Warn if using a memory sanitizer on AESNI
Clang-Msan is known to report spurious errors when MBEDTLS_AESNI_C is
enabled, due to the use of assembly code. The error reports don't
mention AES, so they can be difficult to trace back to the use of
AES-NI. Warn about this potential problem at compile time.
diff --git a/library/aesni.c b/library/aesni.c
index 1ca3c3e..062708b 100644
--- a/library/aesni.c
+++ b/library/aesni.c
@@ -32,6 +32,12 @@
#if defined(MBEDTLS_AESNI_C)
+#if defined(__has_feature)
+#if __has_feature(memory_sanitizer)
+#warning "MBEDTLS_AESNI_C is known to cause spurious error reports with some memory sanitizers as they do not understand the assembly code."
+#endif
+#endif
+
#include "mbedtls/aesni.h"
#include <string.h>
