resolve calls to db relations

ql/src/codeql_ql/ast/Ast.qll

@@ -232,6 +232,45 @@ class Predicate extends TPredicate, AstNode, Declaration {
   override string getAPrimaryQlClass() { result = "Predicate" }
 }
 
+/**
+ * A relation in the database.
+ */
+class Relation extends TDBRelation, AstNode, Declaration {
+  Generated::DbTable table;
+
+  Relation() { this = TDBRelation(table) }
+
+  /**
+   * Gets the name of the relation.
+   */
+  override string getName() { result = table.getTableName().getChild().getValue() }
+
+  private Generated::DbColumn getColumn(int i) {
+    result =
+      rank[i + 1](Generated::DbColumn column, int child |
+        table.getChild(child) = column
+      |
+        column order by child
+      )
+  }
+
+  /** Gets the `i`th parameter name */
+  string getParameterName(int i) { result = getColumn(i).getColName().getValue() }
+
+  /** Gets the `i`th parameter type */
+  string getParameterType(int i) {
+    // TODO: This is just using the name of the type, not the actual type. Checkout Type.qll
+    result = getColumn(i).getColType().getChild().(Generated::Token).getValue()
+  }
+
+  /**
+   * Gets the number of parameters.
+   */
+  int getArity() { result = count(getColumn(_)) }
+
+  override string getAPrimaryQlClass() { result = "Relation" }
+}
+
 /**
  * An expression that refers to a predicate, e.g. `BasicBlock::succ/2`.
  */
@@ -2154,9 +2193,6 @@ module YAML {
     /** Gets the version of this qlpack */
     string getVersion() { result = getProperty("version") }
 
-    /** Gets the database scheme of this qlpack */
-    string getDbScheme() { result = getProperty("dbscheme") }
-
     /** Gets the extractor of this qlpack */
     string getExtractor() { result = getProperty("extractor") }
 
@@ -2190,6 +2226,19 @@ module YAML {
       )
     }
 
+    /** Gets the database scheme of this qlpack */
+    File getDBScheme() {
+      result.getBaseName() = getProperty("dbscheme") and
+      result = file.getParentContainer().getFile(any(string s | s.matches("%.dbscheme")))
+    }
+
+    pragma[noinline]
+    Container getAFileInPack() {
+      result.getParentContainer() = file.getParentContainer()
+      or
+      result = getAFileInPack().(Folder).getAChildContainer()
+    }
+
     /**
      * Gets a QLPack that this QLPack depends on.
      */

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

@@ -10,6 +10,7 @@ newtype TAstNode =
   TClass(Generated::Dataclass dc) or
   TCharPred(Generated::Charpred pred) or
   TClassPredicate(Generated::MemberPredicate pred) or
+  TDBRelation(Generated::DbTable table) or
   TSelect(Generated::Select sel) or
   TModule(Generated::Module mod) or
   TNewType(Generated::Datatype dt) or
@@ -153,6 +154,8 @@ Generated::AstNode toGenerated(AST::AstNode n) {
   or
   n = TClassPredicate(result)
   or
+  n = TDBRelation(result)
+  or
   n = TSelect(result)
   or
   n = TModule(result)
@@ -184,7 +187,7 @@ Generated::AstNode toGenerated(AST::AstNode n) {
   n = TSuper(result)
 }
 
-class TPredicate = TCharPred or TClasslessPredicate or TClassPredicate;
+class TPredicate = TCharPred or TClasslessPredicate or TClassPredicate or TDBRelation;
 
 class TModuleMember = TModuleDeclaration or TImport or TSelect or TQLDoc;
 

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

@@ -88,11 +88,37 @@ private module Cached {
     )
   }
 
+  pragma[noinline]
+  private predicate candidate(Relation rel, PredicateCall pc) {
+    rel.getName() = pc.getPredicateName()
+  }
+
+  private predicate resolveDBRelation(PredicateCall pc, DefinedPredicate p) {
+    exists(Relation rel | p = TPred(rel) |
+      candidate(rel, pc) and
+      rel.getArity() = pc.getNumberOfArguments() and
+      (
+        exists(YAML::QLPack libPack, YAML::QLPack qlPack |
+          rel.getLocation().getFile() = libPack.getDBScheme() and
+          qlPack.getADependency*() = libPack and
+          qlPack.getAFileInPack() = pc.getLocation().getFile()
+        )
+        or
+        // upgrade scripts don't have a qlpack
+        rel.getLocation().getFile().getParentContainer() =
+          pc.getLocation().getFile().getParentContainer()
+      )
+    )
+  }
+
   cached
   predicate resolveCall(Call c, PredicateOrBuiltin p) {
     resolvePredicateCall(c, p)
     or
     resolveMemberCall(c, p)
+    or
+    not resolvePredicateCall(c, _) and
+    resolveDBRelation(c, p)
   }
 
   cached