From 508fc1b5ec0df20e57bfcc23e22d54c3c79e2d0b Mon Sep 17 00:00:00 2001
From: David Perez <david@fccma.com>
Date: Thu, 12 Mar 2015 15:30:43 +0100
Subject: [PATCH 1/4] Issue 1900, more robustness in help system

---
 main/command/src/main/scala/sbt/BasicCommands.scala | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/main/command/src/main/scala/sbt/BasicCommands.scala b/main/command/src/main/scala/sbt/BasicCommands.scala
index 3310158b8..36072ecc6 100644
--- a/main/command/src/main/scala/sbt/BasicCommands.scala
+++ b/main/command/src/main/scala/sbt/BasicCommands.scala
@@ -27,7 +27,10 @@ object BasicCommands {
 
   def helpParser(s: State) =
     {
-      val h = (Help.empty /: s.definedCommands)(_ ++ _.help(s))
+      val h = (Help.empty /: s.definedCommands) { (a, b) ⇒
+        a ++
+          (try b.help(s) catch { case ex: Throwable ⇒ Help.empty })
+      }
       val helpCommands = h.detail.keySet
       val spacedArg = singleArgument(helpCommands).?
       applyEffect(spacedArg)(runHelp(s, h))
@@ -35,7 +38,12 @@ object BasicCommands {
 
   def runHelp(s: State, h: Help)(arg: Option[String]): State =
     {
-      val message = Help.message(h, arg)
+      val message = try
+        Help.message(h, arg)
+      catch {
+        case ex: Throwable ⇒
+          ex.toString
+      }
       System.out.println(message)
       s
     }

From 79ef77221954e2f8f5dd8bbb2d1b166b55b8f139 Mon Sep 17 00:00:00 2001
From: David Perez <david@fccma.com>
Date: Tue, 24 Mar 2015 14:54:10 +0100
Subject: [PATCH 2/4] Removed unicode arrow

---
 main/command/src/main/scala/sbt/BasicCommands.scala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/main/command/src/main/scala/sbt/BasicCommands.scala b/main/command/src/main/scala/sbt/BasicCommands.scala
index 36072ecc6..6338c6b5d 100644
--- a/main/command/src/main/scala/sbt/BasicCommands.scala
+++ b/main/command/src/main/scala/sbt/BasicCommands.scala
@@ -29,7 +29,7 @@ object BasicCommands {
     {
       val h = (Help.empty /: s.definedCommands) { (a, b) ⇒
         a ++
-          (try b.help(s) catch { case ex: Throwable ⇒ Help.empty })
+          (try b.help(s) catch { case ex: Throwable => Help.empty })
       }
       val helpCommands = h.detail.keySet
       val spacedArg = singleArgument(helpCommands).?

From 2c52efeca5675eca6cefe9e3b8a22468a747781b Mon Sep 17 00:00:00 2001
From: David Perez <david@fccma.com>
Date: Wed, 25 Mar 2015 13:14:48 +0100
Subject: [PATCH 3/4] Removed unicode arrow

---
 main/command/src/main/scala/sbt/BasicCommands.scala | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/main/command/src/main/scala/sbt/BasicCommands.scala b/main/command/src/main/scala/sbt/BasicCommands.scala
index 6338c6b5d..50cabf7cd 100644
--- a/main/command/src/main/scala/sbt/BasicCommands.scala
+++ b/main/command/src/main/scala/sbt/BasicCommands.scala
@@ -27,7 +27,7 @@ object BasicCommands {
 
   def helpParser(s: State) =
     {
-      val h = (Help.empty /: s.definedCommands) { (a, b) ⇒
+      val h = (Help.empty /: s.definedCommands) { (a, b) =>
         a ++
           (try b.help(s) catch { case ex: Throwable => Help.empty })
       }
@@ -41,7 +41,7 @@ object BasicCommands {
       val message = try
         Help.message(h, arg)
       catch {
-        case ex: Throwable ⇒
+        case ex: Throwable =>
           ex.toString
       }
       System.out.println(message)

From 5ce11c67c54190d7137b91f8f5289113e4b547d4 Mon Sep 17 00:00:00 2001
From: David Perez <david@fccma.com>
Date: Wed, 25 Mar 2015 15:02:45 +0100
Subject: [PATCH 4/4] Catch exceptions with NonFatal

---
 main/command/src/main/scala/sbt/BasicCommands.scala | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/main/command/src/main/scala/sbt/BasicCommands.scala b/main/command/src/main/scala/sbt/BasicCommands.scala
index 50cabf7cd..caab8ea5c 100644
--- a/main/command/src/main/scala/sbt/BasicCommands.scala
+++ b/main/command/src/main/scala/sbt/BasicCommands.scala
@@ -13,6 +13,8 @@ import BasicKeys._
 
 import java.io.File
 
+import scala.util.control.NonFatal
+
 object BasicCommands {
   lazy val allBasicCommands = Seq(nop, ignore, help, completionsCommand, multi, ifLast, append, setOnFailure, clearOnFailure, stashOnFailure, popOnFailure, reboot, call, early, exit, continuous, history, shell, read, alias) ++ compatCommands
 
@@ -29,7 +31,7 @@ object BasicCommands {
     {
       val h = (Help.empty /: s.definedCommands) { (a, b) =>
         a ++
-          (try b.help(s) catch { case ex: Throwable => Help.empty })
+          (try b.help(s) catch { case NonFatal(ex) => Help.empty })
       }
       val helpCommands = h.detail.keySet
       val spacedArg = singleArgument(helpCommands).?
@@ -41,7 +43,7 @@ object BasicCommands {
       val message = try
         Help.message(h, arg)
       catch {
-        case ex: Throwable =>
+        case NonFatal(ex) =>
           ex.toString
       }
       System.out.println(message)