Added checks to avoid bad sanitizer combinations.

Some sanitizers are not compatible with other sanitizers. Added some checks to
avoid these combinations at configuration time.

cmake/FindASan.cmake

@@ -33,9 +33,18 @@ set(FLAG_CANDIDATES
 )
 
 
+if (SANITIZE_ADDRESS AND (SANITIZE_THREAD OR SANITIZE_MEMORY))
+    message(FATAL_ERROR "AddressSanitizer is not compatible with "
+        "ThreadSanitizer or MemorySanitizer.")
+endif ()
+
+
 include(sanitize-helpers)
 
-sanitizer_check_compiler_flags("${FLAG_CANDIDATES}" "AddressSanitizer" "ASan")
+if (SANITIZE_ADDRESS)
+    sanitizer_check_compiler_flags("${FLAG_CANDIDATES}" "AddressSanitizer"
+        "ASan")
+endif ()
 
 function (add_sanitize_address TARGET)
     if (NOT SANITIZE_ADDRESS)

cmake/FindSanitizers.cmake

@@ -22,25 +22,6 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 
-
-# The following options will enable the desired sanitizers.
-option(SANITIZE "Enable all available sanitizers for sanitized targets." OFF)
-
-# If option SANITIZE is enabled, enable all available sanitizers.
-if (SANITIZE)
-    set(SANITIZE_ADDRESS ON CACHE BOOL
-        "Enable AddressSanitizer for sanitized targets." FORCE)
-    set(SANITIZE_THREAD ON CACHE BOOL
-        "Enable ThreadSanitizer for sanitized targets." FORCE)
-    set(SANITIZE_MEMORY ON CACHE BOOL
-        "Enable MemorySanitizer for sanitized targets." FORCE)
-    set(SANITIZE_UNDEFINED ON CACHE BOOL
-        "Enable UndefinedBehaviorSanitizer for sanitized targets." FORCE)
-endif (SANITIZE)
-
-
-
-
 set(FIND_QUIETLY_FLAG "")
 if (DEFINED Sanitizers_FIND_QUIETLY)
     set(FIND_QUIETLY_FLAG "QUIET")

cmake/FindTSan.cmake

@@ -29,6 +29,13 @@ set(FLAG_CANDIDATES
 )
 
 
+# ThreadSanitizer is not compatible with MemorySanitizer.
+if (SANITIZE_THREAD AND SANITIZE_MEMORY)
+    message(FATAL_ERROR "ThreadSanitizer is not compatible with "
+        "MemorySanitizer.")
+endif ()
+
+
 include(sanitize-helpers)
 
 if (SANITIZE_THREAD)

cmake/FindUBSan.cmake

@@ -32,8 +32,10 @@ set(FLAG_CANDIDATES
 
 include(sanitize-helpers)
 
-sanitizer_check_compiler_flags("${FLAG_CANDIDATES}" "UndefinedBehaviorSanitizer"
-    "UBSan")
+if (SANITIZE_UNDEFINED)
+    sanitizer_check_compiler_flags("${FLAG_CANDIDATES}"
+        "UndefinedBehaviorSanitizer" "UBSan")
+endif ()
 
 function (add_sanitize_undefined TARGET)
     if (NOT SANITIZE_UNDEFINED)