QL: improve resolution of buildin predicates (and getAQlClass())

Author: erik-krogh

ql/src/codeql_ql/ast/Ast.qll

@@ -213,7 +213,7 @@ class BuiltinPredicate extends PredicateOrBuiltin, TBuiltin {
   override string getAPrimaryQlClass() { result = "BuiltinPredicate" }
 }
 
-private class BuiltinClassless extends BuiltinPredicate, TBuiltinClassless {
+class BuiltinClassless extends BuiltinPredicate, TBuiltinClassless {
   string name;
   string ret;
   string args;
@@ -227,7 +227,7 @@ private class BuiltinClassless extends BuiltinPredicate, TBuiltinClassless {
   override PrimitiveType getParameterType(int i) { result.getName() = getArgType(args, i) }
 }
 
-private class BuiltinMember extends BuiltinPredicate, TBuiltinMember {
+class BuiltinMember extends BuiltinPredicate, TBuiltinMember {
   string name;
   string qual;
   string ret;

ql/src/codeql_ql/ast/internal/Builtins.qll

@@ -44,7 +44,9 @@ predicate isBuiltinMember(string sig) {
       "string string.toLowerCase()", "string string.toUpperCase()", "string string.trim()",
       "int date.daysTo(date)", "int date.getDay()", "int date.getHours()", "int date.getMinutes()",
       "int date.getMonth()", "int date.getSeconds()", "int date.getYear()",
-      "string date.toString()", "string date.toISO()", "string int.toUnicode()"
+      "string date.toString()", "string date.toISO()", "string int.toUnicode()",
+      "string any.getAQlClass()"
+      /* getAQlClass is special , see Predicate.qll*/
     ]
 }
 

ql/src/codeql_ql/ast/internal/Predicate.qll

@@ -110,14 +110,26 @@ private module Cached {
     )
   }
 
+  private predicate resolveBuildinPredicateCall(PredicateCall call, BuiltinClassless pred) {
+    call.getNumberOfArguments() = pred.getArity() and
+    call.getPredicateName() = pred.getName()
+  }
+
   cached
   predicate resolveCall(Call c, PredicateOrBuiltin p) {
     resolvePredicateCall(c, p)
     or
+    not resolvePredicateCall(c, _) and
+    resolveBuildinPredicateCall(c, p)
+    or
     resolveMemberCall(c, p)
     or
     not resolvePredicateCall(c, _) and
     resolveDBRelation(c, p)
+    or
+    // getAQlClass() is special
+    c.(MemberCall).getMemberName() = "getAQlClass" and
+    p.(BuiltinMember).getName() = "getAQlClass"
   }
 }
 

ql/test/printAst/printAst.expected

@@ -196,6 +196,7 @@ nodes
 | file://:0:0:0:0 | exp | semmle.label | [BuiltinPredicate] exp |
 | file://:0:0:0:0 | floor | semmle.label | [BuiltinPredicate] floor |
 | file://:0:0:0:0 | gcd | semmle.label | [BuiltinPredicate] gcd |
+| file://:0:0:0:0 | getAQlClass | semmle.label | [BuiltinPredicate] getAQlClass |
 | file://:0:0:0:0 | getDay | semmle.label | [BuiltinPredicate] getDay |
 | file://:0:0:0:0 | getHours | semmle.label | [BuiltinPredicate] getHours |
 | file://:0:0:0:0 | getMinutes | semmle.label | [BuiltinPredicate] getMinutes |