Merge bitcoin/bitcoin#27662: build: Bump minimum supported GCC to g++-9

fa953f15bf build: Bump minimum supported GCC to g++-9 (MarcoFalke)
fa69955e74 ci: Bump centos:stream8 to centos:stream9 (MarcoFalke)
fa6a755d9f ci: Document the false positive error for g++-9 (MarcoFalke)

Pull request description:

  It is a bit frustrating to write valid C++ code only to realize that g++-8 fails to parse it later on.

  The only non-EOL operating system still shipping with g++-8 is CentOS Stream 8. I think it is reasonable for users of affected Linux distributions to:

  * Upgrade their operating system, or compiler to a supported version.
  * Alternatively, stay with a previous release of Bitcoin Core as long as it is supported.

  Fixes https://github.com/bitcoin/bitcoin/issues/27537

ACKs for top commit:
  hebasto:
    ACK fa953f15bf
  fanquake:
    ACK fa953f15bf

Tree-SHA512: b9cf7e763d3071e1e008c5010de19601d4773afe46d58cf869d3f59285c53240c739a1cd7235a5525ede1bbdf6b6cb6fb091c8fc314864a28d5b27a400bb7632

.cirrus.yml

@@ -217,11 +217,11 @@ task:
     << : *CIRRUS_EPHEMERAL_WORKER_TEMPLATE_ENV
 
 task:
-  name: '32-bit + dash [gui] [CentOS 8]'
+  name: '32-bit + dash [gui] [CentOS 9]'
   << : *GLOBAL_TASK_TEMPLATE
   container:
     docker_arguments:
-      CI_IMAGE_NAME_TAG: quay.io/centos/centos:stream8
+      CI_IMAGE_NAME_TAG: quay.io/centos/centos:stream9
       FILE_ENV: "./ci/test/00_setup_env_i686_centos.sh"
   # For faster CI feedback, immediately schedule one task that runs all tests
   << : *CREDITS_TEMPLATE

build-aux/m4/l_filesystem.m4

@@ -1,38 +0,0 @@
-dnl Copyright (c) 2022 The Bitcoin Core developers
-dnl Distributed under the MIT software license, see the accompanying
-dnl file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
-# GCC 8.1 and earlier requires -lstdc++fs
-
-m4_define([_CHECK_FILESYSTEM_testbody], [[
-  #include <filesystem>
-
-  namespace fs = std::filesystem;
-
-  int main() {
-    (void)fs::current_path().root_name();
-    return 0;
-  }
-]])
-
-AC_DEFUN([CHECK_FILESYSTEM], [
-
-  AC_LANG_PUSH(C++)
-
-  AC_MSG_CHECKING([whether std::filesystem can be used without link library])
-
-  AC_LINK_IFELSE([AC_LANG_SOURCE([_CHECK_FILESYSTEM_testbody])],[
-      AC_MSG_RESULT([yes])
-    ],[
-      AC_MSG_RESULT([no])
-      LIBS="$LIBS -lstdc++fs"
-      AC_MSG_CHECKING([whether std::filesystem needs -lstdc++fs])
-      AC_LINK_IFELSE([AC_LANG_SOURCE([_CHECK_FILESYSTEM_testbody])],[
-          AC_MSG_RESULT([yes])
-        ],[
-            AC_MSG_FAILURE([cannot figure out how to use std::filesystem])
-        ])
-    ])
-
-  AC_LANG_POP
-])

ci/test/00_setup_env_i686_centos.sh

@@ -8,12 +8,10 @@ export LC_ALL=C.UTF-8
 
 export HOST=i686-pc-linux-gnu
 export CONTAINER_NAME=ci_i686_centos
-export CI_IMAGE_NAME_TAG="quay.io/centos/centos:stream8"
+export CI_IMAGE_NAME_TAG="quay.io/centos/centos:stream9"
-# Use minimum supported python3.8 and gcc-8, see doc/dependencies.md
+export CI_BASE_PACKAGES="gcc-c++ glibc-devel.x86_64 libstdc++-devel.x86_64 glibc-devel.i686 libstdc++-devel.i686 ccache libtool make git python3 python3-pip which patch lbzip2 xz procps-ng dash rsync coreutils bison util-linux"
-export CI_BASE_PACKAGES="gcc-c++ glibc-devel.x86_64 libstdc++-devel.x86_64 glibc-devel.i686 libstdc++-devel.i686 ccache libtool make git python38 python38-pip which patch lbzip2 xz procps-ng dash rsync coreutils bison"
 export PIP_PACKAGES="pyzmq"
 export GOAL="install"
-export NO_WERROR=1 # GCC 8
+export NO_WERROR=1  # Suppress error: #warning _FORTIFY_SOURCE > 2 is treated like 2 on this platform [-Werror=cpp]
 export BITCOIN_CONFIG="--enable-zmq --with-gui=qt5 --enable-reduce-exports"
 export CONFIG_SHELL="/bin/dash"
-export TEST_RUNNER_ENV="LC_ALL=en_US.UTF-8"

ci/test/00_setup_env_native_qt5.sh

@@ -8,14 +8,14 @@ export LC_ALL=C.UTF-8
 
 export CONTAINER_NAME=ci_native_qt5
 export CI_IMAGE_NAME_TAG="ubuntu:20.04"
-# Use minimum supported python3.8 and gcc-8 (or best-effort gcc-9), see doc/dependencies.md
+# Use minimum supported python3.8 and gcc-9, see doc/dependencies.md
 export PACKAGES="gcc-9 g++-9 python3-zmq qtbase5-dev qttools5-dev-tools libdbus-1-dev libharfbuzz-dev"
 export DEP_OPTS="NO_QT=1 NO_UPNP=1 NO_NATPMP=1 DEBUG=1 ALLOW_HOST_PACKAGES=1 CC=gcc-9 CXX=g++-9"
 export TEST_RUNNER_EXTRA="--previous-releases --coverage --extended --exclude feature_dbcrash"  # Run extended tests so that coverage does not fail, but exclude the very slow dbcrash
 export RUN_UNIT_TESTS_SEQUENTIAL="true"
 export RUN_UNIT_TESTS="false"
 export GOAL="install"
-export NO_WERROR=1
+export NO_WERROR=1  # -Werror=maybe-uninitialized
 export DOWNLOAD_PREVIOUS_RELEASES="true"
 export BITCOIN_CONFIG="--enable-zmq --with-libs=no --with-gui=qt5 --enable-reduce-exports \
 --enable-debug CFLAGS=\"-g0 -O2 -funsigned-char\" CXXFLAGS=\"-g0 -O2 -funsigned-char\""

ci/test/01_base_install.sh

@@ -18,8 +18,8 @@ if [ -n "$DPKG_ADD_ARCH" ]; then
 fi
 
 if [[ $CI_IMAGE_NAME_TAG == *centos* ]]; then
-  ${CI_RETRY_EXE} bash -c "dnf -y install epel-release"
+  bash -c "dnf -y install epel-release"
-  ${CI_RETRY_EXE} bash -c "dnf -y --allowerasing install $CI_BASE_PACKAGES $PACKAGES"
+  bash -c "dnf -y --allowerasing install $CI_BASE_PACKAGES $PACKAGES"
 elif [ "$CI_USE_APT_INSTALL" != "no" ]; then
   if [[ -n "${APPEND_APT_SOURCES_LIST}" ]]; then
     echo "${APPEND_APT_SOURCES_LIST}" >> /etc/apt/sources.list

ci/test/06_script_b.sh

@@ -52,7 +52,7 @@ fi
 
 if [ -z "$NO_DEPENDS" ]; then
   if [[ $CI_IMAGE_NAME_TAG == *centos* ]]; then
-    SHELL_OPTS="LC_ALL=en_US.UTF-8 CONFIG_SHELL=/bin/dash"
+    SHELL_OPTS="CONFIG_SHELL=/bin/dash"
   else
     SHELL_OPTS="CONFIG_SHELL="
   fi

configure.ac

@@ -115,9 +115,6 @@ else
 AX_CXX_COMPILE_STDCXX([20], [noext], [mandatory])
 fi
 
-dnl check if additional link flags are required for std::filesystem
-CHECK_FILESYSTEM
-
 dnl Unless the user specified OBJCXX, force it to be the same as CXX. This ensures
 dnl that we get the same -std flags for both.
 m4_ifdef([AC_PROG_OBJCXX],[

doc/dependencies.md

@@ -9,7 +9,7 @@ You can find installation instructions in the `build-*.md` file for your platfor
 | [Autoconf](https://www.gnu.org/software/autoconf/) | [2.69](https://github.com/bitcoin/bitcoin/pull/17769) |
 | [Automake](https://www.gnu.org/software/automake/) | [1.13](https://github.com/bitcoin/bitcoin/pull/18290) |
 | [Clang](https://clang.llvm.org) | [10.0](https://github.com/bitcoin/bitcoin/pull/27682) |
-| [GCC](https://gcc.gnu.org) | [8.1](https://github.com/bitcoin/bitcoin/pull/23060) |
+| [GCC](https://gcc.gnu.org) | [9.1](https://github.com/bitcoin/bitcoin/pull/27662) |
 | [Python](https://www.python.org) (scripts, tests) | [3.8](https://github.com/bitcoin/bitcoin/pull/27483) |
 | [systemtap](https://sourceware.org/systemtap/) ([tracing](tracing.md))| N/A |
 

src/qt/addresstablemodel.cpp

@@ -53,15 +53,14 @@ struct AddressTableEntryLessThan
 };
 
 /* Determine address type from address purpose */
-static AddressTableEntry::Type translateTransactionType(wallet::AddressPurpose purpose, bool isMine)
+constexpr AddressTableEntry::Type translateTransactionType(wallet::AddressPurpose purpose, bool isMine)
 {
     // "refund" addresses aren't shown, and change addresses aren't returned by getAddresses at all.
     switch (purpose) {
     case wallet::AddressPurpose::SEND: return AddressTableEntry::Sending;
     case wallet::AddressPurpose::RECEIVE: return AddressTableEntry::Receiving;
     case wallet::AddressPurpose::REFUND: return AddressTableEntry::Hidden;
-    // No default case to allow for compiler to warn
+    } // no default case, so the compiler can warn about missing cases
-    }
     assert(false);
 }
 

src/txrequest.cpp

@@ -69,7 +69,7 @@ struct Announcement {
     const bool m_is_wtxid : 1;
 
     /** What state this announcement is in.
-     *  This is a uint8_t instead of a State to silence a GCC warning in versions prior to 8.4 and 9.3.
+     *  This is a uint8_t instead of a State to silence a GCC warning in versions prior to 9.3.
      *  See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61414 */
     uint8_t m_state : 3;