cmake: fix SetClangRTLibDir [TO SQUASH]

cmake/SetClangRTLibDir.cmake

@@ -4,46 +4,37 @@
 # libclang_rt.fuzzer_no_main library is composed manually.
 # Function raises a fatal message if C compiler is not Clang.
 #
+# $ clang-15 -print-file-name=libclang_rt.fuzzer_no_main-x86_64.a
+# $ /usr/lib/llvm-15/lib/clang/15.0.7/lib/linux/libclang_rt.fuzzer_no_main-x86_64.a
+#
 # On Linux installations libFuzzer library is typically located at:
 #
 # /usr/lib/<llvm-version>/lib/clang/<clang-version>/lib/linux/libclang_rt.fuzzer_no_main-<architecture>.a
 #
-# Location is LLVM_LIBRARY_DIRS/clang/<version>/lib/<OS>/,
-# for example LLVM_LIBRARY_DIRS/clang/4.0.0/lib/darwin/.
-#
 # 1. https://llvm.org/docs/LibFuzzer.html#using-libfuzzer-as-a-library
 
 function(SetFuzzerNoMainLibPath outvar)
   if (NOT CMAKE_C_COMPILER_ID STREQUAL "Clang")
     message(FATAL_ERROR "C compiler is not a Clang")
   endif ()
 
-  set(ClangRTLibDir $ENV{FUZZER_NO_MAIN_LIBRARY})
-
-  if (NOT ClangRTLibDir)
-    string(REPLACE "." ";" VERSION_LIST ${CMAKE_C_COMPILER_VERSION})
-    list(GET VERSION_LIST 0 CLANG_VERSION_MAJOR)
-    # Clang <= 15: /usr/lib/llvm-xxx/lib/clang/X.Y.Z/lib/linux/
-    # Clang >  15: /usr/lib/llvm-xxx/lib/clang/X/lib/linux/
-    set(CLANG_VERSION ${CMAKE_C_COMPILER_VERSION})
-    if (CLANG_VERSION_MAJOR GREATER 15)
-      set(CLANG_VERSION ${CLANG_VERSION_MAJOR})
-    endif ()
-
-    if (CMAKE_SIZEOF_VOID_P EQUAL 4)
-      set(ARCH "i386")
-    elseif (CMAKE_SIZEOF_VOID_P EQUAL 8)
-      set(ARCH "x86_64")
-    endif ()
-
-    # find_package(LLVM 17 REQUIRED CONFIG)
-    # FIXME: Check presence of LLVM.
-    # set(LLVM_BASE "${LLVM_LIBRARY_DIRS}/clang/")
-
-    string(TOLOWER ${CMAKE_HOST_SYSTEM_NAME} OS_NAME)
+  if (CMAKE_SIZEOF_VOID_P EQUAL 4)
+    set(ARCH "i386")
+  elseif (CMAKE_SIZEOF_VOID_P EQUAL 8)
+    set(ARCH "x86_64")
+  else ()
+    message(FATAL_ERROR "Unsupported architecture.")
+  endif ()
 
-    set(ClangRTLibDir "/usr/lib/clang/${CLANG_VERSION}/lib/${OS_NAME}/libclang_rt.fuzzer_no_main-${ARCH}.a")
+  set(LIB_FUZZER_NO_MAIN "libclang_rt.fuzzer_no_main-${ARCH}.a")
+  execute_process(COMMAND ${CMAKE_C_COMPILER} "-print-file-name=${LIB_FUZZER_NO_MAIN}"
+    RESULT_VARIABLE CMD_ERROR
+    OUTPUT_VARIABLE CMD_OUTPUT
+    OUTPUT_STRIP_TRAILING_WHITESPACE
+  )
+  if (CMD_ERROR)
+    message(FATAL_ERROR "${CMD_ERROR}")
   endif ()
-  set(${outvar} ${ClangRTLibDir} PARENT_SCOPE)
-  message(STATUS "[SetClangRTLibDir] ${outvar} is ${ClangRTLibDir}")
+  set(${outvar} ${CMD_OUTPUT} PARENT_SCOPE)
+  message(STATUS "[SetClangRTLib] ${outvar} is ${CMD_OUTPUT}")
 endfunction()