Missing returned object destructor call after exception throw

[llvmbot]

Bugzilla Link	51523
Version	trunk
OS	Linux
Reporter	LLVM Bugzilla Contributor

Extended Description

14.3.2 Exception handling:Constructors and destructors:2 (https://eel.is/c++draft/except.ctor#2)
says
"If an exception is thrown during the destruction of temporaries or local variables for a return statement ([stmt.return]), the destructor for the returned object (if any) is also invoked"

And it contains example (https://eel.is/c++draft/except.ctor#example-1) with description
"...the local variable y is destroyed, causing stack unwinding, resulting in the destruction of the returned object, ..."

Trying to recreate this example with following code

#include
using namespace std;

struct S{
int i = 123;
S(int i) :i(i) {cout<<"S("<<i<<")"<<endl;}
~S() {cout<<"~S("<<i<<")"<<endl;}
};

struct T {
T() {cout<<"T()"<<endl;}
~T() noexcept(false) {
cout<<"~T()"<<endl;
throw 0;
}
};

S foo() {
try {
T t;
return {3};
} catch (...){}
return {4};
}

int main() {
foo();
}

Output doesn't have S{3}'s (returned object) destruction line:
T()
S(3)
~T()
S(4)
~S(4)

while should be
T()
S(3)
~T()
~S(3) <-----!
S(4)
~S(4)

Link to godbolt:
https://godbolt.org/z/YrasqsvMe

[zygoloid]

Duplicate of #12658

[llvmbot]

@llvm/issue-subscribers-c-1

| | | | --- | --- | | Bugzilla Link | [51523](https://llvm.org/bz51523) | | Version | trunk | | OS | Linux | | Reporter | LLVM Bugzilla Contributor |

Extended Description

14.3.2 Exception handling:Constructors and destructors:2 (https://eel.is/c++draft/except.ctor#2)
says
"If an exception is thrown during the destruction of temporaries or local variables for a return statement ([stmt.return]), the destructor for the returned object (if any) is also invoked"

And it contains example (https://eel.is/c++draft/except.ctor#example-1) with description
"...the local variable y is destroyed, causing stack unwinding, resulting in the destruction of the returned object, ..."

Trying to recreate this example with following code

#include <iostream>
using namespace std;

struct S{
int i = 123;
S(int i) :i(i) {cout<<"S("<<i<<")"<<endl;}
~S() {cout<<"~S("<<i<<")"<<endl;}
};

struct T {
T() {cout<<"T()"<<endl;}
~T() noexcept(false) {
cout<<"~T()"<<endl;
throw 0;
}
};

S foo() {
try {
T t;
return {3};
} catch (...){}
return {4};
}

int main() {
foo();
}

Output doesn't have S{3}'s (returned object) destruction line:
T()
S(3)
~T()
S(4)
~S(4)

while should be
T()
S(3)
~T()
~S(3) <-----!
S(4)
~S(4)

Link to godbolt:
https://godbolt.org/z/YrasqsvMe

[llvmbot]

@llvm/issue-subscribers-clang-codegen

| | | | --- | --- | | Bugzilla Link | [51523](https://llvm.org/bz51523) | | Version | trunk | | OS | Linux | | Reporter | LLVM Bugzilla Contributor |

Extended Description

14.3.2 Exception handling:Constructors and destructors:2 (https://eel.is/c++draft/except.ctor#2)
says
"If an exception is thrown during the destruction of temporaries or local variables for a return statement ([stmt.return]), the destructor for the returned object (if any) is also invoked"

And it contains example (https://eel.is/c++draft/except.ctor#example-1) with description
"...the local variable y is destroyed, causing stack unwinding, resulting in the destruction of the returned object, ..."

Trying to recreate this example with following code

#include <iostream>
using namespace std;

struct S{
int i = 123;
S(int i) :i(i) {cout<<"S("<<i<<")"<<endl;}
~S() {cout<<"~S("<<i<<")"<<endl;}
};

struct T {
T() {cout<<"T()"<<endl;}
~T() noexcept(false) {
cout<<"~T()"<<endl;
throw 0;
}
};

S foo() {
try {
T t;
return {3};
} catch (...){}
return {4};
}

int main() {
foo();
}

Output doesn't have S{3}'s (returned object) destruction line:
T()
S(3)
~T()
S(4)
~S(4)

while should be
T()
S(3)
~T()
~S(3) <-----!
S(4)
~S(4)

Link to godbolt:
https://godbolt.org/z/YrasqsvMe