Exclude identifiers generated from library macros

Library macros are not under user control

Author: lcartey

c/common/test/rules/declaredareservedidentifier/test.c

@@ -169,3 +169,10 @@ tss_delete(        // COMPLIANT - threads.h not included, not external linkage
 struct thrd_yield { // COMPLIANT - threads.h not included
   int thrd_exit;    // COMPLIANT - threads.h not included
 };
+
+#include <sys/select.h>
+void test_macro() {
+  fd_set test_set;
+  FD_ZERO(&test_set); // COMPLIANT - macro expands to variables with `__`
+                      // prefixes, but should be excluded
+}

cpp/common/src/codingstandards/cpp/rules/declaredareservedidentifier/DeclaredAReservedIdentifier.qll

@@ -138,6 +138,19 @@ predicate isCIdentifier(
   )
 }
 
+Macro getGeneratedFrom(Element e) {
+  isCIdentifier(e, _, _, _, _) and
+  exists(MacroInvocation mi |
+    mi = result.getAnInvocation() and
+    mi.getAGeneratedElement() = e and
+    mi.getLocation().getStartColumn() = e.getLocation().getStartColumn() and
+    not exists(MacroInvocation child |
+      child.getParentInvocation() = mi and
+      child.getAGeneratedElement() = e
+    )
+  )
+}
+
 module TargetedCLibrary = CStandardLibrary::C11;
 
 query predicate problems(Element m, string message) {
@@ -146,6 +159,8 @@ query predicate problems(Element m, string message) {
     string name, Scope scope, CNameSpace cNameSpace, string reason, string identifierDescription
   |
     isCIdentifier(m, name, scope, cNameSpace, identifierDescription) and
+    // Exclude cases generated from library macros, because the user does not control them
+    not getGeneratedFrom(m) instanceof LibraryMacro and
     message = identifierDescription + " '" + name + "' " + reason + "."
   |
     // C11 7.1.3/1