build: require glibc 2.18+ for release builds

From what I can see the only platform this drops support for is CentOS
7. CentOS 7 reached the end of it's "full update" support at the end of
2020. It does receive maintenance updates until 2024, however I don't
think supporting glibc 2.17 until 2024 is realistic. Note that anyone
wanting to self-compile and target a glibc 2.17 runtime could build with
--disable-threadlocal.

glibc 2.18 was released in August 2013.
https://sourceware.org/legacy-ml/libc-alpha/2013-08/msg00160.html

configure.ac

@@ -1044,9 +1044,6 @@ AC_COMPILE_IFELSE([AC_LANG_SOURCE([
   [AC_MSG_RESULT([no])]
 )
 
-dnl thread_local is currently disabled when building with glibc back compat.
-dnl Our minimum supported glibc is 2.17, however support for thread_local
-dnl did not arrive in glibc until 2.18.
 if test "x$use_thread_local" = xyes || test "x$use_thread_local" = xauto; then
   TEMP_LDFLAGS="$LDFLAGS"
   LDFLAGS="$TEMP_LDFLAGS $PTHREAD_CFLAGS"

contrib/devtools/symbol-check.py

@@ -19,35 +19,31 @@
 # https://github.com/lief-project/LIEF/pull/562
 LIEF_ELF_ARCH_RISCV = lief.ELF.ARCH(243)
 
-# Debian 8 (Jessie) EOL: 2020. https://wiki.debian.org/DebianReleases#Production_Releases
+# Debian 9 (Stretch) EOL: 2022. https://wiki.debian.org/DebianReleases#Production_Releases
 #
-# - g++ version 4.9.2 (https://packages.debian.org/search?suite=jessie&arch=any&searchon=names&keywords=g%2B%2B)
-# - libc version 2.19 (https://packages.debian.org/search?suite=jessie&arch=any&searchon=names&keywords=libc6)
+# - g++ version 6.3.0 (https://packages.debian.org/search?suite=stretch&arch=any&searchon=names&keywords=g%2B%2B)
+# - libc version 2.24 (https://packages.debian.org/search?suite=stretch&arch=any&searchon=names&keywords=libc6)
 #
-# Ubuntu 16.04 (Xenial) EOL: 2024. https://wiki.ubuntu.com/Releases
+# Ubuntu 16.04 (Xenial) EOL: 2026. https://wiki.ubuntu.com/Releases
 #
-# - g++ version 5.3.1 (https://packages.ubuntu.com/search?keywords=g%2B%2B&searchon=names&suite=xenial&section=all)
-# - libc version 2.23.0 (https://packages.ubuntu.com/search?keywords=libc6&searchon=names&suite=xenial&section=all)
+# - g++ version 5.3.1
+# - libc version 2.23
 #
-# CentOS 7 EOL: 2024. https://wiki.centos.org/FAQ/General
+# CentOS Stream 8 EOL: 2024. https://wiki.centos.org/About/Product
 #
-# - g++ version 4.8.5 (http://mirror.centos.org/centos/7/os/x86_64/Packages/)
-# - libc version 2.17 (http://mirror.centos.org/centos/7/os/x86_64/Packages/)
-#
-# Taking the minimum of these as our target.
-#
-# According to GNU ABI document (https://gcc.gnu.org/onlinedocs/libstdc++/manual/abi.html) this corresponds to:
-#   GCC 4.8.5: GCC_4.8.0
-#   (glibc)    GLIBC_2_17
+# - g++ version 8.5.0 (http://mirror.centos.org/centos/8-stream/AppStream/x86_64/os/Packages/)
+# - libc version 2.28 (http://mirror.centos.org/centos/8-stream/AppStream/x86_64/os/Packages/)
 #
+# See https://gcc.gnu.org/onlinedocs/libstdc++/manual/abi.html for more info.
+
 MAX_VERSIONS = {
 'GCC':       (4,8,0),
 'GLIBC': {
-    lief.ELF.ARCH.i386:   (2,17),
-    lief.ELF.ARCH.x86_64: (2,17),
-    lief.ELF.ARCH.ARM:    (2,17),
-    lief.ELF.ARCH.AARCH64:(2,17),
-    lief.ELF.ARCH.PPC64:  (2,17),
+    lief.ELF.ARCH.i386:   (2,18),
+    lief.ELF.ARCH.x86_64: (2,18),
+    lief.ELF.ARCH.ARM:    (2,18),
+    lief.ELF.ARCH.AARCH64:(2,18),
+    lief.ELF.ARCH.PPC64:  (2,18),
     LIEF_ELF_ARCH_RISCV:  (2,27),
 },
 'LIBATOMIC': (1,0),

contrib/devtools/test-symbol-check.py

@@ -44,7 +44,7 @@ def test_ELF(self):
             self.skipTest("test not available for RISC-V")
 
         # nextup was introduced in GLIBC 2.24, so is newer than our supported
-        # glibc (2.17), and available in our release build environment (2.24).
+        # glibc (2.18), and available in our release build environment (2.24).
         with open(source, 'w', encoding="utf8") as f:
             f.write('''
                 #define _GNU_SOURCE

contrib/guix/libexec/build.sh

@@ -238,9 +238,6 @@ mkdir -p "$OUTDIR"
 
 # CONFIGFLAGS
 CONFIGFLAGS="--enable-reduce-exports --disable-bench --disable-gui-tests --disable-fuzz-binary"
-case "$HOST" in
-    *linux*) CONFIGFLAGS+=" --disable-threadlocal" ;;
-esac
 
 # CFLAGS
 HOST_CFLAGS="-O2 -g"
@@ -263,7 +260,7 @@ case "$HOST" in
     *mingw*)  HOST_LDFLAGS="-Wl,--no-insert-timestamp" ;;
 esac
 
-# Using --no-tls-get-addr-optimize retains compatibility with glibc 2.17, by
+# Using --no-tls-get-addr-optimize retains compatibility with glibc 2.18, by
 # avoiding a PowerPC64 optimisation available in glibc 2.22 and later.
 # https://sourceware.org/binutils/docs-2.35/ld/PowerPC64-ELF64.html
 case "$HOST" in

doc/dependencies.md

@@ -12,7 +12,7 @@ These are the dependencies currently used by Bitcoin Core. You can find instruct
 | fontconfig | [2.12.1](https://www.freedesktop.org/software/fontconfig/release/) |  | No | Yes |  |
 | FreeType | [2.7.1](https://download.savannah.gnu.org/releases/freetype) |  | No |  | [Yes](https://github.com/bitcoin/bitcoin/blob/master/depends/packages/qt.mk) (Android only) |
 | GCC |  | [8.1](https://gcc.gnu.org/) (C++17 & std::filesystem support) |  |  |  |
-| glibc | | [2.17](https://www.gnu.org/software/libc/) |  |  |  |  |
+| glibc | | [2.18](https://www.gnu.org/software/libc/) |  |  |  |  |
 | HarfBuzz-NG |  |  |  |  | [Yes](https://github.com/bitcoin/bitcoin/blob/master/depends/packages/qt.mk) |
 | libevent | [2.1.12-stable](https://github.com/libevent/libevent/releases) | [2.0.21](https://github.com/bitcoin/bitcoin/pull/18676) | No |  |  |
 | libnatpmp | git commit [4536032...](https://github.com/miniupnp/libnatpmp/tree/4536032ae32268a45c073a4d5e91bbab4534773a) |  | No |  |  |