Cosmetic compiler cleanup (#12718)

* Cleanup compiler code base

* Unify add calls

* Unify len invocations

* Unify range operators

* Fix oversight

* Remove {.procvar.} pragma

* initCandidate -> newCandidate where reasonable

* Unify safeLen calls

compiler/rodutils.nim

@@ -51,10 +51,10 @@ proc toStrMaxPrecision*(f: BiggestFloat, literalPostfix = ""): string =
     setLen(result, n)
 
 proc encodeStr*(s: string, result: var string) =
-  for i in 0 ..< len(s):
+  for i in 0..<s.len:
     case s[i]
-    of 'a'..'z', 'A'..'Z', '0'..'9', '_': add(result, s[i])
-    else: add(result, '\\' & toHex(ord(s[i]), 2))
+    of 'a'..'z', 'A'..'Z', '0'..'9', '_': result.add(s[i])
+    else: result.add('\\' & toHex(ord(s[i]), 2))
 
 proc hexChar(c: char, xi: var int) =
   case c
@@ -73,9 +73,9 @@ proc decodeStr*(s: cstring, pos: var int): string =
       var xi = 0
       hexChar(s[i-2], xi)
       hexChar(s[i-1], xi)
-      add(result, chr(xi))
+      result.add(chr(xi))
     of 'a'..'z', 'A'..'Z', '0'..'9', '_':
-      add(result, s[i])
+      result.add(s[i])
       inc(i)
     else: break
   pos = i
@@ -96,7 +96,7 @@ template encodeIntImpl(self) =
   var v = x
   var rem = v mod 190
   if rem < 0:
-    add(result, '-')
+    result.add('-')
     v = - (v div 190)
     rem = - rem
   else:
@@ -105,7 +105,7 @@ template encodeIntImpl(self) =
   if idx < 62: d = chars[idx]
   else: d = chr(idx - 62 + 128)
   if v != 0: self(v, result)
-  add(result, d)
+  result.add(d)
 
 proc encodeVBiggestIntAux(x: BiggestInt, result: var string) =
   ## encode a biggest int as a variable length base 190 int.