[Bug c++/92407] New: Destruction of objects returned from functions skipped by goto

[Dave.Poston at gs dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92407

Bug ID: 92407
   Summary: Destruction of objects returned from functions skipped
by goto
   Product: gcc
   Version: 9.2.1
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: Dave.Poston at gs dot com
  Target Milestone: ---

The code below only outputs 'Destructed' once:

Godbolt link: https://godbolt.org/z/Foy-vc

Bug appears to be present in all versions of GCC available in godbolt.

---
#include

struct MyStruct
{
MyStruct() {
std::cout << "Constructed" << std::endl;
}
~MyStruct() {
std::cout << "Destructed" << std::endl;
}
int a;
};

MyStruct fill() {
MyStruct bla;
bla.a = 100;
return bla;
}
MyStruct problem() {
int cnt = 100;
start:
MyStruct a = fill();
if( cnt-- )
goto start;
return a;
}

int main( int argc, char** argv )
{
problem();
return 0;
}
---
output is:
Constructed

Constructed

Constructed

Constructed

Constructed

Constructed

Constructed

Constructed
...

[Bug c++/92407] Destruction of objects returned from functions skipped by goto

[Dave.Poston at gs dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92407

--- Comment #1 from Dave Poston  ---
In fact, fill() isn't even needed.

Smaller repro:
https://godbolt.org/z/ubXl7Y

---
#include

struct MyStruct
{
MyStruct() {
std::cout << "Constructed" << std::endl;
}
~MyStruct() {
std::cout << "Destructed" << std::endl;
}
int a;
};

MyStruct problem() {
int cnt = 100;
start:
MyStruct a;
if( cnt-- )
goto start;
return a;
}

int main( int argc, char** argv )
{
problem();
return 0;
}

[Bug c++/92407] Destruction of objects returned from functions skipped by goto

[Dave.Poston at gs dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92407

--- Comment #4 from Dave Poston  ---
Yep, also changing problem()/foo() to void and not returning the struct, works
properly