https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105291
Bug ID: 105291
Summary: include/c++/12.0.1/debug/safe_unordered_container.h:71
:28: error: captured variable '__local_end' cannot
appear here
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: sbergman at redhat dot com
Target Milestone: ---
Since
<https://github.com/llvm/llvm-project/commit/04000c2f928a7adc32138a664d167f01b642bef3>
"[clang] Implement Change scope of lambda trailing-return-type", Clang 15 trunk
implements
<http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2036r3.html> "Change
scope of lambda trailing-return-type" as a DR (in line with
<http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/n4902.html> "N4902
Editors’ Report – Programming Languages – C++"; so enabled with all -std=
versions).
That stated to cause
> $ cat test.cc
> #define _GLIBCXX_DEBUG
> #include <unordered_map>
> $ clang++ -fsyntax-only test.cc
> In file included from test.cc:2:
> In file included from
> /usr/lib/gcc/x86_64-redhat-linux/12/../../../../include/c++/12/unordered_map:52:
> In file included from
> /usr/lib/gcc/x86_64-redhat-linux/12/../../../../include/c++/12/debug/unordered_map:49:
> /usr/lib/gcc/x86_64-redhat-linux/12/../../../../include/c++/12/debug/safe_unordered_container.h:71:28:
> error: captured variable '__local_end' cannot appear here
> [__local_end](__decltype(__local_end) __it)
> ^
> /usr/lib/gcc/x86_64-redhat-linux/12/../../../../include/c++/12/debug/safe_unordered_container.h:71:4:
> note: variable '__local_end' is explicitly captured here
> [__local_end](__decltype(__local_end) __it)
> ^
> /usr/lib/gcc/x86_64-redhat-linux/12/../../../../include/c++/12/debug/safe_unordered_container.h:69:2:
> note: '__local_end' declared here
> auto __local_end = _M_cont()._M_base().cend(0);
> ^
> /usr/lib/gcc/x86_64-redhat-linux/12/../../../../include/c++/12/debug/safe_unordered_container.h:169:44:
> error: captured variable '__end' cannot appear here
> this->_M_invalidate_if([__end](__decltype(__end) __it)
> ^
> /usr/lib/gcc/x86_64-redhat-linux/12/../../../../include/c++/12/debug/safe_unordered_container.h:169:26:
> note: variable '__end' is explicitly captured here
> this->_M_invalidate_if([__end](__decltype(__end) __it)
> ^
> /usr/lib/gcc/x86_64-redhat-linux/12/../../../../include/c++/12/debug/safe_unordered_container.h:168:2:
> note: '__end' declared here
> auto __end = _M_cont()._M_base().cend();
> ^
> 2 errors generated.
to fail.
The relevant code in libstdc++-v3/include/debug/safe_unordered_container.h got
added with
<https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=4b763deedb282b480fe4c2b3a8ad07192393f1b1>
"2018-10-24 François Dumont <fdum...@gcc.gnu.org>".
What made things work for me is
> diff --git a/libstdc++-v3/include/debug/safe_unordered_container.h
> b/libstdc++-v3/include/debug/safe_unordered_container.h
> index 91be256611a..71468198573 100644
> --- a/libstdc++-v3/include/debug/safe_unordered_container.h
> +++ b/libstdc++-v3/include/debug/safe_unordered_container.h
> @@ -67,8 +67,9 @@ namespace __gnu_debug
> _M_invalidate_locals()
> {
> auto __local_end = _M_cont()._M_base().cend(0);
> + using __local_end_t = __decltype(__local_end);
> this->_M_invalidate_local_if(
> - [__local_end](__decltype(__local_end) __it)
> + [__local_end](__local_end_t __it)
> { return __it != __local_end; });
> }
>
> @@ -166,7 +167,8 @@ namespace __gnu_debug
> _M_invalidate_all()
> {
> auto __end = _M_cont()._M_base().cend();
> - this->_M_invalidate_if([__end](__decltype(__end) __it)
> + using __end_t = __decltype(__end);
> + this->_M_invalidate_if([__end](__end_t __it)
> { return __it != __end; });
> _M_invalidate_locals();
> }
