// genAppend generates constraints for a call to append.
func (a *analysis) genAppend(instr *ssa.Call, cgn *cgnode) {
// Consider z = append(x, y). y is optional.
// This may allocate a new [1]T array; call its object w.
// We get the following constraints:
// z = x
// z = &w
// *z = *y
x := instr.Call.Args[0]
z := instr
a.copy(a.valueNode(z), a.valueNode(x), 1) // z = x
if len(instr.Call.Args) == 1 {
return // no allocation for z = append(x) or _ = append(x).
}
// TODO(adonovan): test append([]byte, ...string) []byte.
y := instr.Call.Args[1]
tArray := sliceToArray(instr.Call.Args[0].Type())
var w nodeid
w = a.nextNode()
a.addNodes(tArray, "append")
a.endObject(w, cgn, instr)
a.copyElems(cgn, tArray.Elem(), z, y) // *z = *y
a.addressOf(instr.Type(), a.valueNode(z), w) // z = &w
}
func (ctxt *context) callees(inst *ssa.Call) ([]*ssa.Function, error) {
pos := ctxt.lprog.Fset.Position(inst.Pos())
if pos.Line <= 0 {
return nil, fmt.Errorf("no position")
}
qpos, err := oracle.ParseQueryPos(ctxt.lprog, posStr(pos), true)
if err != nil {
return nil, fmt.Errorf("cannot parse query pos %q: %v", posStr(pos), err)
}
result, err := ctxt.oracle.Query("callees", qpos)
if err != nil {
return nil, fmt.Errorf("query error: %v", err)
}
return calleeFuncs(result), nil
}