text/template causing binary size to be exploded

[eagleonhill]

Go version

1.25.0

Output of go env in your module/workspace:

AR='ar'
CC='gcc'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='g++'
GCCGO='gccgo'
GO111MODULE=''
GOARCH='arm64'
GOARM64='v8.0'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/home/chuanq/.cache/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/home/chuanq/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build1016822352=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='arm64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/home/chuanq/playground/golink/simple/go.mod'
GOMODCACHE='/home/chuanq/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/chuanq/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/chuanq/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.25.0.linux-arm64'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/chuanq/.config/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/chuanq/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.25.0.linux-arm64/pkg/tool/linux_arm64'
GOVCS=''
GOVERSION='go1.25.0'
GOWORK=''
PKG_CONFIG='pkg-config'

What did you do?

When any library linked withtext/template, the binary size will explode and all functions are being included in the final binary.

package main

import (
	"text/template"

	"github.com/aws/aws-sdk-go-v2/service/ec2"
)

type Class struct {
	// Any object with large number of methods.
	c *ec2.Client
}

func (c *Class) I() {}

type I interface {
	I()
}

func useTemplate() {
	// Just some dummy call
	t := &template.Template{}
	t.ExecuteTemplate(nil, "", nil)
}
func getI() I {
	return &Class{}
}

func main() {
	var i I
	i = getI()

	i.I()
	useTemplate()
}

What did you see happen?

The code above produces a binary that is 46MB in size. Checking the linked object, all methods of EC2 clients are being included despite nothing are being used.

If I remove the 2 lines in useTemplate(), it reduces to 5.3MB.

Unfortunately, many common libraries (e.g. GRPC, golang.org/x/net/trace) implicitly include callsite to template and it's not easy to avoid that.

And a type ever referenced by some call chain from an interface type, it will link all methods. This caused the binary size to easily reach a few hundred MBs.

What did you expect to see?

The binary size to be reduced and unnecessary symbols are not included in the final binary.