From 34c1c4b9545e7216503db2f2514c0ff5a8d7bc45 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bastian=20K=C3=B6cher?= <bkchr@users.noreply.github.com>
Date: Wed, 29 Jan 2020 09:52:54 +0100
Subject: [PATCH] Don't run dev light client as validator (#4757)

A light client can not be a validator, so we should not set `authority
== true` in dev mode.
---
 substrate/client/cli/src/lib.rs    | 8 +++++---
 substrate/client/cli/src/params.rs | 5 ++++-
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/substrate/client/cli/src/lib.rs b/substrate/client/cli/src/lib.rs
index fc50259528..d9ea238ba0 100644
--- a/substrate/client/cli/src/lib.rs
+++ b/substrate/client/cli/src/lib.rs
@@ -998,9 +998,11 @@ where
 	fill_config_keystore_password_and_path(&mut config, &cli)?;
 
 	let is_dev = cli.shared_params.dev;
-	let is_authority = cli.validator || cli.sentry || is_dev || cli.keyring.account.is_some();
+	let is_light = cli.light;
+	let is_authority = (cli.validator || cli.sentry || is_dev || cli.keyring.account.is_some())
+		&& !is_light;
 	let role =
-		if cli.light {
+		if is_light {
 			sc_service::Roles::LIGHT
 		} else if is_authority {
 			sc_service::Roles::AUTHORITY
@@ -1056,7 +1058,7 @@ where
 
 	config.dev_key_seed = cli.keyring.account
 		.map(|a| format!("//{}", a)).or_else(|| {
-			if is_dev {
+			if is_dev && !is_light {
 				Some("//Alice".into())
 			} else {
 				None
diff --git a/substrate/client/cli/src/params.rs b/substrate/client/cli/src/params.rs
index 57b90c2e73..ccaf24454d 100644
--- a/substrate/client/cli/src/params.rs
+++ b/substrate/client/cli/src/params.rs
@@ -417,7 +417,10 @@ pub struct RunCmd {
 	pub no_grandpa: bool,
 
 	/// Experimental: Run in light client mode.
-	#[structopt(long = "light")]
+	#[structopt(
+		long = "light",
+		conflicts_with_all = &[ "validator" ]
+	)]
 	pub light: bool,
 
 	/// Listen to all RPC interfaces.