[Backend] Establish standalone build infrastructure

Add the thin monorepo CMake entry point and an independently configurable backend project. Enforce the Clang/C++23 toolchain, expose Make/Ninja-neutral tests and developer checks, export an installable RCCBackend package, and introduce the first Support error abstraction.

1 files changed, 50 insertions, 0 deletions

diff --git a/backend/cmake/modules/RCCBackendDeveloperTools.cmake b/backend/cmake/modules/RCCBackendDeveloperTools.cmake
new file mode 100644
index 0000000..d3693cd
--- /dev/null
+++ b/backend/cmake/modules/RCCBackendDeveloperTools.cmake
@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+function(rcc_backend_add_developer_targets)
+  get_property(FormatFiles GLOBAL PROPERTY RCC_BACKEND_FORMAT_FILES)
+  get_property(TidyFiles GLOBAL PROPERTY RCC_BACKEND_TIDY_FILES)
+
+  if(FormatFiles)
+    list(REMOVE_DUPLICATES FormatFiles)
+
+    add_custom_target(
+      rcc-backend-format
+      COMMAND "${RCC_BACKEND_CLANG_FORMAT}" -i ${FormatFiles}
+      COMMAND_EXPAND_LISTS
+      COMMENT "Formatting RCC Backend C++ sources"
+      VERBATIM
+    )
+
+    add_custom_target(
+      rcc-backend-format-check
+      COMMAND "${RCC_BACKEND_CLANG_FORMAT}" --dry-run --Werror ${FormatFiles}
+      COMMAND_EXPAND_LISTS
+      COMMENT "Checking RCC Backend C++ formatting"
+      VERBATIM
+    )
+  endif()
+
+  if(TidyFiles)
+    list(REMOVE_DUPLICATES TidyFiles)
+
+    add_custom_target(
+      rcc-backend-tidy
+      COMMAND
+        "${RCC_BACKEND_CLANG_TIDY}" --warnings-as-errors=*
+        "-p=${CMAKE_BINARY_DIR}" ${TidyFiles}
+      COMMAND_EXPAND_LISTS
+      COMMENT "Running clang-tidy on RCC Backend"
+      VERBATIM
+    )
+
+    add_custom_target(
+      rcc-backend-analyze
+      COMMAND
+        "${RCC_BACKEND_CLANG_TIDY}" "--checks=-*,clang-analyzer-*"
+        --warnings-as-errors=* "-p=${CMAKE_BINARY_DIR}" ${TidyFiles}
+      COMMAND_EXPAND_LISTS
+      COMMENT "Running Clang Static Analyzer checks on RCC Backend"
+      VERBATIM
+    )
+  endif()
+endfunction()