cmd/dist: rewrite mkdeps.bash to work on OS X

My version of bash doesn't know what 'declare -A' means.

Change-Id: Icf6b0e60ebaea3feaa8661ec0423012f213b53e8
Reviewed-on: https://go-review.googlesource.com/17070Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/dist/mkdeps.bash

@@ -5,23 +5,26 @@
 
 set -e
 
-declare -A alldeps
-
 # We need to test enough GOOS/GOARCH combinations to pick up all the
 # package dependencies.
 gooslist="windows linux darwin solaris"
 goarchlist="386 amd64 arm arm64 ppc64"
 
-for goos in $gooslist; do
-  for goarch in $goarchlist; do
-    deps=$(GOOS=$goos GOARCH=$goarch go list -tags cmd_go_bootstrap -f '{{join .Deps "\n"}}' cmd/go | grep -v '^unsafe$')
-    for dep in $deps cmd/go; do
-      alldeps[$dep]="${alldeps[$dep]} $(GOOS=$goos GOARCH=$goarch go list -tags cmd_go_bootstrap -f '{{range .Deps}}{{if not (eq . "unsafe")}}{{print .}} {{end}}{{end}}' $dep)"
-    done
-  done
-done
+echo NOTE: errors about loading internal/syscall/windows are ok
+
+deps_of() {
+	for goos in $gooslist
+	do
+		for goarch in $goarchlist
+		do
+			GOOS=$goos GOARCH=$goarch go list -tags cmd_go_bootstrap -f '{{range .Deps}}{{$.ImportPath}} {{.}}
+{{end}}' $*
+		done
+	done | sort -u | grep . | grep -v ' unsafe$'
+}
 
-export GOOS=windows
+all="$(deps_of cmd/go | awk '{print $2}') cmd/go"
+deps_of $all >tmp.all.deps
 
 (
 	echo '// generated by mkdeps.bash'
@@ -29,16 +32,16 @@ export GOOS=windows
 	echo 'package main'
 	echo
 	echo 'var builddeps = map[string][]string{'
-
-	for dep in $(for dep in ${!alldeps[@]}; do echo $dep; done | grep -v '^cmd/go$' | sort) cmd/go; do
-	  echo -n '"'$dep'"': {
-	  for subdep in ${alldeps[$dep]}; do
-	    echo $subdep
-	  done | sort -u | while read subdep; do
-	    echo -n '"'$subdep'"',
-	  done
-	  echo },
+	for pkg in $all
+	do
+		echo -n "\"$pkg\": {"
+		for dep in $(awk -v pkg=$pkg '$1==pkg {print $2}' tmp.all.deps)
+		do
+			echo -n "\"$dep\","
+		done
+		echo '},'
 	done
-
 	echo '}'
 ) |gofmt >deps.go
+
+rm -f tmp.all.deps