Revert "Merge pull request #18235 from owen-mc/go/varargs-out-param"

This reverts commit 4f8645b, reversing
changes made to 22aaf74.

Author: Dave Bartolomeo

go/ql/lib/change-notes/2024-12-06-improve-flow-out-of-variadic-parameter.md

@@ -66,11 +66,6 @@ predicate containerReadStep(Node node1, Node node2, Content c) {
     (
       node2.(Read).readsElement(node1, _)
       or
-      exists(ImplicitVarargsSlice ivs |
-        node1.(PostUpdateNode).getPreUpdateNode() = ivs and
-        node2.(PostUpdateNode).getPreUpdateNode() = ivs.getCallNode().getAnImplicitVarargsArgument()
-      )
-      or
       node2.(RangeElementNode).getBase() = node1
       or
       // To model data flow from array elements of the base of a `SliceNode` to

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

@@ -845,9 +845,6 @@ module Public {
         or
         preupd = getAWrittenNode()
         or
-        preupd instanceof ImplicitVarargsSlice and
-        mutableType(preupd.(ImplicitVarargsSlice).getType().(SliceType).getElementType())
-        or
         preupd = any(ArgumentNode arg).getACorrespondingSyntacticArgument() and
         mutableType(preupd.getType())
       ) and

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

@@ -9,9 +9,9 @@ import semmle.go.dataflow.internal.FlowSummaryImpl as FlowSummaryImpl
 import utils.test.InlineFlowTest
 
 module Config implements DataFlow::ConfigSig {
-  predicate isSource(DataFlow::Node source) { sourceNode(source, "qltest") }
+  predicate isSource(DataFlow::Node src) { sourceNode(src, "qltest") }
 
-  predicate isSink(DataFlow::Node sink) { sinkNode(sink, "qltest") }
+  predicate isSink(DataFlow::Node src) { sinkNode(src, "qltest") }
 }
 
 import ValueFlowTest<Config>

go/ql/test/library-tests/semmle/go/dataflow/ExternalValueFlow/completetest.ql

@@ -4,7 +4,7 @@ func source() string {
 	return "untrusted data"
 }
 
-func sink(any) {
+func sink(string) {
 }
 
 type A struct {
@@ -19,10 +19,6 @@ func functionWithVarArgsParameter(s ...string) string {
 	return s[1]
 }
 
-func functionWithVarArgsOutParameter(in string, out ...*string) {
-	*out[0] = in
-}
-
 func functionWithSliceOfStructsParameter(s []A) string {
 	return s[1].f
 }
@@ -42,12 +38,6 @@ func main() {
 	sink(functionWithVarArgsParameter(sSlice...)) // $ hasValueFlow="call to functionWithVarArgsParameter"
 	sink(functionWithVarArgsParameter(s0, s1))    // $ hasValueFlow="call to functionWithVarArgsParameter"
 
-	var out1 *string
-	var out2 *string
-	functionWithVarArgsOutParameter(source(), out1, out2)
-	sink(out1) // $ MISSING: hasValueFlow="out1"
-	sink(out2) // $ MISSING: hasValueFlow="out2"
-
 	sliceOfStructs := []A{{f: source()}}
 	sink(sliceOfStructs[0].f) // $ hasValueFlow="selection of f"