fixes #18858 [backport] (#18868)

* fixes #18858 [backport]

* ensure async tests work with --experimental:strictEffects [backport]

* ensure async tests work with --experimental:strictEffects [backport]

lib/pure/asyncfutures.nim

@@ -93,7 +93,7 @@ proc setCallSoonProc*(p: (proc(cbproc: proc ()) {.gcsafe.})) =
   ## Change current implementation of `callSoon`. This is normally called when dispatcher from `asyncdispatcher` is initialized.
   callSoonProc = p
 
-proc callSoon*(cbproc: proc ()) =
+proc callSoon*(cbproc: proc () {.gcsafe.}) =
   ## Call `cbproc` "soon".
   ##
   ## If async dispatcher is running, `cbproc` will be executed during next dispatcher tick.

lib/pure/osproc.nim

@@ -330,12 +330,16 @@ proc countProcessors*(): int {.rtl, extern: "nosp$1".} =
   ## It is implemented just calling `cpuinfo.countProcessors`.
   result = cpuinfo.countProcessors()
 
+when not defined(nimHasEffectsOf):
+  {.pragma: effectsOf.}
+
 proc execProcesses*(cmds: openArray[string],
     options = {poStdErrToStdOut, poParentStreams}, n = countProcessors(),
     beforeRunEvent: proc(idx: int) = nil,
     afterRunEvent: proc(idx: int, p: Process) = nil):
   int {.rtl, extern: "nosp$1",
-        tags: [ExecIOEffect, TimeEffect, ReadEnvEffect, RootEffect].} =
+        tags: [ExecIOEffect, TimeEffect, ReadEnvEffect, RootEffect],
+        effectsOf: [beforeRunEvent, afterRunEvent].} =
   ## Executes the commands `cmds` in parallel.
   ## Creates `n` processes that execute in parallel.
   ##

lib/pure/unicode.nim

@@ -705,8 +705,11 @@ proc capitalize*(s: string): string {.noSideEffect,
   fastRuneAt(s, i, rune, doInc = true)
   result = $toUpper(rune) & substr(s, i)
 
+when not defined(nimHasEffectsOf):
+  {.pragma: effectsOf.}
+
 proc translate*(s: string, replacements: proc(key: string): string): string {.
-  rtl, extern: "nuc$1".} =
+  rtl, extern: "nuc$1", effectsOf: replacements.} =
   ## Translates words in a string using the ``replacements`` proc to substitute
   ## words inside ``s`` with their replacements.
   ##

tests/async/nim.cfg

@@ -0,0 +1 @@
+--experimental:strictEffects