enable_stdatomic=true breaks C++ on GCC 11 and earlier
https://bugs.dpdk.org/show_bug.cgi?id=1425
Bug ID: 1425
Summary: enable_stdatomic=true breaks C++ on GCC 11 and
earlier
Product: DPDK
Version: 23.11
Hardware: All
OS: Linux
Status: UNCONFIRMED
Severity: normal
Priority: Normal
Component: core
Assignee: [email protected]
Reporter: [email protected]Target Milestone: ---
On GCC 11 and earlier, configuring enable_stdatomic=true prevents the use of all DPDK header files that directly or indirectly include <rte_stdatomic.h> from a C++ translation unit (e.g., app).
<rte_stdatomic.h> includes <stdatomic.h>, which in turn is not necessarily C++-compatible.
Signature · 2 lines
You are receiving this mail because: You are the assignee for the bug.
Quoted 15 lines · On Mon, Apr 29, 2024 at 06:21:13AM +0000, [email protected] wrote:
https://bugs.dpdk.org/show_bug.cgi?id=1425
Bug ID: 1425 Summary: enable_stdatomic=true breaks C++ on GCC 11 and earlier Product: DPDK Version: 23.11 Hardware: All OS: Linux Status: UNCONFIRMED Severity: normal Priority: Normal Component: core Assignee: [email protected] Reporter: [email protected]
Quoted 8 lines
Target Milestone: ---
On GCC 11 and earlier, configuring enable_stdatomic=true prevents the use of all DPDK header files that directly or indirectly include <
rte_stdatomic.h> from a C++ translation unit (e.g., app).<
rte_stdatomic.h> includes <stdatomic.h>, which in turn is not necessarily C++-compatible.
This is known but to add some information.
C++ and enable_stdatomic=true for llvm and gcc are not currently supported. the combination will remain unsupported for C++ compilers that do not support -std=c++23 which is the first C++ standard that requires interoperability with C11 stdatomic.h
When enable_stdatomic=true there are bugs/incorrect usages of atomic qualifier in casts that (even when using C++23) cause compilation failure. These are a fixable but are low priority without -std=c++23.
Finally, the legacy atomics remain unconverted to stdatomic. This will cause enable_stdatomic=true not to build when using llvm (but not gcc) because llvm strictly enforces qualification when using atomic generics.
Quoted 4 lines
Signature · 3 lines
-- You are receiving this mail because: You are the assignee for the bug.
Quoted 18 lines · Tyler Retzlaff
Quoted 17 lines · On Mon, Apr 29, 2024 at 06:21:13AM +0000, [email protected] wrote:
https://bugs.dpdk.org/show_bug.cgi?id=1425
Bug ID: 1425 Summary: enable_stdatomic=true breaks C++ on GCC 11 and earlier Product: DPDK Version: 23.11 Hardware: All OS: Linux Status: UNCONFIRMED Severity: normal Priority: Normal Component: core Assignee: [email protected] Reporter: [email protected]Target Milestone: ---
Quoted 9 lines
Quoted 6 lines
On GCC 11 and earlier, configuring enable_stdatomic=true prevents the use of all DPDK header files that directly or indirectly include <
rte_stdatomic.h> from a C++ translation unit (e.g., app).<
rte_stdatomic.h> includes <stdatomic.h>, which in turn is not necessarily C++-compatible.This is known but to add some information.
Is it also documented?
Quoted 8 lines
C++ and enable_stdatomic=true for llvm and gcc are not currently supported. the combination will remain unsupported for C++ compilers that do not support -std=c++23 which is the first C++ standard that requires interoperability with C11
stdatomic.h>
When enable_stdatomic=true there are bugs/incorrect usages of atomic qualifier in casts that (even when using C++23) cause compilation failure. These are a fixable but are low priority without -std=c++23.
Quoted 4 lines
Finally, the legacy atomics remain unconverted to stdatomic. This will cause enable_stdatomic=true not to build when using llvm (but not gcc) because llvm strictly enforces qualification when using atomic generics.
OK, I see. It'll be a while until enable_stdatomic is usable outside Windows then, for generic builds.
Am I right if I say that C++23-capable compilers/run-times are supposed to have a <stdatomic.h> which interoperates with C++ even in C++11-mode? Or need the application be compiled as C++23.
Quoted 4 lines
Quoted 4 lines
Signature · 3 lines
-- You are receiving this mail because: You are the assignee for the bug.
Quoted 23 lines · Mattias Rönnblom
Quoted 22 lines · Tyler Retzlaff
Quoted 21 lines · On Mon, Apr 29, 2024 at 06:21:13AM +0000, [email protected] wrote:
https://bugs.dpdk.org/show_bug.cgi?id=1425
Bug ID: 1425 Summary: enable_stdatomic=true breaks C++ on GCC 11 and earlier Product: DPDK Version: 23.11 Hardware: All OS: Linux Status: UNCONFIRMED Severity: normal Priority: Normal Component: core Assignee: [email protected] Reporter: [email protected]Target Milestone: ---
On GCC 11 and earlier, configuring enable_stdatomic=true prevents the use of all DPDK header files that directly or indirectly include <
rte_stdatomic.h> from a C++ translation unit (e.g., app).
Quoted 7 lines
Quoted 5 lines
Quoted 2 lines
<
rte_stdatomic.h> includes <stdatomic.h>, which in turn is not necessarily C++-compatible.This is known but to add some information.
Is it also documented?
we don't document anything about C++ right now including minimum compiler requirements or -std. i agree we probably should, if i find cycles i'll see if i can provide some text.
Quoted 14 lines
Quoted 9 lines
C++ and enable_stdatomic=true for llvm and gcc are not currently supported. the combination will remain unsupported for C++ compilers that do not support -std=c++23 which is the first C++ standard that requires interoperability with C11
stdatomic.h>
When enable_stdatomic=true there are bugs/incorrect usages of atomic qualifier in casts that (even when using C++23) cause compilation failure. These are a fixable but are low priority without -std=c++23.Quoted 4 lines
Finally, the legacy atomics remain unconverted to stdatomic. This will cause enable_stdatomic=true not to build when using llvm (but not gcc) because llvm strictly enforces qualification when using atomic generics.
Quoted 6 lines
OK, I see. It'll be a while until
enable_stdatomicis usable outside Windows then, for generic builds.Am I right if I say that C++23-capable compilers/run-times are supposed to have a <
stdatomic.h> which interoperates with C++ even in C++11-mode? Or need the application be compiled as C++23.
the application will need to be compiled with -std=C++23 though i think llvm does have a stdatomic.h that may work with lower -std, gcc does not last i checked. in general i think (as you found with _Generic) the compiler vendors are limiting leaking of C into C++ and vice versa where it is not explicitly intended to operate in one language or the other.
i'll be looking into this more beyond 24.07 since there is work to do even consuming with msvc that is not upstream.
Quoted 5 lines
Quoted 5 lines
Quoted 5 lines
Signature · 3 lines
-- You are receiving this mail because: You are the assignee for the bug.