Set using_sanitizer if use_cfi_diag is true.

build/config/sanitizers/sanitizers.gni

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/toolchain/toolchain.gni")
 
 declare_args() {
   # Compile for Address Sanitizer to find memory bugs.
@@ skipping 147 matching lines @@
 }
 
 if ((use_afl || use_libfuzzer) && sanitizer_coverage_flags == "") {
   sanitizer_coverage_flags = "trace-pc-guard"
 } else if (use_sanitizer_coverage && sanitizer_coverage_flags == "") {
   sanitizer_coverage_flags = "trace-pc-guard,indirect-calls"
 }
 
 using_sanitizer =
     is_asan || is_lsan || is_tsan || is_msan || is_ubsan || is_ubsan_null ||
-    is_ubsan_vptr || is_ubsan_security || use_sanitizer_coverage
+    is_ubsan_vptr || is_ubsan_security || use_sanitizer_coverage || use_cfi_diag
 
 assert(!using_sanitizer || is_clang,
        "Sanitizers (is_*san) require setting is_clang = true in 'gn args'")
 
 prebuilt_instrumented_libraries_available =
     is_msan && (msan_track_origins == 0 || msan_track_origins == 2)
 
 if (use_libfuzzer && is_linux) {
   if (is_asan) {
     # We do leak checking with libFuzzer on Linux. Set is_lsan for code that
@@ skipping 26 matching lines @@
 
 # ASAN build on Windows is not working in debug mode. Intercepting memory
 # allocation functions is hard on Windows and not yet implemented in LLVM.
 assert(!is_win || !is_debug || !is_asan,
        "ASan on Windows doesn't work in debug (set is_debug=false).")
 
 # Make sure that if we recover on detection (i.e. not crash), diagnostics are
 # printed.
 assert(!use_cfi_recover || use_cfi_diag,
        "Only use CFI recovery together with diagnostics.")