doc: Describe behaviour of enums with fixed underlying type [PR109532]

gcc/ChangeLog:

	PR c++/109532
	* doc/invoke.texi (Code Gen Options): Note that -fshort-enums
	is ignored for a fixed underlying type.
	(C++ Dialect Options): Likewise for -fstrict-enums.

Reviewed-by: Marek Polacek <polacek@redhat.com>

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 2c525762171b3ce0f010541e63cb1592c9497bba..ee78591c73e9508c4871b792dbd7536017fc6076 100644 (file)
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -3495,6 +3495,8 @@ defined in the C++ standard; basically, a value that can be
 represented in the minimum number of bits needed to represent all the
 enumerators).  This assumption may not be valid if the program uses a
 cast to convert an arbitrary integer value to the enumerated type.
+This option has no effect for an enumeration type with a fixed underlying
+type.
 
 @opindex fstrong-eval-order
 @item -fstrong-eval-order
@@ -18306,6 +18308,8 @@ Use it to conform to a non-default application binary interface.
 Allocate to an @code{enum} type only as many bytes as it needs for the
 declared range of possible values.  Specifically, the @code{enum} type
 is equivalent to the smallest integer type that has enough room.
+This option has no effect for an enumeration type with a fixed underlying
+type.
 
 @strong{Warning:} the @option{-fshort-enums} switch causes GCC to generate
 code that is not binary compatible with code generated without that switch.