[libc++] Remove anchors for agent queues from the BuildKite pipeline configuration (#75359)

We didn't save that much boilerplate with those anchors, but it made the
pipeline description harder to understand because the definition of the
jobs and the agents they run on were so far apart. Anchors are useful
for the other common boilerplate we truly share between all jobs, but it
seems reasonable to define agent queues in-line.

Author: ldionne

libcxx/utils/ci/buildkite-pipeline.yml

@@ -41,45 +41,6 @@ definitions:
       - "**/*.abilist"
       - "**/crash_diagnostics/*"
 
-# Define agents using YAML anchors to reduce duplication
-agents_definitions:
-  _windows_agent: &windows_agent
-    agents:
-      queue: windows
-
-  # Mac OS Builders
-  _mac_agent_x86: &mac_agent_x86
-    agents:
-      queue: libcxx-builders
-      os: macos
-      arch: x86_64
-  _mac_agent_arm64: &mac_agent_arm64
-    agents:
-      queue: libcxx-builders
-      os: macos
-      arch: arm64
-  _mac_agent_any_arch: &mac_agent_any_arch
-    agents:
-      queue: libcxx-builders
-      os: macos
-  _arm_agent_aarch64: &arm_agent_aarch64
-    agents:
-      queue: libcxx-builders-linaro-arm
-      arch: aarch64
-  _arm_agent_armv8l: &arm_agent_armv8l
-    agents:
-      queue: libcxx-builders-linaro-arm
-      arch: armv8l
-  _aix_agent: &aix_agent
-    agents:
-      queue: libcxx-builders
-      os: aix
-  _android_agent: &android_agent
-    agents:
-      queue: libcxx-builders
-      os: android
-
-
 environment_definitions:
   _common_env: &common_env
       ENABLE_CLANG_TIDY: "On"
@@ -101,122 +62,166 @@ steps:
   steps:
   - label: Clang-cl (DLL)
     command: bash libcxx/utils/ci/run-buildbot clang-cl-dll
-    <<: *windows_agent
+    agents:
+      queue: windows
     <<: *common
 
   - label: Clang-cl (Static)
     command: bash libcxx/utils/ci/run-buildbot clang-cl-static
-    <<: *windows_agent
+    agents:
+      queue: windows
     <<: *common
 
   - label: Clang-cl (no vcruntime exceptions)
     command: bash libcxx/utils/ci/run-buildbot clang-cl-no-vcruntime
     <<: *common
-    <<: *windows_agent
+    agents:
+      queue: windows
 
   - label: Clang-cl (Debug mode)
     command: bash libcxx/utils/ci/run-buildbot clang-cl-debug
-    <<: *windows_agent
+    agents:
+      queue: windows
     <<: *common
 
   - label: Clang-cl (Static CRT)
     command: bash libcxx/utils/ci/run-buildbot clang-cl-static-crt
-    <<: *windows_agent
+    agents:
+      queue: windows
     <<: *common
 
   - label: MinGW (DLL, x86_64)
     command: bash libcxx/utils/ci/run-buildbot mingw-dll
-    <<: *windows_agent
+    agents:
+      queue: windows
     <<: *common
 
   - label: MinGW (Static, x86_64)
     command: bash libcxx/utils/ci/run-buildbot mingw-static
-    <<: *windows_agent
+    agents:
+      queue: windows
     <<: *common
 
   - label: MinGW (DLL, i686)
     command: bash libcxx/utils/ci/run-buildbot mingw-dll-i686
-    <<: *windows_agent
+    agents:
+      queue: windows
     <<: *common
 
 - group: ':mac: Apple'
   steps:
   - label: MacOS x86_64
     command: libcxx/utils/ci/run-buildbot generic-cxx23
-    <<: *mac_agent_x86
+    agents:
+      queue: libcxx-builders
+      os: macos
+      arch: x86_64
     <<: *common
 
   - label: MacOS arm64
     command: libcxx/utils/ci/run-buildbot generic-cxx23
-    <<: *mac_agent_arm64
+    agents:
+      queue: libcxx-builders
+      os: macos
+      arch: arm64
     <<: *common
 
   - label: MacOS with Modules
     command: libcxx/utils/ci/run-buildbot generic-modules
-    <<: *mac_agent_any_arch
+    agents:
+      queue: libcxx-builders
+      os: macos
     <<: *common
 
   - label: MacOS with C++03
     command: libcxx/utils/ci/run-buildbot generic-cxx03
-    <<: *mac_agent_any_arch
+    agents:
+      queue: libcxx-builders
+      os: macos
     <<: *common
 
     # Build with the configuration we use to generate libc++.dylib on Apple platforms
   - label: Apple system
     command: libcxx/utils/ci/run-buildbot apple-system
-    <<: *mac_agent_arm64  # This can technically run on any architecture, but we have more resources on arm64 so we pin this job to arm64
+    agents:
+      queue: libcxx-builders
+      os: macos
+      arch: arm64 # This can technically run on any architecture, but we have more resources on arm64 so we pin this job to arm64
     <<: *common
 
   - label: Apple back-deployment macosx10.13
     command: libcxx/utils/ci/run-buildbot apple-system-backdeployment-10.13
-    <<: *mac_agent_x86 # We need to use x86_64 for back-deployment CI on this target since macOS didn't support arm64 back then
+    agents:
+      queue: libcxx-builders
+      os: macos
+      arch: x86_64 # We need to use x86_64 for back-deployment CI on this target since macOS didn't support arm64 back then
     <<: *common
 
   - label: Apple back-deployment macosx10.15
     command: libcxx/utils/ci/run-buildbot apple-system-backdeployment-10.15
-    <<: *mac_agent_x86 # We need to use x86_64 for back-deployment CI on this target since macOS didn't support arm64 back then
+    agents:
+      queue: libcxx-builders
+      os: macos
+      arch: x86_64 # We need to use x86_64 for back-deployment CI on this target since macOS didn't support arm64 back then
     <<: *common
 
   - label: Apple back-deployment with hardening enabled
     command: libcxx/utils/ci/run-buildbot apple-system-backdeployment-hardened-11.0
-    <<: *mac_agent_x86  # TODO: Remove this once we are able to run back-deployment on arm64 again, since this isn't x86_64 specific
+    agents:
+      queue: libcxx-builders
+      os: macos
+      arch: x86_64 # TODO: Remove this once we are able to run back-deployment on arm64 again, since this isn't x86_64 specific
     <<: *common
 
 - group: ARM
   steps:
   - label: AArch64
     command: libcxx/utils/ci/run-buildbot aarch64
-    <<: *arm_agent_aarch64
+    agents:
+      queue: libcxx-builders-linaro-arm
+      arch: aarch64
     <<: *common
 
   - label: AArch64 -fno-exceptions
     command: libcxx/utils/ci/run-buildbot aarch64-no-exceptions
-    <<: *arm_agent_aarch64
+    agents:
+      queue: libcxx-builders-linaro-arm
+      arch: aarch64
     <<: *common
 
   - label: Armv8
     command: libcxx/utils/ci/run-buildbot armv8
-    <<: *arm_agent_armv8l
+    agents:
+      queue: libcxx-builders-linaro-arm
+      arch: armv8l
     <<: *common
 
   - label: Armv8 -fno-exceptions
     command: libcxx/utils/ci/run-buildbot armv8-no-exceptions
-    <<: *arm_agent_armv8l
+    agents:
+      queue: libcxx-builders-linaro-arm
+      arch: armv8l
     <<: *common
 
   - label: Armv7
     command: libcxx/utils/ci/run-buildbot armv7
-    <<: *arm_agent_armv8l
+    agents:
+      queue: libcxx-builders-linaro-arm
+      arch: armv8l
     <<: *common
 
   - label: Armv7 -fno-exceptions
     command: libcxx/utils/ci/run-buildbot armv7-no-exceptions
-    <<: *arm_agent_armv8l
+    agents:
+      queue: libcxx-builders-linaro-arm
+      arch: armv8l
     <<: *common
 
   - label: Armv7-M picolibc
     command: libcxx/utils/ci/run-buildbot armv7m-picolibc
-    <<: *arm_agent_aarch64
+    agents:
+      queue: libcxx-builders-linaro-arm
+      arch: aarch64
     <<: *common
 
 - group: AIX
@@ -227,7 +232,9 @@ steps:
       CC: clang
       CXX: clang++
       OBJECT_MODE: '32'
-    <<: *aix_agent
+    agents:
+      queue: libcxx-builders
+      os: aix
     <<: *common
 
   - label: AIX (64-bit)
@@ -236,7 +243,9 @@ steps:
       CC: clang
       CXX: clang++
       OBJECT_MODE: '64'
-    <<: *aix_agent
+    agents:
+      queue: libcxx-builders
+      os: aix
     <<: *common
 
 - group: ':freebsd: FreeBSD'
@@ -256,12 +265,16 @@ steps:
   steps:
   - label: Android 5.0, x86 NDK
     command: libcxx/utils/ci/run-buildbot android-ndk-21-def-x86
-    <<: *android_agent
+    agents:
+      queue: libcxx-builders
+      os: android
     <<: *common
 
   - label: Android 13, x86_64 NDK
     command: libcxx/utils/ci/run-buildbot android-ndk-33-goog-x86_64
-    <<: *android_agent
+    agents:
+      queue: libcxx-builders
+      os: android
     <<: *common