Add a few useful shortcuts.

Author: Max Schaefer

ql/src/semmle/go/Decls.qll

@@ -124,9 +124,7 @@ class FuncDef extends @funcdef, StmtParent, ExprParent {
    */
   Parameter getParameter(int i) { result.isParameterOf(this, i) }
 
-  /**
-   * Gets a parameter of this function.
-   */
+  /** Gets a parameter of this function. */
   Parameter getAParameter() { result.getFunction() = this }
 
   /**

ql/src/semmle/go/Scopes.qll

@@ -412,13 +412,19 @@ class Function extends ValueEntity, @functionobject {
   Type getResultType(int i) { result = getType().(SignatureType).getResultType(i) }
 
   /** Gets the body of this function, if any. */
-  BlockStmt getBody() { none() }
+  BlockStmt getBody() { result = getFuncDecl().getBody() }
 
   /** Gets the `i`th parameter of this function. */
-  Parameter getParameter(int i) { none() }
+  Parameter getParameter(int i) { result.isParameterOf(getFuncDecl(), i) }
 
   /** Gets a parameter of this function. */
   Parameter getAParameter() { result = getParameter(_) }
+
+  /** Gets the `i`th reslt variable of this function. */
+  ResultVariable getResult(int i) { result.isResultOf(getFuncDecl(), i) }
+
+  /** Gets a result variable of this function. */
+  ResultVariable getAResult() { result = getResult(_) }
 }
 
 /**
@@ -528,10 +534,6 @@ class Method extends Function {
 class DeclaredFunction extends Function, DeclaredEntity, @declfunctionobject {
   override FuncDecl getFuncDecl() { result.getNameExpr() = this.getDeclaration() }
 
-  override BlockStmt getBody() { result = getFuncDecl().getBody() }
-
-  override Parameter getParameter(int i) { result = getFuncDecl().getParameter(i) }
-
   override predicate mayHaveSideEffects() {
     not exists(getBody())
     or

ql/src/semmle/go/dataflow/internal/DataFlowUtil.qll

@@ -245,6 +245,13 @@ abstract class FunctionNode extends Node {
    * Gets the data-flow node corresponding to the `i`th result of this function.
    */
   ResultNode getResult(int i) { result = getAResult() and result.getIndex() = i }
+
+  /**
+   * Gets the function entity this node corresponds to.
+   *
+   * Note that this predicate has no result for function literals.
+   */
+  Function getFunction() { none() }
 }
 
 /** A representation of a function that is declared in the module scope. */
@@ -257,8 +264,7 @@ class GlobalFunctionNode extends FunctionNode, MkGlobalFunctionNode {
 
   override string getName() { result = func.getName() }
 
-  /** Gets the function this node corresponds to. */
-  Function getFunction() { result = func }
+  override Function getFunction() { result = func }
 
   override ReceiverNode getReceiver() { result = receiverNode(func.(Method).getReceiver()) }