remove default argument for readLines (nim-lang#12807) [backport]

(cherry picked from commit c949b81)

compiler/vmops.nim

@@ -143,7 +143,7 @@ proc registerAdditionalOps*(c: PCtx) =
     wrap1s(fileExists, osop)
     wrapDangerous(writeFile, ioop)
     wrap1s(readFile, ioop)
-    wrap2si(readLines, ioop)
+    wrap2si(staticReadLines, ioop)
     systemop getCurrentExceptionMsg
     systemop getCurrentException
     registerCallback c, "stdlib.*.staticWalkDir", proc (a: VmArgs) {.nimcall.} =

lib/system/io.nim

@@ -686,10 +686,10 @@ proc writeFile*(filename, content: string) {.tags: [WriteIOEffect], benign.} =
     sysFatal(IOError, "cannot open: " & filename)
 
 
-proc readLines*(filename: string, n = 1.Natural): seq[TaintedString] =
-  ## read `n` lines from the file named `filename`. Raises an IO exception
+proc staticReadLines*(filename: string, n: Natural): seq[TaintedString] =
+  ## Compile time read `n` lines from the file named `filename`. Raises an IO exception
   ## in case of an error. Raises EOF if file does not contain at least `n` lines.
-  ## Available at compile time. A line of text may be delimited by ``LF`` or ``CRLF``.
+  ## A line of text may be delimited by ``LF`` or ``CRLF``.
   ## The newline character(s) are not part of the returned strings.
   var f: File
   if open(f, filename):

tests/vm/tfile_rw.nim

@@ -13,7 +13,7 @@ static:
   writeFile(filename, mytext)
 const myfile_str = staticRead(filename)
 const myfile_str2 = readFile(filename)
-const myfile_str_seq = readLines(filename, 3)
+const myfile_str_seq = staticReadLines(filename, 3)
 
 static:
   doAssert myfile_str == mytext