strconv: ParseComplex fails to accept "0_0+0x_0p0i"

[griesemer]

Reproducer:

package main

import "fmt"
import "strconv"

func main() {
	x, err := strconv.ParseComplex("0_0+0x_0p0i", 128)
	if err != nil {
		panic(err)
	}
	fmt.Println(x)
}

We just added function ParseComplex to strconv so this is a release blocker.

The problem is in readFloat where we check for underscoreOk for the whole string rather than only the string read so far (atof.go:303).

Fix is trivial, need more tests.

[gopherbot]

Change https://golang.org/cl/233017 mentions this issue: strconv: fix ParseComplex for strings with separators