Detect TSAN instead of relying on #ifdef THREAD_SANITIZER.

src/core/SkSharedMutex.cpp

Index: src/core/SkSharedMutex.cpp
diff --git a/src/core/SkSharedMutex.cpp b/src/core/SkSharedMutex.cpp
index aeaf5776bf4e04cb162d31283b37323212892c94..17714a7185625434171c915f84875ec9e93e5027 100644
--- a/src/core/SkSharedMutex.cpp
+++ b/src/core/SkSharedMutex.cpp
@@ -11,58 +11,62 @@
 #include "SkTypes.h"
 #include "SkSemaphore.h"
 
-#if defined(THREAD_SANITIZER)
-
-/* Report that a lock has been created at address "lock". */
-#define ANNOTATE_RWLOCK_CREATE(lock) \
-    AnnotateRWLockCreate(__FILE__, __LINE__, lock)
-
-/* Report that the lock at address "lock" is about to be destroyed. */
-#define ANNOTATE_RWLOCK_DESTROY(lock) \
-    AnnotateRWLockDestroy(__FILE__, __LINE__, lock)
-
-/* Report that the lock at address "lock" has been acquired.
-   is_w=1 for writer lock, is_w=0 for reader lock. */
-#define ANNOTATE_RWLOCK_ACQUIRED(lock, is_w) \
-    AnnotateRWLockAcquired(__FILE__, __LINE__, lock, is_w)
-
-/* Report that the lock at address "lock" is about to be released. */
-#define ANNOTATE_RWLOCK_RELEASED(lock, is_w) \
-  AnnotateRWLockReleased(__FILE__, __LINE__, lock, is_w)
-
-#ifdef DYNAMIC_ANNOTATIONS_WANT_ATTRIBUTE_WEAK
-# ifdef __GNUC__
-#  define DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK __attribute__((weak))
-# else
-/* TODO(glider): for Windows support we may want to change this macro in order
-   to prepend __declspec(selectany) to the annotations' declarations. */
-#  error weak annotations are not supported for your compiler
-# endif
-#else
-# define DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK
+#if !defined(__has_feature)
+    #define __has_feature(x) 0
 #endif
 
-extern "C" {
-void AnnotateRWLockCreate(
-    const char *file, int line,
-    const volatile void *lock) DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK;
-void AnnotateRWLockDestroy(
-    const char *file, int line,
-    const volatile void *lock) DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK;
-void AnnotateRWLockAcquired(
-    const char *file, int line,
-    const volatile void *lock, long is_w) DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK;
-void AnnotateRWLockReleased(
-    const char *file, int line,
-    const volatile void *lock, long is_w) DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK;
-}
+#if __has_feature(thread_sanitizer)
+
+    /* Report that a lock has been created at address "lock". */
+    #define ANNOTATE_RWLOCK_CREATE(lock) \
+        AnnotateRWLockCreate(__FILE__, __LINE__, lock)
+
+    /* Report that the lock at address "lock" is about to be destroyed. */
+    #define ANNOTATE_RWLOCK_DESTROY(lock) \
+        AnnotateRWLockDestroy(__FILE__, __LINE__, lock)
+
+    /* Report that the lock at address "lock" has been acquired.
+       is_w=1 for writer lock, is_w=0 for reader lock. */
+    #define ANNOTATE_RWLOCK_ACQUIRED(lock, is_w) \
+        AnnotateRWLockAcquired(__FILE__, __LINE__, lock, is_w)
+
+    /* Report that the lock at address "lock" is about to be released. */
+    #define ANNOTATE_RWLOCK_RELEASED(lock, is_w) \
+      AnnotateRWLockReleased(__FILE__, __LINE__, lock, is_w)
+
+    #if defined(DYNAMIC_ANNOTATIONS_WANT_ATTRIBUTE_WEAK)
+        #if defined(__GNUC__)
+            #define DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK __attribute__((weak))
+        #else
+            /* TODO(glider): for Windows support we may want to change this macro in order
+               to prepend __declspec(selectany) to the annotations' declarations. */
+            #error weak annotations are not supported for your compiler
+        #endif
+    #else
+        #define DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK
+    #endif
+
+    extern "C" {
+    void AnnotateRWLockCreate(
+        const char *file, int line,
+        const volatile void *lock) DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK;
+    void AnnotateRWLockDestroy(
+        const char *file, int line,
+        const volatile void *lock) DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK;
+    void AnnotateRWLockAcquired(
+        const char *file, int line,
+        const volatile void *lock, long is_w) DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK;
+    void AnnotateRWLockReleased(
+        const char *file, int line,
+        const volatile void *lock, long is_w) DYNAMIC_ANNOTATIONS_ATTRIBUTE_WEAK;
+    }
 
 #else
 
-#define ANNOTATE_RWLOCK_CREATE(lock)
-#define ANNOTATE_RWLOCK_DESTROY(lock)
-#define ANNOTATE_RWLOCK_ACQUIRED(lock, is_w)
-#define ANNOTATE_RWLOCK_RELEASED(lock, is_w)
+    #define ANNOTATE_RWLOCK_CREATE(lock)
+    #define ANNOTATE_RWLOCK_DESTROY(lock)
+    #define ANNOTATE_RWLOCK_ACQUIRED(lock, is_w)
+    #define ANNOTATE_RWLOCK_RELEASED(lock, is_w)
 
 #endif