[Bug tree-optimization/102359] ICE gimplification failed since r12-3433-ga25e0b5e6ac8a77a

["rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102359

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu.org

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.  So we end with '&__closure->__this' which indeed isn't an lvalue.

The issue here is that we are initializing the VAR_DECL 'this' but that
has a DECL_VALUE_EXPR expanding to &__closure->__this:

const struct A * const this [value-expr: &__closure->__this];

note the variable is const as well, so emitting a runtime initializer might
have other issues (like trapping ...), or in this case, not being an lvalue.

But note the FE fails to mark the decl as TREE_READONLY - that would be an
easy thing to check (and something we fail to check in is_var_need_auto_init).
Thus sth like

diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index f680292fd91..b2bfab47a2f 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -1824,7 +1824,9 @@ gimple_add_padding_init_for_auto_var (tree decl, bool
is_vla,
 static bool
 is_var_need_auto_init (tree decl)
 {
-  if (auto_var_p (decl)
+  if (VAR_P (decl)
+      && !TREE_READONLY (decl)
+      && auto_var_p (decl)
       && (flag_auto_var_init > AUTO_INIT_UNINITIALIZED)
       && (!lookup_attribute ("uninitialized", DECL_ATTRIBUTES (decl)))
       && !is_empty_type (TREE_TYPE (decl)))

should be needed.

Jason, any idea?