cmake: sparse: deprecate old sparse support

Deprecate old sparse support as Zephyr now provides a proper
infrastructure for SCA tools. Set ZEPHYR_SCA_VARIANT to sparse if user
is using deprecated way.

This allows to cleanup sparse code in various places and thus have a
cleaner build system.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

CMakeLists.txt

@@ -301,12 +301,6 @@ if(CONFIG_COMPILER_COLOR_DIAGNOSTICS)
 zephyr_compile_options($<TARGET_PROPERTY:compiler,diagnostic>)
 endif()
 
-if("${SPARSE}" STREQUAL "y")
-  list(APPEND TOOLCHAIN_C_FLAGS -D__CHECKER__)
-  # Avoid compiler "attribute directive ignored" warnings
-  list(APPEND TOOLCHAIN_C_FLAGS -Wno-attributes)
-endif()
-
 zephyr_compile_options(
   ${TOOLCHAIN_C_FLAGS}
 )

cmake/compiler/gcc/target.cmake

@@ -5,39 +5,8 @@ set_ifndef(C++ g++)
 # Configures CMake for using GCC, this script is re-used by several
 # GCC-based toolchains
 
-if("${SPARSE}" STREQUAL "y")
-  # No search PATHS because we need more than cgcc in the default PATH
-  find_program(CMAKE_C_COMPILER cgcc REQUIRED)
-  message(STATUS "Found sparse: ${CMAKE_C_COMPILER}")
-
-  find_program(SPARSE_REAL_COMPILER ${CROSS_COMPILE}${CC} PATHS ${TOOLCHAIN_HOME} NO_DEFAULT_PATH REQUIRED)
-
-  # We know what REAL_CC _must_ be, so why do we ask the user to define it?  Because CMake
-  # cannot set (evil) build time env variables at configure time:
-  # https://gitlab.kitware.com/cmake/community/-/wikis/FAQ#how-can-i-get-or-set-environment-variables
-  # As of Sep. 2022, sparse/cgcc has unfortunately no --real-cc option as it should.
-  #
-  # In theory we could define REAL_CC ourselves here and fix the configure-time
-  # --print-file-name below (and maybe others). Then ask the user to define REAL_CC later
-  # at _build_ time. But in practice who would define environment variables at build time
-  # _only_?  So best to fail early and clearly here.
-  if ("$ENV{REAL_CC}" STREQUAL "")
-    message(FATAL_ERROR
-      "The only way to override its 'cc' default when cross-compiling with sparse is "
-      "unfortunately an environment variable. So you _must_ set REAL_CC at both configuration "
-      "time and build time to: ${SPARSE_REAL_COMPILER}")
-  else() # check ENV{REAL_CC}
-    file(REAL_PATH "${SPARSE_REAL_COMPILER}" real_compiler_rp)
-    file(REAL_PATH "$ENV{REAL_CC}" env_real_cc_rp)
-    cmake_path(COMPARE "${real_compiler_rp}" EQUAL "${env_real_cc_rp}" expected_env_REAL_CC)
-    if(NOT expected_env_REAL_CC)
-      message(FATAL_ERROR
-        "Unexpected environment variable REAL_CC: $ENV{REAL_CC}, must be: ${SPARSE_REAL_COMPILER}")
-    endif()
-  endif()
-else() # SPARSE
-  find_program(CMAKE_C_COMPILER ${CROSS_COMPILE}${CC} PATHS ${TOOLCHAIN_HOME} NO_DEFAULT_PATH)
-endif()
+find_package(Deprecated COMPONENTS SPARSE)
+find_program(CMAKE_C_COMPILER ${CROSS_COMPILE}${CC} PATHS ${TOOLCHAIN_HOME} NO_DEFAULT_PATH)
 
 if(${CMAKE_C_COMPILER} STREQUAL CMAKE_C_COMPILER-NOTFOUND)
   message(FATAL_ERROR "C compiler ${CROSS_COMPILE}${CC} not found - Please check your toolchain installation")

cmake/linker/ld/target.cmake

@@ -66,12 +66,6 @@ macro(configure_linker_script linker_script_gen linker_pass_define)
     zephyr_get_include_directories_for_lang(C current_includes)
     get_property(current_defines GLOBAL PROPERTY PROPERTY_LINKER_SCRIPT_DEFINES)
 
-    if("${SPARSE}" STREQUAL "y")
-      set(ld_command ${SPARSE_REAL_COMPILER})
-    else()
-      set(ld_command ${CMAKE_C_COMPILER})
-    endif()
-
     add_custom_command(
       OUTPUT ${linker_script_gen}
       DEPENDS
@@ -80,7 +74,7 @@ macro(configure_linker_script linker_script_gen linker_pass_define)
       ${extra_dependencies}
       # NB: 'linker_script_dep' will use a keyword that ends 'DEPENDS'
       ${linker_script_dep}
-      COMMAND ${ld_command}
+      COMMAND ${CMAKE_C_COMPILER}
       -x assembler-with-cpp
       ${NOSYSDEF_CFLAG}
       -MD -MF ${linker_script_gen}.dep -MT ${linker_script_gen}

cmake/modules/FindDeprecated.cmake

@@ -78,6 +78,18 @@ if("XTOOLS" IN_LIST Deprecated_FIND_COMPONENTS)
                       "Please set ZEPHYR_TOOLCHAIN_VARIANT to 'zephyr'")
 endif()
 
+if("SPARSE" IN_LIST Deprecated_FIND_COMPONENTS)
+  list(REMOVE_ITEM Deprecated_FIND_COMPONENTS SPARSE)
+  # This code was deprecated after Zephyr v3.2.0
+  if(SPARSE)
+    message(DEPRECATION
+        "Setting SPARSE=${SPARSE} is deprecated. "
+        "Please set ZEPHYR_SCA_VARIANT to 'sparse'"
+    )
+    set_ifndef(ZEPHYR_SCA_VARIANT sparse)
+  endif()
+endif()
+
 if("SOURCES" IN_LIST Deprecated_FIND_COMPONENTS)
   list(REMOVE_ITEM Deprecated_FIND_COMPONENTS SOURCES)
   if(SOURCES)