Go version
go version go1.26.3 linux/amd64
Output of go env in your module/workspace:
AR='ar'
CC='x86_64-linux-gnu-gcc'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='x86_64-linux-gnu-g++'
GCCGO='gccgo'
GO111MODULE=''
GOAMD64='v1'
GOARCH='amd64'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/home/bozar/.cache/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/home/bozar/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build209784865=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/dev/null'
GOMODCACHE='/home/bozar/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/bozar/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/lib/go-1.26'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/bozar/.config/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/lib/go-1.26/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.26.3'
GOWORK=''
PKG_CONFIG='pkg-config'
What did you do?
Currenty go fmt does not truncate the symlinked file, as it compares the size of the recorded data not with the real file size, but with the symlink reference path length.
A script to reproduce the issue:
#!/bin/bash -e
rm -f issue*.go
cat <<EOF > issue-original.go
package main;
import "fmt"
func main() {
fmt.Println( "Hello, world!!!" )
}
EOF
# Go fmt regular file (expected content)
cp issue-original.go issue-expected.go
go fmt issue-expected.go
# Go fmt symlink file
ln -s issue-original.go issue-symlink.go
go fmt issue-symlink.go
# Expected same file content
diff -c issue-expected.go issue-symlink.goWhat did you see happen?
Expected same content on issue-symlink.go and issue-expected.go files.
What did you expect to see?
issue-symlink.go has extra bytes at end of files:
issue-expected.go
issue-symlink.go
*** issue-expected.go 2026-05-28 13:37:52.450203694 +0300
--- issue-symlink.go 2026-05-28 13:37:52.479204129 +0300
***************
*** 5,7 ****
--- 5,9 ----
func main() {
fmt.Println("Hello, world!!!")
}
+ )
+ }
Go version
go version go1.26.3 linux/amd64
Output of
go envin your module/workspace:What did you do?
Currenty
go fmtdoes not truncate the symlinked file, as it compares the size of the recorded data not with the real file size, but with the symlink reference path length.A script to reproduce the issue:
What did you see happen?
Expected same content on
issue-symlink.goandissue-expected.gofiles.What did you expect to see?
issue-symlink.gohas extra bytes at end of files: