build: Require python 3.5

17 files changed, 18 insertions, 122 deletions

diff --git a/.python-version b/.python-version
index 7bcbb3808b..5a958026da 100644
--- a/.python-version
+++ b/.python-version
@@ -1 +1 @@
-3.4.9
+3.5
diff --git a/.travis.yml b/.travis.yml
index 0ede31b4a6..fea6b6d7bf 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -46,7 +46,7 @@ jobs:
       env:
       cache: false
       language: python
-      python: '3.4' # Oldest supported version according to doc/dependencies.md
+      python: '3.5' # Oldest supported version according to doc/dependencies.md
       install:
         - set -o errexit; source .travis/lint_04_install.sh
       before_script:
@@ -158,7 +158,7 @@ jobs:
       name: 'macOS 10.10  [GOAL: deploy] [no functional tests]'
       env: >-
         HOST=x86_64-apple-darwin14
-        PACKAGES="cmake imagemagick libcap-dev librsvg2-bin libz-dev libbz2-dev libtiff-tools python-dev python3-setuptools-git"
+        PACKAGES="cmake imagemagick libcap-dev librsvg2-bin libz-dev libbz2-dev libtiff-tools python3-dev python3-setuptools-git"
         OSX_SDK=10.11
         RUN_UNIT_TESTS=false
         RUN_FUNCTIONAL_TESTS=false
diff --git a/configure.ac b/configure.ac
index 984c595ead..a3ba8ce808 100644
--- a/configure.ac
+++ b/configure.ac
@@ -85,8 +85,8 @@ AC_PATH_TOOL(RANLIB, ranlib)
 AC_PATH_TOOL(STRIP, strip)
 AC_PATH_TOOL(GCOV, gcov)
 AC_PATH_PROG(LCOV, lcov)
-dnl Python 3.4 is specified in .python-version and should be used if available, see doc/dependencies.md
-AC_PATH_PROGS([PYTHON], [python3.4 python3.5 python3.6 python3.7 python3 python])
+dnl Python 3.5 is specified in .python-version and should be used if available, see doc/dependencies.md
+AC_PATH_PROGS([PYTHON], [python3.5 python3.6 python3.7 python3.8 python3 python])
 AC_PATH_PROG(GENHTML, genhtml)
 AC_PATH_PROG([GIT], [git])
 AC_PATH_PROG(CCACHE,ccache)
diff --git a/contrib/devtools/README.md b/contrib/devtools/README.md
index 6ee65f40be..d66eff66be 100644
--- a/contrib/devtools/README.md
+++ b/contrib/devtools/README.md
@@ -167,7 +167,7 @@ still compatible with the minimum supported Linux distribution versions.
 
 Example usage after a gitian build:
 
-    find ../gitian-builder/build -type f -executable | xargs python contrib/devtools/symbol-check.py 
+    find ../gitian-builder/build -type f -executable | xargs python3 contrib/devtools/symbol-check.py
 
 If only supported symbols are used the return value will be 0 and the output will be empty.
 
diff --git a/contrib/devtools/symbol-check.py b/contrib/devtools/symbol-check.py
index c6158c9422..7729dd7257 100755
--- a/contrib/devtools/symbol-check.py
+++ b/contrib/devtools/symbol-check.py
@@ -9,7 +9,7 @@ still compatible with the minimum supported Linux distribution versions.
 
 Example usage:
 
-    find ../gitian-builder/build -type f -executable | xargs python contrib/devtools/symbol-check.py
+    find ../gitian-builder/build -type f -executable | xargs python3 contrib/devtools/symbol-check.py
 '''
 import subprocess
 import re
diff --git a/contrib/gitian-descriptors/gitian-linux.yml b/contrib/gitian-descriptors/gitian-linux.yml
index e97072c80a..1fc1ce98a9 100644
--- a/contrib/gitian-descriptors/gitian-linux.yml
+++ b/contrib/gitian-descriptors/gitian-linux.yml
@@ -30,7 +30,7 @@ packages:
 - "faketime"
 - "bsdmainutils"
 - "ca-certificates"
-- "python"
+- "python3"
 remotes:
 - "url": "https://github.com/bitcoin/bitcoin.git"
   "dir": "bitcoin"
diff --git a/contrib/gitian-descriptors/gitian-osx.yml b/contrib/gitian-descriptors/gitian-osx.yml
index 87d8007ccb..1d9c31f9e7 100644
--- a/contrib/gitian-descriptors/gitian-osx.yml
+++ b/contrib/gitian-descriptors/gitian-osx.yml
@@ -23,9 +23,9 @@ packages:
 - "libcap-dev"
 - "libz-dev"
 - "libbz2-dev"
-- "python"
-- "python-dev"
-- "python-setuptools"
+- "python3"
+- "python3-dev"
+- "python3-setuptools"
 - "fonts-tuffy"
 remotes:
 - "url": "https://github.com/bitcoin/bitcoin.git"
diff --git a/contrib/gitian-descriptors/gitian-win.yml b/contrib/gitian-descriptors/gitian-win.yml
index 31b9c309c7..2f1fb14c10 100644
--- a/contrib/gitian-descriptors/gitian-win.yml
+++ b/contrib/gitian-descriptors/gitian-win.yml
@@ -20,7 +20,7 @@ packages:
 - "nsis"
 - "zip"
 - "ca-certificates"
-- "python"
+- "python3"
 - "rename"
 remotes:
 - "url": "https://github.com/bitcoin/bitcoin.git"
diff --git a/contrib/linearize/README.md b/contrib/linearize/README.md
index 2985106982..25a1c7351a 100644
--- a/contrib/linearize/README.md
+++ b/contrib/linearize/README.md
@@ -1,6 +1,5 @@
 # Linearize
-Construct a linear, no-fork, best version of the Bitcoin blockchain. The scripts
-run using Python 3 but are compatible with Python 2.
+Construct a linear, no-fork, best version of the Bitcoin blockchain.
 
 ## Step 1: Download hash list
 
diff --git a/contrib/zmq/zmq_sub3.4.py b/contrib/zmq/zmq_sub3.4.py
deleted file mode 100644
index 66fdf7887f..0000000000
--- a/contrib/zmq/zmq_sub3.4.py
+++ /dev/null
@@ -1,90 +0,0 @@
-#!/usr/bin/env python3
-# Copyright (c) 2014-2018 The Bitcoin Core developers
-# Distributed under the MIT software license, see the accompanying
-# file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
-"""
-    ZMQ example using python3's asyncio
-
-    Bitcoin should be started with the command line arguments:
-        bitcoind -testnet -daemon \
-                -zmqpubrawtx=tcp://127.0.0.1:28332 \
-                -zmqpubrawblock=tcp://127.0.0.1:28332 \
-                -zmqpubhashtx=tcp://127.0.0.1:28332 \
-                -zmqpubhashblock=tcp://127.0.0.1:28332
-
-    We use the asyncio library here.  `self.handle()` installs itself as a
-    future at the end of the function.  Since it never returns with the event
-    loop having an empty stack of futures, this creates an infinite loop.  An
-    alternative is to wrap the contents of `handle` inside `while True`.
-
-    The `@asyncio.coroutine` decorator and the `yield from` syntax found here
-    was introduced in python 3.4 and has been deprecated in favor of the `async`
-    and `await` keywords respectively.
-
-    A blocking example using python 2.7 can be obtained from the git history:
-    https://github.com/bitcoin/bitcoin/blob/37a7fe9e440b83e2364d5498931253937abe9294/contrib/zmq/zmq_sub.py
-"""
-
-import binascii
-import asyncio
-import zmq
-import zmq.asyncio
-import signal
-import struct
-import sys
-
-if (sys.version_info.major, sys.version_info.minor) < (3, 4):
-    print("This example only works with Python 3.4 and greater")
-    sys.exit(1)
-
-port = 28332
-
-class ZMQHandler():
-    def __init__(self):
-        self.loop = asyncio.get_event_loop()
-        self.zmqContext = zmq.asyncio.Context()
-
-        self.zmqSubSocket = self.zmqContext.socket(zmq.SUB)
-        self.zmqSubSocket.setsockopt(zmq.RCVHWM, 0)
-        self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "hashblock")
-        self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "hashtx")
-        self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "rawblock")
-        self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "rawtx")
-        self.zmqSubSocket.connect("tcp://127.0.0.1:%i" % port)
-
-    @asyncio.coroutine
-    def handle(self) :
-        msg = yield from self.zmqSubSocket.recv_multipart()
-        topic = msg[0]
-        body = msg[1]
-        sequence = "Unknown"
-        if len(msg[-1]) == 4:
-          msgSequence = struct.unpack('<I', msg[-1])[-1]
-          sequence = str(msgSequence)
-        if topic == b"hashblock":
-            print('- HASH BLOCK ('+sequence+') -')
-            print(binascii.hexlify(body))
-        elif topic == b"hashtx":
-            print('- HASH TX  ('+sequence+') -')
-            print(binascii.hexlify(body))
-        elif topic == b"rawblock":
-            print('- RAW BLOCK HEADER ('+sequence+') -')
-            print(binascii.hexlify(body[:80]))
-        elif topic == b"rawtx":
-            print('- RAW TX ('+sequence+') -')
-            print(binascii.hexlify(body))
-        # schedule ourselves to receive the next message
-        asyncio.ensure_future(self.handle())
-
-    def start(self):
-        self.loop.add_signal_handler(signal.SIGINT, self.stop)
-        self.loop.create_task(self.handle())
-        self.loop.run_forever()
-
-    def stop(self):
-        self.loop.stop()
-        self.zmqContext.destroy()
-
-daemon = ZMQHandler()
-daemon.start()
diff --git a/depends/README.md b/depends/README.md
index 693bc36197..b69584193a 100644
--- a/depends/README.md
+++ b/depends/README.md
@@ -34,7 +34,7 @@ No other options are needed, the paths are automatically configured.
 
 #### For macOS cross compilation
 
-    sudo apt-get install curl librsvg2-bin libtiff-tools bsdmainutils cmake imagemagick libcap-dev libz-dev libbz2-dev python-setuptools
+    sudo apt-get install curl librsvg2-bin libtiff-tools bsdmainutils cmake imagemagick libcap-dev libz-dev libbz2-dev python3-setuptools
 
 #### For Win32/Win64 cross compilation
 
diff --git a/doc/dependencies.md b/doc/dependencies.md
index e4be63772c..0fb36184c2 100644
--- a/doc/dependencies.md
+++ b/doc/dependencies.md
@@ -22,7 +22,7 @@ These are the dependencies currently used by Bitcoin Core. You can find instruct
 | OpenSSL | [1.0.1k](https://www.openssl.org/source) |  | Yes |  |  |
 | PCRE |  |  |  |  | [Yes](https://github.com/bitcoin/bitcoin/blob/master/depends/packages/qt.mk#L66) |
 | protobuf | [2.6.1](https://github.com/google/protobuf/releases) |  | No |  |  |
-| Python (tests) |  | [3.4](https://www.python.org/downloads) |  |  |  |
+| Python (tests) |  | [3.5](https://www.python.org/downloads) |  |  |  |
 | qrencode | [3.4.4](https://fukuchi.org/works/qrencode) |  | No |  |  |
 | Qt | [5.9.7](https://download.qt.io/official_releases/qt/) | [5.5.1](https://github.com/bitcoin/bitcoin/issues/13478) | No |  |  |
 | XCB |  |  |  |  | [Yes](https://github.com/bitcoin/bitcoin/blob/master/depends/packages/qt.mk#L87) (Linux only) |
diff --git a/test/functional/test_framework/mininode.py b/test/functional/test_framework/mininode.py
index ac7cc068bd..ee070981ed 100755
--- a/test/functional/test_framework/mininode.py
+++ b/test/functional/test_framework/mininode.py
@@ -218,10 +218,7 @@ class P2PConnection(asyncio.Protocol):
         def maybe_write():
             if not self._transport:
                 return
-            # Python <3.4.4 does not have is_closing, so we have to check for
-            # its existence explicitly as long as Bitcoin Core supports all
-            # Python 3.4 versions.
-            if hasattr(self._transport, 'is_closing') and self._transport.is_closing():
+            if self._transport.is_closing():
                 return
             self._transport.write(raw_message_bytes)
         NetworkThread.network_event_loop.call_soon_threadsafe(maybe_write)
diff --git a/test/functional/test_framework/script.py b/test/functional/test_framework/script.py
index f7df7d23f5..0661367a45 100644
--- a/test/functional/test_framework/script.py
+++ b/test/functional/test_framework/script.py
@@ -449,10 +449,6 @@ class CScript(bytes):
         # join makes no sense for a CScript()
         raise NotImplementedError
 
-    # Python 3.4 compatibility
-    def hex(self):
-        return self.hex()
-
     def __new__(cls, value=b''):
         if isinstance(value, bytes) or isinstance(value, bytearray):
             return super(CScript, cls).__new__(cls, value)
diff --git a/test/functional/test_framework/test_node.py b/test/functional/test_framework/test_node.py
index 37fd2a8744..9d8560c4d8 100755
--- a/test/functional/test_framework/test_node.py
+++ b/test/functional/test_framework/test_node.py
@@ -31,9 +31,6 @@ from .util import (
     p2p_port,
 )
 
-# For Python 3.4 compatibility
-JSONDecodeError = getattr(json, "JSONDecodeError", ValueError)
-
 BITCOIND_PROC_WAIT_TIMEOUT = 60
 
 
@@ -565,5 +562,5 @@ class TestNodeCLI():
             raise subprocess.CalledProcessError(returncode, self.binary, output=cli_stderr)
         try:
             return json.loads(cli_stdout, parse_float=decimal.Decimal)
-        except JSONDecodeError:
+        except json.JSONDecodeError:
             return cli_stdout.rstrip("\n")
diff --git a/test/functional/test_framework/util.py b/test/functional/test_framework/util.py
index fb2ee8e90c..f7f1b277e4 100644
--- a/test/functional/test_framework/util.py
+++ b/test/functional/test_framework/util.py
@@ -182,9 +182,6 @@ def check_json_precision():
 def count_bytes(hex_string):
     return len(bytearray.fromhex(hex_string))
 
-def b_2_x(byte_str):
-    return byte_str.hex()
-
 def hash256(byte_str):
     sha256 = hashlib.sha256()
     sha256.update(byte_str)
diff --git a/test/lint/lint-python-dead-code.sh b/test/lint/lint-python-dead-code.sh
index 2ec7574718..863caa9d5c 100755
--- a/test/lint/lint-python-dead-code.sh
+++ b/test/lint/lint-python-dead-code.sh
@@ -15,5 +15,5 @@ fi
 
 vulture \
     --min-confidence 60 \
-    --ignore-names "b_2_x,argtypes,connection_lost,connection_made,converter,data_received,daemon,errcheck,get_ecdh_key,get_privkey,is_compressed,is_fullyvalid,msg_generic,on_*,optionxform,restype,set_privkey,profile_with_perf" \
+    --ignore-names "argtypes,connection_lost,connection_made,converter,data_received,daemon,errcheck,get_ecdh_key,get_privkey,is_compressed,is_fullyvalid,msg_generic,on_*,optionxform,restype,set_privkey,profile_with_perf" \
     $(git ls-files -- "*.py" ":(exclude)contrib/" ":(exclude)test/functional/data/invalid_txs.py")