Require explicit sendable and error on warnings in CI

Motivation:

Now that strict concurrency has been adopted the AHC should avoid
regressing by treating all warnings as errors in CI and by enabling
explicit sendable checking.

Modifications:

- Add the correct flags to enable explicit sendable checking
- Treat warnings as errors in CI

Result:

Stricter CI

Author: glbrntt

.github/workflows/main.yml

@@ -12,11 +12,11 @@ jobs:
         uses: apple/swift-nio/.github/workflows/unit_tests.yml@main
         with:
             linux_5_9_enabled: false
-            linux_5_10_arguments_override: "--explicit-target-dependency-import-check error"
-            linux_6_0_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
-            linux_6_1_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
-            linux_nightly_next_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
-            linux_nightly_main_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+            linux_5_10_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -Xfrontend -Xswiftc -require-explicit-sendable -Xswiftc -warnings-as-errors"
+            linux_6_0_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -Xfrontend -Xswiftc -require-explicit-sendable -Xswiftc -warnings-as-errors"
+            linux_6_1_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -Xfrontend -Xswiftc -require-explicit-sendable -Xswiftc -warnings-as-errors"
+            linux_nightly_next_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -Xfrontend -Xswiftc -require-explicit-sendable"
+            linux_nightly_main_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -Xfrontend -Xswiftc -require-explicit-sendable"
 
     static-sdk:
         name: Static SDK

.github/workflows/pull_request.yml

@@ -15,11 +15,11 @@ jobs:
         uses: apple/swift-nio/.github/workflows/unit_tests.yml@main
         with:
             linux_5_9_enabled: false
-            linux_5_10_arguments_override: "--explicit-target-dependency-import-check error"
-            linux_6_0_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
-            linux_6_1_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
-            linux_nightly_next_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
-            linux_nightly_main_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable"
+            linux_5_10_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -Xfrontend -Xswiftc -require-explicit-sendable -Xswiftc -warnings-as-errors"
+            linux_6_0_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -Xfrontend -Xswiftc -require-explicit-sendable -Xswiftc -warnings-as-errors"
+            linux_6_1_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -Xfrontend -Xswiftc -require-explicit-sendable -Xswiftc -warnings-as-errors"
+            linux_nightly_next_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -Xfrontend -Xswiftc -require-explicit-sendable"
+            linux_nightly_main_arguments_override: "--explicit-target-dependency-import-check error -Xswiftc -Xfrontend -Xswiftc -require-explicit-sendable"
 
     cxx-interop:
         name: Cxx interop