Try CI flags

.bazelci/presubmit.yml

@@ -12,6 +12,9 @@ tasks:
     bazel: 6.5.0 # test minimum supported version of bazel
     build_targets:
       - "//..."
+    build_flags:
+      - "--per_file_copt=external/.*@-w"
+      - "--host_per_file_copt=external/.*@-w"
     test_targets:
       - "//..."
       # Nogo includes/excludes doesn't work before bazel 7
@@ -21,6 +24,9 @@ tasks:
       - "-//tests/runfiles:runfiles_test"
       # TODO: Investigate why this fails.
       - "-//tests/core/starlark/cgo:missing_cc_toolchain_explicit_pure_off_test"
+    test_flags:
+      - "--per_file_copt=external/.*@-w"
+      - "--host_per_file_copt=external/.*@-w"
   ubuntu2004:
     # enable some unflipped incompatible flags on this platform to ensure we don't regress.
     build_flags:

.bazelrc

@@ -6,9 +6,6 @@ common --enable_platform_specific_config
 common --noexperimental_enable_bzlmod
 test --test_output=errors
 
-# Disable warnings in external code.
-build --per_file_copt=external/.*@-w
-
 # Go requires a C toolchain that accepts options and emits errors like
 # gcc or clang. The Go SDK does not support MSVC.
 build:windows --cpu=x64_windows