[analyzer][NFC] Prove that we only track the evaluated part of the condition

[Szelethus]

Summary

...because we're working with a BugReporterVisitor, and the non-evaluated part of the condition isn't in the bugpath.

[NoQ]

Just as planned!

[xazax.hun]

More tests are always welcome :)

cfe/trunk/test/Analysis/track-control-dependency-conditions.cpp

void f(int flag) {
   if (flag) // expected-note{{'flag' is not equal to 0}}
             // expected-note@-1{{Taking true branch}}
             // debug-note@-2{{Tracking condition 'flag'}}
     *x = 5; // expected-warning{{Dereference of null pointer}}
             // expected-note@-1{{Dereference of null pointer}}
 }
 
 #undef assert
+
 } // end of namespace dont_track_assertlike_and_conditions
 
 namespace dont_track_assertlike_or_conditions {
 
 extern void __assert_fail(__const char *__assertion, __const char *__file,
                           unsigned int __line, __const char *__function)
     __attribute__((__noreturn__));
 #define assert(expr) \
if (flag) // expected-note{{'flag' is not equal to 0}}
             // expected-note@-1{{Taking true branch}}
             // debug-note@-2{{Tracking condition 'flag'}}
     *x = 5; // expected-warning{{Dereference of null pointer}}
             // expected-note@-1{{Dereference of null pointer}}
 }
 
 #undef assert
 } // end of namespace dont_track_assert2like_or_conditions
+
+namespace only_track_the_evaluated_condition {
+
+bool coin();
+
+void bar(int &flag) {
+  flag = coin(); // tracking-note{{Value assigned to 'flag'}}
+}
+
+void bar2(int &flag2) {
+  flag2 = coin();
+}
+
+void f(int *x) {
+  if (x) // expected-note{{Assuming 'x' is null}}
+         // debug-note@-1{{Tracking condition 'x'}}
+         // expected-note@-2{{Taking false branch}}
+    return;
+
+  int flag, flag2;
+  bar(flag); // tracking-note{{Calling 'bar'}}
+             // tracking-note@-1{{Returning from 'bar'}}
+  bar2(flag2);
+
+  if (flag && flag2) // expected-note   {{Assuming 'flag' is 0}}
+                     // expected-note@-1{{Left side of '&&' is false}}
+                     // debug-note@-2{{Tracking condition 'flag'}}
+    return;
+
+  *x = 5; // expected-warning{{Dereference of null pointer}}
+          // expected-note@-1{{Dereference of null pointer}}
+}
+
+} // end of namespace only_track_the_evaluated_condition