https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52884
--- Comment #2 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
I am planning to submit the following patch
--- ../_clean/gcc/fortran/invoke.texi 2016-03-13 09:07:16.000000000 +0100
+++ gcc/fortran/invoke.texi 2016-04-06 20:44:26.000000000 +0200
@@ -361,9 +361,10 @@ it does not promote variables with expli
@opindex @code{fdefault-double-8}
Set the @code{DOUBLE PRECISION} type to an 8 byte wide type. Do nothing if
this
is already the default. If @option{-fdefault-real-8} is given,
-@code{DOUBLE PRECISION} would instead be promoted to 16 bytes if possible, and
+@code{DOUBLE PRECISION} would instead be promoted to 16 bytes if possible,
+as well as double real constants like @code{1.d0}, and
@option{-fdefault-double-8} can be used to prevent this. The kind of real
-constants like @code{1.d0} will not be changed by @option{-fdefault-real-8}
+constants like @code{1.0_8} will not be changed by @option{-fdefault-real-8}
though, so also @option{-fdefault-double-8} does not affect it.
@item -finteger-4-integer-8
