Update: Using C++26 with contracts enabled

cmake/Cppcheck.cmake

@@ -0,0 +1,42 @@
+function(course_add_cppcheck_targets)
+    find_program(CPPCHECK_EXECUTABLE cppcheck)
+    if(NOT CPPCHECK_EXECUTABLE)
+        message(STATUS "cppcheck not found; cppcheck targets will not be available")
+        return()
+    endif()
+
+    set(_compile_commands "${CMAKE_BINARY_DIR}/compile_commands.json")
+    set(_suppressions "${CMAKE_SOURCE_DIR}/cppcheck/suppressions.txt")
+
+    add_custom_target(
+        cppcheck_modules
+        COMMAND
+            "${CPPCHECK_EXECUTABLE}"
+            --project=${_compile_commands}
+            --enable=warning,style,performance
+            --std=c++26
+            --inline-suppr
+            --suppressions-list=${_suppressions}
+            -i${CMAKE_SOURCE_DIR}/support
+            -i${CMAKE_BINARY_DIR}/_deps
+            --quiet
+        WORKING_DIRECTORY "${CMAKE_BINARY_DIR}"
+        COMMENT "Running cppcheck on course modules (build once before running this target)"
+        VERBATIM
+    )
+
+    add_custom_target(
+        cppcheck_project
+        COMMAND
+            "${CPPCHECK_EXECUTABLE}"
+            --project=${_compile_commands}
+            --enable=warning,style,performance
+            --std=c++26
+            --inline-suppr
+            --suppressions-list=${_suppressions}
+            --quiet
+        WORKING_DIRECTORY "${CMAKE_BINARY_DIR}"
+        COMMENT "Running cppcheck on entire project (build once before running this target)"
+        VERBATIM
+    )
+endfunction()

cppcheck/suppressions.txt

@@ -0,0 +1,8 @@
+# Suppress Cppcheck noise for this GCC 16 / C++26 project.
+#
+# The CLion Cppcheck plugin analyzes headers in isolation and often reports
+# false positives (missing system includes, GCC libstdc++ syntax errors).
+# Prefer: cmake --build build --target cppcheck_modules
+
+missingIncludeSystem
+syntaxError