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correctly document closure return promotion

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Tom Tromey
2015-12-17 16:58:10 -07:00
parent 8a7cdeb041
commit 6affad7911
1 changed files with 11 additions and 7 deletions
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18
doc/libffi.texi
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@@ -806,13 +806,17 @@ The @code{ffi_cif} passed to @code{ffi_prep_closure_loc}.
@item ret @item ret
A pointer to the memory used for the function's return value. A pointer to the memory used for the function's return value.
@var{fun} must fill this, unless the function is declared as returning
@code{void}. Note that this points to memory that is exactly the size If the function is declared as returning @code{void}, then this value
of the type given as the return type when initializing the CIF. In is garbage and should not be used.
particular, closures do not have the special promotion behavior of
@code{ffi_call}. Otherwise, @var{fun} must fill the object to which this points,
@c FIXME: is this NULL for void-returning functions? following the same special promotion behavior as @code{ffi_call}.
@c (experimentally it is not, but it seems like a good idea) That is, in most cases, @var{ret} points to an object of exactly the
size of the type specified when @var{cif} was constructed. However,
integral types narrower than the system register size are widened. In
these cases your program may assume that @var{ret} points to an
@code{ffi_arg} object.
@item args @item args
A vector of pointers to memory holding the arguments to the function. A vector of pointers to memory holding the arguments to the function.