Add Amazon Linux 2 in PR testing (take 2) (#1326)

Restores the changes from #1322 that were reverted in #1324.

Resolves #1325.

Author: grynspan

.github/workflows/pull_request.yml

@@ -14,6 +14,7 @@ jobs:
     uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@main
     with:
       linux_swift_versions: '["nightly-main", "nightly-6.2"]'
+      linux_os_versions: '["amazonlinux2", "jammy"]'
       windows_swift_versions: '["nightly-main", "nightly-6.2"]'
       enable_macos_checks: true
       macos_exclude_xcode_versions: "[{\"xcode_version\": \"16.2\"}, {\"xcode_version\": \"16.3\"}]"

Sources/Testing/ExitTests/ExitTest.swift

@@ -525,11 +525,11 @@ func callExitTest(
   }
 
   // Plumb the exit test's result through the general expectation machinery.
+  let expression = __Expression(String(describingForTest: expectedExitCondition))
   return __checkValue(
     expectedExitCondition.isApproximatelyEqual(to: result.exitStatus),
     expression: expression,
     expressionWithCapturedRuntimeValues: expression.capturingRuntimeValues(result.exitStatus),
-    mismatchedExitConditionDescription: String(describingForTest: expectedExitCondition),
     comments: comments(),
     isRequired: isRequired,
     sourceLocation: sourceLocation

Sources/Testing/Support/FileHandle.swift

@@ -704,9 +704,9 @@ func setFD_CLOEXEC(_ flag: Bool, onFileDescriptor fd: CInt) throws {
     throw CError(rawValue: swt_errno())
   case let oldValue:
     let newValue = if flag {
-      oldValue & ~FD_CLOEXEC
-    } else {
       oldValue | FD_CLOEXEC
+    } else {
+      oldValue & ~FD_CLOEXEC
     }
     if oldValue == newValue {
       // No need to make a second syscall as nothing has changed.

Tests/TestingTests/ExitTestTests.swift

@@ -14,12 +14,19 @@ private import _TestingInternals
 #if !SWT_NO_EXIT_TESTS
 @Suite("Exit test tests") struct ExitTestTests {
   @Test("Signal names are reported (where supported)") func signalName() {
-    let exitStatus = ExitStatus.signal(SIGABRT)
-#if SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD) || os(OpenBSD) || os(Android)
-    #expect(String(describing: exitStatus) == ".signal(SIGABRT → \(SIGABRT))")
-#else
-    #expect(String(describing: exitStatus) == ".signal(\(SIGABRT))")
+    var hasSignalNames = false
+#if SWT_TARGET_OS_APPLE || os(FreeBSD) || os(OpenBSD) || os(Android)
+    hasSignalNames = true
+#elseif os(Linux) && !SWT_NO_DYNAMIC_LINKING
+    hasSignalNames = (symbol(named: "sigabbrev_np") != nil)
 #endif
+
+    let exitStatus = ExitStatus.signal(SIGABRT)
+    if Bool(hasSignalNames) {
+      #expect(String(describing: exitStatus) == ".signal(SIGABRT → \(SIGABRT))")
+    } else {
+      #expect(String(describing: exitStatus) == ".signal(\(SIGABRT))")
+    }
   }
 
   @Test("Exit tests (passing)") func passing() async {