libarchive: Backport "parse_date: handle dates in 2038 and beyond"

Backport libarchive commit `2d987e725f` (parse_date: handle dates in
2038 and beyond if time_t is big enough, 2025-09-26).

Add a cmake-specific test case.

Fixes: #27263

Tests/CMakeLib/CMakeLists.txt

@@ -15,6 +15,7 @@ set(CMakeLib_TESTS
   testCTestResourceAllocator.cxx
   testCTestResourceSpec.cxx
   testCTestResourceGroups.cxx
+  testDateTime.cxx
   testDebug.cxx
   testDocumentationFormatter.cxx
   testGccDepfileReader.cxx

Tests/CMakeLib/testDateTime.cxx

@@ -0,0 +1,32 @@
+#include <ctime>
+
+#include "cm_parse_date.h"
+
+#include "testCommon.h"
+
+namespace {
+
+bool parse_date()
+{
+  std::cout << "parse_date()\n";
+  std::time_t now;
+  std::time(&now);
+  {
+    std::time_t t = cm_parse_date(now, "20000101 00:01:02 -0000");
+    ASSERT_EQUAL(t, 946684862);
+  }
+  {
+    std::time_t t = cm_parse_date(now, "20380601 00:01:02 -0000");
+    ASSERT_EQUAL(t, sizeof(time_t) <= 4 ? -1 : 2158963262);
+  }
+  return true;
+}
+
+}
+
+int testDateTime(int /*unused*/, char* /*unused*/[])
+{
+  return runTests({
+    parse_date,
+  });
+}

Utilities/cmlibarchive/libarchive/archive_parse_date.c

@@ -705,9 +705,7 @@ Convert(time_t Month, time_t Day, time_t Year,
 		Year += 1900;
 	DaysInMonth[1] = Year % 4 == 0 && (Year % 100 != 0 || Year % 400 == 0)
 	    ? 29 : 28;
-	/* Checking for 2038 bogusly assumes that time_t is 32 bits.  But
-	   I'm too lazy to try to check for time_t overflow in another way.  */
-	if (Year < EPOCH || Year >= 2038
+	if (Year < EPOCH || (sizeof(time_t) <= 4 && Year >= 2038)
 	    || Month < 1 || Month > 12
 	    /* Lint fluff:  "conversion from long may lose accuracy" */
 	    || Day < 1 || Day > DaysInMonth[(int)--Month]