Merge #15846: [POLICY] Make sending to future native witness outputs standard

c634b1e20 [POLICY] Make sending to future native witness outputs standard (Pieter Wuille)

Pull request description:

  As discussed in the April 18 2019 IRC meeting.

  This makes sending to future Segwit versions via native outputs (bech32) standard for relay, mempool acceptance, and mining. The reasons are:
  * This may interfere with smooth adoption of future segwit versions, if they're defined (by the sender wallet/node).
  * It violates BIP173 ("Version 0 witness addresses are always 42 or 62 characters, but implementations MUST allow the use of any version."), though admittedly this code was written before BIP173.
  * It doesn't protect much, as P2SH-embedded segwit cannot be filtered in this way.
  * As a general policy, the sender shouldn't care what the receiver likes his outputs to be.

  Note that _spending_ such outputs (including P2SH-embedded ones) remains nonstandard, as that is actually required for softfork safety.

ACKs for commit c634b1:
  MarcoFalke:
    utACK c634b1e2076d8e15a8284638475e26c691d4e100
  harding:
    Tested ACK c634b1e2076d8e15a8284638475e26c691d4e100
  meshcollider:
    utACK https://github.com/bitcoin/bitcoin/pull/15846/commits/c634b1e2076d8e15a8284638475e26c691d4e100

Tree-SHA512: e37168a1be9f445a04d4280593f0a92bdae33eee00ecd803d5eb16acb5c9cfc0f1f0a1dfbd5a0cc73da2c9928ec11cbdac7911513a78f85b789ae0d00e1b5962

1 files changed, 1 insertions, 1 deletions

diff --git a/src/policy/policy.cpp b/src/policy/policy.cpp
index 6f8542123d..63a3d06267 100644
--- a/src/policy/policy.cpp
+++ b/src/policy/policy.cpp
@@ -59,7 +59,7 @@ bool IsStandard(const CScript& scriptPubKey, txnouttype& whichType)
     std::vector<std::vector<unsigned char> > vSolutions;
     whichType = Solver(scriptPubKey, vSolutions);
 
-    if (whichType == TX_NONSTANDARD || whichType == TX_WITNESS_UNKNOWN) {
+    if (whichType == TX_NONSTANDARD) {
         return false;
     } else if (whichType == TX_MULTISIG) {
         unsigned char m = vSolutions.front()[0];