fix(Lib/errno): #ifdef wrongly inserted(missing in fact)...

previous ifdef exists in emit of a macro, so just ignored
... fixes errno cannot compile on Windows

Author: litlighilit

src/pylib/Lib/errno_impl/private/errorcodeInit.nim

@@ -2,6 +2,7 @@
 
 import ./errnos
 import ./loopErrno
+import ./clike
 export errnos
 
 import std/enumutils
@@ -13,12 +14,34 @@ macro initErrorcodeMap*(K, V; res: untyped, initFunc: typed) =
   let N = newLit ErrnoCount
   result.add quote do:
     var `res` = `initFunc`[`K`, `V`](`N`)
-  forErrno e:
-    let
-      errName = symbolName e
-      errNameNode = newLit errName
-      errId = ident errName
-    result.add quote do:
-      `res`[`errId`] = `errNameNode`
+  #[
+  XXX: NIM-BUG: if using `let` in forErrno loop (in Windows):
+  errorcodeInit.nim(18, 7) Error: redefinition of 'errName'; previous declaration here: errorcodeInit.nim(18, 7)
+  ]#
+  var
+    errName: string
+    errNameNode, errId: NimNode
+  result.forErrno e:
+    errName = symbolName e
+    errNameNode = newLit errName
+    errId = ident errName
+    let addErrnoId = genSym(nskProc, errName)
+    when CLike:
+      # NOTE: just wrap in `res`[`errId`] = `errNameNode` directly in `#ifdef`
+      #   doesn't work, as `#ifdef ..  #endif` will not be placed right
+      #   around stmt, but
+      #   very early in the C file.
+      #  so we use a proc.
+      result.add quote do:
+        proc `addErrnoId`(){.inline.} =
+          {.emit: "\n#ifdef " & `errNameNode` & '\n'.}
+          `res`[`errId`] = `errNameNode`
+          {.emit: "\n#endif\n".}
+      result.add newCall(addErrnoId)
+    else:
+      result.add quote do:
+        `res`[`errId`] = `errNameNode`
 
-template declErrorcodeWith*[K, V](initFunc: typed) = initErrorcodeMap K, V,errorcode, initFunc
+template declErrorcodeWith*[K, V](initFunc: typed) =
+  bind initErrorcodeMap
+  initErrorcodeMap K, V,errorcode, initFunc

src/pylib/Lib/errno_impl/private/exportUtils.nim

@@ -16,7 +16,7 @@ template eno(E) =
 
 macro exportAllErrnosViaEnumOrImportc*() =
   result = newStmtList()
-  forErrno e:
+  result.forErrno e:
     result.add newCall(bindSym"eno", ident symbolName e)    
 
 

src/pylib/Lib/errno_impl/private/loopErrno.nim

@@ -1,17 +1,30 @@
+import std/macros
+import std/enumutils
 import ./clike
 import ./errnos
-template whenDefErrno*(err; body) =
-  bind CLike
-  when not CLike: body
+
+template emitPragma(body: string): NimNode =
+  nnkPragma.newTree(
+    nnkExprColonExpr.newTree(
+      newIdentNode("emit"),
+      newLit(body)
+    )
+  )
+
+template whenDefErrno*(res: NimNode; errnoName: string; body): untyped{.dirty.} =
+  bind CLike, add, quote, emitPragma
+  when CLike:
+    # hint: following takes the responsibility to make declaration of errnoName
+    #       to be wrapped by `#ifdef`
+    res.add emitPragma "\n#ifdef " & errnoName & '\n'
+    body
+    res.add emitPragma "\n#endif\n"
   else:
-    const errS = astToStr(err)
-    {.emit: "\n#ifdef " & errS & '\n'.}
     body
-    {.emit: "\n#endif\n".}
 
-template forErrno*(err; body) =
+template forErrno*(res: NimNode; err; body) =
   bind whenDefErrno, Errno
-  for err{.inject.} in Errno:
-    if err == Errno.E_SUCCESS: continue
-    whenDefErrno err:
+  for err{.inject.} in succ(Errno.E_SUCCESS)..high(Errno):
+    #if err == Errno.E_SUCCESS: continue
+    result.whenDefErrno symbolName err:
       body