net: "src/net/ip.go:17:2: package internal/strconv is not in std" for Go < 1.26

[eliasnaur]

TinyGo fails to build programs importing "net" with Go < 1.26:

$ cd tinygo
$ go version
go version go1.25.6 darwin/arm64
$ go run . version
ld: warning: directory not found for option '-L/opt/homebrew/opt/llvm@20/lib'
ld: warning: directory not found for option '-L/opt/homebrew/opt/llvm@20/lib'
tinygo version 0.41.0 darwin/arm64 (using go version go1.25.6 and LLVM version 20.1.8)
$ cat ~/Downloads/importnet.go
package main

import _ "net"

func main() {
}
$ go run . run ~/Downloads/importnet.go
# github.com/tinygo-org/tinygo
ld: warning: directory not found for option '-L/opt/homebrew/opt/llvm@20/lib'
ld: warning: directory not found for option '-L/opt/homebrew/opt/llvm@20/lib'
../../Library/Caches/tinygo/goroot-1cd19649925db87b1ac4588e9d03dd2778470b0ea5fd74f2d3b6016e92ff344f/src/net/ip.go:17:2: package internal/strconv is not in std (/Users/a/Library/Caches/tinygo/goroot-1cd19649925db87b1ac4588e9d03dd2778470b0ea5fd74f2d3b6016e92ff344f/src/internal/strconv)
exit status 1

Presumably the upgrade #5298 triggered this issue, but it seems to me the root cause is that TinyGo doesn't implement an "internal/strconv" package for Go < 1.26.

[aykevl]

I can reproduce this issue with Go 1.24.

[aykevl]

Looks like a regression introduced in tinygo-org/net#46, and something we might want to fix before the coming release.
@deadprogram can you take a look?

(Also, why didn't CI catch this?)

[dgryski]

The 1.26 update switched out internal/strconv for our own internal/itoa because it's much lighter. If we need to keep internal/strconv, that's going to bloat a lot of binaries.

[deadprogram]

The 1.26 update switched out internal/strconv for our own internal/itoa because it's much lighter. If we need to keep internal/strconv, that's going to bloat a lot of binaries.

Can we swap in internal/itoa for <1.26? I think there is a little more to it as I recall but have not looked.

[deadprogram]

See tinygo-org/net#51 for my proposed fix. It is the least instrusive, but assumes that if you want to get the smallest binary, you would need to update to Go 1.26.

[deadprogram]

In my tests using the updated net package:

Go 1.25.7

$ tinygo flash -target xiao-esp32c3 -ldflags="-X main.ssid=ssid -X main.password=passwordy" -size short ./webserver
   code    data     bss |   flash     ram
 953264   36436  361786 |  989700  398222

Go 1.26.2

$ tinygo flash -target xiao-esp32c3 -ldflags="-X main.ssid=ssid -X main.password=passwordy" -size short ./webserver
   code    data     bss |   flash     ram
 961966   37396  369926 |  999362  407322

The Go 1.26 code is somewhat larger, and takes up more RAM, but it is notably faster at responding to incoming web requests on my ESP32C3 device.