[Bug c++/96485] New: Lambda parsing regression in GCCs 9 and onwards

[Bug c++/96485] New: Lambda parsing regression in GCCs 9 and onwards

[s_gccbugzilla at nedprod dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96485

            Bug ID: 96485
           Summary: Lambda parsing regression in GCCs 9 and onwards
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: s_gccbugzilla at nedprod dot com
  Target Milestone: ---

As the repro at https://godbolt.org/z/Gvx75e shows, the following code compiled
fine in GCCs up to and including GCC 8.3:

```
void test()
{
    []()
#if 1
    __attribute__((no_sanitize_undefined))
#endif
    ->int {
        return 0;
    };
}
```

>From GCC 9 onwards, we get:

```
<source>: In lambda function:
<source>:7:5: error: expected '{' before '->' token
    7 |     ->int {
      |     ^~
<source>: In function 'void test()':
<source>:7:5: error: base operand of '->' has non-pointer type
'test()::<lambda()>'
<source>:7:7: error: expected unqualified-id before 'int'
    7 |     ->int {
      |       ^~~
Compiler returned: 1
```

This code compiles fine in clang, incidentally, though it doesn't recognise the
attribute.

[Bug c++/96485] Lambda parsing regression in GCCs 9 and onwards

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96485

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |jason at gcc dot gnu.org

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
This has changed in r265787.

[Bug c++/96485] Lambda parsing regression in GCCs 9 and onwards

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96485

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
[[gnu::no_sanitize_undefined]] instead of the GNU __attribute__ is accepted,
but as the C++ specification requires it applies to the type not the
declaration and therefore it is ignored.

[Bug c++/96485] Lambda parsing regression in GCCs 9 and onwards

[s_gccbugzilla at nedprod dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96485

--- Comment #3 from Niall Douglas <s_gccbugzilla at nedprod dot com> ---
(In reply to Jakub Jelinek from comment #2)
> [[gnu::no_sanitize_undefined]] instead of the GNU __attribute__ is accepted,
> but as the C++ specification requires it applies to the type not the
> declaration and therefore it is ignored.

Obviously the above is an extract from production code. We were using lambdas
to wrap individual bits of unsafe code which trips the UB sanitiser. It would
be useful to retain that ability, as having to sprinkle the code with:

struct { auto operator()(auto...) const __attribute__((no_sanitize_undefined))
{ } }()(...); 

... seems retrograde.

[Bug c++/96485] [9/10/11 Regression] Lambda parsing regression in GCCs 9 and onwards

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96485

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|unknown                     |9.3.1
           Keywords|                            |rejects-valid
      Known to work|                            |8.3.0
      Known to fail|                            |9.1.0
   Target Milestone|---                         |9.4
            Summary|Lambda parsing regression   |[9/10/11 Regression] Lambda
                   |in GCCs 9 and onwards       |parsing regression in GCCs
                   |                            |9 and onwards

[Bug c++/96485] [9/10/11 Regression] Lambda parsing regression in GCCs 9 and onwards

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96485

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2

[Bug c++/96485] [9/10/11 Regression] Lambda parsing regression in GCCs 9 and onwards

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96485

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |DUPLICATE
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> ---
Duplicate.

*** This bug has been marked as a duplicate of bug 90333 ***