From 896c60d18c86b5062c0645a1cad0c2d991074d24 Mon Sep 17 00:00:00 2001
From: Stephen Heumann <stephenheumann@gmail.com>
Date: Mon, 21 Nov 2016 00:25:58 -0600
Subject: [PATCH] Determine the type to use for computing a >>= or <<=
 operation based only on the left operand.
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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 | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/Expression.pas b/Expression.pas
index b7d0977..0001b58 100644
--- a/Expression.pas
+++ b/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: