js -r defines nodejs & program result undeclared if unavailable (#21849)

* js -r defines nodejs & program result undefined if unavailable

fixes #16985, fixes #16074

* fix

* add changelog too

* minor word change

changelogs/changelog_2_0_0.md

@@ -249,6 +249,10 @@
   these deprecated aliases are likely not used anymore and it may make sense
   to simply remove these statements.
 
+- `getProgramResult` and `setProgramResult` in `std/exitprocs` are no longer
+  declared when they are not available on the backend. Previously it would call
+  `doAssert false` at runtime despite the condition being compile-time.
+
 ## Standard library additions and changes
 
 [//]: # "Changes:"

compiler/commands.nim

@@ -654,6 +654,9 @@ proc processSwitch*(switch, arg: string, pass: TCmdLinePass, info: TLineInfo;
     if backend == TBackend.default: localError(conf, info, "invalid backend: '$1'" % arg)
     if backend == backendJs: # bug #21209
       conf.globalOptions.excl {optThreadAnalysis, optThreads}
+      if optRun in conf.globalOptions:
+        # for now, -r uses nodejs, so define nodejs
+        defineSymbol(conf.symbols, "nodejs")
     conf.backend = backend
   of "doccmd": conf.docCmd = arg
   of "define", "d":
@@ -864,6 +867,9 @@ proc processSwitch*(switch, arg: string, pass: TCmdLinePass, info: TLineInfo;
       setTarget(conf.target, conf.target.targetOS, cpu)
   of "run", "r":
     processOnOffSwitchG(conf, {optRun}, arg, pass, info)
+    if conf.backend == backendJs:
+      # for now, -r uses nodejs, so define nodejs
+      defineSymbol(conf.symbols, "nodejs")
   of "maxloopiterationsvm":
     expectArg(conf, switch, arg, pass, info)
     conf.maxLoopIterationsVM = parseInt(arg)

lib/pure/unittest.nim

@@ -519,6 +519,12 @@ proc exceptionTypeName(e: ref Exception): string {.inline.} =
   if e == nil: "<foreign exception>"
   else: $e.name
 
+when not declared(setProgramResult):
+  {.warning: "setProgramResult not available on platform, unittest will not" &
+    " give failing exit code on test failure".}
+  template setProgramResult(a: int) =
+    discard
+
 template test*(name, body) {.dirty.} =
   ## Define a single test case identified by `name`.
   ##

lib/std/exitprocs.nim

@@ -69,23 +69,19 @@ proc addExitProc*(cl: proc() {.noconv.}) =
     fun()
     gFuns.add Fun(kind: kNoconv, fun2: cl)
 
-when not defined(nimscript):
+when not defined(nimscript) and (not defined(js) or defined(nodejs)):
   proc getProgramResult*(): int =
     when defined(js) and defined(nodejs):
       asm """
 `result` = process.exitCode;
 """
-    elif not defined(js):
-      result = programResult
     else:
-      doAssert false
+      result = programResult
 
   proc setProgramResult*(a: int) =
     when defined(js) and defined(nodejs):
       asm """
 process.exitCode = `a`;
 """
-    elif not defined(js):
-      programResult = a
     else:
-      doAssert false
+      programResult = a