cmd/go: add --as-needed and --no-as-needed to the linker flags whitelist

[dmitris]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

go1.9.4

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/dsavints/go"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build379375121=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"

What did you do?

build github.com/miekg/pkcs11 package

$ go get github.com/miekg/pkcs11
go build github.com/miekg/pkcs11: invalid flag in #cgo LDFLAGS: -Wl,--no-as-needed

caused by #23672 and link flag whitelist on https://github.com/golang/go/blob/master/src/cmd/go/internal/work/security.go#L88-L89 missing -Wl,--no-as-needed. Suggested fix - add -Wl,--(no)?-as-needed to the whitelist (will send a PR shortly). See also miekg/pkcs11#63 and miekg/pkcs11#66.

About --as-needed and --no-as-needed flags, see https://sourceware.org/binutils/docs/ld/Options.html

--as-needed
--no-as-needed
This option affects ELF DT_NEEDED tags for dynamic libraries mentioned on the command line after the --as-needed option. Normally the linker will add a DT_NEEDED tag for each dynamic library mentioned on the command line, regardless of whether the library is actually needed or not. --as-needed causes a DT_NEEDED tag to only be emitted for a library that at that point in the link satisfies a non-weak undefined symbol reference from a regular object file or, if the library is not found in the DT_NEEDED lists of other needed libraries, a non-weak undefined symbol reference from another needed dynamic library. Object files or libraries appearing on the command line after the library in question do not affect whether the library is seen as needed. This is similar to the rules for extraction of object files from archives. --no-as-needed restores the default behaviour.

[gopherbot]

Change https://golang.org/cl/92795 mentions this issue: cmd/go: add --as-needed and --no-as-needed to allowed linker flags

[ianlancetaylor]

Closing in favor of a general issue for all whitelist changes in #23749.