Makefile: add "shell-completion" target

Signed-off-by: Sebastiaan van Stijn <[email protected]>

Makefile

@@ -60,12 +60,10 @@ fmt: ## run gofumpt (if present) or gofmt
 .PHONY: binary
 binary: ## build executable for Linux
 	./scripts/build/binary
-	./scripts/build/completion
 
 .PHONY: dynbinary
 dynbinary: ## build dynamically linked binary
 	GO_LINKMODE=dynamic ./scripts/build/binary
-	./scripts/build/completion
 
 .PHONY: plugins
 plugins: ## build example CLI plugins
@@ -89,8 +87,8 @@ authors: ## generate AUTHORS file from git history
 	scripts/docs/generate-authors.sh
 
 .PHONY: completion
-completion: binary
-completion: ## generate and install the completion scripts
+completion: shell-completion
+completion: ## generate and install the shell-completion scripts
 # Note: this uses system-wide paths, and so may overwrite completion
 # scripts installed as part of deb/rpm packages.
 #
@@ -103,6 +101,14 @@ completion: ## generate and install the completion scripts
 	install -D -p -m 0644 ./build/completion/fish/docker.fish debian/docker-ce-cli/usr/share/fish/vendor_completions.d/docker.fish
 	install -D -p -m 0644 ./build/completion/zsh/_docker debian/docker-ce-cli/usr/share/zsh/vendor-completions/_docker
 
+.PHONY: shell-completion
+shell-completion: ## generate shell-completion scripts
+# requires either "binary" or "dynbinary" to be built.
+# but only build if it's not there, to prevent existing binaries
+# from being replaced.
+	@ [ -f build/docker ] || $(MAKE) binary
+	@ ./scripts/build/completion
+
 .PHONY: manpages
 manpages: ## generate man pages from go source and markdown
 	scripts/docs/generate-man.sh