Pull request: all: imp go version setting and detection

Merge in DNS/adguard-home from imp-make to master

Squashed commit of the following:

commit 9ecb3422a55f5d010000bf4253a2766fefa67173
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Apr 22 19:59:36 2021 +0300

    all: fix spelling

commit c136f6562af80a67e627b472621ac68763f85fde
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Apr 22 19:50:07 2021 +0300

    all: imp go version setting and detection

Makefile

@@ -7,13 +7,15 @@
 CHANNEL = development
 CLIENT_BETA_DIR = client2
 CLIENT_DIR = client
-COMMIT = $$(git rev-parse --short HEAD)
+COMMIT = $$( git rev-parse --short HEAD )
 DIST_DIR = dist
-# TODO(a.garipov): Find out a way to make this work in GNU Make.
+# Don't name this macro "GO", because GNU Make apparenly makes it an
+# exported environment variable with the literal value of "${GO:-go}",
+# which is not what we need.  Use a dot in the name to make sure that
+# users don't have an environment variable with the same name.
 #
-#  GO = $${GO:-go}
+# See https://unix.stackexchange.com/q/646255/105635.
-#
+GO.MACRO = $${GO:-go}
-GO = go
 GOPROXY = https://goproxy.cn|https://proxy.golang.org|direct
 GPG_KEY = devteam@adguard.com
 GPG_KEY_PASSPHRASE = not-a-real-password
@@ -37,9 +39,9 @@ ENV = env\
 	GPG_KEY='$(GPG_KEY)'\
 	GPG_KEY_PASSPHRASE='$(GPG_KEY_PASSPHRASE)'\
 	DIST_DIR='$(DIST_DIR)'\
-	GO='$(GO)'\
+	GO="$(GO.MACRO)"\
 	GOPROXY='$(GOPROXY)'\
-	PATH="$${PWD}/bin:$$($(GO) env GOPATH)/bin:$${PATH}"\
+	PATH="$${PWD}/bin:$$( "$(GO.MACRO)" env GOPATH )/bin:$${PATH}"\
 	RACE='$(RACE)'\
 	SIGN='$(SIGN)'\
 	VERBOSE='$(VERBOSE)'\
@@ -97,10 +99,10 @@ go-check: go-tools go-lint go-test
 # A quick check to make sure that all supported operating systems can be
 # typechecked and built successfully.
 go-os-check:
-	env GOOS='darwin'  $(GO) vet ./internal/...
+	env GOOS='darwin'  "$(GO.MACRO)" vet ./internal/...
-	env GOOS='freebsd' $(GO) vet ./internal/...
+	env GOOS='freebsd' "$(GO.MACRO)" vet ./internal/...
-	env GOOS='linux'   $(GO) vet ./internal/...
+	env GOOS='linux'   "$(GO.MACRO)" vet ./internal/...
-	env GOOS='windows' $(GO) vet ./internal/...
+	env GOOS='windows' "$(GO.MACRO)" vet ./internal/...
 
 openapi-lint: ; cd ./openapi/ && $(YARN) test
 openapi-show: ; cd ./openapi/ && $(YARN) start

scripts/make/go-lint.sh

@@ -27,7 +27,7 @@ set -f -u
 
 # Deferred Helpers
 
-not_found_msg='
+readonly not_found_msg='
 looks like a binary not found error.
 make sure you have installed the linter binaries using:
 
@@ -49,6 +49,29 @@ trap not_found EXIT
 
 
 
+# Warnings
+
+readonly go_min_version='go1.15'
+readonly go_min_version_prefix="go version ${go_min_version}"
+readonly go_version_msg="
+warning: your go version different from the recommended minimal one (${go_min_version}).
+if you have the version installed, please set the GO environment variable.
+for example:
+
+	export GO='${go_min_version}'
+"
+case "$( "$GO" version )"
+in
+("$go_min_version_prefix"*)
+	# Go on.
+	;;
+(*)
+	echo "$go_version_msg" 1>&2
+	;;
+esac
+
+
+
 # Simple Analyzers
 
 # blocklist_imports is a simple check against unwanted packages.
@@ -99,7 +122,7 @@ exit_on_output() (
 	cmd="$1"
 	shift
 
-	output="$("$cmd" "$@" 2>&1)"
+	output="$( "$cmd" "$@" 2>&1 )"
 	exitcode="$?"
 	if [ "$exitcode" != '0' ]
 	then