The issue here was that with a complex expression in DECL_SIZE for z,
when wrap_cleanups tried to protect the initializer of m it walked into
the sizeof and thus the bounds expression, which it really shouldn't be
messing with.
This patch avoids this issue by saving bounds values which have side
effects into a local automatic variable (since VLAs can only appear in
automatic variables). We stick with the SAVE_EXPR approach for bounds
without side-effects to avoid breaking vla9.C.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit e491243ab5dce11b38cae78911f107652fa0048b
Author: Jason Merrill <ja...@redhat.com>
Date: Fri Apr 8 17:43:42 2011 -0400
PR c++/48446
* decl.c (compute_array_index_type): Use get_temp_regvar instead
of variable_size.
* init.c (get_temp_regvar): No longer static.
* cp-tree.h: Declare it.
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 15c1974..3ca44c2 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -4964,6 +4964,7 @@ extern tree build_offset_ref (tree,
tree, bool);
extern tree build_new (VEC(tree,gc) **, tree, tree,
VEC(tree,gc) **, int,
tsubst_flags_t);
+extern tree get_temp_regvar (tree, tree);
extern tree build_vec_init (tree, tree, tree, bool, int,
tsubst_flags_t);
extern tree build_delete (tree, tree,
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 7dea9b7..2c0f80f 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -7710,8 +7710,16 @@ compute_array_index_type (tree name, tree size,
tsubst_flags_t complain)
processing_template_decl = saved_processing_template_decl;
if (!TREE_CONSTANT (itype))
- /* A variable sized array. */
- itype = variable_size (itype);
+ {
+ /* A variable sized array. */
+ if (TREE_SIDE_EFFECTS (itype))
+ /* Use get_temp_regvar rather than variable_size here so that
+ people walking expressions that use a variable of this type
+ don't walk into this expression. */
+ itype = get_temp_regvar (TREE_TYPE (itype), itype);
+ else
+ itype = variable_size (itype);
+ }
/* Make sure that there was no overflow when creating to a signed
index type. (For example, on a 32-bit machine, an array with
size 2^32 - 1 is too big.) */
diff --git a/gcc/cp/init.c b/gcc/cp/init.c
index 3131690..32afa03 100644
--- a/gcc/cp/init.c
+++ b/gcc/cp/init.c
@@ -45,7 +45,6 @@ static void expand_virtual_init (tree, tree);
static tree sort_mem_initializers (tree, tree);
static tree initializing_context (tree);
static void expand_cleanup_for_base (tree, tree);
-static tree get_temp_regvar (tree, tree);
static tree dfs_initialize_vtbl_ptrs (tree, void *);
static tree build_dtor_call (tree, special_function_kind, int);
static tree build_field_list (tree, tree, int *);
@@ -2875,7 +2874,7 @@ create_temporary_var (tree type)
things when it comes time to do final cleanups (which take place
"outside" the binding contour of the function). */
-static tree
+tree
get_temp_regvar (tree type, tree init)
{
tree decl;
diff --git a/gcc/testsuite/g++.dg/ext/vla10.C b/gcc/testsuite/g++.dg/ext/vla10.C
new file mode 100644
index 0000000..17cdb2f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/vla10.C
@@ -0,0 +1,32 @@
+// PR c++/48446
+// { dg-options "" }
+
+template<typename T>
+struct A
+{
+ ~A ();
+ T *operator-> () const;
+};
+
+struct B
+{
+ typedef A <B> P;
+ static P foo (int);
+};
+
+struct C
+{
+ typedef A<C> P;
+ static const int c = 80;
+};
+
+C::P bar ();
+
+void
+baz ()
+{
+ char z[bar ()->c];
+ {
+ B::P m = B::foo (sizeof (z));
+ }
+}
