Merge pull request #1615 from geoffw0/exprowninit

CPP: Test + workaround for UseInOwnInitializer.ql

change-notes/1.22/analysis-cpp.md

@@ -17,6 +17,7 @@
 | No space for zero terminator (`cpp/no-space-for-terminator`) | Fewer false positive results | False positives involving strings that are not null-terminated have been excluded. |
 | Suspicious pointer scaling (`cpp/suspicious-pointer-scaling`) | Lower precision | The precision of this query has been reduced to "medium". This coding pattern is used intentionally and safely in a number of real-world projects. Results are no longer displayed on LGTM unless you choose to display them. |
 | Non-constant format string (`cpp/non-constant-format`) | Fewer false positive results | Rewritten using the taint-tracking library. |
+| Variable used in its own initializer (`cpp/use-in-own-initializer`) | Fewer false positive results | False positives for constant variables with the same name in different namespaces have been removed. |
 
 ## Changes to QL libraries
 

cpp/ql/src/Likely Bugs/UseInOwnInitializer.ql

@@ -32,6 +32,7 @@ where va.initializesItself(v, init)
     exists (CrementOperation crement | crement.getAnOperand() = va)
   )
   and not va.isUnevaluated()
+  and not v.isConst()
   and not (
     va.getParent() = init and
     exists(MacroInvocation mi |

cpp/ql/test/query-tests/Likely Bugs/UseInOwnInitializer/test.cpp

@@ -66,3 +66,26 @@ void test11() {
 void test12() {
 	self_initialize(int, x); // GOOD (statement is from a macro)
 }
+
+namespace ns1
+{
+	const int v2 = 1;
+	const int v4 = 1;
+	const int v6 = 1;
+};
+
+namespace ns2
+{
+	const int v1 = ns1::v2; // GOOD
+	const int v2 = ns1::v2; // GOOD [produces INVALID_KEY trap warning]
+};
+
+const int v3 = ns1::v4; // GOOD
+const int v4 = ns1::v4; // GOOD
+
+namespace ns3
+{
+	const int v5 = ns1::v6 + 1; // GOOD
+	const int v6 = ns1::v6 + 1; // GOOD  [produces INVALID_KEY trap warning]
+	const int v7 = ns3::v7; // BAD [NOT DETECTED]
+};