Revert "Make FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION depend on optim…

…ize_for_fuzzing GN arg."

This reverts commit 2b4c029.

FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION, introduced in r452783, is the
documented macro to be used by code that should behave differently when
targeting fuzzers. Since r562499, this macro is only defined when when
optimize_for_fuzzing=true is used. In r597184, optimize_for_fuzzing was
made impossible to use on Windows. As a result of all of this,
FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION doesn't work on Windows because
there is no build configuration that results in it being set.

This CL resolves the problem by making
FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION conditional only on
use_fuzzing_engine=true so that it is set for all builds that target
fuzzers.

Fixed: 1483560
Change-Id: I29a20f42e222b4547ed5191014289582dd058d86
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4874264
Reviewed-by: Jonathan Metzman <[email protected]>
Commit-Queue: Greg Thompson <[email protected]>
Reviewed-by: Dirk Pranke <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1201378}

build/config/compiler/BUILD.gn

@@ -15,7 +15,6 @@ import("//build/config/dcheck_always_on.gni")
 import("//build/config/gclient_args.gni")
 import("//build/config/host_byteorder.gni")
 import("//build/config/rust.gni")
-import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/ui.gni")
 import("//build/config/unwind.gni")
 import("//build/toolchain/cc_wrapper.gni")
@@ -86,6 +85,10 @@ declare_args() {
   # the needed gcov profiling data.
   auto_profile_path = ""
 
+  # Optimize for coverage guided fuzzing (balance between speed and number of
+  # branches)
+  optimize_for_fuzzing = false
+
   # Path to an AFDO profile to use while building with clang, if any. Empty
   # implies none.
   clang_sample_profile_path = ""

build/config/sanitizers/BUILD.gn

@@ -286,7 +286,7 @@ config("asan_flags") {
       # odr-violation errors in rust code, and link failures for cros/asan.
       # Clang recently turned it on by default for all ELF targets (it was
       # already on for Fuchsia). Pass the flag to turn it back off.
-      cflags += ["-fno-sanitize-address-globals-dead-stripping"]
+      cflags += [ "-fno-sanitize-address-globals-dead-stripping" ]
     }
     if (is_win) {
       if (!defined(asan_win_blocklist_path)) {
@@ -550,7 +550,7 @@ config("ubsan_vptr_flags") {
 }
 
 config("fuzzing_build_mode") {
-  if (use_fuzzing_engine && optimize_for_fuzzing) {
+  if (use_fuzzing_engine) {
     defines = [ "FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION" ]
   }
 }

build/config/sanitizers/sanitizers.gni

@@ -86,10 +86,6 @@ declare_args() {
   # Not for client use.
   disable_libfuzzer = false
 
-  # Optimize for coverage guided fuzzing (balance between speed and number of
-  # branches). Can be also used to remove non-determinism and other issues.
-  optimize_for_fuzzing = false
-
   # Value for -fsanitize-coverage flag. Setting this causes
   # use_sanitizer_coverage to be enabled.
   # This flag is not used for libFuzzer (use_libfuzzer=true). Instead, we use: