fix warnings for deprecated low and high (#15291)

compiler/ast.nim

@@ -1356,8 +1356,8 @@ proc newType*(kind: TTypeKind, owner: PSym): PType =
       writeStackTrace()
 
 proc mergeLoc(a: var TLoc, b: TLoc) =
-  if a.k == low(a.k): a.k = b.k
-  if a.storage == low(a.storage): a.storage = b.storage
+  if a.k == low(typeof(a.k)): a.k = b.k
+  if a.storage == low(typeof(a.storage)): a.storage = b.storage
   a.flags.incl b.flags
   if a.lode == nil: a.lode = b.lode
   if a.r == nil: a.r = b.r

compiler/saturate.nim

@@ -15,33 +15,33 @@ proc `|+|`*(a, b: BiggestInt): BiggestInt =
   if (result xor a) >= 0'i64 or (result xor b) >= 0'i64:
     return result
   if a < 0 or b < 0:
-    result = low(result)
+    result = low(typeof(result))
   else:
-    result = high(result)
+    result = high(typeof(result))
 
 proc `|-|`*(a, b: BiggestInt): BiggestInt =
   result = a -% b
   if (result xor a) >= 0'i64 or (result xor not b) >= 0'i64:
     return result
   if b > 0:
-    result = low(result)
+    result = low(typeof(result))
   else:
-    result = high(result)
+    result = high(typeof(result))
 
 proc `|abs|`*(a: BiggestInt): BiggestInt =
-  if a != low(a):
+  if a != low(typeof(a)):
     if a >= 0: result = a
     else: result = -a
   else:
-    result = low(a)
+    result = low(typeof(a))
 
 proc `|div|`*(a, b: BiggestInt): BiggestInt =
   # (0..5) div (0..4) == (0..5) div (1..4) == (0 div 4)..(5 div 1)
   if b == 0'i64:
     # make the same as ``div 1``:
     result = a
-  elif a == low(a) and b == -1'i64:
-    result = high(result)
+  elif a == low(typeof(a)) and b == -1'i64:
+    result = high(typeof(result))
   else:
     result = a div b
 
@@ -74,6 +74,6 @@ proc `|*|`*(a, b: BiggestInt): BiggestInt =
     return result
 
   if floatProd >= 0.0:
-    result = high(result)
+    result = high(typeof(result))
   else:
-    result = low(result)
+    result = low(typeof(result))

compiler/vmgen.nim

@@ -611,7 +611,7 @@ proc genField(c: PCtx; n: PNode): TRegister =
   if n.kind != nkSym or n.sym.kind != skField:
     globalError(c.config, n.info, "no field symbol")
   let s = n.sym
-  if s.position > high(result):
+  if s.position > high(typeof(result)):
     globalError(c.config, n.info,
         "too large offset! cannot generate code for: " & s.name.s)
   result = s.position