Give DataFlowCallable a user-facing name (Callable), move to Scopes.qll

I removed asFunctionNode() because it would need an import, but it
doesn't seem to be used anywhere.

ql/lib/semmle/go/Scopes.qll

@@ -591,6 +591,54 @@ class BuiltinFunction extends Function, BuiltinEntity, @builtinfunctionobject {
   predicate isPure() { not this.mayHaveSideEffects() }
 }
 
+private newtype TCallable =
+  TFunctionCallable(Function f) or
+  TFuncLitCallable(FuncLit l)
+
+/**
+ * This is either a `Function` or a `FuncLit`, because of limitations of both
+ * `Function` and `FuncDef`:
+ *   - `Function` is an entity, and therefore does not include function literals, and
+ *   - `FuncDef` is an AST node, and so is not extracted for functions from external libraries.
+ */
+class Callable extends TCallable {
+  /** Gets a textual representation of this callable. */
+  string toString() { result = [this.asFunction().toString(), this.asFuncLit().toString()] }
+
+  /** Gets this callable as a function, if it is one. */
+  Function asFunction() { this = TFunctionCallable(result) }
+
+  /** Gets this callable as a function literal, if it is one. */
+  FuncLit asFuncLit() { this = TFuncLitCallable(result) }
+
+  /** Gets this function's definition, if it exists. */
+  FuncDef getFuncDef() { result = [this.asFuncLit().(FuncDef), this.asFunction().getFuncDecl()] }
+
+  /** Gets the type of this callable. */
+  SignatureType getType() {
+    result = this.asFunction().getType() or
+    result = this.asFuncLit().getType()
+  }
+
+  /** Gets the name of this callable. */
+  string getName() {
+    result = this.asFunction().getName() or
+    result = this.asFuncLit().getName()
+  }
+
+  /**
+   * Holds if this element is at the specified location.
+   * The location spans column `sc` of line `sl` to
+   * column `ec` of line `el` in file `fp`.
+   * For more information, see
+   * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
+   */
+  predicate hasLocationInfo(string fp, int sl, int sc, int el, int ec) {
+    this.asFunction().hasLocationInfo(fp, sl, sc, el, ec) or
+    this.asFuncLit().hasLocationInfo(fp, sl, sc, el, ec)
+  }
+}
+
 /** A statement label. */
 class Label extends Entity, @labelobject { }
 

ql/lib/semmle/go/dataflow/internal/DataFlowNodes.qll

@@ -104,7 +104,7 @@ module Public {
     ControlFlow::Root getRoot() { none() } // overridden in subclasses
 
     /** INTERNAL: Use `getRoot()` instead. */
-    DataFlowCallable getEnclosingCallable() {
+    Callable getEnclosingCallable() {
       result.getFuncDef() = this.getRoot()
       or
       this = MkSummarizedParameterNode(result, _)
@@ -457,7 +457,7 @@ module Public {
      * For virtual calls, we look up possible targets in all types that implement the receiver
      * interface type.
      */
-    DataFlowCallable getACalleeIncludingExternals() {
+    Callable getACalleeIncludingExternals() {
       result.asFunction() = this.getTarget()
       or
       exists(DataFlow::Node calleeSource | calleeSource = this.getACalleeSource() |
@@ -558,7 +558,7 @@ module Public {
   /** A representation of a parameter initialization. */
   abstract class ParameterNode extends DataFlow::Node {
     /** Holds if this node initializes the `i`th parameter of `fd`. */
-    abstract predicate isParameterOf(DataFlowCallable c, int i);
+    abstract predicate isParameterOf(Callable c, int i);
   }
 
   /**
@@ -566,7 +566,7 @@ module Public {
    * already have a parameter nodes.
    */
   class SummarizedParameterNode extends ParameterNode, MkSummarizedParameterNode {
-    DataFlowCallable c;
+    Callable c;
     int i;
 
     SummarizedParameterNode() { this = MkSummarizedParameterNode(c, i) }
@@ -582,7 +582,7 @@ module Public {
       i = -1 and result = c.asFunction().(Method).getReceiverType()
     }
 
-    override predicate isParameterOf(DataFlowCallable call, int idx) { c = call and i = idx }
+    override predicate isParameterOf(Callable call, int idx) { c = call and i = idx }
 
     override string toString() { result = "parameter " + i + " of " + c.toString() }
 
@@ -601,9 +601,7 @@ module Public {
     /** Gets the parameter this node initializes. */
     override Parameter asParameter() { result = parm }
 
-    override predicate isParameterOf(DataFlowCallable c, int i) {
-      parm.isParameterOf(c.getFuncDef(), i)
-    }
+    override predicate isParameterOf(Callable c, int i) { parm.isParameterOf(c.getFuncDef(), i) }
   }
 
   /** A representation of a receiver initialization. */

ql/lib/semmle/go/dataflow/internal/DataFlowPrivate.qll

@@ -191,68 +191,14 @@ class CastNode extends ExprNode {
   override ConversionExpr expr;
 }
 
-private newtype TCallable =
-  TFunctionCallable(Function f) or
-  TFuncLitCallable(FuncLit l)
-
-/**
- * A data-flow callable.
- *
- * This is either a `Function` or a `FuncLit`, because of limitations of both
- * `Function` and `FuncDef`:
- *   - `Function` is an entity, and therefore does not include function literals, and
- *   - `FuncDef` is an AST node, and so is not extracted for functions from external libraries.
- */
-class DataFlowCallable extends TCallable {
-  /** Gets a textual representation of this callable. */
-  string toString() { result = [this.asFunction().toString(), this.asFuncLit().toString()] }
-
-  FunctionNode asFunctionNode() {
-    this.asFunction() = result.getFunction()
-    or
-    this.asFuncLit() = result.asExpr()
-  }
-
-  /** Gets this callable as a function, if it is one. */
-  Function asFunction() { this = TFunctionCallable(result) }
-
-  /** Gets this callable as a function literal, if it is one. */
-  FuncLit asFuncLit() { this = TFuncLitCallable(result) }
-
-  /** Gets this function's definition, if it exists. */
-  FuncDef getFuncDef() { result = [this.asFuncLit().(FuncDef), this.asFunction().getFuncDecl()] }
-
-  /** Gets the type of this callable. */
-  SignatureType getType() {
-    result = this.asFunction().getType() or
-    result = this.asFuncLit().getType()
-  }
-
-  /** Gets the name of this callable. */
-  string getName() {
-    result = this.asFunction().getName() or
-    result = this.asFuncLit().getName()
-  }
-
-  /**
-   * Holds if this element is at the specified location.
-   * The location spans column `sc` of line `sl` to
-   * column `ec` of line `el` in file `fp`.
-   * For more information, see
-   * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
-   */
-  predicate hasLocationInfo(string fp, int sl, int sc, int el, int ec) {
-    this.asFunction().hasLocationInfo(fp, sl, sc, el, ec) or
-    this.asFuncLit().hasLocationInfo(fp, sl, sc, el, ec)
-  }
-}
-
 class DataFlowExpr = Expr;
 
 class DataFlowType = Type;
 
 class DataFlowLocation = Location;
 
+class DataFlowCallable = Callable;
+
 /** A function call relevant for data flow. */
 class DataFlowCall extends Expr {
   DataFlow::CallNode call;