Document that the auto-hinter needs a valid cmap.
diff --git a/include/freetype/freetype.h b/include/freetype/freetype.h
index 6fe1166..f7dd889 100644
--- a/include/freetype/freetype.h
+++ b/include/freetype/freetype.h
@@ -2507,6 +2507,13 @@ FT_BEGIN_HEADER
* Besides deciding which hinter to use, you can also decide which
* hinting algorithm to use. See @FT_LOAD_TARGET_XXX for details.
*
+ * Note that the auto-hinter needs a valid Unicode cmap (either a native
+ * one or synthesized by FreeType) for producing correct results. If a
+ * font provides an incorrect mapping (for example, assigning the
+ * character code U+005A, LATIN CAPITAL LETTER Z, to a glyph depicting a
+ * mathematical integral sign), the auto-hinter might produce useless
+ * results.
+ *
*/
#define FT_LOAD_DEFAULT 0x0
#define FT_LOAD_NO_SCALE ( 1L << 0 )