Re: [perl #34984] [PATCH] Fix segfault with const

[Nick Glencross]

Leopold Toetsch via RT wrote:
Nick Glencross <[EMAIL PROTECTED]> wrote:
 

This patch fixes a problem which can occur in this example:
   

 

.sub test
       .const float a = 12
       print a
       print_newline
.end
   

Ah yep.
 

+    if (t != 'P' && t != val->set)
+        IMCC_fataly(interp, E_TypeError,
+                    "const types do not match");
   

I think, we could be a bit more graceful here for I/N mismatch and set
for the above case the constant val->set to 'N'.
 

Yes, I was planning to do something a bit more thorough, but fixing the 
immediate segfault was the first challenge.

I've looked over the code a bit more now, and see that the value is 
still stored textually at this point, so setting the type as you've said 
is pretty simple. It's a shame that strings can be in a number of 
different formats, and probably quoted, preventing this from working for 
them too.

Anyhow, here's a new patch for you to review, and perhaps apply...?
Cheers,
Nick
Index: imcc/symreg.c
===================================================================
--- imcc/symreg.c       (revision 7843)
+++ imcc/symreg.c       (working copy)
@@ -307,6 +307,7 @@
     INS(interp, unit, "set_p_pc", "", r, 2, 0, 1);
     return NULL;
 }
+
 /* Makes a new identifier constant with value val */
 SymReg *
 mk_const_ident(Interp *interp,
@@ -314,6 +315,16 @@
 {
     SymReg *r;
 
+    // Forbid assigning a string to anything other than a string const
+    // for now
+    if (t != 'S' && val->set == 'S')
+        IMCC_fataly(interp, E_TypeError,
+                    "bad const initialisation");
+
+    // Cast value to const type
+    if (t == 'S' || t == 'I')
+        val->set = t;
+
     if (global) {
         if (t == 'P') {
             IMCC_fataly(interp, E_SyntaxError,