What version of Go are you using (go version)?
$ go version
go version go1.14.2 darwin/amd64
Does this issue reproduce with the latest release?
Yes.
What operating system and processor architecture are you using (go env)?
go env Output
$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/didi/Library/Caches/go-build"
GOENV="/Users/didi/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/didi/dev/source/golang/gopath"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/n5/26_m50tn4_j2n3gmvt19300h0000gn/T/go-build965858086=/tmp/go-build -gno-record-gcc-switches -fno-common"
What did you do?
file, _ := macho.Open("xxx.o") // which has Mach-O format with MH_OBJECT type
for i, l := range file.Loads {
switch lo := l.(type) {
case *macho.Symtab:
fmt.Println(lo.SymtabCmd) // nothing but zero value
}
}What did you expect to see?
Non-zero value of lo.SymtabCmd.
What did you see instead?
Zero value of lo.SymtabCmd.
Possible causes
parseSymtab() function in debug/macho/file.go:
...
st := new(Symtab)
st.LoadBytes = LoadBytes(cmddat)
st.Syms = symtab
return st, nil
}
ignore st.SymtabCmd ? It cound be:
...
st := new(Symtab)
st.LoadBytes = LoadBytes(cmddat)
st.Syms = symtab
st.SymtabCmd = *hdr
return st, nil
} 
What version of Go are you using (
go version)?Does this issue reproduce with the latest release?
Yes.
What operating system and processor architecture are you using (
go env)?go envOutputWhat did you do?
What did you expect to see?
Non-zero value of lo.SymtabCmd.
What did you see instead?
Zero value of lo.SymtabCmd.
Possible causes
parseSymtab() function in debug/macho/file.go:
ignore st.SymtabCmd ? It cound be: