add required lib if UMF_BUILD_FUZZTESTS is set

Author: bratpiorka

CMakeLists.txt

@@ -579,12 +579,32 @@ if(UMF_USE_MSAN)
                     "prevent reporting false-positives")
     add_sanitizer_flag(memory)
 endif()
+
 # Fuzzer instrumentation for the whole library
 if(UMF_BUILD_FUZZTESTS
    AND CMAKE_CXX_COMPILER_ID MATCHES "Clang"
    AND LINUX)
     add_compile_options("-fsanitize=fuzzer-no-link")
     add_link_options("-fsanitize=fuzzer-no-link")
+
+    # We need to find the fuzzer lib in the LLVM installation dir and link it
+    # statically
+    string(REGEX MATCH "^[0-9]+" CMAKE_C_COMPILER_MAJOR_VERSION
+                 ${CMAKE_C_COMPILER_VERSION})
+    find_library(
+        FUZZER_NO_MAIN_LIB
+        NAMES libclang_rt.fuzzer_no_main-x86_64.a
+        PATHS
+            "/usr/lib/llvm-${CMAKE_C_COMPILER_MAJOR_VERSION}/lib/clang/${CMAKE_C_COMPILER_MAJOR_VERSION}/lib/linux/"
+    )
+
+    if(FUZZER_NO_MAIN_LIB)
+        message(STATUS "Found fuzzer lib: ${FUZZER_NO_MAIN_LIB}")
+        # Fuzzer lib requires libstdc++
+        link_libraries(${FUZZER_NO_MAIN_LIB} "stdc++")
+    else()
+        message(FATAL_ERROR "libclang_rt.fuzzer_no_main-x86_64 not found!")
+    endif()
 endif()
 
 # A header-only lib to specify include directories in transitive dependencies