Le 11/09/2025 à 20:28, Harald Anlauf a écrit :
Dear all,
here's a - once found - seemingly simple and obvious fix for a memory
corruption happening when intrinsic assignment is used to set a scalar
allocatable polymorphic component of a derived type when the latter
is instanciated as an array of rank > 0. Just get the dimension
attribute right when using gfc_variable_attr ...
The testcase is an extended version of the reporter's with unlimited
polymorphism, including another simpler one contributed by a friend.
Without the fix, both tests crash with memory corruption of various
kinds.
Regtested on x86_64-pc-linux-gnu. OK for mainline?
Hello Harald,
diff --git a/gcc/fortran/primary.cc b/gcc/fortran/primary.cc
index 6df95558bb1..2cb930d83b8 100644
--- a/gcc/fortran/primary.cc
+++ b/gcc/fortran/primary.cc
@@ -3057,12 +3057,14 @@ gfc_variable_attr (gfc_expr *expr, gfc_typespec *ts)
if (comp->ts.type == BT_CLASS)
{
+ dimension = CLASS_DATA (comp)->attr.dimension;
codimension = CLASS_DATA (comp)->attr.codimension;
pointer = CLASS_DATA (comp)->attr.class_pointer;
allocatable = CLASS_DATA (comp)->attr.allocatable;
}
else
{
+ dimension = comp->attr.dimension;
codimension = comp->attr.codimension;
if (expr->ts.type == BT_CLASS && strcmp (comp->name, "_data") == 0)
pointer = comp->attr.class_pointer;
I think the dimension flag should additionally be cleared if there is an
array element reference after the component. Otherwise one could get
the dimension attribute for a scalar expression (say
derived%array_comp(123)).
I don't really have a testcase that would exhibit a failure, I'm just
being overly cautious.
Thanks for the patch in any case.
