v3 empty binary size is +3Mb

[abitrolly]

Why empty v3 project is so big?

-rwxr-xr-x.   1 anatoli anatoli 1523883 Jan 24 11:34 00empty
-rwxr-xr-x.   1 anatoli anatoli 2732071 Jan 24 11:33 00empty-cobra
-rwxr-xr-x.   1 anatoli anatoli 4839568 Jan 24 11:37 00empty-urfave

00empty.go

package main

func main() {
}

00empty-cobra.go

package main

import "github.com/spf13/cobra"

func main() {
	_ = &cobra.Command{}
}

00empty-urfave.go

package main

import "github.com/urfave/cli/v3"

func main() {
	_ = &cli.Command{}
}

[Skeeve]

Maybe because it has so much to offer compared to other libraries?

[abitrolly]

But Go should tree shake all unused stuff.

https://www.reddit.com/r/golang/comments/yzpbcj/does_the_go_compiler_use_tree_shaking/

[Skeeve]

I have no clue. Maybe there are some inits?

[dearchap]

@abitrolly Interesting. The CI reports following

1.9MB is the current binary size
  ✅ 1.5MB is the target min size
  ✅ 2.2MB is the target max size

[abitrolly]

➜  ~ cd /tmp
➜  /tmp mkdir 111
➜  /tmp cd 111
➜  111 go mod init
go: cannot determine module path for source directory /tmp/111 (outside GOPATH, module path must be specified)

Example usage:
        'go mod init example.com/m' to initialize a v0 or v1 module
        'go mod init example.com/m/v2' to initialize a v2 module

Run 'go help mod init' for more information.
➜  111 go mod init xxx
go: creating new go.mod: module xxx
➜  111 wl-paste > main.go
➜  111 go get github.com/urfave/cli/v3@latest
go: added github.com/urfave/cli/v3 v3.0.0-beta1
➜  111 go build
➜  111 ls -la
total 4740
drwxr-xr-x.  2 anatoli anatoli     120 Jan 26 02:34 .
drwxrwxrwt. 22 root    root        520 Jan 26 02:34 ..
-rw-r--r--.  1 anatoli anatoli      81 Jan 26 02:34 go.mod
-rw-r--r--.  1 anatoli anatoli     179 Jan 26 02:34 go.sum
-rw-r--r--.  1 anatoli anatoli      85 Jan 26 02:33 main.go
-rwxr-xr-x.  1 anatoli anatoli 4839568 Jan 26 02:34 xxx
➜  111

I don't know what CI is doing.

[abitrolly]

My Go is from Homebrew FWIW.

[dearchap]

@abitrolly Here is the relevant optimization

cli/scripts/build.go

Line 662 in 435b91c

"-ldflags", "-s -w",

You have to pass in

go build -ldflags="-s -w" 

That disables the symbol table and dwarf generation.

[abitrolly]

That doesn't explain why cobra binary size is less even without optimization. And why Go doesn't do tree shaking to realize there is nothing called at all.