[Bug c++/19699] New: [4.0 Regression] warning about not returning from end of a non-void function because of dead code

[Bug c++/19699] New: [4.0 Regression] warning about not returning from end of a non-void function because of dead code

[pinskia at gcc dot gnu dot org]

Reduced testcase (why don't we remove the dead code before inlining).
void g(void);
inline int f(void)
{
  return 1;
  g();
}
int h(void)
{
  return f();
}

Note this is reduced from:
#include <string>
#include <vector>
void foo(std::vector<std::string> & matches)
{
 char * buf[10];
 matches.insert(matches.end(), buf, buf + 10);
}

(also why does libstdc++ have dead code in its headers.

-- 
           Summary: [4.0 Regression] warning about not returning from end of
                    a non-void function because of dead code
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug c++/19699] [4.0 Regression] warning about not returning from end of a non-void function because of dead code

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.0.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0 Regression] warning about not returning from end of a non-void function because of dead code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-01-29 19:25 -------
I also happens with the C front-end too.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c++                         |middle-end


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0 Regression] warning about not returning from end of a non-void function because of dead code

[larsbj at gullik dot net]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |larsbj at gullik dot net


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0 Regression] warning about not returning from end of a non-void function because of dead code

[rth at gcc dot gnu dot org]

------- Additional Comments From rth at gcc dot gnu dot org  2005-01-30 09:48 -------
There is zero chance that this will be fixed for 4.0.  That's exactly why Ian
implemented the minimalistic check that he did in solving PR19583 and related.

You may retartget this pr to fixing the silliness in libstdc++, if you want.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.0.0                       |---


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0 Regression] warning about not returning from end of a non-void function because of dead code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-01-30 15:02 -------
Confirmed.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |minor
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2005-01-30 15:02:09
               date|                            |
   Target Milestone|---                         |4.1.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0 Regression] warning about not returning from end of a non-void function because of dead code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-01-30 15:05 -------
(In reply to comment #2)
> You may retartget this pr to fixing the silliness in libstdc++, if you want.
Actually it is only silliness as try/catch is changed to be "if (true)"/"if (false)" if we don't have exceptions.  
There is nothing can be done to the libstdc++ headers to fix this.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0/4.1 Regression] warning about not returning from end of a non-void function because of dead code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-23 23:14 -------
*** Bug 21183 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mj1 at cog dot brown dot edu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0/4.1 Regression] warning about not returning from end of a non-void function because of dead code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-24 15:23 -------
*** Bug 21191 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mattias at virtutech dot se


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0/4.1 Regression] warning about not returning from end of a non-void function because of dead code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-29 21:52 -------
*** Bug 21290 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gcc at magfr dot user dot
                   |                            |lysator dot liu dot se


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0/4.1 Regression] warning about not returning from end of a non-void function because of dead code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-10 17:36 -------
*** Bug 21483 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |veksler at il dot ibm dot
                   |                            |com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0/4.1 Regression] warning about not returning from end of a non-void function because of dead code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-14 18:14 -------
*** Bug 21572 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ismail at kde dot org dot tr


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0/4.1 Regression] warning about not returning from end of a non-void function because of dead code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-28 17:46 -------
*** Bug 21800 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mj at ucw dot cz


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0/4.1 Regression] warning about not returning from end of a non-void function because of dead code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-28 17:50 -------
Fixed on the mainline by the moving the warning to right after CFG creation which is now done for all 
functions, even unused ones.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0/4.1 Regression] warning about not returning from end of a non-void function because of dead code

[ismail at kde dot org dot tr]

------- Additional Comments From ismail at kde dot org dot tr  2005-05-29 07:41 -------
Will the patch be applied to 4.0 branch too? 

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0/4.1 Regression] warning about not returning from end of a non-void function because of dead code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-29 14:16 -------
(In reply to comment #12)
> Will the patch be applied to 4.0 branch too? 
No because it is too big in that it also changes the inliner to be a CFG aware inliner.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0/4.1 Regression] warning about not returning from end of a non-void function because of dead code

[veksler at il dot ibm dot com]

------- Additional Comments From veksler at il dot ibm dot com  2005-06-06 15:20 -------
(In reply to comment #13)
> (In reply to comment #12)
> > Will the patch be applied to 4.0 branch too? 
> No because it is too big in that it also changes the inliner to be a CFG aware
inliner.

In that case, it should not be marked "RESOLVED" for gcc-4.0 until:
  1.  either it is marked WONTFIX for gcc-4.0
  2.  or a new patch is written specifically for the gcc-4.0 branch.

>From comment #2 I understand that option 2 is out of the question.
Does it mean that "gcc-4.0 is dead, long live gcc-4.1" ?

This is how I came to this "conclusion":
There are new (not very rare) regressions in gcc-4.0 that will never
be fixed. These regressions will be fixed only in gcc-4.1.
As a result, it sounds like gcc-4.0 is much less maintained than
any other (active) branch (or trunk) at the moment. This is
very different from any of the previous releases of GCC (up to
gcc-2.95)

If this is true, then gcc-4.1 schedule should be changed
to reflect that.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0/4.1 Regression] warning about not returning from end of a non-void function because of dead code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-06-06 16:07 -------
(In reply to comment #14)
> This is how I came to this "conclusion":
> There are new (not very rare) regressions in gcc-4.0 that will never
> be fixed. These regressions will be fixed only in gcc-4.1.
> As a result, it sounds like gcc-4.0 is much less maintained than
> any other (active) branch (or trunk) at the moment. This is
> very different from any of the previous releases of GCC (up to
> gcc-2.95)

This is only a diagnostic regression.  In fact before this patch which added the warning in the inliner, 
we had a diagnostic regression.  So it is either false postive or false negatives.  Take your pick, I rather 
have the false postives as it means you have to look at your code to double check, if we don't get a 
diagnostic at all, the person will complain when we get it right again the next major release.  Again take 
your pick.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0/4.1 Regression] warning about not returning from end of a non-void function because of dead code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-06-07 18:00 -------
*** Bug 21951 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dank at kegel dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699

[Bug middle-end/19699] [4.0/4.1 Regression] warning about not returning from end of a non-void function because of dead code

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-12 15:28 -------
*** Bug 22435 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fw at deneb dot enyo dot de


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19699