[Bug libfortran/95104] [9/10 Regression] Segfault on a legal WAIT statement

[ro at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95104

Rainer Orth <ro at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|FIXED                       |---
             Status|RESOLVED                    |REOPENED
                 CC|                            |ro at gcc dot gnu.org

--- Comment #13 from Rainer Orth <ro at gcc dot gnu.org> ---
The new testcase FAILs on (at least): Solaris (both sparc and x86):

+FAIL: gfortran.dg/pr95104.f90   -O0  execution test
+FAIL: gfortran.dg/pr95104.f90   -O1  execution test
+FAIL: gfortran.dg/pr95104.f90   -O2  execution test
+FAIL: gfortran.dg/pr95104.f90   -O3 -fomit-frame-pointer -funroll-loops
-fpeel-loops -ftracer -finline-functions  execution test
+FAIL: gfortran.dg/pr95104.f90   -O3 -g  execution test
+FAIL: gfortran.dg/pr95104.f90   -Os  execution test

Program received signal SIGSEGV: Segmentation fault - invalid memory reference.

Backtrace for this error:

After recompiling libgfortran with -g3 -O0, I see

Thread 2 received signal SIGSEGV, Segmentation fault.
[Switching to Thread 1 (LWP 1)]
0xfec554a8 in pthread_mutex_unlock () from /lib/libc.so.1
(gdb) where
#0  0xfec554a8 in pthread_mutex_unlock () from /lib/libc.so.1
#1  0xff1287bc in __gthread_mutex_unlock (__mutex=0xc8)
    at ../libgcc/gthr-default.h:779
#2  0xff12a178 in _gfortrani_unlock_unit (u=0x0)
    at /vol/gcc/src/hg/master/local/libgfortran/io/unit.c:771
#3  0xff127ffc in _gfortran_st_wait_async (wtp=0xffbfe750)
    at /vol/gcc/src/hg/master/local/libgfortran/io/transfer.c:4511
#4  0x00010eac in test ()
    at /vol/gcc/src/hg/master/local/gcc/testsuite/gfortran.dg/pr95104.f90:5
#5  0x00010f40 in main (argc=1, argv=0xffbfe992)
    at /vol/gcc/src/hg/master/local/gcc/testsuite/gfortran.dg/pr95104.f90:8
#6  0x00010c74 in _start ()

#3  0xff127ffc in _gfortran_st_wait_async (wtp=0xffbfe750)
    at /vol/gcc/src/hg/master/local/libgfortran/io/transfer.c:4511
4511      unlock_unit (u);
(gdb) p u
$2 = (gfc_unit *) 0x0

Either the unlock_unit needs to be guarded by if (u) or moved into the 
if (ASYNC_IO && u ...) check.