Go: ParameterPosition and ArgumentPosition

Corresponds to #7260, though some
of those changes had already been made.

Author: owen-mc

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

@@ -109,22 +109,18 @@ predicate mayBenefitFromCallContext(DataFlowCall call, DataFlowCallable f) { non
  */
 DataFlowCallable viableImplInCallContext(DataFlowCall call, DataFlowCall ctx) { none() }
 
-/** Holds if `i` is a valid parameter position. */
-predicate parameterPosition(int i) {
-  i = [-1 .. any(DataFlowCallable c).getType().getNumParameter()]
+private int parameterPosition() {
+  result = [-1 .. any(DataFlowCallable c).getType().getNumParameter()]
 }
 
-/** Gets the parameter position of the instance parameter. */
-int instanceParameterPosition() { result = -1 }
-
 /** A parameter position represented by an integer. */
 class ParameterPosition extends int {
-  ParameterPosition() { parameterPosition(this) }
+  ParameterPosition() { this = parameterPosition() }
 }
 
 /** An argument position represented by an integer. */
 class ArgumentPosition extends int {
-  ArgumentPosition() { parameterPosition(this) }
+  ArgumentPosition() { this = parameterPosition() }
 }
 
 /** Holds if arguments at position `apos` match parameters at position `ppos`. */

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

@@ -25,6 +25,8 @@ private newtype TNode =
 
 /** Nodes intended for only use inside the data-flow libraries. */
 module Private {
+  private import DataFlowDispatch
+
   /** Gets the callable in which this node occurs. */
   DataFlowCallable nodeGetEnclosingCallable(Node n) {
     result.asCallable() = n.getEnclosingCallable()
@@ -33,10 +35,15 @@ module Private {
   }
 
   /** Holds if `p` is a `ParameterNode` of `c` with position `pos`. */
-  predicate isParameterNode(ParameterNode p, DataFlowCallable c, int pos) {
+  predicate isParameterNode(ParameterNode p, DataFlowCallable c, ParameterPosition pos) {
     p.isParameterOf(c.asCallable(), pos)
   }
 
+  /** Holds if `arg` is an `ArgumentNode` of `c` with position `pos`. */
+  predicate isArgumentNode(ArgumentNode arg, DataFlowCall c, ArgumentPosition pos) {
+    arg.argumentOf(c, pos)
+  }
+
   /** A data flow node that represents returning a value from a function. */
   class ReturnNode extends Node {
     ReturnKind kind;

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

@@ -19,6 +19,9 @@ class SummarizedCallableBase = Callable;
 
 DataFlowCallable inject(SummarizedCallable c) { result.asCallable() = c }
 
+/** Gets the parameter position of the instance parameter. */
+ArgumentPosition instanceParameterPosition() { result = -1 }
+
 /** Gets the textual representation of a parameter position in the format used for flow summaries. */
 string getParameterPositionCsv(ParameterPosition pos) { result = pos.toString() }
 
@@ -245,7 +248,10 @@ predicate interpretInputSpecific(string c, InterpretNode mid, InterpretNode n) {
   )
 }
 
-/** Holds if specification component `c` parses as return value `n`. */
+/**
+ * Holds if specification component `c` parses as return value `n` or a range
+ * containing `n`.
+ */
 predicate parseReturn(AccessPathToken c, int n) {
   (
     c = "ReturnValue" and n = 0
@@ -266,8 +272,10 @@ private int parseConstantOrRange(string arg) {
   )
 }
 
+/** Gets the argument position obtained by parsing `X` in `Parameter[X]`. */
 bindingset[arg]
 ArgumentPosition parseParamBody(string arg) { result = parseConstantOrRange(arg) }
 
+/** Gets the parameter position obtained by parsing `X` in `Argument[X]`. */
 bindingset[arg]
 ParameterPosition parseArgBody(string arg) { result = parseConstantOrRange(arg) }