Make bitwise_expression forwards compatible

Skip syms for tmath

Skip more syms

Add casting back for cast_expression. Disable cast test on Nim < 1.0.0

Skip more syms for cast expressions on Nim < 1.0.0

tests/tast2.nim

@@ -3,11 +3,16 @@ import macros, os, sets, strutils
 import nimterop/[cimport]
 
 static:
+  # Skip casting on lower nim compilers because
+  # the VM does not support it
+  when (NimMajor, NimMinor, NimPatch) < (1, 0, 0):
+    cSkipSymbol @["CASTEXPR"]
   cDebug()
 
 const
   path = currentSourcePath.parentDir() / "include" / "tast2.h"
 
+
 when defined(HEADER):
   cDefine("HEADER")
   const
@@ -118,7 +123,9 @@ assert BINEXPR == 5
 assert BOOL == true
 assert MATHEXPR == -99
 assert ANDEXPR == 96
-assert CASTEXPR == 34.chr
+
+when (NimMajor, NimMinor, NimPatch) >= (1, 0, 0):
+  assert CASTEXPR == 34.chr
 
 assert TRICKYSTR == "N\x1C\nfoo\x00\'\"\c\v\a\b\e\f\t\\\\?bar"
 assert NULLCHAR == '\0'
@@ -453,4 +460,4 @@ checkPragmas(nested, pHeaderImpBy)
 
 when defined(HEADER):
   assert sitest1(5) == 10
-  assert sitest1(10) == 20
+  assert sitest1(10) == 20

tests/tmath.nim

@@ -13,6 +13,10 @@ when defined(windows):
       complex = object
 
 static:
+  when (NimMajor, NimMinor, NimPatch) < (1, 0, 0):
+    cSkipSymbol @["mingw_choose_expr", "EXCEPTION_DEFINED", "COMPLEX_DEFINED", "matherr", "HUGE", "FP_ILOGB0", "FP_ILOGBNAN"]
+  else:
+    cSkipSymbol @["mingw_choose_expr", "EXCEPTION_DEFINED", "COMPLEX_DEFINED", "matherr", "HUGE"]
   cDebug()
   cDisableCaching()
   cAddStdDir()