Fix FP for issue 215

Author: knewbury01

cpp/cert/src/rules/DCL51-CPP/UseOfDoubleUnderscoreReservedPrefix.ql

@@ -33,6 +33,8 @@ predicate isGeneratedByUserMacro(Declaration d) {
 from Locatable l, string s
 where
   not isExcluded(l, NamingPackage::useOfDoubleUnderscoreReservedPrefixQuery()) and
+  //exclude uses of __func__, which are modelled as LocalVariable declarations
+  not(l.(LocalVariable).getName() = "__func__") and
   (
     exists(Macro m | l = m and isReservedMacroPrefix(m) and s = m.getName())
     or
@@ -47,4 +49,4 @@ where
       )
     )
   )
-select l, "Name $@ uses the reserved prefix '__'.", l, s
+select l, "Name $@ uses the reserved prefix '__'.", l, s

cpp/cert/test/rules/DCL51-CPP/UseOfDoubleUnderscoreReservedPrefix.expected

@@ -1,2 +1,2 @@
-| test.cpp:24:5:24:7 | __x | Name $@ uses the reserved prefix '__'. | test.cpp:24:5:24:7 | __x | __x |
-| test.cpp:29:5:29:7 | __x | Name $@ uses the reserved prefix '__'. | test.cpp:29:5:29:7 | __x | __x |
+| test.cpp:25:5:25:7 | __x | Name $@ uses the reserved prefix '__'. | test.cpp:25:5:25:7 | __x | __x |
+| test.cpp:30:5:30:7 | __x | Name $@ uses the reserved prefix '__'. | test.cpp:30:5:30:7 | __x | __x |

cpp/cert/test/rules/DCL51-CPP/test.cpp

@@ -1,4 +1,5 @@
 #include <cstdint>
+#include <string>
 
 #include "test.h"
 
@@ -35,4 +36,8 @@ F(i); // NON_COMPLIANT - user macro
 
 #define FD_SET(X)                                                              \
   int _##X // NON_COMPLIANT - redefinition of standard library macro
-FD_SET(j); // COMPLIANT - standard library macro
+FD_SET(j); // COMPLIANT - standard library macro
+
+void f() {
+  std::string x = __func__; // COMPLIANT
+}