Index: Mk/Uses/go.mk
===================================================================
--- Mk/Uses/go.mk	(revision 527971)
+++ Mk/Uses/go.mk	(working copy)
@@ -187,6 +187,20 @@
 	else \
 		${ECHO_MSG} "===> Please install \"${GO_PORT}\""; \
 	fi
+
+gomod-vendor-diff: patch
+	@if ! type ${GO_CMD} > /dev/null 2>&1; then \
+		${ECHO_MSG} "===> Please install \"${GO_PORT}\""; \
+		return 1; \
+	fi; \
+	if ! type ${_MODULES2TUPLE_CMD} > /dev/null 2>&1; then \
+		${ECHO_MSG} "===> Please install \"ports-mgmt/modules2tuple\""; \
+		return 1; \
+	fi; \
+	cd ${WRKSRC} && ${GO_CMD} mod vendor && \
+	echo ${GH_TUPLE} | ${TR} -s " " "\n" | ${SED} "s|^|		|" > GH_TUPLE-old.txt && \
+	[ -r vendor/modules.txt ] && ${_MODULES2TUPLE_CMD} vendor/modules.txt | ${GREP} -v "^GH_TUPLE=" | ${SED} 's| \\$$||' > GH_TUPLE-new.txt && \
+	${DIFF} GH_TUPLE-old.txt GH_TUPLE-new.txt
 .endif
 
 .endif # defined(_POSTMKINCLUDED) && !defined(_INCLUDE_USES_GO_POST_MK)