system.nim cleanup some exported constants which should never have be… (#17909)

* system.nim cleanup some exported constants which should never have been exported

lib/pure/coro.nim

@@ -21,6 +21,8 @@
 ##
 ## Unstable API.
 
+import system/coro_detection
+
 when not nimCoroutines and not defined(nimdoc):
   when defined(noNimCoroutines):
     {.error: "Coroutines can not be used with -d:noNimCoroutines".}

lib/pure/os.nim

@@ -1910,7 +1910,7 @@ proc copyFileToDir*(source, dir: string, options = {cfSymlinkFollow})
   copyFile(source, dir / source.lastPathPart, options)
 
 when not declared(ENOENT) and not defined(windows):
-  when NoFakeVars:
+  when defined(nimscript):
     when not defined(haiku):
       const ENOENT = cint(2) # 2 on most systems including Solaris
     else:

lib/system.nim

@@ -537,7 +537,7 @@ const
 
 include "system/inclrtl"
 
-const NoFakeVars* = defined(nimscript) ## `true` if the backend doesn't support \
+const NoFakeVars = defined(nimscript) ## `true` if the backend doesn't support \
   ## "fake variables" like `var EBADF {.importc.}: cint`.
 
 const notJSnotNims = not defined(js) and not defined(nimscript)
@@ -1132,7 +1132,6 @@ const
 const
   hasThreadSupport = compileOption("threads") and not defined(nimscript)
   hasSharedHeap = defined(boehmgc) or defined(gogc) # don't share heaps; every thread has its own
-  nimEnableCovariance* = defined(nimEnableCovariance) # or true
 
 when hasThreadSupport and defined(tcc) and not compileOption("tlsEmulation"):
   # tcc doesn't support TLS
@@ -1920,24 +1919,7 @@ include "system/gc_interface"
 # we have to compute this here before turning it off in except.nim anyway ...
 const NimStackTrace = compileOption("stacktrace")
 
-template coroutinesSupportedPlatform(): bool =
-  when defined(sparc) or defined(ELATE) or defined(boehmgc) or defined(gogc) or
-    defined(nogc) or defined(gcRegions) or defined(gcMarkAndSweep):
-    false
-  else:
-    true
-
-when defined(nimCoroutines):
-  # Explicit opt-in.
-  when not coroutinesSupportedPlatform():
-    {.error: "Coroutines are not supported on this architecture and/or garbage collector.".}
-  const nimCoroutines* = true
-elif defined(noNimCoroutines):
-  # Explicit opt-out.
-  const nimCoroutines* = false
-else:
-  # Autodetect coroutine support.
-  const nimCoroutines* = false
+import system/coro_detection
 
 {.push checks: off.}
 # obviously we cannot generate checking operations here :-)

lib/system/ansi_c.nim

@@ -74,7 +74,7 @@ elif defined(haiku):
     SIGPIPE* = cint(7)
     SIG_DFL* = cast[CSighandlerT](0)
 else:
-  when NoFakeVars:
+  when defined(nimscript):
     {.error: "SIGABRT not ported to your platform".}
   else:
     var

lib/system/coro_detection.nim

@@ -0,0 +1,20 @@
+## Coroutine detection logic
+
+template coroutinesSupportedPlatform(): bool =
+  when defined(sparc) or defined(ELATE) or defined(boehmgc) or defined(gogc) or
+    defined(nogc) or defined(gcRegions) or defined(gcMarkAndSweep):
+    false
+  else:
+    true
+
+when defined(nimCoroutines):
+  # Explicit opt-in.
+  when not coroutinesSupportedPlatform():
+    {.error: "Coroutines are not supported on this architecture and/or garbage collector.".}
+  const nimCoroutines* = true
+elif defined(noNimCoroutines):
+  # Explicit opt-out.
+  const nimCoroutines* = false
+else:
+  # Autodetect coroutine support.
+  const nimCoroutines* = false

lib/system/excpt.nim

@@ -146,7 +146,7 @@ proc closureIterSetupExc(e: ref Exception) {.compilerproc, inline.} =
 
 # some platforms have native support for stack traces:
 const
-  nativeStackTraceSupported* = (defined(macosx) or defined(linux)) and
+  nativeStackTraceSupported = (defined(macosx) or defined(linux)) and
                               not NimStackTrace
   hasSomeStackTrace = NimStackTrace or defined(nimStackTraceOverride) or
     (defined(nativeStackTrace) and nativeStackTraceSupported)

lib/system/io.nim

@@ -252,7 +252,7 @@ proc write*(f: File, s: string) {.tags: [WriteIOEffect], benign.} =
       raiseEIO("cannot write string to file")
 {.pop.}
 
-when NoFakeVars:
+when defined(nimscript):
   when defined(windows):
     const
       IOFBF = cint(0)