Fix tagged date on old *OS

.swiftpm/xcode/xcshareddata/xcschemes/KSCrash-Package.xcscheme

@@ -140,15 +140,6 @@
                <Test
                   Identifier = "KSObjC_Tests/testCopyArrayContentsMutable">
                </Test>
-               <Test
-                  Identifier = "KSObjC_Tests/testDateDescription">
-               </Test>
-               <Test
-                  Identifier = "KSObjC_Tests/testDateIsValid">
-               </Test>
-               <Test
-                  Identifier = "KSObjC_Tests/testGetDateContents">
-               </Test>
             </SkippedTests>
          </TestableReference>
          <TestableReference

Sources/KSCrashRecordingCore/KSObjC.c

@@ -398,43 +398,52 @@ static uint64_t decodeExponent(uint64_t exp)
  */
 static CFAbsoluteTime extractTaggedNSDate(const void* const object)
 {
-    #pragma pack(4)
-    union {
-        uintptr_t raw;
-        struct {
-            uint64_t fraction : 52;
-            uint64_t exponent : 7;
-            uint64_t sign : 1;
-            uint64_t unused : 4;
-        } bits;
-    } encodedBits = { .raw = getTaggedPayload(object) };
-
-    if (encodedBits.raw == 0)
-    {
-        return 0.0;
-    }
-    if (encodedBits.raw == UINT64_MAX) 
-    {
-        return -0.0;
-    }
-
-    #pragma pack(4)
-    union {
-        CFAbsoluteTime value;
-        struct {
-            uint64_t fraction : 52;
-            uint64_t exponent : 11;
-            uint64_t sign : 1;
-        } bits;
-    } decodedBits = {
-        .bits = {
-            .fraction = encodedBits.bits.fraction,
-            .exponent = decodeExponent(encodedBits.bits.exponent),
-            .sign = encodedBits.bits.sign
-        }
-    };
+    uintptr_t payload = getTaggedPayload(object);
+
+    if (kCFCoreFoundationVersionNumber > 1600) // https://github.com/apple/llvm-project/blob/5dc9d563e5a6cd2cdd44117697dead98955ccddf/lldb/source/Plugins/Language/ObjC/Cocoa.cpp#L1041
+    {
+        union {
+            uintptr_t raw;
+            struct {
+                uint64_t fraction : 52;
+                uint64_t exponent : 7;
+                uint64_t sign : 1;
+                uint64_t unused : 4;
+            } bits;
+        } encodedBits = { .raw = payload };
+
+        if (encodedBits.raw == 0)
+            return 0.0;
+        if (encodedBits.raw == UINT64_MAX)
+            return -0.0;
+
+        union {
+            CFAbsoluteTime value;
+            struct {
+                uint64_t fraction : 52;
+                uint64_t exponent : 11;
+                uint64_t sign : 1;
+            } bits;
+        } decodedBits = {
+            .bits = {
+                .fraction = encodedBits.bits.fraction,
+                .exponent = decodeExponent(encodedBits.bits.exponent),
+                .sign = encodedBits.bits.sign
+            }
+        };
 
-    return decodedBits.value;
+        return decodedBits.value;
+    }
+    else
+    {
+        // Payload is a 60-bit float. Fortunately we can just cast across from
+        // an integer pointer after shifting out the upper 4 bits.
+        union {
+            CFAbsoluteTime value;
+            uintptr_t raw;
+        } payloadBits = { .raw = payload << 4 };
+        return payloadBits.value;
+    }
 }
 #endif
 /** Get any special class metadata we have about the specified class.