cmake: Disable ctime_tests if build with -fsanitize=memory

Clang >= 16 has `-fsanitize-memory-param-retval` turned on by default,
which is incompatible with

Author: hebasto

CMakeLists.txt

@@ -263,6 +263,17 @@ endif()
 
 set(CMAKE_C_VISIBILITY_PRESET hidden)
 
+set(print_msan_notice)
+if(SECP256K1_BUILD_CTIME_TESTS)
+  include(CheckMemorySanitizer)
+  check_memory_sanitizer(msan_enabled)
+  if(msan_enabled)
+    try_append_c_flags(-fno-sanitize-memory-param-retval)
+    set(print_msan_notice YES)
+  endif()
+  unset(msan_enabled)
+endif()
+
 # Ask CTest to create a "check" target (e.g., make check) as alias for the "test" target.
 # CTEST_TEST_TARGET_ALIAS is not documented but supposed to be user-facing.
 # See: https://gitlab.kitware.com/cmake/cmake/-/commit/816c9d1aa1f2b42d40c81a991b68c96eb12b6d2
@@ -358,7 +369,14 @@ endif()
 if(SECP256K1_LATE_CFLAGS)
   message("SECP256K1_LATE_CFLAGS ................. ${SECP256K1_LATE_CFLAGS}")
 endif()
-message("\n")
+message("")
+if(print_msan_notice)
+  message(
+    "Note:\n"
+    "  MemorySanitizer detected, tried to add -fno-sanitize-memory-param-retval to compile options\n"
+    "  to avoid false positives in ctime_tests. Pass -DSECP256K1_BUILD_CTIME_TESTS=OFF to avoid this.\n"
+  )
+endif()
 if(SECP256K1_EXPERIMENTAL)
   message(
     "  ******\n"

cmake/CheckMemorySanitizer.cmake

@@ -0,0 +1,18 @@
+include_guard(GLOBAL)
+include(CheckCSourceCompiles)
+
+function(check_memory_sanitizer output)
+  set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
+  check_c_source_compiles("
+    #if defined(__has_feature)
+    #  if __has_feature(memory_sanitizer)
+         /* MemorySanitizer is enabled. */
+    #  elif
+    #    error \"MemorySanitizer is disabled.\"
+    #  endif
+    #else
+    #  error \"__has_feature is not defined.\"
+    #endif
+  " HAVE_MSAN)
+  set(${output} ${HAVE_MSAN} PARENT_SCOPE)
+endfunction()