a92e48b02d test: move TEST_RUNNER_EXTRA into native tsan setup (fanquake)
Pull request description:
`feature_block.py` is being run in the tsan job, i.e [here](https://travis-ci.org/github/bitcoin/bitcoin/jobs/703122309), even though it should be excluded. My hasty assumption is that this will fix it. In any case, all other instances of `TEST_RUNNER_EXTRA` seem to have moved out of `.travis.yml` and into the different CI configurations.
ACKs for top commit:
MarcoFalke:
ACK a92e48b02d
practicalswift:
ACK a92e48b02d -- patch looks correct
hebasto:
ACK a92e48b02d, I have reviewed the code and it looks OK, I agree it can be merged.
Tree-SHA512: 86057bef2cc87c6acdbbf94f8cd7a5147510448c3e67aacde8daf247e3ccf649cfc5afbbd10693e084f426042d98150616c0e49bfa5f32b949dff9cebd2fd95d
9b009fae6e qa: Test concurrent wallet loading (João Barbosa)
b9971ae585 wallet: Handle concurrent wallet loading (João Barbosa)
Pull request description:
This PR handles concurrent wallet loading.
This can be tested by running in parallel the following script a couple of times:
```sh
for i in {1..10}
do
src/bitcoin-cli -regtest loadwallet foo
src/bitcoin-cli -regtest unloadwallet foo
done
```
Eventually the error occurs:
```
error code: -4
error message:
Wallet already being loading.
```
For reference, loading and already loaded wallet gives:
```
error code: -4
error message:
Wallet file verification failed. Error loading wallet w1. Duplicate -wallet filename specified.
```
Fixes#19232.
ACKs for top commit:
MarcoFalke:
Concept ACK 9b009fae6e I have not reviewed the code
hebasto:
ACK 9b009fae6e, tested on Linux Mint 20 (x86_64):
ryanofsky:
Code review good-but-not-ideal ACK 9b009fae6e
Tree-SHA512: 0ccd77b03c0926e4c4e51efb31e193b93cb4b9ffe8bac6bb018f7344c55dfd939b873b8cf5e657dca73e6202eb75aa672de2acb787cc133184b0b3b51e47b972
9952242c03 build: improve builtin_clz* detection (fanquake)
Pull request description:
Fixes#19402.
The way we currently test for `__builtin_clz*` support with `AC_CHECK_DECLS` does not work with Clang:
```bash
configure:21492: clang++-10 -std=c++11 -c -g -O2 -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS conftest.cpp >&5
conftest.cpp💯10: error: builtin functions must be directly called
(void) __builtin_clz;
^
1 error generated.
```
This also removes the `__builtin_clz()` check, as we don't actually use it anywhere, and it's trvial to re-add detection if we do start using it at some point. If this is controversial then I'll add a test for it as well.
ACKs for top commit:
sipa:
ACK 9952242c03
laanwj:
ACK 9952242c03
Tree-SHA512: 695abb1a694a01a25aaa483b4fffa7d598842f2ba4fe8630fbed9ce5450b915c33bf34bb16ad16a16b702dd7c91ebf49fe509a2498b9e28254fe0ec5177bbac0
fa525e4d1c net: Avoid wasting inv traffic during IBD (MarcoFalke)
fa06d7e934 refactor: block import implies IsInitialBlockDownload (MarcoFalke)
faba65e696 Add ChainstateManager::ActiveChainstate (MarcoFalke)
fabf3d64ff test: Add FeeFilterRounder test (MarcoFalke)
Pull request description:
Tx-inv messages are ignored during IBD, so it would be nice if we told peers to not send them in the first place. Do that by sending two `feefilter` messages: One when the connection is made (and the node is in IBD), and another one when the node leaves IBD.
ACKs for top commit:
jamesob:
ACK fa525e4d1c ([`jamesob/ackr/19204.1.MarcoFalke.p2p_reduce_inv_traffic_d`](https://github.com/jamesob/bitcoin/tree/ackr/19204.1.MarcoFalke.p2p_reduce_inv_traffic_d))
naumenkogs:
utACK fa525e4
gzhao408:
ACK fa525e4d1c
jonatack:
re-ACK fa525e4 checked diff `git range-diff 19612ca fa8a66c fa525e4`, re-reviewed, ran tests, ran a custom p2p IBD behavior test at 9321e0f223.
hebasto:
re-ACK fa525e4d1c, only rebased since the [previous](https://github.com/bitcoin/bitcoin/pull/19204#pullrequestreview-429519667) review (verified with `git range-diff`).
Tree-SHA512: 2c22a5def9822396fca45d808b165b636f1143c4bdb2eaa5c7e977f1f18e8b10c86d4c180da488def38416cf3076a26de15014dfd4d86b2a7e5af88c74afb8eb
53361ddc75 [build] Remove unused RES_IMAGES (Bushstar)
Pull request description:
Remove RES_IMAGES. Seems to be unused since 2015 in the commit below.
98c222b5aa (diff-9a4f3a253de77bf90b107bdf5283ebc3R317)
The src/qt/res/images to which it was used with is no longer present either.
ACKs for top commit:
hebasto:
ACK 53361ddc75, tested on Linux Mint 20 (x86_64).
Tree-SHA512: d2f09ae225a4c6c171e1aae4c4a444064dc0502e96130e04ccb718f9fcf611a287c56630dec3e9a8937b5e29040d931a237da36180d2343c23cef30359e46323
fa74a54fad ci: Increase test timeout for sanitizer configs (MarcoFalke)
Pull request description:
Hopefully fixes#19369
ACKs for top commit:
practicalswift:
ACK fa74a54fad -- patch looks correct!
fanquake:
ACK fa74a54fad - the test failure here is a different issue, and the problem referenced by this PR hasn't occurred, so I think this can be merged. It's also fixing the use of `--factor` which was replaced in #18986.
Tree-SHA512: bec44fff454f20b7c5f8a461560d2496765dea61186027cc0cdce5ac55be0488b6f7f172fec49b89fe59a75b455501e2b4ae91a98c4a17d5c1a722846d2b3b60
8578c6fccd build: Fix search for brew-installed BDB 4 on OS X (Glenn Willen)
Pull request description:
~~NOTE: This PR contains one important fix that I need (to make Bitcoin Core build cleanly on my system without shenanigans), plus some related general cleanup that is not really necessary, and could be annoying. (I am prepared to defend my argument that BDB_CFLAGS is wrong here, and BDB_CPPFLAGS is right, but this could bite anybody who has gotten in the habit of -- or scripted -- setting the former.)~~
Ok, I have been convinced that I was too clever with the refactor and I have removed it. Now it's just the tiny change to fix the build on my local machine.
---
On OS X, when searching Homebrew keg-only packages for BDB 4.8, if we find it,
use BDB_CPPFLAGS and BDB_LIBS instead of CFLAGS and LIBS for the result. This
is (1) more correct, and (2) necessary in order to give this location
priority over other directories in the include search path, which may include
system include directories with other versions of BDB.
ACKs for top commit:
theuni:
ACK 8578c6fccd.
Tree-SHA512: a28f48fc81a25736f7e77c663f21cd9a6ae1cd115682031c5aa695c94cb5afa11920330a60cd6a54832822a2aec1eb23123ac2e2dcd4f0b3835aef9c9339ac97
The way we currently test with AC_CHECK_DECLS do not work with Clang:
```bash
configure:21492: clang++-10 -std=c++11 -c -g -O2 -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS conftest.cpp >&5
conftest.cpp💯10: error: builtin functions must be directly called
(void) __builtin_clz;
^
1 error generated.
```
This also removes the __builtin_clz() check, as we don't actually use
it anywhere, and it's trvial to re-add detection if we do start using
it at some point.
fa32adf9dc scripted-diff: TxoutType C++11 scoped enum class (MarcoFalke)
fa95a694c4 doc: Update outdated txnouttype documentation (MarcoFalke)
fa58469c77 rpc: Properly use underlying type in GetAllOutputTypes (MarcoFalke)
fa41c65702 rpc: Simplify GetAllOutputTypes with the Join helper (MarcoFalke)
Pull request description:
Non-scoped enums can accidentally and silently decay into an integral type. Also, the symbol names of the keys are exported to the surrounding (usually global) namespace.
Fix both issues by switching to an `enum class TxoutType` in a (mostly) scripted-diff.
ACKs for top commit:
practicalswift:
ACK fa32adf9dc -- patch looks correct
hebasto:
re-ACK fa32adf9dc, since fa5997bd6fc82e16b597ea96e3c5c665f1f174ab (https://github.com/bitcoin/bitcoin/pull/19114#pullrequestreview-421425198) rebased only (verified with `git range-diff`).
Tree-SHA512: f42a9db47f9be89fa4bdd8d2fb05a16726286d8b12e3d87327b67d723f91c7d5a57deb4b2ddae9e1d16fee7a5f8c00828b6dc8909c5db680fc5e0a3cf07cd465
6d35d0d18f doc: add release note for -getinfo displaying multiwallet balances (Jon Atack)
Pull request description:
Release note for #18594. This is one of the commits from #19089, which had one concept ACK and approach ACK since late May. It seems better to submit the changes atomically.
Top commit has no ACKs.
Tree-SHA512: 38616d14b02c39f4ee4b93bf14f72043423cef177b595e85181bc9dc610fbe19d8271f2d2c9e5e17bb46423ffe27746e8e510b13a23ae6fd0e5bc4418a00dafa
0ac09c9793 qt: Do not truncate node flag strings in debugwindow.ui peers details tab. (saibato)
Pull request description:
Fix: When fiddling around with new node flags other than the usual.
I saw that not all possible node flag strings i.e. the UNKNOWN[..] where
visible in peers details tab.
Since v18.2 fixed size was set to 300 and sliding is thereby limited.
A fix on my old linux cruft and small screen was to set minimumSize width to -1 or 0.
Qt will then autosize the slider to the max string length.
Thereby i had full display of all flags inclusive sliding without to fullscreen the window.
Not sure if this is even an issue for those who can afford big screens or high res macs?
Feedback welcome.
BTW: nice side effect now again easy to scroll trough long version names of the node.
can't wait to see strings like /Satoshi:0.23.99/NOX2NOX4NOX32 or what ever fits in the version string.
ACKs for top commit:
hebasto:
ACK 0ac09c9793, tested on Linux Mint 20 (x86_64, Qt 5.12.8).
promag:
Tested ACK 0ac09c9793 on macos.
Tree-SHA512: a1601b5e35f10b1fd9407b28142ca00c1b985a822be5d23be4d7d3376211450f06e17f962c44b8b40977f8f8bbbb701cac1c5abb4afb3618da76385dfac848a3
d906aaa117 qt: Fix regression in TransactionTableModel (Hennadii Stepanov)
Pull request description:
Since https://github.com/bitcoin/bitcoin/pull/17993 a crash is possible on exit.
Steps to reproduce:
- precondition: the old chain
- start `bitcoin-qt`
- wait until sync
- on main window: Menu -> File -> Quit
- crash
This PR is based on ryanofsky's [suggestion](https://github.com/bitcoin-core/gui/issues/7#issuecomment-646639251).
Fixes#7.
ACKs for top commit:
promag:
Code review ACK d906aaa117.
ryanofsky:
Code review ACK d906aaa117. Only changes are squashing, adding assert and adding const
vasild:
ACK d906aaa1
Tree-SHA512: 99a475fd90dff50407a58537fdc6099a2a074018e9078452bf86defc1a4b9e546aa94f916d242355900b21638c6cfef845598a5282661a9343556c4514eb155f
1087807b2b tests: Provide main(...) function in fuzzer (practicalswift)
Pull request description:
Provide `main(...)` function in fuzzer. Allow building uninstrumented harnesses with only `--enable-fuzz`.
This PR restores the behaviour to how things worked prior to #18008. #18008 worked around an macOS specific issue but did it in a way which unnecessarily affected platforms not in need of the workaround :)
Before this patch:
```
# Build uninstrumented fuzzing harness (no libFuzzer/AFL/other-fuzzer-instrumentation)
$ ./configure --enable-fuzz
$ make
CXXLD test/fuzz/span
/usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status
Makefile:7244: recipe for target 'test/fuzz/span' failed
make[2]: *** [test/fuzz/span] Error 1
make[2]: *** Waiting for unfinished jobs....
$
```
After this patch:
```
# Build uninstrumented fuzzing harness (no libFuzzer/AFL/other-fuzzer-instrumentation)
$ ./configure --enable-fuzz
$ make
$ echo foo | src/test/fuzz/span
$
```
The examples above show the change in non-macOS functionality. macOS functionality is unaffected by this patch.
ACKs for top commit:
MarcoFalke:
ACK 1087807b2b
Tree-SHA512: 9c16ea32ffd378057c4fae9d9124636d11e3769374d340f68a1b761b9e3e3b8a33579e60425293c96b8911405d8b96ac3ed378e669ea4c47836af06892aca73d
25dac9fa65 doc: add release notes for explicit fee estimators and bumpfee change (Karl-Johan Alm)
05227a3554 tests for bumpfee / estimate_modes (Karl-Johan Alm)
3404c1b753 policy: optional FeeEstimateMode param to CFeeRate::ToString (Karl-Johan Alm)
6fcf448430 rpc/wallet: add two explicit modes to estimate_mode (Karl-Johan Alm)
b188d80c2d MOVEONLY: Make FeeEstimateMode available to CFeeRate (Karl-Johan Alm)
5d1a411eb1 fees: add FeeModes doc helper function (Karl-Johan Alm)
91f6d2bc8f rpc/wallet: add conf_target as alias to confTarget in bumpfee (Karl-Johan Alm)
69158b41fc added CURRENCY_ATOM to express minimum indivisible unit (Karl-Johan Alm)
Pull request description:
This lets users pick their own fees when using `sendtoaddress`/`sendmany` if they prefer this over the estimators.
ACKs for top commit:
Sjors:
re-utACK 25dac9fa65: rebased, more fancy C++,
jonatack:
ACK 25dac9fa65 I think this should be merged after all this time, even though it looks to me like there are needed follow-ups, fixes and test coverage to be added (see further down), which I don't mind helping out with, if wanted.
fjahr:
Code review ACK 25dac9fa65
Tree-SHA512: f31177e6cabf3187a43cdfe93477144f8e8385c7344613743cbbd16e8490d53ff5144aec7b9de6c9a65eb855b55e0f99d7f164dee4b6bf3cfea4dce51cf11d33
39d526bde4 test: Bump linter versions (Duncan Dean)
Pull request description:
As per #19346, `mypy==0.700` was incompatible with Python 3.8.
I've bumped the versions of all the linters to their latest stable versions.
Checked with both Python 3.7 and 3.8 and everything still seems to work fine.
ACKs for top commit:
hebasto:
ACK 39d526bde4, I have reviewed the code and it looks OK, I agree it can be merged.
Tree-SHA512: f3ee7fda8095aa25aa68685e863076d52a6b82649770d24b0064d652763c0ceb8ebcbf9024fc74fca45c754e67b2a831dd070b3af23bc099140e6d27e89a5319
1307686798 refactor: Use Mutex type for g_cs_recent_confirmed_transactions (Hennadii Stepanov)
Pull request description:
No need the `RecursiveMutex` type for the `g_cs_recent_confirmed_transactions`.
Related to #19303.
ACKs for top commit:
MarcoFalke:
ACK 1307686798
vasild:
ACK 13076867
Tree-SHA512: 67f1be10c80ec18d0f80b9f5036e5a20986314da9b9364ef4e193ad1d9f3f4c8e4c2e16253ca79d649ff602d5b8c2aff58d7dd1085841afb760479a4875cffbe
67bb7be864 tests: Add fuzzing harness for CHash{160,256}, C{HMAC_,}SHA{1,256,512}, CRIPEMD160, CSipHasher, etc. (practicalswift)
Pull request description:
Add fuzzing harness for `CHash{160,256}`, `C{HMAC_,}SHA{1,256,512}`, `CRIPEMD160`, `CSipHasher`, etc.
See [`doc/fuzzing.md`](https://github.com/bitcoin/bitcoin/blob/master/doc/fuzzing.md) for information on how to fuzz Bitcoin Core. Don't forget to contribute any coverage increasing inputs you find to the [Bitcoin Core fuzzing corpus repo](https://github.com/bitcoin-core/qa-assets).
Happy fuzzing :)
Top commit has no ACKs.
Tree-SHA512: 5377b361097211a7d0b90a26ed1c6dadb9ecce11349036d19f8c9ad2818cd98709bbcbf1c2361dd18eae122b8dbce1c71bb5aa2e85660677e235b8974ae33fcc
fa8337fcdb clang-format scheduler (MarcoFalke)
fa3d41b5ab doc: Switch scheduler to doxygen comments (MarcoFalke)
fac43f9889 scheduler: Replace stop(true) with StopWhenDrained() (MarcoFalke)
fa9cca0550 doc: Remove unused documentation about unimplemented features (MarcoFalke)
fab2950d70 doc: Switch boost::thread to std::thread in scheduler (MarcoFalke)
fa9819695a test: Remove unused scheduler.h include from the common setup (MarcoFalke)
fa609c4f76 scheduler: Remove unused REVERSE_LOCK (MarcoFalke)
Pull request description:
This accumulates a bunch of cleanup that was long overdue, but I haven't yet gotten around to address. Specifically, but not limited to:
* Remove unused code, documentation and includes
* Upgrade to doxygen documentation
Please refer to the individual commits for more details.
ACKs for top commit:
jnewbery:
utACK fa8337fcdb
Tree-SHA512: 0c825ad9767e2697a3ef1ec1be13fdc2b18eeb7493ad0be5b65cc9f209391e78b17ee66e35e094c5e171c12b0f1624f287a110f6bddaf3024b708877afa8552e
3f686d1a28 ci: Run fuzz testing test cases (bitcoin-core/qa-assets) under valgrind to catch memory errors (practicalswift)
Pull request description:
Re-introduce the Travis valgrind fuzzing job which was removed by PR #18899. The removal seems to have been made by accident since the removed job does not appear to be the source of the problem the PR set out to fix.
---
Run fuzz testing [test cases (bitcoin-core/qa-assets)](https://github.com/bitcoin-core/qa-assets) under `valgrind`.
This would have caught `util: Avoid potential uninitialized read in FormatISO8601DateTime(int64_t) by checking gmtime_s/gmtime_r return value` (#18162) and similar cases.
This fuzzing job was introduced in #18166.
Top commit has no ACKs.
Tree-SHA512: 6e2681eb0ade6af465c5ea91ac163a337465d2130ec9880ba57a36d9af7c25682734586a32977dc25972d4f78483f339d680ea48c0ae13cf1dfa52b617aae401
37ae687f95 Add tests for CPubKey serialization/unserialization (Elichai Turkel)
9b8907fade Check size after Unserializing CPubKey (Elichai Turkel)
Pull request description:
Found by practicalswift, closes#19235
Currently all the public API(except the pointer-like API) in CPubKey that sets/constructs a pubkey goes through `CPubKey::Set` which checks if that the length and size match and if not invalidates the key.
This adds the same check to `CPubKey::Unserialize`, sadly I don't see an easy way to just push this to the existing checks in `CPubKey::Set` but it's only a simple condition.
The problem with not invalidating is that if you write a pubkey like: `{0x02,0x00}` it will think the actual length is 33(because of `size()`) and will access uninitialized memory if you call any of the functions on CPubKey.
ACKs for top commit:
practicalswift:
re-ACK 37ae687f95
jonatack:
Code review re-ACK 37ae687 per `git diff eab8ee3 37ae687` only change since last review at eab8ee3 is passing the `pubkey` param by reference to const instead of by value in `src/test/key_tests.cpp::CmpSerializationPubkey`
MarcoFalke:
ACK 37ae687f95
Tree-SHA512: 30173755555dfc76d6263fb6a59f41be36049ffae7b4e1b92b922d668f5e5e2331f7374d5fa10d5d59fc53020d2966156905ffcfa8b8129c1f6d0ca062174ff1
56010f9256 test: hoist p2p values to test framework constants (Jon Atack)
75447f0893 test: improve msg sends and p2p disconnections in p2p_invalid_messages (Jon Atack)
57960192a5 test: refactor test_large_inv() into 3 tests with common method (Jon Atack)
e2b21d8a59 test: add p2p_invalid_messages logging (Jon Atack)
9fa494dc09 net: update misbehavior logging for oversized messages (Jon Atack)
Pull request description:
...seen while reviewing #19264, #19252, #19304 and #19107:
in `net_processing.cpp`
- make the debug logging for oversized message size misbehavior the same for `addr`, `getdata`, `headers` and `inv` messages
in `p2p_invalid_messages`
- add missing logging
- improve assertions/message sends, move cleanup disconnections outside the assertion scopes
- split a slowish 3-part test into 3 order-independent tests
- add a few p2p constants to the test framework
ACKs for top commit:
troygiorshev:
reACK 56010f9256
MarcoFalke:
ACK 56010f9256 🎛
Tree-SHA512: db67b70278f8d4c318907e105af54b54eb3afd15500f9aa0c98034f6fd4bd1cf9ad1663037bd9b237ff4890f3059b37291a6498d8d6ae2cc38efb9f045f73310
bd93e32292 refactor: Replace HexStr(o.begin(), o.end()) with HexStr(o) (Wladimir J. van der Laan)
Pull request description:
HexStr can be called with anything that bas `begin()` and `end()` functions, so clean up the redundant calls.
(context: I tried to convert `HexStr` to use span, but this turns out to be somewhat more involved than I thought, because of the limitation to pre-c++17 Span lacking iterator-based constructor) . This commit is a first step which stands on its own though)
ACKs for top commit:
jonatack:
ACK bd93e32292
troygiorshev:
ACK bd93e32292
MarcoFalke:
review ACK bd93e32292🔌
Tree-SHA512: 7e4c9d0259b8d23271d233095f1c51db1ee021e865361d74c05c10dd5129aa6d34a243323e2b4596d648e2d7b25c7ebdee37a3e4f99a27883cb4c3cd26432b08
4f9d9efb4e qt: Remove needless headers (Hennadii Stepanov)
Pull request description:
No symbols from the removed headers are used in the `qt/walletview.cpp`.
This is a small followup of https://github.com/bitcoin/bitcoin/pull/18027.
Top commit has no ACKs.
Tree-SHA512: 986ed5c8f3bac4c0053736ce84d738f8593d3dbf713109af3cb9b7051cd838f23152a39bb3c1e9694a993c4e7accf14e94e5beff5e7881155638cd44fbf7f46f
On OS X, when searching Homebrew keg-only packages for BDB 4.8, if we find it,
use BDB_CPPFLAGS and BDB_LIBS instead of CFLAGS and LIBS for the result. This
is (1) more correct, and (2) necessary in order to give this location
priority over other directories in the include search path, which may include
system include directories with other versions of BDB.
adf543d714 darwin: pass mlinker-version so that clang enables new features (Cory Fields)
2418f739f7 macos: Bump to xcode 11.3.1 and 10.15 SDK (Cory Fields)
5c2c835433 depends: bump MacOS toolchain (Cory Fields)
85b5e42088 contrib: macdeploy: Remove historical extraction notes (Carl Dong)
351beb5c9a contrib: macdeploy: Use apple-sdk-tools instead of xar+pbzx (Carl Dong)
fbcfcf6954 native_cctools: Don't use libc++ from pinned clang (Carl Dong)
3381e4a189 Adapt rest of tooling to new SDK naming scheme (Carl Dong)
b3394ab235 contrib: macdeploy: Correctly generate macOS SDK (Carl Dong)
Pull request description:
This PR achieves 3 main things:
1. It simplifies the macOS SDK generation by putting the logic inside a (semi-)portable python3 script `gen-sdk`
2. It transitions us to using `libc++` headers extracted from the `Xcode.app`, which is more correct as those headers better match the `.tbd` library stubs we use from the `MacOSX.sdk` (located under the same `Xcode.app`). Previously, we used `libc++` headers copied from our downloaded, pinned clang (see `native_cctools.mk`).
3. It bumps the macOS toolchain in a way that fulfills all of the following constraints:
1. The new SDK should support compiling with C++17 (our current one doesn't)
2. The new toolchain should not change our minimum supported macOS version (`-mmacosx-version-min`)
3. The new toolchain should expect to use a version of `cctools` that is supported by https://github.com/tpoechtrager/cctools-port
For the constraints in (3), you can reference [this chart](https://en.wikipedia.org/wiki/Xcode#Xcode_7.0_-_11.x_(since_Free_On-Device_Development)) to see that the newest toolchain we can use with our `cctools-port` is `11.3.1`, and the rest of the constraints were tested with local builds.
#### But [the other Wikipedia chart](https://en.wikipedia.org/wiki/Xcode#Xcode_11.x_(since_SwiftUI_framework)) says that the "min macOS to run" for Xcode 11.3.1 is 10.14.4, doesn't that violate constraint (ii)?
This confused me at first too, but the "min macOS to run" is for the Xcode.app App itself. The SDK still supports 10.12, as evident in a few plist files and as proven through local builds.
#### Why bundle all of this together in a single PR?
We need (1) and (2) together, because if we don't, manually adding the `libc++` headers and writing that out in a `README.md` is going to result in a lot of user error, so it's great to have these together to be more correct and also make it easier on the user at the same time.
We need (3) together with everything else because bumping (or in the case of (1), renaming) the SDK requires some human coordination and may break some builds. And since it's not that complicated a change, it makes sense to do it together with the rest.
ACKs for top commit:
theuni:
ACK adf543d714.
fanquake:
ACK adf543d714 - I'll take a look at the linker issue.
Tree-SHA512: 3813b69ebfe9610bee14100f26296fb5438d9bf0dd184ea55e6c38f5ebd94f7c171d98b150fc9e52fde626533f347f7ec51a2b72b79859d946284f578c1084a3
