[Bug c++/70741] New: segfault when jumping into statement expression in array initializer

[donald.chai at synopsys dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70741

Bug ID: 70741
   Summary: segfault when jumping into statement expression in
array initializer
   Product: gcc
   Version: 5.2.1
Status: UNCONFIRMED
  Severity: minor
  Priority: P3
 Component: c++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: donald.chai at synopsys dot com
  Target Milestone: ---

Preface:
1) Apologies if this is the wrong component.
2) Yes, this code is crazy.  I was testing our own compiler.  :)

GCC 5.x segfaults on the below code in C++ mode.

$ cat test.c
void testE_statement() {
int x[10] = {
({ L: 0; })
};
goto L;
}

$ gcc-5 -c test.c   
test.c: In function ‘testE_statement’:
test.c:5:5: error: jump into statement expression
 goto L;
 ^
test.c:3:12: note: label ‘L’ defined here
 ({ L: 0; })

$ gcc-5 -c -x c++ test.c  
test.c: In function ‘void testE_statement()’:
test.c:1:6: internal compiler error: Segmentation fault
 void testE_statement() {
  ^
Please submit a full bug report,
with preprocessed source if appropriate.
See  for instructions.

$ gcc-5 --version
gcc-5 (Ubuntu 5.2.1-23ubuntu1~12.04) 5.2.1 20151031
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

GCC 4.9 appears to do something somewhat reasonable:

$ cat test.cpp 
#include 

int main() {
int iters = 0;
int x[10] = {
({ printf("0\n"); iters; }),
({ L: iters++; printf("1\n"); iters; })
};
if (iters < 2)
goto L;
printf("x[0]: %d\n", x[0]);
printf("x[1]: %d\n", x[1]);
}
$ gcc-4.9 test.cpp
$ ./a.out 
0
1
1
x[0]: 0
x[1]: 2

[Bug c++/70744] New: preincrements possibly double-evaluated in GNU ternaries

[donald.chai at synopsys dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70744

Bug ID: 70744
   Summary: preincrements possibly double-evaluated in GNU
ternaries
   Product: gcc
   Version: 5.2.1
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: donald.chai at synopsys dot com
  Target Milestone: ---

GCC, in C++ mode, appears to evaluate pre-increments twice in GNU ternaries:

$ gcc-5 --version
gcc-5 (Ubuntu 5.2.1-23ubuntu1~12.04) 5.2.1 20151031
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ cat test.c
int main() {
int x = 1;
++x ?: 1337;
return x;
}
$ gcc-5 -x c test.c; ./a.out; echo $?
2
$ gcc-5 -x c++ test.c; ./a.out; echo $? 
3

Clang appears to work:

$ clang --version
Ubuntu clang version 3.4-1ubuntu3~precise2 (tags/RELEASE_34/final) (based on
LLVM 3.4)
Target: x86_64-pc-linux-gnu
Thread model: posix

$ clang -x c++ test.c; ./a.out; echo $?
test.c:3:5: warning: expression result unused [-Wunused-value]
++x ?: 1337;
^~~
1 warning generated.
2

[Bug c++/70744] preincrements possibly double-evaluated in GNU ternaries

[donald.chai at synopsys dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70744

--- Comment #5 from Donald Chai  ---
For what it's worth, post-increments behave as I would expect:

$ cat test.c
int main() {
int x = 1;
x++ ?: 0xbeef;
return x;
}
$ gcc-5 -x c test.c; ./a.out; echo $?
2
$ gcc-5 -x c++ test.c; ./a.out; echo $?
2