func gofumptFormatExpr(w io.Writer, fset *token.FileSet, expr ast.Expr, opt gofumpt.Options) error {
// First use go/format to convert the expression to Go syntax.
var tmp bytes.Buffer
if err := format.Node(&tmp, fset, expr); err != nil {
return err
}
rs := []rune(tmp.String())
var firstNum int
for i, v := range rs {
if v == '(' {
if rs[i+1] >= '0' && rs[i+1] <= '9' {
firstNum = i + 1
break
}
}
}
if firstNum > 0 {
rs0 := rs[:firstNum]
rs1 := rs[firstNum:]
var hasChar bool
for _, v := range rs1 {
if v < '0' || v > '9' {
hasChar = true
break
}
}
if hasChar {
rs1 = append([]rune{'_'}, rs1...)
}
rs = append(rs0, rs1...)
}
tmpString := string(formatCompositeLiterals(rs))
time.Duration will cause ( missing ',' in argument list ) error
i wrote a hack and it can work well. change method gofumptFormatExpr