Getting spurious FAILS in testsuite?

[Georg-Johann Lay <avr at gjlay dot de>]

Hi, when I am running the gcc testsuite in $builddir/gcc then

$ make check-gcc RUNTESTFLAGS='ubsan.exp'

comes up with spurious fails.

Running target unix
Using /usr/share/dejagnu/baseboards/unix.exp as board description file 
for target.
Using /usr/share/dejagnu/config/unix.exp as generic interface file for 
target.
Using /home/georg/gnu/gcc.gnu.org/trunk/gcc/testsuite/config/default.exp 
as tool-and-target-specific interface file.
Running 
/home/georg/gnu/gcc.gnu.org/trunk/gcc/testsuite/gcc.dg/ubsan/ubsan.exp ...
FAIL: c-c++-common/ubsan/float-cast-overflow-8.c   -O2  output pattern test
FAIL: c-c++-common/ubsan/overflow-mul-4.c   -O0  output pattern test

...

when I am running the 1st test alone, then it works:

$ make check-gcc RUNTESTFLAGS='ubsan.exp=float-cast-overflow-8.c'

In an older log file I found for a different test from the same folder:

/home/georg/gnu/gcc.gnu.org/trunk/gcc/testsuite/c-c++-common/ubsan/float-cast-overflow-7.h:149:1: 
runtime error: value <unknown> is outside the range of representable 
values of type 'unsigned int'
/home/georg/gnu/gcc.gnu.org/trunk/gcc/testsuite/c-c++-common/ubsan/float-cast-overflow-7.h:149:1: 
runtime error: value <unknown> is outside the range of representable 
values of type 'long int'
/home/georg/gnu/gcc.gnu.org/trunk/gcc/testsuite/c-c++-common/ubsan/float-cast-overflow-7.h:149:1: 
runtime error: PASS: c-c++-common/ubsan

BANG: "PASS" output from previous test run shreds this one?

/float-cast-overflow-10.c   -O2 -flto -fuse-linker-plugin 
-fno-fat-lto-objects  execution test
FAIL: c-c++-common/ubsan/float-cast-overflow-10.c   -O2 -flto 
-fuse-linker-plugin -fno-fat-lto-objects  output pattern test
Output was:
c-c++-common/ubsan/float-cast-overflow-7.h:147:1: runtime error: value 
<unknown> is outside the range of representable values of type 'signed char'
...
c-c++-common/ubsan/float-cast-overflow-7.h:149:1: runtime error:
Should match:

The last output line stops after "runtime error: ", i.e. at the place
where the "PASS" appears.

Any ideas?

Johann