diff --git a/test/Analysis/unions.cpp b/test/Analysis/unions.cpp
index 2bffe78..f363ab8 100644
--- a/test/Analysis/unions.cpp
+++ b/test/Analysis/unions.cpp
@@ -1,5 +1,7 @@
-// RUN: %clang_cc1 -analyze -analyzer-checker=core %s -verify
-// expected-no-diagnostics
+// RUN: %clang_cc1 -analyze -analyzer-checker=core,unix.Malloc,debug.ExprInspection %s -verify
+
+extern void clang_analyzer_eval(bool);
+extern "C" char *strdup(const char *s);
 
 namespace PR14054_reduced {
   struct Definition;
@@ -49,3 +51,58 @@
     x = pn->pn_u.name.lexdef->pn_u.name.lexdef;
   }
 }
+
+namespace PR17596 {
+  union IntOrString {
+    int i;
+    char *s;
+  };
+
+  extern void process(IntOrString);
+
+  void test() {
+    IntOrString uu;
+    uu.s = strdup("");
+    process(uu);
+  }
+
+  void testPositive() {
+    IntOrString uu;
+    uu.s = strdup("");
+  } // expected-warning{{leak}}
+
+  void testCopy() {
+    IntOrString uu;
+    uu.i = 4;
+    clang_analyzer_eval(uu.i == 4); // expected-warning{{TRUE}}
+
+    IntOrString vv;
+    vv.i = 5;
+    uu = vv;
+    // FIXME: Should be true.
+    clang_analyzer_eval(uu.i == 5); // expected-warning{{UNKNOWN}}
+  }
+
+  void testInvalidation() {
+    IntOrString uu;
+    uu.s = strdup("");
+
+    IntOrString vv;
+    char str[] = "abc";
+    vv.s = str;
+
+    // FIXME: This is a leak of uu.s.
+    uu = vv;
+  }
+
+  void testIndirectInvalidation() {
+    IntOrString uu;
+    char str[] = "abc";
+    uu.s = str;
+
+    clang_analyzer_eval(uu.s[0] == 'a'); // expected-warning{{TRUE}}
+
+    process(uu);
+    clang_analyzer_eval(uu.s[0] == 'a'); // expected-warning{{UNKNOWN}}
+  }
+}