From 6926e2c484e75bf17407f89f8200f5d18b34b84c Mon Sep 17 00:00:00 2001
From: Yehuda Katz <wycats@gmail.com>
Date: Wed, 1 Mar 2023 10:47:52 -0800
Subject: [PATCH] `make` bails on the wrong go version

This code:

1. Extracts the required go minor from `go.mod`
2. Gets the current go version from `go version` and normalizes it
3. Checks whether the required go minor is a version prefix for the current go
version, and bails if it isn't.
---
 make.sh | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/make.sh b/make.sh
index 60a938426..7e5d3a61a 100755
--- a/make.sh
+++ b/make.sh
@@ -1,5 +1,19 @@
 #!/bin/sh
 set -eu
+
+REQUIRED_GO_MINOR=$(sed -En 's/^go[[:space:]]+([[:digit:].]+)$/\1/p' go.mod)
+ACTUAL_GO_VERSION=$(go version | sed -n 's/^go version go\([0-9]*\.[0-9]*\.[0-9]*\)\(.*\)/\1/p')
+
+# We use 'case' instead of '[' to match values against complex patterns, because POSIX
+# does not guarantee that '[' supports advanced features like globs and regex.
+if case "$ACTUAL_GO_VERSION" in "$REQUIRED_GO_MINOR".*) false ;; *) true ;; esac then
+  red="\e[0;91m"
+  reset="\e[0m"
+
+  printf "${red}PROBLEM: You need go %s to build d2, but you have %s installed.${reset}\n" "$REQUIRED_GO_MINOR" "$ACTUAL_GO_VERSION"
+  exit 1
+fi
+
 if [ ! -e "$(dirname "$0")/ci/sub/.git" ]; then
   set -x
   git submodule update --init