[sanitizers] Remove unneeded MaybeCall*DefaultOptions() and nullptr checks

[MaskRay]

Summary

D28596 added SANITIZER_INTERFACE_WEAK_DEF which can guarantee *_default_options are always defined.
The weak attributes on the __{asan,lsan,msan,ubsan}_default_options declarations can thus be removed.

MaybeCall*DefaultOptions no longer need nullptr checks, so their call sites can just be replaced by __*_default_options.

[vitalybuka]

clang-format: please reformat the code?

[MaskRay]

clang-format two const pointer* to const pointer *

compiler-rt/lib/asan/asan_flags.cpp

 #include "sanitizer_common/sanitizer_flag_parser.h"
 #include "ubsan/ubsan_flags.h"
 #include "ubsan/ubsan_platform.h"
 
 namespace __asan {
 
 Flags asan_flags_dont_use_directly;  // use via flags().
 
-static const char *MaybeCallAsanDefaultOptions() {
-  return (&__asan_default_options) ? __asan_default_options() : "";
-}
-
 static const char *MaybeUseAsanDefaultOptionsCompileDefinition() {
 #ifdef ASAN_DEFAULT_OPTIONS
   return SANITIZER_STRINGIFY(ASAN_DEFAULT_OPTIONS);
 #else
   return "";
 #endif
 }
 
if (SANITIZER_MAC) {
     }
   }
 
   // Override from ASan compile definition.
   const char *asan_compile_def = MaybeUseAsanDefaultOptionsCompileDefinition();
   asan_parser.ParseString(asan_compile_def);
 
   // Override from user-specified string.
-  const char *asan_default_options = MaybeCallAsanDefaultOptions();
+  const char *asan_default_options = __asan_default_options();
   asan_parser.ParseString(asan_default_options);
 #if CAN_SANITIZE_UB
-  const char *ubsan_default_options = __ubsan::MaybeCallUbsanDefaultOptions();
+  const char *ubsan_default_options = __ubsan_default_options();
   ubsan_parser.ParseString(ubsan_default_options);
 #endif
 #if CAN_SANITIZE_LEAKS
-  const char *lsan_default_options = __lsan::MaybeCallLsanDefaultOptions();
+  const char *lsan_default_options = __lsan_default_options();
   lsan_parser.ParseString(lsan_default_options);
 #endif
 
   // Override from command line.
   asan_parser.ParseStringFromEnv("ASAN_OPTIONS");
 #if CAN_SANITIZE_LEAKS
   lsan_parser.ParseStringFromEnv("LSAN_OPTIONS");
 #endif

compiler-rt/lib/asan/asan_interface_internal.h

extern "C" {
   SANITIZER_INTERFACE_ATTRIBUTE
   void __asan_set_error_report_callback(void (*callback)(const char*));
 
   SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
   void __asan_on_error();
 
   SANITIZER_INTERFACE_ATTRIBUTE void __asan_print_accumulated_stats();
 
-  SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-  const char* __asan_default_options();
+  SANITIZER_INTERFACE_ATTRIBUTE
+  const char *__asan_default_options();
 
   SANITIZER_INTERFACE_ATTRIBUTE
   extern uptr __asan_shadow_memory_dynamic_address;
 
   // Global flag, copy of ASAN_OPTIONS=detect_stack_use_after_return
   SANITIZER_INTERFACE_ATTRIBUTE
   extern int __asan_option_detect_stack_use_after_return;
 

compiler-rt/lib/cfi/cfi.cpp

#endif
   RegisterCommonFlags(&cfi_parser);
   cfi_parser.ParseStringFromEnv("CFI_OPTIONS");
 
 #ifdef CFI_ENABLE_DIAG
   FlagParser ubsan_parser;
   __ubsan::RegisterUbsanFlags(&ubsan_parser, uf);
   RegisterCommonFlags(&ubsan_parser);
 
-  const char *ubsan_default_options = __ubsan::MaybeCallUbsanDefaultOptions();
+  const char *ubsan_default_options = __ubsan_default_options();
   ubsan_parser.ParseString(ubsan_default_options);
   ubsan_parser.ParseStringFromEnv("UBSAN_OPTIONS");
 #endif
 
   InitializeCommonFlags();
 
   if (Verbosity())
     ReportUnrecognizedFlags();

compiler-rt/lib/hwasan/hwasan.cpp

#if HWASAN_CONTAINS_UBSAN
   __ubsan::RegisterUbsanFlags(&ubsan_parser, uf);
   RegisterCommonFlags(&ubsan_parser);
 #endif
 
   // Override from user-specified string.
   if (__hwasan_default_options)
     parser.ParseString(__hwasan_default_options());
 #if HWASAN_CONTAINS_UBSAN
-  const char *ubsan_default_options = __ubsan::MaybeCallUbsanDefaultOptions();
+  const char *ubsan_default_options = __ubsan_default_options();
   ubsan_parser.ParseString(ubsan_default_options);
 #endif
 
   parser.ParseStringFromEnv("HWASAN_OPTIONS");
 #if HWASAN_CONTAINS_UBSAN
   ubsan_parser.ParseStringFromEnv("UBSAN_OPTIONS");
 #endif
 

compiler-rt/lib/lsan/lsan.cpp

static void InitializeFlags() {
   Flags *f = flags();
   f->SetDefaults();
 
   FlagParser parser;
   RegisterLsanFlags(&parser, f);
   RegisterCommonFlags(&parser);
 
   // Override from user-specified string.
-  const char *lsan_default_options = MaybeCallLsanDefaultOptions();
+  const char *lsan_default_options = __lsan_default_options();
   parser.ParseString(lsan_default_options);
   parser.ParseStringFromEnv("LSAN_OPTIONS");
 
   SetVerbosity(common_flags()->verbosity);
 
   if (Verbosity()) ReportUnrecognizedFlags();
 
   if (common_flags()->help) parser.PrintFlagDescriptions();

compiler-rt/lib/lsan/lsan_common.cpp

 InternalMmapVector<RootRegion> const *GetRootRegions() { return root_regions; }
 
 void InitializeRootRegions() {
   CHECK(!root_regions);
   ALIGNED(64) static char placeholder[sizeof(InternalMmapVector<RootRegion>)];
   root_regions = new (placeholder) InternalMmapVector<RootRegion>();
 }
 
-const char *MaybeCallLsanDefaultOptions() {
-  return (&__lsan_default_options) ? __lsan_default_options() : "";
-}
-
 void InitCommonLsan() {
   InitializeRootRegions();
   if (common_flags()->detect_leaks) {
     // Initialization which can fail or print warnings should only be done if
     // LSan is actually enabled.
     InitializeSuppressions();
     InitializePlatformSpecificModules();
   }

 int __lsan_do_recoverable_leak_check() {
 #if CAN_SANITIZE_LEAKS
   if (common_flags()->detect_leaks)
     return __lsan::DoRecoverableLeakCheck();
 #endif // CAN_SANITIZE_LEAKS
   return 0;
 }
 
-#if !SANITIZER_SUPPORTS_WEAK_HOOKS
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-const char * __lsan_default_options() {
+SANITIZER_INTERFACE_WEAK_DEF(const char *, __lsan_default_options, void) {
   return "";
 }
 
+#if !SANITIZER_SUPPORTS_WEAK_HOOKS
 SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 int __lsan_is_turned_off() {
   return 0;
 }
 
 SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 const char *__lsan_default_suppressions() {
   return "";
 }
 #endif
 } // extern "C"

compiler-rt/lib/msan/msan.cpp

#if MSAN_CONTAINS_UBSAN
   uf->SetDefaults();
 
   FlagParser ubsan_parser;
   __ubsan::RegisterUbsanFlags(&ubsan_parser, uf);
   RegisterCommonFlags(&ubsan_parser);
 #endif
 
   // Override from user-specified string.
-  if (__msan_default_options)
-    parser.ParseString(__msan_default_options());
 #if MSAN_CONTAINS_UBSAN
-  const char *ubsan_default_options = __ubsan::MaybeCallUbsanDefaultOptions();
+  const char *ubsan_default_options = __ubsan_default_options();
   ubsan_parser.ParseString(ubsan_default_options);
 #endif
 
   parser.ParseStringFromEnv("MSAN_OPTIONS");
 #if MSAN_CONTAINS_UBSAN
   ubsan_parser.ParseStringFromEnv("UBSAN_OPTIONS");
 #endif
 
internal_memset(__msan_param_origin_tls, 0,
                     sizeof(__msan_param_origin_tls));
     internal_memset(&__msan_retval_origin_tls, 0,
                     sizeof(__msan_retval_origin_tls));
     internal_memset(__msan_va_arg_origin_tls, 0,
                     sizeof(__msan_va_arg_origin_tls));
   }
 }
 
-#if !SANITIZER_SUPPORTS_WEAK_HOOKS
-extern "C" {
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-const char* __msan_default_options() { return ""; }
-}  // extern "C"
-#endif
+SANITIZER_INTERFACE_WEAK_DEF(const char *, __msan_default_options, void) {
+  return "";
+}
 
 extern "C" {
 SANITIZER_INTERFACE_ATTRIBUTE
 void __sanitizer_print_stack_trace() {
   GET_FATAL_STACK_TRACE_PC_BP(StackTrace::GetCurrentPc(), GET_CURRENT_FRAME());
   stack.Print();
 }
 } // extern "C"

compiler-rt/lib/msan/msan_interface_internal.h

 void __msan_clear_on_return();
 
 SANITIZER_INTERFACE_ATTRIBUTE
 void __msan_set_keep_going(int keep_going);
 
 SANITIZER_INTERFACE_ATTRIBUTE
 int __msan_set_poison_in_malloc(int do_poison);
 
-SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
-/* OPTIONAL */ const char* __msan_default_options();
+SANITIZER_INTERFACE_ATTRIBUTE
+const char *__msan_default_options();
 
 // For testing.
 SANITIZER_INTERFACE_ATTRIBUTE
 void __msan_set_expect_umr(int expect_umr);
 SANITIZER_INTERFACE_ATTRIBUTE
 void __msan_print_shadow(const void *x, uptr size);
 SANITIZER_INTERFACE_ATTRIBUTE
 void __msan_dump_shadow(const void *x, uptr size);

compiler-rt/lib/tsan/rtl/tsan_flags.cpp

#if TSAN_CONTAINS_UBSAN
   FlagParser ubsan_parser;
   __ubsan::RegisterUbsanFlags(&ubsan_parser, uf);
   RegisterCommonFlags(&ubsan_parser);
 #endif
 
   // Let a frontend override.
   parser.ParseString(__tsan_default_options());
 #if TSAN_CONTAINS_UBSAN
-  const char *ubsan_default_options = __ubsan::MaybeCallUbsanDefaultOptions();
+  const char *ubsan_default_options = __ubsan_default_options();
   ubsan_parser.ParseString(ubsan_default_options);
 #endif
   // Override from command line.
   parser.ParseString(env, env_option_name);
 #if TSAN_CONTAINS_UBSAN
   ubsan_parser.ParseStringFromEnv("UBSAN_OPTIONS");
 #endif
 

compiler-rt/lib/ubsan/ubsan_flags.h

 };
 
 extern Flags ubsan_flags;
 inline Flags *flags() { return &ubsan_flags; }
 
 void InitializeFlags();
 void RegisterUbsanFlags(FlagParser *parser, Flags *f);
 
-const char *MaybeCallUbsanDefaultOptions();
-
 }  // namespace __ubsan
 
 extern "C" {
 // Users may provide their own implementation of __ubsan_default_options to
 // override the default flag values.
 SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 const char *__ubsan_default_options();
 }  // extern "C"
 
 #endif  // UBSAN_FLAGS_H

compiler-rt/lib/ubsan/ubsan_flags.cpp

 #include "sanitizer_common/sanitizer_common.h"
 #include "sanitizer_common/sanitizer_flags.h"
 #include "sanitizer_common/sanitizer_flag_parser.h"
 
 #include <stdlib.h>
 
 namespace __ubsan {
 
-const char *MaybeCallUbsanDefaultOptions() {
-  return (&__ubsan_default_options) ? __ubsan_default_options() : "";
-}
-
 static const char *GetFlag(const char *flag) {
   // We cannot call getenv() from inside a preinit array initializer
   if (SANITIZER_CAN_USE_PREINIT_ARRAY) {
     return GetEnv(flag);
   } else {
     return getenv(flag);
   }
 }
void InitializeFlags() {
   Flags *f = flags();
   f->SetDefaults();
 
   FlagParser parser;
   RegisterCommonFlags(&parser);
   RegisterUbsanFlags(&parser, f);
 
   // Override from user-specified string.
-  parser.ParseString(MaybeCallUbsanDefaultOptions());
+  parser.ParseString(__ubsan_default_options());
   // Override from environment variable.
   parser.ParseStringFromEnv("UBSAN_OPTIONS");
   InitializeCommonFlags();
   if (Verbosity()) ReportUnrecognizedFlags();
 
   if (common_flags()->help) parser.PrintFlagDescriptions();
 }
 
 }  // namespace __ubsan
 
 SANITIZER_INTERFACE_WEAK_DEF(const char *, __ubsan_default_options, void) {
   return "";
 }
 
 #endif  // CAN_SANITIZE_UB