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* [Bug c++/105794] New: Spurious "control reaches end of non-void function" warning with a combination of destructor, try/catch and if (true)
@ 2022-05-31 15:42 kamil.sliwak at codepoets dot it
2022-05-31 20:14 ` [Bug c++/105794] " mpolacek at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: kamil.sliwak at codepoets dot it @ 2022-05-31 15:42 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105794
Bug ID: 105794
Summary: Spurious "control reaches end of non-void function"
warning with a combination of destructor, try/catch
and if (true)
Product: gcc
Version: 12.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: kamil.sliwak at codepoets dot it
Target Milestone: ---
After switching to GCC 12 I noticed that in several places in the C++ project
I'm working on I'm now getting the `control reaches end of non-void function`
warning. This seems like a regression since it's not happening with earlier GCC
versions or with latest Clang.
I managed to distill the problematic code into a small repro (see below) and
it's reproducible via https://godbolt.org so it does not seem dependent on my
specific environment.
The original code is more complicated but in the end a combination of three
things seems to be causing this:
1. A variable of a custom class type that has an explicitly defined destructor
(which can be empty though).
2. A try/catch block with a return.
3. A `throw` wrapped in a condition that's a compile-time constant.
Removing any of the above makes the warning go away.
### Environment
- GCC version: 12.1.0
- System: Arch Linux
### Repro
#### Command
```
g++ test.cpp
```
#### `test.cpp`
```
#include <exception>
class C {
public:
~C() {}
};
int foo()
{
C c;
try
{
return 1;
}
catch (std::exception const&)
{
}
if (true)
throw std::exception();
}
int main() {
return 0;
}
```
#### Output
```
test.cpp: In function ‘int foo()’:
test.cpp:22:1: warning: control reaches end of non-void function
[-Wreturn-type]
22 | }
| ^
```
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/105794] Spurious "control reaches end of non-void function" warning with a combination of destructor, try/catch and if (true)
2022-05-31 15:42 [Bug c++/105794] New: Spurious "control reaches end of non-void function" warning with a combination of destructor, try/catch and if (true) kamil.sliwak at codepoets dot it
@ 2022-05-31 20:14 ` mpolacek at gcc dot gnu.org
2022-05-31 20:33 ` mpolacek at gcc dot gnu.org
2022-06-01 19:41 ` [Bug c++/105794] [12/13 Regression] " jason at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2022-05-31 20:14 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105794
Marek Polacek <mpolacek at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Last reconfirmed| |2022-05-31
CC| |mpolacek at gcc dot gnu.org
Keywords| |diagnostic
Status|UNCONFIRMED |NEW
Target Milestone|--- |12.2
Priority|P3 |P2
--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Confirmed, started with r12-5638-ga3e75c1491cd2d
commit a3e75c1491cd2d501081210925a89a65b1c1e5e5
Author: Jason Merrill <jason@redhat.com>
Date: Thu Nov 25 10:50:59 2021 -0500
c++: don't fold away 'if' with constant condition
It changed:
--- 105794.ii.005t.original 2022-05-31 16:12:51.932479674 -0400
+++ 105794.ii.005t.original.1 2022-05-31 16:10:21.158400398 -0400
@@ -502,13 +502,16 @@ if (<<cleanup_point std::__exception_ptr
__cxa_end_catch ();
}
} >>> >>>;
- <<cleanup_point <<< Unknown tree: expr_stmt
+ if (1)
+ {
+ <<cleanup_point <<< Unknown tree: expr_stmt
<<< Unknown tree: throw_expr
<<cleanup_point TARGET_EXPR <D.7348, __cxa_allocate_exception (8)>;,
*(struct exception *) D.7348 = TARGET_EXPR <D.7345, <<< Unknown tree:
aggr_init_expr
4
__ct_comp
D.7345
(struct exception *) <<< Unknown tree: void_cst >>> >>>>;>>;, __cxa_throw
(D.7348, (void *) &_ZTISt9exception, __dt_comp ); >>> >>>>>;
+ }
}
finally
{
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/105794] Spurious "control reaches end of non-void function" warning with a combination of destructor, try/catch and if (true)
2022-05-31 15:42 [Bug c++/105794] New: Spurious "control reaches end of non-void function" warning with a combination of destructor, try/catch and if (true) kamil.sliwak at codepoets dot it
2022-05-31 20:14 ` [Bug c++/105794] " mpolacek at gcc dot gnu.org
@ 2022-05-31 20:33 ` mpolacek at gcc dot gnu.org
2022-06-01 19:41 ` [Bug c++/105794] [12/13 Regression] " jason at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2022-05-31 20:33 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105794
--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Probably the same issue:
struct C {
~C();
};
int foo() {
C c;
return 1;
if (true)
;
}
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/105794] [12/13 Regression] Spurious "control reaches end of non-void function" warning with a combination of destructor, try/catch and if (true)
2022-05-31 15:42 [Bug c++/105794] New: Spurious "control reaches end of non-void function" warning with a combination of destructor, try/catch and if (true) kamil.sliwak at codepoets dot it
2022-05-31 20:14 ` [Bug c++/105794] " mpolacek at gcc dot gnu.org
2022-05-31 20:33 ` mpolacek at gcc dot gnu.org
@ 2022-06-01 19:41 ` jason at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: jason at gcc dot gnu.org @ 2022-06-01 19:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105794
Jason Merrill <jason at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |DUPLICATE
CC| |jason at gcc dot gnu.org
--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> ---
Dup.
*** This bug has been marked as a duplicate of bug 104787 ***
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-06-01 19:41 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2022-05-31 15:42 [Bug c++/105794] New: Spurious "control reaches end of non-void function" warning with a combination of destructor, try/catch and if (true) kamil.sliwak at codepoets dot it
2022-05-31 20:14 ` [Bug c++/105794] " mpolacek at gcc dot gnu.org
2022-05-31 20:33 ` mpolacek at gcc dot gnu.org
2022-06-01 19:41 ` [Bug c++/105794] [12/13 Regression] " jason at gcc dot gnu.org
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