style: Updates the style file with a self-written one, and update CMake files.

CMakeLists.txt

@@ -20,8 +20,8 @@ project(libbase VERSION 1.0
   LANGUAGES C)
 
 # Requires out-of-source builds.
-file(TO_CMAKE_PATH "${PROJECT_BINARY_DIR}/CMakeLists.txt" LOCATION_PATH)
-if(EXISTS "${LOCATION_PATH}")
+file(TO_CMAKE_PATH "${PROJECT_BINARY_DIR}/CMakeLists.txt" location_path)
+if(EXISTS "${location_path}")
   message(
     FATAL_ERROR
     "You cannot build into a source directory (containing a CMakeLists.txt file).\n"
@@ -51,29 +51,31 @@ set(IWYU_MODE OFF CACHE STRING "Whether to run `iwyu`. OFF, WARN or FAIL.")
 set_property(CACHE IWYU_MODE PROPERTY STRINGS "OFF" "WARN" "FAIL")
 
 # Toplevel compile options, for Clang and GCC.
+add_library(libbase_compiler_flags INTERFACE)
+
 if(CMAKE_C_COMPILER_ID MATCHES "Clang|GNU")
   if(config_DEBUG)
-    add_compile_options(-ggdb -DDEBUG)
+    target_compile_options(libbase_compiler_flags INTERFACE -ggdb -DDEBUG)
   endif()
 
   if(config_OPTIM)
-    add_compile_options(-O2)
+    target_compile_options(libbase_compiler_flags INTERFACE -O2)
   else()
-    add_compile_options(-O0)
+    target_compile_options(libbase_compiler_flags INTERFACE -O0)
   endif()
-  add_compile_options(-Wall -Wextra)
+  target_compile_options(libbase_compiler_flags INTERFACE -Wall -Wextra)
 
   if(config_WERROR)
-    add_compile_options(-Werror)
+    target_compile_options(libbase_compiler_flags INTERFACE -Werror)
   endif()
 
   # CMake provides absolute paths to GCC, hence the __FILE__ macro includes the
   # full path. This option resets it to a path relative to project source.
-  add_compile_options(-fmacro-prefix-map=${PROJECT_SOURCE_DIR}/src=.)
+  target_compile_options(libbase_compiler_flags INTERFACE -fmacro-prefix-map=${PROJECT_SOURCE_DIR}/src=.)
 
   # Target system.
   if(LINUX)
-    add_compile_options(-D__LIBBASE_LINUX)
+    target_compile_options(libbase_compiler_flags INTERFACE -D__LIBBASE_LINUX)
   endif()
 
   # Run iwyu when available.
@@ -129,15 +131,15 @@ endif()
 find_package(Doxygen)
 if(DOXYGEN_FOUND)
   # Set input and output files.
-  set(DOXYGEN_IN ${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile.in)
-  set(DOXYGEN_OUT ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile)
+  set(doxygen_in ${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile.in)
+  set(doxygen_out ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile)
 
   # Configure the file.
-  configure_file(${DOXYGEN_IN} ${DOXYGEN_OUT} @ONLY)
+  configure_file(${doxygen_in} ${doxygen_out} @ONLY)
   add_custom_target(
     libbase_doc
-    COMMAND ${DOXYGEN_EXECUTABLE} ${DOXYGEN_OUT}
-    DEPENDS ${DOXYGEN_OUT}
+    COMMAND ${DOXYGEN_EXECUTABLE} ${doxygen_out}
+    DEPENDS ${doxygen_out}
     WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
     COMMENT "Generating API documentation with Doxygen."
     VERBATIM)
@@ -158,8 +160,8 @@ endif()
 if(config_COVERAGE)
   find_program(GCOVR_FOUND gcovr OPTIONAL)
   if(GCOVR_FOUND)
-    add_compile_options(--coverage)
-    add_link_options(--coverage)
+    target_compile_options(libbase_compiler_flags INTERFACE --coverage)
+    target_link_options(libbase_compiler_flags INTERFACE --coverage)
 
     message(NOTICE "Coverage configured, adding 'coverage' target.")
     add_custom_target(coverage

STYLE.md

@@ -1,40 +1,30 @@
-# Style Reference
+# CMake Style Guidelines
 
-## CMake Style Guidelines
+This document outlines the style conventions used in the CMake configuration files for this project.
 
-(c) Copyright 2015-2026 Zephyr Project members and individual contributors.
+## 1. Command and Function Casing
+* **Lowercase commands:** All built-in CMake commands and functions are written in lowercase (e.g., `cmake_minimum_required`, `set`, `add_executable`, `target_link_libraries`, `install`).
 
-### General Formatting
+## 2. Indentation, Control Flow, and Line Wrapping
+* **Indentation:** 2-space indentation is used for commands inside control blocks (like `if` / `endif`).
+* **Control Flow:** Closing commands (e.g., `endif()`, `endforeach()`, `endmacro()`, `endfunction()`) must not repeat the condition or arguments of the opening command (e.g., use `endif()` instead of `endif(config_DEBUG)`).
+* **Argument Wrapping:** 
+  * Short, simple commands are kept on a single line (e.g., `set(CMAKE_C_STANDARD 11)`).
+  * Long commands or those with multiple arguments/keywords are wrapped, with each argument placed on a new line and indented by 2 spaces relative to the command (e.g., `add_executable`, `target_include_directories`).
+  * The closing parenthesis `)` is either placed on the same line as the last argument or on its own line aligned with the command name (usually in block-style commands like `install` or `set_target_properties`).
 
-* **Indentation**: Use 2 spaces for indentation. Avoid tabs to ensure consistency across different environments.
-* **Line Length**: Limit line length to 80 characters where possible.
-* **Empty Lines**: Use empty lines to separate logically distinct sections within a CMake file.
-* **No Space Before Opening Brackets**: Do not add a space between a command and the opening parenthesis. Use `if(...)` instead of `if (...)`.
+## 3. Naming Conventions
+* **Local and private variables:** Written in uppercase in legacy project code (e.g., `PUBLIC_HEADER_FILES`, `SOURCES`, `DOXYGEN_IN`), but official guidance recommends using **lowercase** or **snake_case** (e.g., `public_header_files`, `sources`) to distinguish them from CMake's built-in variables.
+* **Options/Cache variables:** Formatted using either a lowercase/mixed-case prefix (e.g., `config_DEBUG`, `config_WERROR`) or full uppercase (e.g., `IWYU_MODE`).
 
-### Commands and Syntax
+## 4. Quoting
+* **Variable expansion and paths:** Double quotes are used for file paths, generator expressions, and strings containing variable expansion (e.g., `"${CMAKE_CURRENT_BINARY_DIR}/analyzer.c"`, `"${CURSES_INCLUDE_DIRS}"`).
+* **Identifiers and keywords:** Unquoted for target names, libraries, command keywords, and constant literals (e.g., `libbase`, `STATIC`, `PUBLIC`, `FATAL_ERROR`).
 
-* **Lowercase Commands**: Always use lowercase CMake commands (e.g., `add_executable`, `find_package`). This improves readability and consistency.
-* **One File Argument per Line**: Break the file arguments across multiple lines to make it easier to scan and identify each source file or item.
+## 5. File Header and Comments
+* **Headers:** Every CMake file begins with a standardized Apache 2.0 license and copyright header.
+* **Comments:** Standard `#` comments are placed above the relevant block or line. Inline comments are generally lowercase-first or capitalized, providing short descriptions.
 
-### Variable Naming
+## 6. Target-Based Configuration
+* **Prefer target-based configuration:** Define compile options, compile definitions, include directories, and link libraries on specific targets using `target_*` commands (e.g., `target_include_directories`, `target_compile_options`, `target_compile_definitions`, `target_link_libraries`) rather than modifying global/directory-wide settings (e.g., `add_compile_options`).
 
-* **Use Uppercase for Cache Variables or variables shared across CMake files**: When defining cache variables using `option` or `set(... CACHE ...)`, use UPPERCASE names.
-* **Use Lowercase for Local Variables**: For local variables within CMake files, use *lowercase* or *snake_case*.
-* **Consistent Prefixing**: Use consistent prefixes for variables to avoid name conflicts, especially in large projects.
-
-### Quoting
-
-* **Quote Strings and Variables**: Always quote string literals and variables to prevent unintended behavior, especially when dealing with paths or arguments that may contain spaces.
-* **Do Not Quote Boolean Values**: For boolean values (`ON`, `OFF`, `TRUE`, `FALSE`), avoid quoting them.
-
-### Avoid Hardcoding Paths
-
-* Use CMake variables (`CMAKE_SOURCE_DIR`, `CMAKE_BINARY_DIR`, `CMAKE_CURRENT_SOURCE_DIR`) instead of hardcoding paths.
-
-### Conditional Logic
-
-* Use `if`, `elseif`, and `else`  with proper indentation, and close with `endif()`.
-
-### Documentation
-
-* Use comments to document complex logic in the CMake files.

src/CMakeLists.txt

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-set(PUBLIC_HEADER_FILES
+set(public_header_files
   arg.h
   assert.h
   atomic.h
@@ -39,7 +39,7 @@ set(PUBLIC_HEADER_FILES
   time.h
   vector.h)
 
-set(SOURCES
+set(sources
   arg.c
   atomic.c
   avltree.c
@@ -62,18 +62,18 @@ set(SOURCES
   time.c)
 
 add_library(libbase STATIC)
-target_sources(libbase PRIVATE ${SOURCES})
+target_sources(libbase PRIVATE ${sources})
 target_include_directories(
   libbase
   PUBLIC
   $<INSTALL_INTERFACE:include>
   $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/../include>)
 target_include_directories(libbase PRIVATE "${CURSES_INCLUDE_DIRS}")
-target_link_libraries(libbase PRIVATE "${CURSES_LIBRARIES}")
+target_link_libraries(libbase PRIVATE "${CURSES_LIBRARIES}" libbase_compiler_flags)
 set_target_properties(
   libbase PROPERTIES
   VERSION 1.0
-  PUBLIC_HEADER "${PUBLIC_HEADER_FILES}"
+  PUBLIC_HEADER "${public_header_files}"
 )
 
 if(iwyu_path_and_options)

src/plist/CMakeLists.txt

@@ -28,7 +28,7 @@ bison_target(
 
 add_flex_bison_dependency(analyzer grammar)
 
-set(PUBLIC_HEADER_FILES
+set(public_header_files
   "${PROJECT_SOURCE_DIR}/include/libbase/plist/decode.h"
   "${PROJECT_SOURCE_DIR}/include/libbase/plist/model.h"
   "${PROJECT_SOURCE_DIR}/include/libbase/plist/parse.h")
@@ -50,11 +50,11 @@ target_include_directories(
 # TODO(kaeser@gubbe.ch):Remove, once updating post bison 3.8.2 (Aug 2022).
 # See: https://github.com/phkaeser/wlmaker/issues/53
 target_compile_options(libbase_plist PRIVATE -Wno-unused-but-set-variable)
-target_link_libraries(libbase_plist libbase)
+target_link_libraries(libbase_plist PRIVATE libbase libbase_compiler_flags)
 set_target_properties(
   libbase_plist
   PROPERTIES VERSION 1.0
-  PUBLIC_HEADER "${PUBLIC_HEADER_FILES}")
+  PUBLIC_HEADER "${public_header_files}")
 if(iwyu_path_and_options)
   set_target_properties(
     libbase_plist PROPERTIES

tests/CMakeLists.txt

@@ -17,44 +17,75 @@ add_executable(
   libbase_test.c)
 target_link_libraries(
   libbase_test
-  libbase)
+  PRIVATE
+  libbase
+  libbase_compiler_flags)
 # Refer to the source path for relative testdata.
 target_compile_definitions(
-  libbase_test PUBLIC BS_TEST_DATA_DIR="${CMAKE_CURRENT_SOURCE_DIR}")
+  libbase_test
+  PUBLIC
+  BS_TEST_DATA_DIR="${CMAKE_CURRENT_SOURCE_DIR}")
 
 target_compile_definitions(
-  libbase_test PUBLIC BS_TEST_BINARY_DIR="${CMAKE_CURRENT_BINARY_DIR}")
+  libbase_test
+  PUBLIC
+  BS_TEST_BINARY_DIR="${CMAKE_CURRENT_BINARY_DIR}")
 
 add_executable(
   libbase_benchmark
   libbase_benchmark.c)
 target_link_libraries(
   libbase_benchmark
-  libbase)
+  PRIVATE
+  libbase
+  libbase_compiler_flags)
 
 add_executable(
   subprocess_test_hang
   subprocess_test_hang.c)
+target_link_libraries(
+  subprocess_test_hang
+  PRIVATE
+  libbase_compiler_flags)
+
 add_executable(
   subprocess_test_failure
   subprocess_test_failure.c)
+target_link_libraries(
+  subprocess_test_failure
+  PRIVATE
+  libbase_compiler_flags)
+
 add_executable(
   subprocess_test_sigpipe
   subprocess_test_sigpipe.c)
+target_link_libraries(
+  subprocess_test_sigpipe
+  PRIVATE
+  libbase_compiler_flags)
+
 add_executable(
   subprocess_test_success
   subprocess_test_success.c)
+target_link_libraries(
+  subprocess_test_success
+  PRIVATE
+  libbase_compiler_flags)
 
 add_executable(
   plist_test
   plist_test.c)
 target_link_libraries(
   plist_test
+  PRIVATE
   libbase
-  libbase_plist)
+  libbase_plist
+  libbase_compiler_flags)
 target_include_directories(plist_test PRIVATE "${CMAKE_CURRENT_BINARY_DIR}/")
 target_compile_definitions(
-  plist_test PUBLIC TEST_DATA_DIR="${CMAKE_CURRENT_SOURCE_DIR}/data")
+  plist_test
+  PUBLIC
+  TEST_DATA_DIR="${CMAKE_CURRENT_SOURCE_DIR}/data")
 
 add_test(NAME libbase_test COMMAND libbase_test)
 add_test(NAME plist_test COMMAND plist_test)

tools/CMakeLists.txt

@@ -17,8 +17,10 @@ add_executable(
   plist_parse.c)
 target_link_libraries(
   plist_parse
+  PRIVATE
   libbase
-  libbase_plist)
+  libbase_plist
+  libbase_compiler_flags)
 target_include_directories(plist_parse PRIVATE "${CMAKE_CURRENT_BINARY_DIR}/")
 
 if(iwyu_path_and_options)