chore: enable Nim 2.0.x and fix compilation issues (#1146)

This PR enables Nim 2.0.x with `refc` garbage collector on CI.

The following compilation error had to be fixed: Error: undeclared
identifier: 'acceptHandler`gensym435'; if declared in a template, this
identifier may be inconsistently marked inject or gensym

.github/workflows/ci.yml

@@ -27,7 +27,7 @@ jobs:
             cpu: amd64
           #- os: windows
             #cpu: i386
-        branch: [version-1-6]
+        branch: [version-1-6, version-2-0]
         include:
           - target:
               os: linux

libp2p.nimble

@@ -126,7 +126,7 @@ task examples_build, "Build the samples":
   buildSample("tutorial_5_discovery", true)
   exec "nimble install -y nimpng@#HEAD"
     # this is to fix broken build on 1.7.3, remove it when nimpng version 0.3.2 or later is released
-  exec "nimble install -y nico"
+  exec "nimble install -y nico@#af99dd60bf2b395038ece815ea1012330a80d6e6"
   buildSample("tutorial_6_game", false, "--styleCheck:off")
 
 # pin system

tests/commontransport.nim

@@ -144,7 +144,7 @@ template commonTransportTest*(prov: TransportProvider, ma1: string, ma2: string
       let transport1 = transpProvider()
       await transport1.start(addrs)
 
-      proc acceptHandler() {.async.} =
+      proc acceptHandler() {.async, gensym.} =
         while true:
           let conn = await transport1.accept()
           await conn.write(newSeq[byte](0))
@@ -208,7 +208,7 @@ template commonTransportTest*(prov: TransportProvider, ma1: string, ma2: string
       let transport1 = transpProvider()
       await transport1.start(ma)
 
-      proc acceptHandler() {.async.} =
+      proc acceptHandler() {.async, gensym.} =
         let conn = await transport1.accept()
         await conn.close()
 

tests/config.nims

@@ -18,6 +18,9 @@ import strutils, os
 --d:
   unittestPrintTime
 --skipParentCfg
+--mm:
+  refc
+  # reconsider when there's a version-2-2 branch worth testing with as we might switch to orc
 
 # Only add chronicles param if the
 # user didn't specify any