Fixed the constant folding to use a type for Int based on the compilation target rather than just assuming Int32

However, it is possible that there will still be a problem if the C and C++ compiler have different int sizes, because the constant folding has to know the type at compile time, and thus we have to arbitrarily choose to use the C version.  In future, we could perhaps swap all Ints for the appropriate substiution (e.g. Int64) at run-time, based on the flags and prior knowledge about C/C++ int sizes

common/EvalLiterals.hs

@@ -33,6 +33,7 @@ import qualified AST as A
 import CompState hiding (CSM) -- everything here is read-only
 import Errors
 import Metadata
+import TypeSizes
 
 type EvalM = ErrorT ErrorReport (StateT CompState Identity)
 
@@ -48,7 +49,7 @@ data OccValue =
   | OccUInt64 Word64
   | OccInt8 Int8
   | OccInt16 Int16
-  | OccInt Int32
+  | OccInt CIntReplacement
   | OccInt32 Int32
   | OccInt64 Int64
   | OccArray [OccValue]

config/TypeSizes.hs.in

@@ -1,8 +1,17 @@
 -- | This module is auto-generated by autoconf from TypeSizes.hs.in
 module TypeSizes where
 
+import Data.Int
+import qualified AST as A
+
 cBoolSize, cxxBoolSize, cIntSize, cxxIntSize :: Int
 cBoolSize = @C_BOOL_SIZE@
 cxxBoolSize = @CXX_BOOL_SIZE@
 cIntSize = @C_INT_SIZE@
 cxxIntSize = @CXX_INT_SIZE@
+type CIntReplacement = @C_INT_EQUIV@
+type CXXIntReplacement = @CXX_INT_EQUIV@
+cIntReplacement, cXXIntReplacement :: A.Type
+cIntReplacement = A.@C_INT_EQUIV@
+cXXIntReplacement = A.@CXX_INT_EQUIV@
+

configure.ac

@@ -193,6 +193,27 @@ AC_CHECK_SIZEOF(int)
 AC_COMPUTE_INT(C_INT_SIZE,SIZEOF_INT)
 AC_SUBST(C_INT_SIZE)
 
+if test "x$C_INT_SIZE" = "x2"; then
+C_INT_EQUIV=Int16
+fi
+if test "x$C_INT_SIZE" = "x4"; then
+C_INT_EQUIV=Int32
+fi
+if test "x$C_INT_SIZE" = "x8"; then
+C_INT_EQUIV=Int64
+fi
+if test "x$CXX_INT_SIZE" = "x2"; then
+CXX_INT_EQUIV=Int16
+fi
+if test "x$CXX_INT_SIZE" = "x4"; then
+CXX_INT_EQUIV=Int32
+fi
+if test "x$CXX_INT_SIZE" = "x8"; then
+CXX_INT_EQUIV=Int64
+fi
+AC_SUBST(C_INT_EQUIV)
+AC_SUBST(CXX_INT_EQUIV)
+
 CFLAGS="$CFLAGS $no_strict_overflow $no_tree_vrp"
 # The reason for -fno-strict-overflow and -fno-tree-vrp above is that with the way I have implemented
 # range checking, on GCC 4.3.2 (and probably other versions), GCC has