Historically, the headers have been bumped some time after a file has
been touched. Do it now to avoid having to touch them again in the
future for that reason.
-BEGIN VERIFY SCRIPT-
sed -i --regexp-extended 's;( 20[0-2][0-9])(-20[0-2][0-9])? The Bitcoin Core developers;\1-present The Bitcoin Core developers;g' $( git show --pretty="" --name-only HEAD~1 )
-END VERIFY SCRIPT-
This uses a macro, which can be a bit more brittle than an alias
template. However, class template argument deduction for alias templates
is only implemented in clang-19.
In theory this commit should only touch the span.h header, because
std::span can implicilty convert into Span in most places, if needed.
However, at least when using the clang compiler, there are some
false-positive lifetimebound warnings and some implicit conversions can
not be resolved.
Thus, this refactoring commit also changed the affected places to
replace Span with std::span.
Also add test to make sure this doesn't get broken in the future.
This was breaking vector<bool> serialization in multiprocess code because
template current deduction guides would make it appear like vector<bool> could
be converted to a span, but then the actual conversion to span would fail.
Replace calls to AsBytePtr with direct calls to AsBytes or reinterpret_cast.
AsBytePtr is just a wrapper around reinterpret_cast. It accepts any type of
pointer as an argument and uses reinterpret_cast to cast the argument to a
std::byte pointer.
Despite taking any type of pointer as an argument, it is not useful to call
AsBytePtr on most types of pointers, because byte representations of most types
will be implmentation-specific. Also, because it is named similarly to the
AsBytes function, AsBytePtr looks safer than it actually is. Both AsBytes and
AsBytePtr call reinterpret_cast internally and may be unsafe to use with
certain types, but AsBytes at least has some type checking and can only be
called on Span objects, while AsBytePtr can be called on any pointer argument.
Co-authored-by: Pieter Wuille <pieter@wuille.net>
Building with iPhoneOS SDK fails because it also has `BytePtr` defined
in /usr/include/MacTypes.h.
-BEGIN VERIFY SCRIPT-
sed -i 's/BytePtr/AsBytePtr/' $(git grep -l "BytePtr" src)
-END VERIFY SCRIPT-
faa3ec2304051be7cfbe301cfbfbda3faf7514fc span: Add std::byte helpers (MarcoFalke)
fa18038f519db76befb9a7bd0b1540143bfeb12b refactor: Use ignore helper when unserializing an invalid pubkey (MarcoFalke)
fabe18d0b39b4b918bf60e3a313eaa36fb4067f2 Use value_type in CDataStream where possible (MarcoFalke)
Pull request description:
This adds (currently unused) span std::byte helpers, so that they can be used in new code.
The refactors are also required for https://github.com/bitcoin/bitcoin/pull/23438, but they are split up because the other pull doesn't compile with msvc right now.
The third commit is not needed for the other pull, but still nice.
ACKs for top commit:
klementtan:
reACK faa3ec2. Verified that all the new `std::byte` helper functions are tested.
laanwj:
Code review ACK faa3ec2304051be7cfbe301cfbfbda3faf7514fc
Tree-SHA512: b1f6af39f03ea4dfebf20d4a8538fa993a6104e7fc92ddf0c4606a7efc3ca9a8c1a4741d98a1418569c11bb9ce9258bf0c0c06d93d85ed7e208902a2db04e407
33c6a208a9e2512a174c99c224a933a59f091bc2 span, doc: provide span.h context and explain lifetimebound definition (Jon Atack)
d14395bc5db55331115fa3c1e71741d1de7f092f net, doc: provide context for UnserializeV1Array() (Jon Atack)
Pull request description:
Add contextual documentation for developers and future readers of the code regarding
- CNetAddr::UnserializeV1Array (see #22140)
- Span and why it defines Clang lifetimebound locally rather than using the one in attributes.h
ACKs for top commit:
laanwj:
Documentation review ACK 33c6a208a9e2512a174c99c224a933a59f091bc2
Tree-SHA512: cb8e6a6c23b36c9ef7499257e97c5378ec895bb9122b79b63b572d9721a1ae6ce6c0be7ad61bdf976c255527ae750fc9ff4b3e03c07c6c797d14dbc82ea9fb3a
e3e7446305329ce96e9cf5f5161658eb2e1ea888 Add lifetimebound to attributes for general-purpose usage (Cory Fields)
1d58cc7cb040a70f768b632f294db4e0797d3a34 span: add lifetimebound attribute (Cory Fields)
62733fee874bfe7e833e71380eb8efd6a3126fbd span: (almost) match std::span's constructor behavior (Cory Fields)
Pull request description:
Replaces #19382 with a different approach. See [this comment](https://github.com/bitcoin/bitcoin/pull/19382#discussion_r446332852) for the reasoning behind the switch.
--
Description from #19382:
See [here](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0936r0.pdf) for more detail on lifetimebound.
This is implemented using preprocesor macros rather than configure checks in order to keep span.h self-contained.
The ```[[clang::lifetimebound]]``` syntax was chosen over ```__attribute__((lifetimebound))``` because the former is more flexible and works to guard ```this``` as well as function parameters, and also because at least for now, it's available only in clang.
There are currently no violations in our codebase, but this can easily be tested by inserting one like this somewhere and compiling with a modern clang:
```c++
Span<const int> bad(std::vector<int>{1,2,3});
```
The result:
> warning: temporary whose address is used as value of local variable 'bad' will be destroyed at the end of the full-expression [-Wdangling]
Span<const int> bad(std::vector<int>{1,2,3});
```
ACKs for top commit:
sipa:
ACK e3e7446305329ce96e9cf5f5161658eb2e1ea888
ajtowns:
ACK e3e7446305329ce96e9cf5f5161658eb2e1ea888 (drive by; only a quick skim of code and some basic sanity checks)
MarcoFalke:
review ACK e3e7446305329ce96e9cf5f5161658eb2e1ea888 🔗
jonatack:
ACK e3e7446 change since last review is adding `[[clang::lifetimebound]]` as `LIFETIMEBOUND` to src/attributes.h as suggested in https://github.com/bitcoin/bitcoin/pull/19387#issuecomment-650752959.
Tree-SHA512: 05a3440ee595ef0e8d693a2820b360707695c016a68e15df47c20cd8d053646cc6c8cca8addd7db40e72b3fce208879a41c8102ba7ae9223e4366e5de1175211
This prevents constructing a Span<A> given two pointers into an array
of B (where B is a subclass of A), at least without explicit cast to
pointers to A.
c31cbe7cfefc18123eb85ffb2ce509748435efde Add C++17 test to Travis (Pieter Wuille)
7829685e27aae25efb32e07368175c8f664b2218 Add configure option for c++17 (Pieter Wuille)
0fbde488b24f62b4bbbde216647941dcac65c81a Support conversion between Spans of compatible types (Pieter Wuille)
7cbfebbf3df0d26f518811e0bfb7abf270c83e37 Update ax_cxx_compile_stdcxx.m4 (Pieter Wuille)
Pull request description:
This adds a `--enable-c++17` option to the configure script, fixes the only C++17 incompatibility (with a commit taken from #18468), and adds a Travis test for it.
This is all off by default, and release builds remain C++11.
It implements the first step of the plan in https://github.com/bitcoin/bitcoin/issues/16684.
ACKs for top commit:
elichai:
tACK c31cbe7cfefc18123eb85ffb2ce509748435efde
practicalswift:
Tested ACK c31cbe7cfefc18123eb85ffb2ce509748435efde
hebasto:
ACK c31cbe7cfefc18123eb85ffb2ce509748435efde, tested on Linux Mint 19.3 both C++11 and C++17 modes. Compiled and passed tests locally.
Tree-SHA512: a4b00776dbceef9c12abbb404c6bcd48f7916ce24c8c7a14116355f64e817578b7fcddbedd5ce435322319d1e4de43429b68553f4d96d970c308fe3e3e59b9d1
