[RFC] dim: add a simple facility to require minimum dim version

[Jani Nikula]

Add simple single-digit dim version scheme, and add 'dim version'
subcommand to print it. Start off with version 0.

If $DIM_MIN_VERSION is set, bail out if the requirement is not met. The
idea is to set this in nightly.conf to be able to soft-enforce dim
updates before rolling out changes. (It's obviously possible to bypass
the requirement.)

We do have the dim uptodate nag, but it never bails out.

Signed-off-by: Jani Nikula <jani.nikula at intel.com>

---

Background: We're planning on finally dropping drm-intel-next-queued
branch in favor of just using drm-intel-next directly. This will need
some flag day updates. First roll out a way to enforce new
dim... although the users need to first update to a dim version that has
the facility. But gotta start somewhere.
---
 dim | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/dim b/dim
index 33e2400c32cc..8f2151365556 100755
--- a/dim
+++ b/dim
@@ -305,6 +305,11 @@ function branch_to_repo # branch
 	echo ""
 }
 
+function dim_version
+{
+	echo "0"
+}
+
 function dim_uptodate
 {
 	local using
@@ -417,6 +422,14 @@ function check_git_version
 	fi
 }
 
+function check_dim_version
+{
+	if [[ -n "$DIM_MIN_VERSION" ]] && [[ "$(dim_version)" < "$DIM_MIN_VERSION" ]]; then
+		echoerr "ERROR: required minimum dim version $DIM_MIN_VERSION, you have $(dim_version)"
+		exit 1
+	fi
+}
+
 function check_dim_config
 {
 	if [[ "$DIM_REPO" == "drm-tip" || "$DIM_REPO" == "drm-rerere" || "$DIM_REPO" == "maintainer-tools" ]];  then
@@ -2365,6 +2378,7 @@ function list_developer_commands
 		# help commands
 		"help"
 		"usage"
+		"version"
 		# include setup
 		"setup"
 	)
@@ -2622,6 +2636,7 @@ else
 	read_integration_config
 
 	check_for_updates
+	check_dim_version
 	check_git_version
 fi
 
-- 
2.20.1