DCL51-CPP: Ignore compiler generated

change_notes/2023-05-02-single-reserved-prefix-generated.md

@@ -0,0 +1 @@
+ * `DCL51-CPP` - `cpp/cert/use-of-single-underscore-reserved-prefix` - remove false positives which were compiler generated, such as the function `_FUN` generated by the compiler for lambdas converted to function pointers.

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

@@ -53,5 +53,8 @@ where
         isGeneratedByUserMacro(d)
       )
     )
-  )
+  ) and
+  // Ignore compiler generated functions and variables
+  not l.(Function).isCompilerGenerated() and
+  not l.(Variable).isCompilerGenerated()
 select l, "Name $@ uses the reserved prefix '_'.", l, s

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

@@ -1,8 +1,8 @@
+#include "test.h"
 #include <cstdint>
+#include <functional>
 #include <string>
 
-#include "test.h"
-
 #undef INT_MAX       // NON_COMPLIANT
 #define SIZE_MAX 256 // NON_COMPLIANT
 
@@ -40,4 +40,12 @@ FD_SET(j); // COMPLIANT - standard library macro
 
 void f() {
   std::string x = __func__; // COMPLIANT
+}
+
+void g(int (*l)(int)) {}
+
+void test_lambda(const int y) {
+  // Lambda generates a static function called `_FUN` when the lambda is
+  // converted to a function pointer
+  g([](int x) { return x; }); // COMPLIANT - compiler generated
 }