cmake: Add option to run include-what-you-use with compiler

Author: hebasto

CMakeLists.txt

@@ -132,6 +132,17 @@ option(SECP256K1_BUILD_EXHAUSTIVE_TESTS "Build exhaustive tests." ON)
 option(SECP256K1_BUILD_CTIME_TESTS "Build constant-time tests." ${SECP256K1_VALGRIND})
 option(SECP256K1_BUILD_EXAMPLES "Build examples." OFF)
 
+if(CMAKE_VERSION VERSION_GREATER 3.2)
+  option(SECP256K1_ENABLE_IWYU "Run include-what-you-use (IWYU) with the compiler." OFF)
+  if(SECP256K1_ENABLE_IWYU)
+    find_program(INCLUDE_WHAT_YOU_USE_COMMAND NAMES include-what-you-use)
+    if(NOT INCLUDE_WHAT_YOU_USE_COMMAND)
+      message(FATAL_ERROR "SECP256K1_ENABLE_IWYU is ON but include-what-you-use is not found.")
+    endif()
+    set(CMAKE_C_INCLUDE_WHAT_YOU_USE "${INCLUDE_WHAT_YOU_USE_COMMAND}")
+  endif()
+endif()
+
 # Redefine configuration flags.
 # We leave assertions on, because they are only used in the examples, and we want them always on there.
 if(MSVC)
@@ -269,6 +280,9 @@ get_directory_property(definitions COMPILE_DEFINITIONS)
 string(REPLACE ";" " " definitions "${definitions}")
 message("Preprocessor defined macros ........... ${definitions}")
 message("C compiler ............................ ${CMAKE_C_COMPILER}")
+if(SECP256K1_ENABLE_IWYU)
+  message("Run IWYU with the compiler ............ ${CMAKE_C_INCLUDE_WHAT_YOU_USE}")
+endif()
 message("CFLAGS ................................ ${CMAKE_C_FLAGS}")
 get_directory_property(compile_options COMPILE_OPTIONS)
 string(REPLACE ";" " " compile_options "${compile_options}")