Reintroduce Debian 11 "bullseye" Clang and GCC jobs

(cherry picked from commit 5e1120d9a3)

.gitlab-ci.yml

@@ -150,6 +150,10 @@ stages:
   image: "$CI_REGISTRY_IMAGE:debian-buster-amd64"
   <<: *linux_amd64
 
+.debian-bullseye-amd64: &debian_bullseye_amd64_image
+  image: "$CI_REGISTRY_IMAGE:debian-bullseye-amd64"
+  <<: *linux_amd64
+
 .respdiff-debian-bookworm-amd64: &respdiff_debian_bookworm_amd64_image
   image: "$CI_REGISTRY_IMAGE:debian-bookworm-amd64"
   <<: *linux_respdiff_amd64
@@ -1195,6 +1199,59 @@ unit:clang:tsan:
     - job: clang:tsan
       artifacts: true
 
+# Jobs for Debian 11 "bullseye" (amd64)
+
+clang:bullseye:amd64:
+  variables:
+    CC: ${CLANG}
+    CFLAGS: "${CFLAGS_COMMON} -Wenum-conversion"
+    # See https://gitlab.isc.org/isc-projects/bind9/-/issues/3444
+    EXTRA_CONFIGURE: "--without-jemalloc"
+  <<: *debian_bullseye_amd64_image
+  <<: *build_job
+
+system:clang:bullseye:amd64:
+  # Set up environment variables that allow the "keyfromlabel" system test to be run
+  variables:
+    DEFAULT_OPENSSL_CONF: "/etc/ssl/openssl.cnf"
+    OPENSSL_CONF: "/var/tmp/etc/openssl.cnf"
+    SOFTHSM2_CONF: "/var/tmp/softhsm2/softhsm2.conf"
+    SOFTHSM2_MODULE: "/usr/lib/softhsm/libsofthsm2.so"
+  <<: *debian_bullseye_amd64_image
+  <<: *system_test_job
+  needs:
+    - job: clang:bullseye:amd64
+      artifacts: true
+
+unit:clang:bullseye:amd64:
+  <<: *debian_bullseye_amd64_image
+  <<: *unit_test_job
+  needs:
+    - job: clang:bullseye:amd64
+      artifacts: true
+
+gcc:bullseye:amd64:
+  variables:
+    CC: gcc
+    CFLAGS: "${CFLAGS_COMMON}"
+    EXTRA_CONFIGURE: "--with-libidn2"
+  <<: *debian_bullseye_amd64_image
+  <<: *build_job
+
+system:gcc:bullseye:amd64:
+  <<: *debian_bullseye_amd64_image
+  <<: *system_test_job
+  needs:
+    - job: gcc:bullseye:amd64
+      artifacts: true
+
+unit:gcc:bullseye:amd64:
+  <<: *debian_bullseye_amd64_image
+  <<: *unit_test_job
+  needs:
+    - job: gcc:bullseye:amd64
+      artifacts: true
+
 # Jobs for Clang builds on Debian 12 "bookworm" (amd64)
 # The -Wno-compound-token-split-by-macro option prevents warning when compiling
 # Perl DLZ module with Clang against Perl older than version 5.35.2.

doc/arm/platforms.inc.rst

@@ -45,7 +45,7 @@ Regularly Tested Platforms
 Current versions of BIND 9 are fully supported and regularly tested on the
 following systems:
 
--  Debian 10, 12
+-  Debian 10, 11, 12
 -  Ubuntu LTS 18.04, 20.04, 22.04
 -  Fedora 38
 -  Red Hat Enterprise Linux / CentOS / Oracle Linux 7, 8, 9