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Clang: "anonymous structs are a GNU extension" #14130

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DesWurstes opened this issue Sep 2, 2018 · 0 comments · Fixed by #18088
Closed

Clang: "anonymous structs are a GNU extension" #14130

DesWurstes opened this issue Sep 2, 2018 · 0 comments · Fixed by #18088
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@DesWurstes
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bitcoin/src/prevector.h

Lines 152 to 158 in 68f3c7e

union direct_or_indirect {
char direct[sizeof(T) * N];
struct {
size_type capacity;
char* indirect;
};
} _union;

I'm opening an issue as its fix is too tiny to become a pull request.

Can be solved by renaming the struct to

     struct indirect_contents { 
         size_type capacity; 
         char* indirect; 
     };
@DesWurstes DesWurstes mentioned this issue Jan 12, 2019
Closed
@fanquake fanquake mentioned this issue Feb 7, 2020
Merged
sidhujag pushed a commit to syscoin/syscoin that referenced this issue May 5, 2020
@fanquake
Merge bitcoin#18088: build: ensure we aren't using GNU extensions
fae55b6 
0ae8f18 build: add -Wgnu to compile flags (fanquake)
3a0fd77 Remove use of non-standard zero variadic macros (Ben Woosley)
49f6178 Drop unused LOG_TIME_MICROS helper (Ben Woosley)
5d49999 prevector: Avoid unnamed struct, which is a GNU extension (DesWurstes)

Pull request description:

  Since we [started using](bitcoin#7165) the `ax_cxx_compile_stdcxx.m4` macro we've been passing `[noext]` to indicate that we don't want to use an extended mode, i.e GNU extensions. Speaking to Cory he clarified that the intention was to "require only vanilla c++11 and turn _off_ extension support so they would fail to compile".

  However in the codebase we are currently making use of some GNU extensions. We should either remove there usage, or at least amend our CXX compiler checks. I'd prefer the former.

  #### anonymous structs
  ```bash
  ./prevector.h:153:9: warning: anonymous structs are a GNU extension [-Wgnu-anonymous-struct]
          struct {
  ```

  This is fixed in bitcoin@b849212.

  #### variadic macros

  ```bash
  ./undo.h:57:50: warning: must specify at least one argument for '...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]
              ::Unserialize(s, VARINT(nVersionDummy));
  ```

  This is taken care of in bitcoin#18087.

  The `LOG_TIME_*` macros introduced in bitcoin#16805 make use of a [GNU extension](https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html).

  ```bash
  In file included from validation.cpp:22:
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::milliseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                                    ^
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:101:92: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::seconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                             ^
  6 warnings generated.
  ```

  This is fixed in 081a0ab and 612e8e1.

  #### prevention
  To ensure that usage doesn't creep back in we can add [`-Wgnu`](https://clang.llvm.org/docs/DiagnosticsReference.html#wgnu) to our compile time flags, which will make Clang warn whenever it encounters GNU extensions.

  This would close bitcoin#14130.
  Also related to bitcoin#17230, where it's suggested we use a GNU extension, the `gnu::pure` attribute.

ACKs for top commit:
  practicalswift:
    ACK 0ae8f18 -- diff looks correct
  MarcoFalke:
    ACK 0ae8f18
  vasild:
    utACK 0ae8f18
  dongcarl:
    ACK 0ae8f18

Tree-SHA512: c517404681ef8edf04c785731d26105bac9f3c9c958605aa24cbe399c649e7c5ee0c4aa8e714fd2b2d335e2fbea4d571e09b0dec36678ef871f0a6683ba6bb7f
@bitcoin bitcoin locked as resolved and limited conversation to collaborators Feb 15, 2022
vijaydasmp pushed a commit to vijaydasmp/dash that referenced this issue Jan 20, 2023
@fanquake @vijaydasmp
Merge bitcoin#18088: build: ensure we aren't using GNU extensions
9a440af 
0ae8f18 build: add -Wgnu to compile flags (fanquake)
3a0fd77 Remove use of non-standard zero variadic macros (Ben Woosley)
49f6178 Drop unused LOG_TIME_MICROS helper (Ben Woosley)
5d49999 prevector: Avoid unnamed struct, which is a GNU extension (DesWurstes)

Pull request description:

  Since we [started using](bitcoin#7165) the `ax_cxx_compile_stdcxx.m4` macro we've been passing `[noext]` to indicate that we don't want to use an extended mode, i.e GNU extensions. Speaking to Cory he clarified that the intention was to "require only vanilla c++11 and turn _off_ extension support so they would fail to compile".

  However in the codebase we are currently making use of some GNU extensions. We should either remove there usage, or at least amend our CXX compiler checks. I'd prefer the former.

  #### anonymous structs
  ```bash
  ./prevector.h:153:9: warning: anonymous structs are a GNU extension [-Wgnu-anonymous-struct]
          struct {
  ```

  This is fixed in bitcoin@b849212.

  #### variadic macros

  ```bash
  ./undo.h:57:50: warning: must specify at least one argument for '...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]
              ::Unserialize(s, VARINT(nVersionDummy));
  ```

  This is taken care of in bitcoin#18087.

  The `LOG_TIME_*` macros introduced in bitcoin#16805 make use of a [GNU extension](https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html).

  ```bash
  In file included from validation.cpp:22:
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::milliseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                                    ^
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:101:92: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::seconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                             ^
  6 warnings generated.
  ```

  This is fixed in 081a0ab and 612e8e1.

  #### prevention
  To ensure that usage doesn't creep back in we can add [`-Wgnu`](https://clang.llvm.org/docs/DiagnosticsReference.html#wgnu) to our compile time flags, which will make Clang warn whenever it encounters GNU extensions.

  This would close bitcoin#14130.
  Also related to bitcoin#17230, where it's suggested we use a GNU extension, the `gnu::pure` attribute.

ACKs for top commit:
  practicalswift:
    ACK 0ae8f18 -- diff looks correct
  MarcoFalke:
    ACK 0ae8f18
  vasild:
    utACK 0ae8f18
  dongcarl:
    ACK 0ae8f18

Tree-SHA512: c517404681ef8edf04c785731d26105bac9f3c9c958605aa24cbe399c649e7c5ee0c4aa8e714fd2b2d335e2fbea4d571e09b0dec36678ef871f0a6683ba6bb7f
vijaydasmp pushed a commit to vijaydasmp/dash that referenced this issue Jan 20, 2023
@fanquake @vijaydasmp
Merge bitcoin#18088: build: ensure we aren't using GNU extensions
4349758 
0ae8f18 build: add -Wgnu to compile flags (fanquake)
3a0fd77 Remove use of non-standard zero variadic macros (Ben Woosley)
49f6178 Drop unused LOG_TIME_MICROS helper (Ben Woosley)
5d49999 prevector: Avoid unnamed struct, which is a GNU extension (DesWurstes)

Pull request description:

  Since we [started using](bitcoin#7165) the `ax_cxx_compile_stdcxx.m4` macro we've been passing `[noext]` to indicate that we don't want to use an extended mode, i.e GNU extensions. Speaking to Cory he clarified that the intention was to "require only vanilla c++11 and turn _off_ extension support so they would fail to compile".

  However in the codebase we are currently making use of some GNU extensions. We should either remove there usage, or at least amend our CXX compiler checks. I'd prefer the former.

  #### anonymous structs
  ```bash
  ./prevector.h:153:9: warning: anonymous structs are a GNU extension [-Wgnu-anonymous-struct]
          struct {
  ```

  This is fixed in bitcoin@b849212.

  #### variadic macros

  ```bash
  ./undo.h:57:50: warning: must specify at least one argument for '...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]
              ::Unserialize(s, VARINT(nVersionDummy));
  ```

  This is taken care of in bitcoin#18087.

  The `LOG_TIME_*` macros introduced in bitcoin#16805 make use of a [GNU extension](https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html).

  ```bash
  In file included from validation.cpp:22:
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::milliseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                                    ^
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:101:92: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::seconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                             ^
  6 warnings generated.
  ```

  This is fixed in 081a0ab and 612e8e1.

  #### prevention
  To ensure that usage doesn't creep back in we can add [`-Wgnu`](https://clang.llvm.org/docs/DiagnosticsReference.html#wgnu) to our compile time flags, which will make Clang warn whenever it encounters GNU extensions.

  This would close bitcoin#14130.
  Also related to bitcoin#17230, where it's suggested we use a GNU extension, the `gnu::pure` attribute.

ACKs for top commit:
  practicalswift:
    ACK 0ae8f18 -- diff looks correct
  MarcoFalke:
    ACK 0ae8f18
  vasild:
    utACK 0ae8f18
  dongcarl:
    ACK 0ae8f18

Tree-SHA512: c517404681ef8edf04c785731d26105bac9f3c9c958605aa24cbe399c649e7c5ee0c4aa8e714fd2b2d335e2fbea4d571e09b0dec36678ef871f0a6683ba6bb7f
vijaydasmp pushed a commit to vijaydasmp/dash that referenced this issue Feb 17, 2023
@fanquake @vijaydasmp
Merge bitcoin#18088: build: ensure we aren't using GNU extensions
6cab5a8 
0ae8f18 build: add -Wgnu to compile flags (fanquake)
3a0fd77 Remove use of non-standard zero variadic macros (Ben Woosley)
49f6178 Drop unused LOG_TIME_MICROS helper (Ben Woosley)
5d49999 prevector: Avoid unnamed struct, which is a GNU extension (DesWurstes)

Pull request description:

  Since we [started using](bitcoin#7165) the `ax_cxx_compile_stdcxx.m4` macro we've been passing `[noext]` to indicate that we don't want to use an extended mode, i.e GNU extensions. Speaking to Cory he clarified that the intention was to "require only vanilla c++11 and turn _off_ extension support so they would fail to compile".

  However in the codebase we are currently making use of some GNU extensions. We should either remove there usage, or at least amend our CXX compiler checks. I'd prefer the former.

  #### anonymous structs
  ```bash
  ./prevector.h:153:9: warning: anonymous structs are a GNU extension [-Wgnu-anonymous-struct]
          struct {
  ```

  This is fixed in bitcoin@b849212.

  #### variadic macros

  ```bash
  ./undo.h:57:50: warning: must specify at least one argument for '...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]
              ::Unserialize(s, VARINT(nVersionDummy));
  ```

  This is taken care of in bitcoin#18087.

  The `LOG_TIME_*` macros introduced in bitcoin#16805 make use of a [GNU extension](https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html).

  ```bash
  In file included from validation.cpp:22:
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::milliseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                                    ^
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:101:92: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::seconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                             ^
  6 warnings generated.
  ```

  This is fixed in 081a0ab and 612e8e1.

  #### prevention
  To ensure that usage doesn't creep back in we can add [`-Wgnu`](https://clang.llvm.org/docs/DiagnosticsReference.html#wgnu) to our compile time flags, which will make Clang warn whenever it encounters GNU extensions.

  This would close bitcoin#14130.
  Also related to bitcoin#17230, where it's suggested we use a GNU extension, the `gnu::pure` attribute.

ACKs for top commit:
  practicalswift:
    ACK 0ae8f18 -- diff looks correct
  MarcoFalke:
    ACK 0ae8f18
  vasild:
    utACK 0ae8f18
  dongcarl:
    ACK 0ae8f18

Tree-SHA512: c517404681ef8edf04c785731d26105bac9f3c9c958605aa24cbe399c649e7c5ee0c4aa8e714fd2b2d335e2fbea4d571e09b0dec36678ef871f0a6683ba6bb7f
vijaydasmp pushed a commit to vijaydasmp/dash that referenced this issue Feb 18, 2023
@fanquake @vijaydasmp
Merge bitcoin#18088: build: ensure we aren't using GNU extensions
71bb12a 
0ae8f18 build: add -Wgnu to compile flags (fanquake)
3a0fd77 Remove use of non-standard zero variadic macros (Ben Woosley)
49f6178 Drop unused LOG_TIME_MICROS helper (Ben Woosley)
5d49999 prevector: Avoid unnamed struct, which is a GNU extension (DesWurstes)

Pull request description:

  Since we [started using](bitcoin#7165) the `ax_cxx_compile_stdcxx.m4` macro we've been passing `[noext]` to indicate that we don't want to use an extended mode, i.e GNU extensions. Speaking to Cory he clarified that the intention was to "require only vanilla c++11 and turn _off_ extension support so they would fail to compile".

  However in the codebase we are currently making use of some GNU extensions. We should either remove there usage, or at least amend our CXX compiler checks. I'd prefer the former.

  #### anonymous structs
  ```bash
  ./prevector.h:153:9: warning: anonymous structs are a GNU extension [-Wgnu-anonymous-struct]
          struct {
  ```

  This is fixed in bitcoin@b849212.

  #### variadic macros

  ```bash
  ./undo.h:57:50: warning: must specify at least one argument for '...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]
              ::Unserialize(s, VARINT(nVersionDummy));
  ```

  This is taken care of in bitcoin#18087.

  The `LOG_TIME_*` macros introduced in bitcoin#16805 make use of a [GNU extension](https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html).

  ```bash
  In file included from validation.cpp:22:
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::milliseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                                    ^
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:101:92: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::seconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                             ^
  6 warnings generated.
  ```

  This is fixed in 081a0ab and 612e8e1.

  #### prevention
  To ensure that usage doesn't creep back in we can add [`-Wgnu`](https://clang.llvm.org/docs/DiagnosticsReference.html#wgnu) to our compile time flags, which will make Clang warn whenever it encounters GNU extensions.

  This would close bitcoin#14130.
  Also related to bitcoin#17230, where it's suggested we use a GNU extension, the `gnu::pure` attribute.

ACKs for top commit:
  practicalswift:
    ACK 0ae8f18 -- diff looks correct
  MarcoFalke:
    ACK 0ae8f18
  vasild:
    utACK 0ae8f18
  dongcarl:
    ACK 0ae8f18

Tree-SHA512: c517404681ef8edf04c785731d26105bac9f3c9c958605aa24cbe399c649e7c5ee0c4aa8e714fd2b2d335e2fbea4d571e09b0dec36678ef871f0a6683ba6bb7f
vijaydasmp pushed a commit to vijaydasmp/dash that referenced this issue Feb 18, 2023
@fanquake @vijaydasmp
Merge bitcoin#18088: build: ensure we aren't using GNU extensions
3135f0d 
0ae8f18 build: add -Wgnu to compile flags (fanquake)
3a0fd77 Remove use of non-standard zero variadic macros (Ben Woosley)
49f6178 Drop unused LOG_TIME_MICROS helper (Ben Woosley)
5d49999 prevector: Avoid unnamed struct, which is a GNU extension (DesWurstes)

Pull request description:

  Since we [started using](bitcoin#7165) the `ax_cxx_compile_stdcxx.m4` macro we've been passing `[noext]` to indicate that we don't want to use an extended mode, i.e GNU extensions. Speaking to Cory he clarified that the intention was to "require only vanilla c++11 and turn _off_ extension support so they would fail to compile".

  However in the codebase we are currently making use of some GNU extensions. We should either remove there usage, or at least amend our CXX compiler checks. I'd prefer the former.

  #### anonymous structs
  ```bash
  ./prevector.h:153:9: warning: anonymous structs are a GNU extension [-Wgnu-anonymous-struct]
          struct {
  ```

  This is fixed in bitcoin@b849212.

  #### variadic macros

  ```bash
  ./undo.h:57:50: warning: must specify at least one argument for '...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]
              ::Unserialize(s, VARINT(nVersionDummy));
  ```

  This is taken care of in bitcoin#18087.

  The `LOG_TIME_*` macros introduced in bitcoin#16805 make use of a [GNU extension](https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html).

  ```bash
  In file included from validation.cpp:22:
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::milliseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                                    ^
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:101:92: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::seconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                             ^
  6 warnings generated.
  ```

  This is fixed in 081a0ab and 612e8e1.

  #### prevention
  To ensure that usage doesn't creep back in we can add [`-Wgnu`](https://clang.llvm.org/docs/DiagnosticsReference.html#wgnu) to our compile time flags, which will make Clang warn whenever it encounters GNU extensions.

  This would close bitcoin#14130.
  Also related to bitcoin#17230, where it's suggested we use a GNU extension, the `gnu::pure` attribute.

ACKs for top commit:
  practicalswift:
    ACK 0ae8f18 -- diff looks correct
  MarcoFalke:
    ACK 0ae8f18
  vasild:
    utACK 0ae8f18
  dongcarl:
    ACK 0ae8f18

Tree-SHA512: c517404681ef8edf04c785731d26105bac9f3c9c958605aa24cbe399c649e7c5ee0c4aa8e714fd2b2d335e2fbea4d571e09b0dec36678ef871f0a6683ba6bb7f
vijaydasmp pushed a commit to vijaydasmp/dash that referenced this issue Feb 20, 2023
@fanquake @vijaydasmp
Merge bitcoin#18088: build: ensure we aren't using GNU extensions
8030834 
0ae8f18 build: add -Wgnu to compile flags (fanquake)
3a0fd77 Remove use of non-standard zero variadic macros (Ben Woosley)
49f6178 Drop unused LOG_TIME_MICROS helper (Ben Woosley)
5d49999 prevector: Avoid unnamed struct, which is a GNU extension (DesWurstes)

Pull request description:

  Since we [started using](bitcoin#7165) the `ax_cxx_compile_stdcxx.m4` macro we've been passing `[noext]` to indicate that we don't want to use an extended mode, i.e GNU extensions. Speaking to Cory he clarified that the intention was to "require only vanilla c++11 and turn _off_ extension support so they would fail to compile".

  However in the codebase we are currently making use of some GNU extensions. We should either remove there usage, or at least amend our CXX compiler checks. I'd prefer the former.

  #### anonymous structs
  ```bash
  ./prevector.h:153:9: warning: anonymous structs are a GNU extension [-Wgnu-anonymous-struct]
          struct {
  ```

  This is fixed in bitcoin@b849212.

  #### variadic macros

  ```bash
  ./undo.h:57:50: warning: must specify at least one argument for '...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]
              ::Unserialize(s, VARINT(nVersionDummy));
  ```

  This is taken care of in bitcoin#18087.

  The `LOG_TIME_*` macros introduced in bitcoin#16805 make use of a [GNU extension](https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html).

  ```bash
  In file included from validation.cpp:22:
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::milliseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                                    ^
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:101:92: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::seconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                             ^
  6 warnings generated.
  ```

  This is fixed in 081a0ab and 612e8e1.

  #### prevention
  To ensure that usage doesn't creep back in we can add [`-Wgnu`](https://clang.llvm.org/docs/DiagnosticsReference.html#wgnu) to our compile time flags, which will make Clang warn whenever it encounters GNU extensions.

  This would close bitcoin#14130.
  Also related to bitcoin#17230, where it's suggested we use a GNU extension, the `gnu::pure` attribute.

ACKs for top commit:
  practicalswift:
    ACK 0ae8f18 -- diff looks correct
  MarcoFalke:
    ACK 0ae8f18
  vasild:
    utACK 0ae8f18
  dongcarl:
    ACK 0ae8f18

Tree-SHA512: c517404681ef8edf04c785731d26105bac9f3c9c958605aa24cbe399c649e7c5ee0c4aa8e714fd2b2d335e2fbea4d571e09b0dec36678ef871f0a6683ba6bb7f
vijaydasmp pushed a commit to vijaydasmp/dash that referenced this issue Feb 20, 2023
@fanquake @vijaydasmp
Merge bitcoin#18088: build: ensure we aren't using GNU extensions
e49ac4c 
0ae8f18 build: add -Wgnu to compile flags (fanquake)
3a0fd77 Remove use of non-standard zero variadic macros (Ben Woosley)
49f6178 Drop unused LOG_TIME_MICROS helper (Ben Woosley)
5d49999 prevector: Avoid unnamed struct, which is a GNU extension (DesWurstes)

Pull request description:

  Since we [started using](bitcoin#7165) the `ax_cxx_compile_stdcxx.m4` macro we've been passing `[noext]` to indicate that we don't want to use an extended mode, i.e GNU extensions. Speaking to Cory he clarified that the intention was to "require only vanilla c++11 and turn _off_ extension support so they would fail to compile".

  However in the codebase we are currently making use of some GNU extensions. We should either remove there usage, or at least amend our CXX compiler checks. I'd prefer the former.

  #### anonymous structs
  ```bash
  ./prevector.h:153:9: warning: anonymous structs are a GNU extension [-Wgnu-anonymous-struct]
          struct {
  ```

  This is fixed in bitcoin@b849212.

  #### variadic macros

  ```bash
  ./undo.h:57:50: warning: must specify at least one argument for '...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]
              ::Unserialize(s, VARINT(nVersionDummy));
  ```

  This is taken care of in bitcoin#18087.

  The `LOG_TIME_*` macros introduced in bitcoin#16805 make use of a [GNU extension](https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html).

  ```bash
  In file included from validation.cpp:22:
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::milliseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                                    ^
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:101:92: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::seconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                             ^
  6 warnings generated.
  ```

  This is fixed in 081a0ab and 612e8e1.

  #### prevention
  To ensure that usage doesn't creep back in we can add [`-Wgnu`](https://clang.llvm.org/docs/DiagnosticsReference.html#wgnu) to our compile time flags, which will make Clang warn whenever it encounters GNU extensions.

  This would close bitcoin#14130.
  Also related to bitcoin#17230, where it's suggested we use a GNU extension, the `gnu::pure` attribute.

ACKs for top commit:
  practicalswift:
    ACK 0ae8f18 -- diff looks correct
  MarcoFalke:
    ACK 0ae8f18
  vasild:
    utACK 0ae8f18
  dongcarl:
    ACK 0ae8f18

Tree-SHA512: c517404681ef8edf04c785731d26105bac9f3c9c958605aa24cbe399c649e7c5ee0c4aa8e714fd2b2d335e2fbea4d571e09b0dec36678ef871f0a6683ba6bb7f
vijaydasmp pushed a commit to vijaydasmp/dash that referenced this issue Feb 22, 2023
@fanquake @vijaydasmp
Merge bitcoin#18088: build: ensure we aren't using GNU extensions
6135b07 
0ae8f18 build: add -Wgnu to compile flags (fanquake)
3a0fd77 Remove use of non-standard zero variadic macros (Ben Woosley)
49f6178 Drop unused LOG_TIME_MICROS helper (Ben Woosley)
5d49999 prevector: Avoid unnamed struct, which is a GNU extension (DesWurstes)

Pull request description:

  Since we [started using](bitcoin#7165) the `ax_cxx_compile_stdcxx.m4` macro we've been passing `[noext]` to indicate that we don't want to use an extended mode, i.e GNU extensions. Speaking to Cory he clarified that the intention was to "require only vanilla c++11 and turn _off_ extension support so they would fail to compile".

  However in the codebase we are currently making use of some GNU extensions. We should either remove there usage, or at least amend our CXX compiler checks. I'd prefer the former.

  #### anonymous structs
  ```bash
  ./prevector.h:153:9: warning: anonymous structs are a GNU extension [-Wgnu-anonymous-struct]
          struct {
  ```

  This is fixed in bitcoin@b849212.

  #### variadic macros

  ```bash
  ./undo.h:57:50: warning: must specify at least one argument for '...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]
              ::Unserialize(s, VARINT(nVersionDummy));
  ```

  This is taken care of in bitcoin#18087.

  The `LOG_TIME_*` macros introduced in bitcoin#16805 make use of a [GNU extension](https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html).

  ```bash
  In file included from validation.cpp:22:
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::milliseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                                    ^
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:101:92: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::seconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                             ^
  6 warnings generated.
  ```

  This is fixed in 081a0ab and 612e8e1.

  #### prevention
  To ensure that usage doesn't creep back in we can add [`-Wgnu`](https://clang.llvm.org/docs/DiagnosticsReference.html#wgnu) to our compile time flags, which will make Clang warn whenever it encounters GNU extensions.

  This would close bitcoin#14130.
  Also related to bitcoin#17230, where it's suggested we use a GNU extension, the `gnu::pure` attribute.

ACKs for top commit:
  practicalswift:
    ACK 0ae8f18 -- diff looks correct
  MarcoFalke:
    ACK 0ae8f18
  vasild:
    utACK 0ae8f18
  dongcarl:
    ACK 0ae8f18

Tree-SHA512: c517404681ef8edf04c785731d26105bac9f3c9c958605aa24cbe399c649e7c5ee0c4aa8e714fd2b2d335e2fbea4d571e09b0dec36678ef871f0a6683ba6bb7f
vijaydasmp pushed a commit to vijaydasmp/dash that referenced this issue Feb 22, 2023
@fanquake @vijaydasmp
Merge bitcoin#18088: build: ensure we aren't using GNU extensions
4bd31ea 
0ae8f18 build: add -Wgnu to compile flags (fanquake)
3a0fd77 Remove use of non-standard zero variadic macros (Ben Woosley)
49f6178 Drop unused LOG_TIME_MICROS helper (Ben Woosley)
5d49999 prevector: Avoid unnamed struct, which is a GNU extension (DesWurstes)

Pull request description:

  Since we [started using](bitcoin#7165) the `ax_cxx_compile_stdcxx.m4` macro we've been passing `[noext]` to indicate that we don't want to use an extended mode, i.e GNU extensions. Speaking to Cory he clarified that the intention was to "require only vanilla c++11 and turn _off_ extension support so they would fail to compile".

  However in the codebase we are currently making use of some GNU extensions. We should either remove there usage, or at least amend our CXX compiler checks. I'd prefer the former.

  #### anonymous structs
  ```bash
  ./prevector.h:153:9: warning: anonymous structs are a GNU extension [-Wgnu-anonymous-struct]
          struct {
  ```

  This is fixed in bitcoin@b849212.

  #### variadic macros

  ```bash
  ./undo.h:57:50: warning: must specify at least one argument for '...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]
              ::Unserialize(s, VARINT(nVersionDummy));
  ```

  This is taken care of in bitcoin#18087.

  The `LOG_TIME_*` macros introduced in bitcoin#16805 make use of a [GNU extension](https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html).

  ```bash
  In file included from validation.cpp:22:
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::milliseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                                    ^
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:101:92: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::seconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                             ^
  6 warnings generated.
  ```

  This is fixed in 081a0ab and 612e8e1.

  #### prevention
  To ensure that usage doesn't creep back in we can add [`-Wgnu`](https://clang.llvm.org/docs/DiagnosticsReference.html#wgnu) to our compile time flags, which will make Clang warn whenever it encounters GNU extensions.

  This would close bitcoin#14130.
  Also related to bitcoin#17230, where it's suggested we use a GNU extension, the `gnu::pure` attribute.

ACKs for top commit:
  practicalswift:
    ACK 0ae8f18 -- diff looks correct
  MarcoFalke:
    ACK 0ae8f18
  vasild:
    utACK 0ae8f18
  dongcarl:
    ACK 0ae8f18

Tree-SHA512: c517404681ef8edf04c785731d26105bac9f3c9c958605aa24cbe399c649e7c5ee0c4aa8e714fd2b2d335e2fbea4d571e09b0dec36678ef871f0a6683ba6bb7f
vijaydasmp pushed a commit to vijaydasmp/dash that referenced this issue Feb 23, 2023
@fanquake @vijaydasmp
Merge bitcoin#18088: build: ensure we aren't using GNU extensions
1b7e99d 
0ae8f18 build: add -Wgnu to compile flags (fanquake)
3a0fd77 Remove use of non-standard zero variadic macros (Ben Woosley)
49f6178 Drop unused LOG_TIME_MICROS helper (Ben Woosley)
5d49999 prevector: Avoid unnamed struct, which is a GNU extension (DesWurstes)

Pull request description:

  Since we [started using](bitcoin#7165) the `ax_cxx_compile_stdcxx.m4` macro we've been passing `[noext]` to indicate that we don't want to use an extended mode, i.e GNU extensions. Speaking to Cory he clarified that the intention was to "require only vanilla c++11 and turn _off_ extension support so they would fail to compile".

  However in the codebase we are currently making use of some GNU extensions. We should either remove there usage, or at least amend our CXX compiler checks. I'd prefer the former.

  #### anonymous structs
  ```bash
  ./prevector.h:153:9: warning: anonymous structs are a GNU extension [-Wgnu-anonymous-struct]
          struct {
  ```

  This is fixed in bitcoin@b849212.

  #### variadic macros

  ```bash
  ./undo.h:57:50: warning: must specify at least one argument for '...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]
              ::Unserialize(s, VARINT(nVersionDummy));
  ```

  This is taken care of in bitcoin#18087.

  The `LOG_TIME_*` macros introduced in bitcoin#16805 make use of a [GNU extension](https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html).

  ```bash
  In file included from validation.cpp:22:
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::milliseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                                    ^
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:101:92: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::seconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                             ^
  6 warnings generated.
  ```

  This is fixed in 081a0ab and 612e8e1.

  #### prevention
  To ensure that usage doesn't creep back in we can add [`-Wgnu`](https://clang.llvm.org/docs/DiagnosticsReference.html#wgnu) to our compile time flags, which will make Clang warn whenever it encounters GNU extensions.

  This would close bitcoin#14130.
  Also related to bitcoin#17230, where it's suggested we use a GNU extension, the `gnu::pure` attribute.

ACKs for top commit:
  practicalswift:
    ACK 0ae8f18 -- diff looks correct
  MarcoFalke:
    ACK 0ae8f18
  vasild:
    utACK 0ae8f18
  dongcarl:
    ACK 0ae8f18

Tree-SHA512: c517404681ef8edf04c785731d26105bac9f3c9c958605aa24cbe399c649e7c5ee0c4aa8e714fd2b2d335e2fbea4d571e09b0dec36678ef871f0a6683ba6bb7f
vijaydasmp pushed a commit to vijaydasmp/dash that referenced this issue Feb 24, 2023
@fanquake @vijaydasmp
Merge bitcoin#18088: build: ensure we aren't using GNU extensions
76c6a57 
0ae8f18 build: add -Wgnu to compile flags (fanquake)
3a0fd77 Remove use of non-standard zero variadic macros (Ben Woosley)
49f6178 Drop unused LOG_TIME_MICROS helper (Ben Woosley)
5d49999 prevector: Avoid unnamed struct, which is a GNU extension (DesWurstes)

Pull request description:

  Since we [started using](bitcoin#7165) the `ax_cxx_compile_stdcxx.m4` macro we've been passing `[noext]` to indicate that we don't want to use an extended mode, i.e GNU extensions. Speaking to Cory he clarified that the intention was to "require only vanilla c++11 and turn _off_ extension support so they would fail to compile".

  However in the codebase we are currently making use of some GNU extensions. We should either remove there usage, or at least amend our CXX compiler checks. I'd prefer the former.

  #### anonymous structs
  ```bash
  ./prevector.h:153:9: warning: anonymous structs are a GNU extension [-Wgnu-anonymous-struct]
          struct {
  ```

  This is fixed in bitcoin@b849212.

  #### variadic macros

  ```bash
  ./undo.h:57:50: warning: must specify at least one argument for '...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]
              ::Unserialize(s, VARINT(nVersionDummy));
  ```

  This is taken care of in bitcoin#18087.

  The `LOG_TIME_*` macros introduced in bitcoin#16805 make use of a [GNU extension](https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html).

  ```bash
  In file included from validation.cpp:22:
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::milliseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                                    ^
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:101:92: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::seconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                             ^
  6 warnings generated.
  ```

  This is fixed in 081a0ab and 612e8e1.

  #### prevention
  To ensure that usage doesn't creep back in we can add [`-Wgnu`](https://clang.llvm.org/docs/DiagnosticsReference.html#wgnu) to our compile time flags, which will make Clang warn whenever it encounters GNU extensions.

  This would close bitcoin#14130.
  Also related to bitcoin#17230, where it's suggested we use a GNU extension, the `gnu::pure` attribute.

ACKs for top commit:
  practicalswift:
    ACK 0ae8f18 -- diff looks correct
  MarcoFalke:
    ACK 0ae8f18
  vasild:
    utACK 0ae8f18
  dongcarl:
    ACK 0ae8f18

Tree-SHA512: c517404681ef8edf04c785731d26105bac9f3c9c958605aa24cbe399c649e7c5ee0c4aa8e714fd2b2d335e2fbea4d571e09b0dec36678ef871f0a6683ba6bb7f
vijaydasmp pushed a commit to vijaydasmp/dash that referenced this issue Feb 28, 2023
@fanquake @vijaydasmp
Merge bitcoin#18088: build: ensure we aren't using GNU extensions
0c169af 
0ae8f18 build: add -Wgnu to compile flags (fanquake)
3a0fd77 Remove use of non-standard zero variadic macros (Ben Woosley)
49f6178 Drop unused LOG_TIME_MICROS helper (Ben Woosley)
5d49999 prevector: Avoid unnamed struct, which is a GNU extension (DesWurstes)

Pull request description:

  Since we [started using](bitcoin#7165) the `ax_cxx_compile_stdcxx.m4` macro we've been passing `[noext]` to indicate that we don't want to use an extended mode, i.e GNU extensions. Speaking to Cory he clarified that the intention was to "require only vanilla c++11 and turn _off_ extension support so they would fail to compile".

  However in the codebase we are currently making use of some GNU extensions. We should either remove there usage, or at least amend our CXX compiler checks. I'd prefer the former.

  #### anonymous structs
  ```bash
  ./prevector.h:153:9: warning: anonymous structs are a GNU extension [-Wgnu-anonymous-struct]
          struct {
  ```

  This is fixed in bitcoin@b849212.

  #### variadic macros

  ```bash
  ./undo.h:57:50: warning: must specify at least one argument for '...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]
              ::Unserialize(s, VARINT(nVersionDummy));
  ```

  This is taken care of in bitcoin#18087.

  The `LOG_TIME_*` macros introduced in bitcoin#16805 make use of a [GNU extension](https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html).

  ```bash
  In file included from validation.cpp:22:
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::milliseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                                    ^
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:101:92: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::seconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                             ^
  6 warnings generated.
  ```

  This is fixed in 081a0ab and 612e8e1.

  #### prevention
  To ensure that usage doesn't creep back in we can add [`-Wgnu`](https://clang.llvm.org/docs/DiagnosticsReference.html#wgnu) to our compile time flags, which will make Clang warn whenever it encounters GNU extensions.

  This would close bitcoin#14130.
  Also related to bitcoin#17230, where it's suggested we use a GNU extension, the `gnu::pure` attribute.

ACKs for top commit:
  practicalswift:
    ACK 0ae8f18 -- diff looks correct
  MarcoFalke:
    ACK 0ae8f18
  vasild:
    utACK 0ae8f18
  dongcarl:
    ACK 0ae8f18

Tree-SHA512: c517404681ef8edf04c785731d26105bac9f3c9c958605aa24cbe399c649e7c5ee0c4aa8e714fd2b2d335e2fbea4d571e09b0dec36678ef871f0a6683ba6bb7f
vijaydasmp pushed a commit to vijaydasmp/dash that referenced this issue Mar 3, 2023
@fanquake @vijaydasmp
Merge bitcoin#18088: build: ensure we aren't using GNU extensions
afdb731 
0ae8f18 build: add -Wgnu to compile flags (fanquake)
3a0fd77 Remove use of non-standard zero variadic macros (Ben Woosley)
49f6178 Drop unused LOG_TIME_MICROS helper (Ben Woosley)
5d49999 prevector: Avoid unnamed struct, which is a GNU extension (DesWurstes)

Pull request description:

  Since we [started using](bitcoin#7165) the `ax_cxx_compile_stdcxx.m4` macro we've been passing `[noext]` to indicate that we don't want to use an extended mode, i.e GNU extensions. Speaking to Cory he clarified that the intention was to "require only vanilla c++11 and turn _off_ extension support so they would fail to compile".

  However in the codebase we are currently making use of some GNU extensions. We should either remove there usage, or at least amend our CXX compiler checks. I'd prefer the former.

  #### anonymous structs
  ```bash
  ./prevector.h:153:9: warning: anonymous structs are a GNU extension [-Wgnu-anonymous-struct]
          struct {
  ```

  This is fixed in bitcoin@b849212.

  #### variadic macros

  ```bash
  ./undo.h:57:50: warning: must specify at least one argument for '...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]
              ::Unserialize(s, VARINT(nVersionDummy));
  ```

  This is taken care of in bitcoin#18087.

  The `LOG_TIME_*` macros introduced in bitcoin#16805 make use of a [GNU extension](https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html).

  ```bash
  In file included from validation.cpp:22:
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::milliseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                                    ^
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:101:92: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::seconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                             ^
  6 warnings generated.
  ```

  This is fixed in 081a0ab and 612e8e1.

  #### prevention
  To ensure that usage doesn't creep back in we can add [`-Wgnu`](https://clang.llvm.org/docs/DiagnosticsReference.html#wgnu) to our compile time flags, which will make Clang warn whenever it encounters GNU extensions.

  This would close bitcoin#14130.
  Also related to bitcoin#17230, where it's suggested we use a GNU extension, the `gnu::pure` attribute.

ACKs for top commit:
  practicalswift:
    ACK 0ae8f18 -- diff looks correct
  MarcoFalke:
    ACK 0ae8f18
  vasild:
    utACK 0ae8f18
  dongcarl:
    ACK 0ae8f18

Tree-SHA512: c517404681ef8edf04c785731d26105bac9f3c9c958605aa24cbe399c649e7c5ee0c4aa8e714fd2b2d335e2fbea4d571e09b0dec36678ef871f0a6683ba6bb7f
PastaPastaPasta pushed a commit to vijaydasmp/dash that referenced this issue Mar 27, 2023
@fanquake @PastaPastaPasta
Merge bitcoin#18088: build: ensure we aren't using GNU extensions
a73baa7 
0ae8f18 build: add -Wgnu to compile flags (fanquake)
3a0fd77 Remove use of non-standard zero variadic macros (Ben Woosley)
49f6178 Drop unused LOG_TIME_MICROS helper (Ben Woosley)
5d49999 prevector: Avoid unnamed struct, which is a GNU extension (DesWurstes)

Pull request description:

  Since we [started using](bitcoin#7165) the `ax_cxx_compile_stdcxx.m4` macro we've been passing `[noext]` to indicate that we don't want to use an extended mode, i.e GNU extensions. Speaking to Cory he clarified that the intention was to "require only vanilla c++11 and turn _off_ extension support so they would fail to compile".

  However in the codebase we are currently making use of some GNU extensions. We should either remove there usage, or at least amend our CXX compiler checks. I'd prefer the former.

  #### anonymous structs
  ```bash
  ./prevector.h:153:9: warning: anonymous structs are a GNU extension [-Wgnu-anonymous-struct]
          struct {
  ```

  This is fixed in bitcoin@b849212.

  #### variadic macros

  ```bash
  ./undo.h:57:50: warning: must specify at least one argument for '...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]
              ::Unserialize(s, VARINT(nVersionDummy));
  ```

  This is taken care of in bitcoin#18087.

  The `LOG_TIME_*` macros introduced in bitcoin#16805 make use of a [GNU extension](https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html).

  ```bash
  In file included from validation.cpp:22:
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::milliseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                                    ^
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:99:99: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
  ./logging/timer.h:101:92: warning: token pasting of ',' and __VA_ARGS__ is a GNU extension [-Wgnu-zero-variadic-macro-arguments]
      BCLog::Timer<std::chrono::seconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
                                                                                             ^
  6 warnings generated.
  ```

  This is fixed in 081a0ab and 612e8e1.

  #### prevention
  To ensure that usage doesn't creep back in we can add [`-Wgnu`](https://clang.llvm.org/docs/DiagnosticsReference.html#wgnu) to our compile time flags, which will make Clang warn whenever it encounters GNU extensions.

  This would close bitcoin#14130.
  Also related to bitcoin#17230, where it's suggested we use a GNU extension, the `gnu::pure` attribute.

ACKs for top commit:
  practicalswift:
    ACK 0ae8f18 -- diff looks correct
  MarcoFalke:
    ACK 0ae8f18
  vasild:
    utACK 0ae8f18
  dongcarl:
    ACK 0ae8f18

Tree-SHA512: c517404681ef8edf04c785731d26105bac9f3c9c958605aa24cbe399c649e7c5ee0c4aa8e714fd2b2d335e2fbea4d571e09b0dec36678ef871f0a6683ba6bb7f
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build: ensure we aren't using GNU extensions fanquake/bitcoin
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@fanquake @DesWurstes