Add compiler warnings override test.

[nradakovic]

Add compiler warnings override tests to verify feature warnings order.

[Copilot]

Pull request overview

Adds a new feature-verification regression test intended to ensure user-provided compiler flags (copts → user_compile_flags) take precedence over warning-related toolchain features by virtue of their ordering.

Changes:

• Added a new cc_test target (warning_override_test) and included it in the root feature_verification_tests suite.
• Added documentation describing the new test and updated expected test counts / listings.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

File	Description
tests/feature_verification/warning_override_test.cpp	New test source meant to validate warning-override flag ordering.
tests/feature_verification/BUILD	Adds the new cc_test target with copts + enabled warning feature(s).
tests/BUILD	Adds the new test to feature_verification_tests.
docs/test_suite.md	Documents the new test and updates expected counts/listing.

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

Suppressed comments (4)

tests/feature_verification/warning_override_test.cpp:23

• This test assumes strict_warnings enables -Wshadow (and that -Wno-shadow can override it), but the toolchain templates don’t add -Wshadow as part of minimal_warnings/strict_warnings (e.g. templates/linux/cc_toolchain_flags.bzl.template:100-151). As written, the test is likely to compile regardless of flag ordering, so it won’t catch regressions.

// 1. strict_warnings (implies minimal_warnings which enables -Wall) and 
//    warnings_as_errors are both enabled, making -Wshadow an error
// 2. Code with variable shadowing would trigger an error
// 3. User provides -Wno-shadow via copts (which becomes user_compile_flags)
// 4. The compilation SUCCEEDS because user_compile_flags comes AFTER warning

tests/feature_verification/BUILD:156

• This test’s copts/commentary are based on -Wshadow, but the toolchain warning features don’t currently enable -Wshadow, so the test may never exercise the intended failure mode. Consider switching to a warning that is actually enabled by strict_warnings/-Wall (e.g. unused parameter) and overriding that instead.

# The test enables both strict_warnings and warnings_as_errors (making warnings
# into errors), then provides -Wno-shadow via copts. If the flag ordering is
# correct, the test compiles successfully because user's -Wno-shadow overrides
# the -Wshadow error. If ordering regresses, compilation will fail with a
# -Wshadow error, immediately catching the regression.

docs/test_suite.md:55

• The documentation describes this test as overriding -Wshadow via -Wno-shadow, but the toolchain warning features don’t currently enable -Wshadow, so that scenario is unlikely to be exercised. If the test is updated to override an actually-enabled warning (e.g. -Wunused-parameter via -Wno-unused-parameter), the docs should be updated to match.

   - Regression test verifying user flags (copts) can override enabled warning features
   - Enables both `strict_warnings` and `warnings_as_errors` features (making warnings into errors)
   - Provides conflicting `-Wno-shadow` via copts to override the warning
   - Validates that the flag ordering is correct: user_compile_flags comes after warning features,
     ensuring user flags take precedence. If ordering regresses, compilation will fail with an error.

tests/feature_verification/warning_override_test.cpp:35

• The code currently triggers shadowing, but -Wshadow is not enabled by the toolchain’s warning features, so this is unlikely to produce a warning/error even with warnings_as_errors. Using a warning that is actually enabled by -Wall/-Wextra (e.g. -Wunused-parameter) will make this a reliable ordering regression test across toolchains.

// This function intentionally has variable shadowing, which triggers -Wshadow
// when strict_warnings or all_wall_warnings are enabled. The test provides
// -Wno-shadow via copts, so this should compile successfully if flag ordering
// is correct.