From 2b9e5377f17824e43b45efa7f647a902786fb681 Mon Sep 17 00:00:00 2001
From: Robert Schadek <rschadek@symmetryinvestments.com>
Date: Thu, 15 Aug 2019 08:49:55 +0100
Subject: [PATCH] adds assert messages to std.concurrency

* Nicholas review
---
 std/concurrency.d | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/std/concurrency.d b/std/concurrency.d
index 1d7d02b59..838fc8f0b 100644
--- a/std/concurrency.d
+++ b/std/concurrency.d
@@ -184,9 +184,12 @@ private
 
     void checkops(T...)(T ops)
     {
+        import std.format : format;
+
         foreach (i, t1; T)
         {
-            static assert(isFunctionPointer!t1 || isDelegate!t1);
+            static assert(isFunctionPointer!t1 || isDelegate!t1,
+                    format!"T %d is not a function pointer or delegates"(i));
             alias a1 = Parameters!(t1);
             alias r1 = ReturnType!(t1);
 
@@ -198,7 +201,6 @@ private
 
                 foreach (t2; T[i + 1 .. $])
                 {
-                    static assert(isFunctionPointer!t2 || isDelegate!t2);
                     alias a2 = Parameters!(t2);
 
                     static assert(!is(a1 == a2),
@@ -1987,7 +1989,7 @@ private
         {
             import std.meta : AliasSeq;
 
-            static assert(T.length);
+            static assert(T.length, "T must not be empty");
 
             static if (isImplicitlyConvertible!(T[0], Duration))
             {
@@ -2028,7 +2030,8 @@ private
 
             bool onLinkDeadMsg(ref Message msg)
             {
-                assert(msg.convertsTo!(Tid));
+                assert(msg.convertsTo!(Tid),
+                        "Message could be converted to Tid");
                 auto tid = msg.get!(Tid);
 
                 if (bool* pDepends = tid in thisInfo.links)
@@ -2205,7 +2208,8 @@ private
         {
             static void onLinkDeadMsg(ref Message msg)
             {
-                assert(msg.convertsTo!(Tid));
+                assert(msg.convertsTo!(Tid),
+                        "Message could be converted to Tid");
                 auto tid = msg.get!(Tid);
 
                 thisInfo.links.remove(tid);
@@ -2350,7 +2354,7 @@ private
         {
             import std.exception : enforce;
 
-            assert(m_count);
+            assert(m_count, "Can not remove from empty Range");
             Node* n = r.m_prev;
             enforce(n && n.next, "attempting to remove invalid list node");