Make sanitizer flags come before user flags

While not super recommended users should be able to override the `-g`
flags set by sanitizers

Author: keith

crosstool/cc_toolchain_config.bzl

@@ -2384,16 +2384,16 @@ please file an issue at https://github.com/bazelbuild/apple_support/issues/new
         apply_implicit_frameworks_feature,
         link_cocoa_feature,
         apply_simulator_compiler_flags_feature,
+        asan_feature,
+        tsan_feature,
+        ubsan_feature,
+        default_sanitizer_flags_feature,
         user_compile_flags_feature,
         unfiltered_compile_flags_feature,
         linker_param_file_feature,
         compiler_input_flags_feature,
         compiler_output_flags_feature,
         set_install_name,
-        asan_feature,
-        tsan_feature,
-        ubsan_feature,
-        default_sanitizer_flags_feature,
         suppress_warnings_feature,
         treat_warnings_as_errors_feature,
         no_warn_duplicate_libraries_feature,

test/sanitizer_tests.bzl

@@ -21,6 +21,13 @@ asan_dbg_test = make_action_command_line_test_rule(
     },
 )
 
+asan_copt_order_test = make_action_command_line_test_rule(
+    config_settings = {
+        "//command_line_option:copt": ["-DFROM_COPTS_FLAG=1"],
+        "//command_line_option:features": ["asan"],
+    },
+)
+
 tsan_test = make_action_command_line_test_rule(
     config_settings = {
         "//command_line_option:compilation_mode": "fastbuild",
@@ -129,6 +136,22 @@ def sanitizer_test_suite(name):
         target_under_test = "//test/test_data:objc_lib",
     )
 
+    asan_copt_order_test(
+        name = "{}_asan_copt_order_test".format(name),
+        tags = [name],
+        expected_argv = [
+            "-fsanitize=address",
+            "-gline-tables-only",
+            "-fno-omit-frame-pointer",
+            "-fno-sanitize-recover=all",
+            "-DCOPTS_ENV=1",
+            "-DFROM_COPTS_FLAG=1",
+            "-DFROM_BUILD_COPTS=1",
+        ],
+        mnemonic = "CppCompile",
+        target_under_test = "//test/test_data:cc_lib",
+    )
+
     asan_test(
         name = "{}_asan_link_test".format(name),
         tags = [name],

toolchain/BUILD

@@ -902,6 +902,10 @@ cc_toolchain(
         "@apple_support_toolchain_env//:linkopts_from_env",  # TODO: Join with the copts below
         ":default_required_flags",
         ":__apply_simulator_compiler_flags",
+        "//toolchain/sanitizers:asan_wrapper",
+        "//toolchain/sanitizers:tsan_wrapper",
+        "//toolchain/sanitizers:ubsan_wrapper",
+        "//toolchain/sanitizers:default_sanitizer_flags",
         "@apple_support_toolchain_env//:copts_from_env",
         ":default_link_flags",
         ":no_deduplicate",
@@ -916,10 +920,6 @@ cc_toolchain(
         "@rules_cc//cc/toolchains/args/compiler_output_flags:feature",
         "@rules_cc//cc/toolchains/args/linker_param_file:feature",
         ":set_install_name",
-        "//toolchain/sanitizers:asan_wrapper",
-        "//toolchain/sanitizers:tsan_wrapper",
-        "//toolchain/sanitizers:ubsan_wrapper",
-        "//toolchain/sanitizers:default_sanitizer_flags",
         ":suppress_warnings_wrapper",
         ":treat_warnings_as_errors_wrapper",
         ":no_warn_duplicate_libraries",