[Bug c++/51494] New: Legal program rejection - capturing "this" when using static method inside lambda

[ulidtko at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51494

 Bug #: 51494
   Summary: Legal program rejection - capturing "this" when using
static method inside lambda
Classification: Unclassified
   Product: gcc
   Version: 4.6.1
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: ulid...@gmail.com


Consider the following source code:

struct A
{
static void f() {}

void foo()
{
[] () { f(); };
}
};


GCC 4.6.1 produces the following error message when compiling it:
test.cpp: In lambda function:
test.cpp:7:27: error: ‘this’ was not captured for this lambda function

However, the member function f is static and it's call doesn't use 'this';
therefore the lambda need not to capture 'this'. The code shall compile.

[Bug preprocessor/89038] New: #pragma GCC diagnostic ignored "-Wunknown-pragmas" does not work

[ulidtko at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89038

Bug ID: 89038
   Summary: #pragma GCC diagnostic ignored "-Wunknown-pragmas"
does not work
   Product: gcc
   Version: unknown
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: preprocessor
  Assignee: unassigned at gcc dot gnu.org
  Reporter: ulidtko at gmail dot com
  Target Milestone: ---

Consider this test.cxx file:

---8<
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpragmas"
#pragma GCC diagnostic ignored "-Wunknown-pragmas"

// this gets silenced correctly (by line 2)
#pragma GCC diagnostic ignored "-Wfoobar-unknown-gcc-pragma"

// this still emits "-Wunknown-pragmas", despite line 3
#pragma clang diagnostic ignored "-Wfoobar-unknown-clang-pragma"

int main() {}

#pragma GCC diagnostic pop
---8<

g++ -Wall -Werror test.cxx

test.cxx:9:0: error: ignoring #pragma clang diagnostic
[-Werror=unknown-pragmas]
 #pragma clang diagnostic ignored "-Wfoobar-unknown-clang-pragma"


This happens despite the fact that "-Wunknown-pragmas" is explicitly silenced
in line 3.

Adding -Wno-unknown-pragmas to the command line works as expected; however, I
expect the in-source #pragma to work as well. But it doesn't.

g++ (GCC) 7.2.1 20180104 (Red Hat 7.2.1-5)

Bug #53431 seems closely related.

[Bug c++/89038] #pragma GCC diagnostic ignored "-Wunknown-pragmas" does not work

[ulidtko at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89038

--- Comment #3 from Maxim Ivanov  ---
(In reply to Eric Gallager from comment #2)
> I think this is a dup of something but I can't remember the bug number right
> now; I'll search harder later...

Eric, take a look at bug #53431, I think that's what you meant. It's a pretty
similar report about in-source pragmas not working in C++.

Further, that thread contains a WIP patch from Manuel López-Ibáñez, which he
expressly abandoned while encouraging others to finish and merge it.

P.S.
I do harbor a hope to resolve this on my own, once I accumulate the necessary
courage to allocate some time for a little GCC contribution. That's why I'm
reporting a separate issue knowing it's a duplicate :)