Determine the type to use for computing a >>= or <<= operation based only on the left operand.

Also, fix a case where an uninitialized value could be used, potentially resulting in errors not being reported (although I haven’t seen that in practice).

This fixes problems where >>= operations might not use an arithmetic shift in certain cases where they should, as in the below program:

#include <stdio.h>
int main (void)
{
    int i;
    unsigned u;
    long l;
    unsigned long ul;

    i = -1;
    u = 1;
    i >>= u;
    printf("%i\n", i); /* should be -1 */

    l = -1;
    ul = 3;
    l >>= ul;
    printf("%li\n", l); /* should be -1 */
}

Expression.pas

@@ -2963,8 +2963,19 @@ case tree^.token.kind of
       else
          kind := lType^.kind;
       GenerateCode(tree^.right);
+      if tree^.token.kind in [gtgteqop,ltlteqop] then
+         if kind = scalarType then
+            if expressionType^.kind = scalarType then begin
+               et := UsualUnaryConversions;
+               if et <> Unary(ltype^.baseType) then begin
+                  Gen2(pc_cnv, et, ord(Unary(ltype^.baseType)));
+                  expressionType := lType;
+                  end; {if}
+               end; {if}
       if kind <> pointerType then
-         et := UsualBinaryConversions(lType);
+         et := UsualBinaryConversions(lType)
+      else
+         et := ccPointer;
       case tree^.token.kind of
 
          pluseqop: