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    CWG Issue 98</TITLE>
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<P><EM>This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21
  Core Issues List revision 118b.
  See http://www.open-std.org/jtc1/sc22/wg21/ for the official
  list.</EM></P>
<P>2025-09-28</P>
<HR>
<A NAME="98"></A><H4>98.
  
Branching into try block
</H4>
<B>Section: </B>Clause 14&#160; [<A href="https://wg21.link/except">except</A>]
 &#160;&#160;&#160;

 <B>Status: </B>TC1
 &#160;&#160;&#160;

 <B>Submitter: </B>Jack Rouse
 &#160;&#160;&#160;

 <B>Date: </B>23 Feb 1999<BR>



<P>At the top of clause 15, in paragraph 2, it says:</P>
<BLOCKQUOTE>
A <TT>goto</TT>, <TT>break</TT>, <TT>return</TT>, or <TT>continue</TT> statement can be used to transfer
control out of a try block or handler, but not into one.
</BLOCKQUOTE>
What about <TT>switch</TT> statements?
<PRE>
    switch ( f() )
    {
    case 1:
         try {
             g();
    case 2:
             h();
         }
         catch (...)
         {
             // handler
         }
    break;
    }
</PRE>

<B>Daveed Vandevoorde:</B>

<P>Consider:</P>
<PRE>
    void f() {
        try {
        label:
            ;
        } catch(...) {
            goto label;
        }
    }
</PRE>

Now the phrase "try block" (without a hyphen) is used in paragraph
1 in a way that causes me to think that it is not intended to
include the corresponding handlers. On the other hand, the grammar
entity "<I>try-block</I>" (with hyphen) does include the handlers.

So is the intent to prohibit the above or not?

<P><B>Proposed resolution (10/00:</B></P>

<P>Change text in Clause 14 [<A href="https://wg21.link/except#2">except</A>] paragraph 2 from:</P>

<BLOCKQUOTE>A <TT>goto</TT>, <TT>break</TT>, <TT>return</TT>, or
<TT>continue</TT> statement
can be used to transfer control out of a try block or handler, but not
into one.
</BLOCKQUOTE>
to:
<BLOCKQUOTE>
A <TT>goto</TT> or <TT>switch</TT> statement shall not be used
to transfer control into a try block or into a handler.
<BR>[ <I>Example:</I>
<BLOCKQUOTE>
<TT>void f() {</TT>
<BR><TT>&#160; goto l1;&#160; // Ill-formed</TT>
<BR><TT>&#160; goto l2;&#160; // Ill-formed</TT>
<BR><TT>&#160; try {</TT>
<BR><TT>&#160;&#160;&#160; goto l1;&#160; // OK</TT>
<BR><TT>&#160;&#160;&#160; goto l2;&#160; // Ill-formed</TT>
<BR><TT>&#160;&#160;&#160; l1: ;</TT>
<BR><TT>&#160; } catch (...) {</TT>
<BR><TT>&#160;&#160;&#160; l2: ;</TT>
<BR><TT>&#160;&#160;&#160; goto l1;&#160; // Ill-formed</TT>
<BR><TT>&#160;&#160;&#160; goto l2;&#160; // OK</TT>
<BR><TT>&#160; }</TT>
<BR><TT>}</TT>
</BLOCKQUOTE>
&#8212;<I>end example</I> ]
<BR>A <TT>goto</TT>, <TT>break</TT>, <TT>return</TT>, or <TT>continue</TT>
statement can be used to transfer control out of a try block or handler.
</BLOCKQUOTE>

<P>(See also <A HREF="246.html">issue 246</A>.)</P>

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