bzl/common/builtin_exec_platforms.bzl

@@ -16,6 +16,9 @@
 See https://github.com/bazelbuild/bazel/discussions/19213.
 """
 
+# TODO: Remove when get_current_os_name is no longer needed
+load("@_builtins//:common/python/py_internal.bzl", "py_internal")
+
 # The fragments that make up Bazel's exec transition. The fragment() calls in
 # this file fill out this map.
 bazel_fragments = {}
@@ -340,8 +343,9 @@ bazel_fragments["CppOptions"] = fragment(
         "//command_line_option:crosstool_top": settings["//command_line_option:host_crosstool_top"],
         "//command_line_option:compiler": settings["//command_line_option:host_compiler"],
         "//command_line_option:grte_top": settings["//command_line_option:host_grte_top"],
-        "//command_line_option:copt": settings["//command_line_option:host_copt"] + ["-g0"],  # Don't add for Windows
-        "//command_line_option:cxxopt": settings["//command_line_option:host_cxxopt"] + ["-g0"],  # Don't add for Windows
+        # TODO: Properly fix https://github.com/bazelbuild/bazel/issues/24545 with features.
+        "//command_line_option:copt": settings["//command_line_option:host_copt"] + ([] if py_internal.get_current_os_name() == "windows" else ["-g0"]),
+        "//command_line_option:cxxopt": settings["//command_line_option:host_cxxopt"] + ([] if py_internal.get_current_os_name() == "windows" else ["-g0"]),
         "//command_line_option:conlyopt": settings["//command_line_option:host_conlyopt"],
         "//command_line_option:per_file_copt": settings["//command_line_option:host_per_file_copt"],
         "//command_line_option:linkopt": settings["//command_line_option:host_linkopt"],

src/test/py/bazel/bazel_windows_cpp_test.py

@@ -1277,6 +1277,33 @@ def testCompilerSettingMingwGcc(self):
     ])
     self.AssertExitCode(exit_code, 0, stderr)
 
+  def testNoUnknownOptionsLeakedToMSVC(self):
+    # Regression test for https://github.com/bazelbuild/bazel/issues/24545.
+    self.createModuleDotBazel()
+    self.ScratchFile(
+        'BUILD',
+        [
+            'cc_binary(',
+            '    name = "main",',
+            '    srcs = ["main.cc"],',
+            ')',
+            'genrule(',
+            '    name = "gen",',
+            '    cmd = "echo $(location :main) > $@",',
+            '    outs = ["output.txt"],',
+            '    tools = [":main"],',
+            ')',
+        ],
+    )
+    self.ScratchFile('main.cc', ['int main() { return 0; }'])
+
+    exit_code, _, stderr = self.RunBazel([
+        'build',
+        '//...',
+        '--copt=/options:strict',
+        '--host_copt=/options:strict',
+    ])
+    self.AssertExitCode(exit_code, 0, stderr)
 
 if __name__ == '__main__':
   absltest.main()