From 9ee32f91b07cabe60d5aefca17b8ee81dc9ac668 Mon Sep 17 00:00:00 2001
From: Colin Walters <walters@verbum.org>
Date: Tue, 31 Mar 2020 15:10:17 +0000
Subject: [PATCH] build-sys: Only build schema if source changed

Previously we were generating the Go schema source each time
`make` is run, which forces the Go compiler to do more work
and slows down iteration.

`Makefile` rules are designed for this, so use that instead.
---
 mantle/Makefile |  7 +++++--
 mantle/build    | 13 ++++++++-----
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/mantle/Makefile b/mantle/Makefile
index 2a9f044771..c9939de072 100644
--- a/mantle/Makefile
+++ b/mantle/Makefile
@@ -4,8 +4,11 @@ DESTDIR ?=
 ARCH:=$(shell uname -m)
 
 .PHONY: build test vendor clean
-build:
-	./build
+build: cosa/cosa_v1.go
+	./build cmd/*
+
+cosa/cosa_v1.go: ../src/schema/v1.json Makefile
+	./build schema
 
 .PHONY: install
 install: bin/ore bin/kola bin/plume bin/kolet
diff --git a/mantle/build b/mantle/build
index c2e6a61efd..7192f6cebc 100755
--- a/mantle/build
+++ b/mantle/build
@@ -7,7 +7,7 @@ cd $(dirname $0)
 source ./env
 
 if [[ $# -eq 0 ]]; then
-	set -- cmd/*
+	set -- cmd/* schema
 fi
 
 version=$(git describe --tags --always --dirty)
@@ -73,8 +73,11 @@ cross_build() {
 	done
 }
 
-schema_generate
-for cmd in "$@"; do
-	cmd=$(basename "${cmd}")
-	host_build "${cmd}"
+for arg in "$@"; do
+    if [ "${arg}" = "schema" ]; then
+        schema_generate
+    else
+	    cmd=$(basename "${arg}")
+	    host_build "${cmd}"
+    fi
 done