make.bash: use [[ rather than [

[[ is a compound command part of the language with structure,
whereas [ is simply a standard program with string arguments.
The former has a few significant advantages over the latter:

* Better syntax, e.g. && and || rather than -a and -o,
  as well as == rather than = for comparisons
* No need for fork+exec to evaluate each conditional
* Forgetting the closing token is an early parse error

The only advantage of [ over [[ is that [[ is Bash syntax,
whereas [ and "test" are portable POSIX Shell utilities.
However, this is a Bash script, so that is not a concern.

Change-Id: I8a4bdd16845bd67bf67a348d7d96d45d5b131d85
Reviewed-on: https://go-review.googlesource.com/c/go/+/531875
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>

diff --git a/src/make.bash b/src/make.bash
index e8f002adb00d90ff2f3c07fd9f002545b68da731..76ad51624ac6eefa927c467f1afaccf45a1124c7 100755 (executable)
--- a/src/make.bash
+++ b/src/make.bash
@@ -78,12 +78,12 @@ bootgo=1.20.6
 
 set -e
 
-if [ ! -f run.bash ]; then
+if [[ ! -f run.bash ]]; then
        echo 'make.bash must be run from $GOROOT/src' 1>&2
        exit 1
 fi
 
-if [ "$GOBUILDTIMELOGFILE" != "" ]; then
+if [[ "$GOBUILDTIMELOGFILE" != "" ]]; then
        echo $(LC_TIME=C date) start make.bash >"$GOBUILDTIMELOGFILE"
 fi
 
@@ -114,7 +114,7 @@ fi
 # so loop through the possible selinux mount points.
 for se_mount in /selinux /sys/fs/selinux
 do
-       if [ -d $se_mount -a -f $se_mount/booleans/allow_execstack -a -x /usr/sbin/selinuxenabled ] && /usr/sbin/selinuxenabled; then
+       if [[ -d $se_mount && -f $se_mount/booleans/allow_execstack && -x /usr/sbin/selinuxenabled ]] && /usr/sbin/selinuxenabled; then
                if ! cat $se_mount/booleans/allow_execstack | grep -c '^1 1$' >> /dev/null ; then
                        echo "WARNING: the default SELinux policy on, at least, Fedora 12 breaks "
                        echo "Go. You can enable the features that Go needs via the following "
@@ -134,7 +134,7 @@ done
 # Test for debian/kFreeBSD.
 # cmd/dist will detect kFreeBSD as freebsd/$GOARCH, but we need to
 # disable cgo manually.
-if [ "$(uname -s)" = "GNU/kFreeBSD" ]; then
+if [[ "$(uname -s)" == "GNU/kFreeBSD" ]]; then
        export CGO_ENABLED=0
 fi
 
@@ -145,17 +145,17 @@ rm -f ./runtime/runtime_defs.go
 
 verbose=false
 vflag=""
-if [ "$1" = "-v" ]; then
+if [[ "$1" == "-v" ]]; then
        verbose=true
        vflag=-v
        shift
 fi
 
 goroot_bootstrap_set=${GOROOT_BOOTSTRAP+"true"}
-if [ -z "$GOROOT_BOOTSTRAP" ]; then
+if [[ -z "$GOROOT_BOOTSTRAP" ]]; then
        GOROOT_BOOTSTRAP="$HOME/go1.4"
        for d in sdk/go$bootgo go$bootgo; do
-               if [ -d "$HOME/$d" ]; then
+               if [[ -d "$HOME/$d" ]]; then
                        GOROOT_BOOTSTRAP="$HOME/$d"
                fi
        done
@@ -168,10 +168,10 @@ nogoenv() {
 
 export GOROOT="$(cd .. && pwd)"
 IFS=$'\n'; for go_exe in $(type -ap go); do
-       if [ ! -x "$GOROOT_BOOTSTRAP/bin/go" ]; then
+       if [[ ! -x "$GOROOT_BOOTSTRAP/bin/go" ]]; then
                goroot=$(GOROOT= nogoenv "$go_exe" env GOROOT)
-               if [ "$goroot" != "$GOROOT" ]; then
-                       if [ "$goroot_bootstrap_set" = "true" ]; then
+               if [[ "$goroot" != "$GOROOT" ]]; then
+                       if [[ "$goroot_bootstrap_set" == "true" ]]; then
                                printf 'WARNING: %s does not exist, found %s from env\n' "$GOROOT_BOOTSTRAP/bin/go" "$go_exe" >&2
                                printf 'WARNING: set %s as GOROOT_BOOTSTRAP\n' "$goroot" >&2
                        fi
@@ -179,7 +179,7 @@ IFS=$'\n'; for go_exe in $(type -ap go); do
                fi
        fi
 done; unset IFS
-if [ ! -x "$GOROOT_BOOTSTRAP/bin/go" ]; then
+if [[ ! -x "$GOROOT_BOOTSTRAP/bin/go" ]]; then
        echo "ERROR: Cannot find $GOROOT_BOOTSTRAP/bin/go." >&2
        echo "Set \$GOROOT_BOOTSTRAP to a working Go tree >= Go $bootgo." >&2
        exit 1
@@ -192,7 +192,7 @@ echo "Building Go cmd/dist using $GOROOT_BOOTSTRAP. ($GOROOT_BOOTSTRAP_VERSION)"
 if $verbose; then
        echo cmd/dist
 fi
-if [ "$GOROOT_BOOTSTRAP" = "$GOROOT" ]; then
+if [[ "$GOROOT_BOOTSTRAP" == "$GOROOT" ]]; then
        echo "ERROR: \$GOROOT_BOOTSTRAP must not be set to \$GOROOT" >&2
        echo "Set \$GOROOT_BOOTSTRAP to a working Go tree >= Go $bootgo." >&2
        exit 1
@@ -202,7 +202,7 @@ GOROOT="$GOROOT_BOOTSTRAP" nogoenv "$GOROOT_BOOTSTRAP/bin/go" build -o cmd/dist/
 
 # -e doesn't propagate out of eval, so check success by hand.
 eval $(./cmd/dist/dist env -p || echo FAIL=true)
-if [ "$FAIL" = true ]; then
+if [[ "$FAIL" == true ]]; then
        exit 1
 fi
 
@@ -210,10 +210,10 @@ if $verbose; then
        echo
 fi
 
-if [ "$1" = "--dist-tool" ]; then
+if [[ "$1" == "--dist-tool" ]]; then
        # Stop after building dist tool.
        mkdir -p "$GOTOOLDIR"
-       if [ "$2" != "" ]; then
+       if [[ "$2" != "" ]]; then
                cp cmd/dist/dist "$2"
        fi
        mv cmd/dist/dist "$GOTOOLDIR"/dist