Merge pull request #79964 from mikeash/fix-varargs-test

[Test] Gate new VarArgs test on new runtime.

Author: mikeash

test/stdlib/VarArgs.swift

@@ -174,14 +174,21 @@ test_varArgs6()
 
 func test_varArgs7() {
 #if canImport(Darwin) && arch(arm64)
-  // Test a workaround for format specifiers and no arguments. We supply eight
-  // words of zeroed memory to give this predictable behavior.
-  my_printf("No parameters: %ld %ld %ld %ld %ld %ld %ld %ld\n")
+  let canTest = if #available(SwiftStdlib 6.2, *) { false } else { true }
 #else
   // va_list is more complicated on other targets so that behavior is not the
-  // same, skip the test by doing a fake print of the expected output.
-  my_printf("No parameters: 0 0 0 0 0 0 0 0\n")
+  // same, skip the test by doing a fake print of the expected output. Also
+  // skip the test if we're testing against an older runtime without the fix.
+  let canTest = false
 #endif
+
+  if canTest {
+    // Test a workaround for format specifiers and no arguments. We supply eight
+    // words of zeroed memory to give this predictable behavior.
+    my_printf("No parameters: %ld %ld %ld %ld %ld %ld %ld %ld\n")
+  } else {
+    my_printf("No parameters: 0 0 0 0 0 0 0 0\n")
+  }
   // CHECK: No parameters: 0 0 0 0 0 0 0 0
 }
 test_varArgs7()