case *CompositeLit:
			if n.Type != nil {
				m = n.Type
				continue
			}
			return n.Pos()
		case *KeyValueExpr:
			m = n.Key
		// case *FuncLit:
		// case *ParenExpr:
		case *SelectorExpr:
			m = n.X
		case *IndexExpr:
			m = n.X
		// case *SliceExpr:
		case *AssertExpr:
			m = n.X
		case *TypeSwitchGuard:
			if n.Lhs != nil {
				m = n.Lhs
				continue
			}
			m = n.X

			t.Errorf("package %s not imported", name)
		}
	}

	// check that qualified identifiers are resolved
	for _, f := range files {
		ast.Inspect(f, func(n ast.Node) bool {
			if s, ok := n.(*ast.SelectorExpr); ok {
				if x, ok := s.X.(*ast.Ident); ok {
					obj := uses[x]
					if obj == nil {
						t.Errorf("%s: unresolved qualified identifier %s", fset.Position(x.Pos()), x.Name)
						return false
					}

		}
		arg := call.Args[0]

		// Retrieve target type name.
		var tname *types.TypeName
		switch fun := call.Fun.(type) {
		case *ast.Ident:
			tname, _ = pass.TypesInfo.Uses[fun].(*types.TypeName)
		case *ast.SelectorExpr:
			tname, _ = pass.TypesInfo.Uses[fun.Sel].(*types.TypeName)
		}
		if tname == nil {
			return
		}

		// In the conversion T(v) of a value v of type V to a target type T, we

	case *FuncLit:
		Walk(v, n.Type)
		Walk(v, n.Body)

	case *CompositeLit:
		if n.Type != nil {
			Walk(v, n.Type)
		}
		walkList(v, n.Elts)

	case *ParenExpr:
		Walk(v, n.X)

	case *SelectorExpr:
		Walk(v, n.X)
		Walk(v, n.Sel)

	case *IndexExpr:
		Walk(v, n.X)
		Walk(v, n.Index)

	case *IndexListExpr:
		Walk(v, n.X)
		walkList(v, n.Indices)

	case *SliceExpr:
		Walk(v, n.X)