[Bug c/48116] New: -Wreturn-type does not work as advertised

[Bug c/48116] New: -Wreturn-type does not work as advertised

[tromey at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48116

           Summary: -Wreturn-type does not work as advertised
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: tromey@gcc.gnu.org


I'm using svn trunk gcc as of today.

-Wreturn-type is documented as:

  [... warn] about a `return' statement with a expression
  in a function whose return-type is `void'.

I tried it with this test case:

void x (void) { }
void y(void) { return x(); }

I expected a warning on the `return', but did not get one:

I used "gcc -Wreturn-type -O2 -c q.c"

[Bug c/48116] -Wreturn-type does not work as advertised

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48116

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2011-03-14 17:18:20 UTC ---
apinski@apinskidesktop:~$ gcc t.c -W -Wall -pedantic -S
t.c: In function ‘y’:
t.c:2: warning: ISO C forbids ‘return’ with expression, in function returning
void

[Bug c/48116] -Wreturn-type does not work as advertised

[tromey at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48116

--- Comment #2 from Tom Tromey <tromey at gcc dot gnu.org> 2011-03-14 17:20:47 UTC ---
Thanks, but I think it is still a bug as-is.
I don't see why -pedantic should be required here.

[Bug c/48116] -Wreturn-type does not work as advertised

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48116

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2014-09-24
                 CC|                            |mpolacek at gcc dot gnu.org
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot gnu.org
   Target Milestone|---                         |5.0
     Ever confirmed|0                           |1

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Mine.

[Bug c/48116] -Wreturn-type does not work as advertised

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48116

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEW
           Assignee|mpolacek at gcc dot gnu.org        |unassigned at gcc dot gnu.org

--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
(In reply to Manuel López-Ibáñez from comment #4)
> Do you have even an unfinished patch? I will add this to the list of
> EasyHacks.

I have nothing so far, I couldn't get to this one yet.  I'm going to unassign
myself for now, maybe I'll get to this one some day.

Feel free to put it on EasyHacks.
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Subject: [Bug c++/55698] gcc does not report warning if operator not used : control reaches end of non-void function [-Wreturn-type]
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55698

--- Comment #3 from Максим Прохоренко <maxim.prohorenko at gmail dot com> ---
Thanks guys.
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Subject: [Bug tree-optimization/63586] New: x+x+x+x -> 4*x in gimple
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idc586

            Bug ID: 63586
           Summary: x+x+x+x -> 4*x in gimple
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: glisse at gcc dot gnu.org

unsigned f(unsigned x){
  unsigned y = x + x;
  y = y + x;
  y = y + x;
  y = y + x;
  y = y + x;
  y = y + x;
  y = y + x;
  return y;
}

The .optimized dump still shows:

  y_2 = x_1(D) + x_1(D);
  y_3 = y_2 + x_1(D);
  y_4 = y_3 + x_1(D);
  y_5 = y_4 + x_1(D);
  y_6 = y_5 + x_1(D);
  y_7 = y_6 + x_1(D);
  y_8 = y_7 + x_1(D);
  return y_8;

RTL later optimizes it to x<<3 (leal), but I am surprised we aren't doing
anything in gimple. I would expect us to canonicalize to 8*x.

[Bug c/48116] -Wreturn-type does not work as advertised

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48116

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|5.0                         |5.2

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 5.1 has been released.

[Bug c/48116] -Wreturn-type does not work as advertised

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48116

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|5.2                         |5.3

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 5.2 is being released, adjusting target milestone to 5.3.