Attached is a minimal patch to avoid an ICE in CHKP upon
encountering one form of an initializer for a flexible array
member, specifically the empty string:
int f ()
{
struct B { int n; char a[]; };
return ((struct B){ 1, "" }).a[0];
}
Although GCC accepts (and doesn't ICE on) non-empty initializers
for flexible array members, such as
(struct B){ 1, "123" }
it generates wrong code for them. This could either be fixed by
emitting correct code, or it could be handled by rejecting all
initializers for non-static objects with such members. Both
approaches seem risky to me at this stage and so I think it's
safest to hold off on implementing either until after the release.
Martin
PR c++/79986 - [CHKP] ICE in fold_convert_loc with a flexible array
gcc/ChangeLog:
PR c++/79986
* tree-chkp.c (chkp_process_stmt): Avoid assuming size is non-null.
gcc/testsuite/ChangeLog:
PR c++/79986
* g++.dg/pr79986.C: New test.
diff --git a/gcc/testsuite/g++.dg/pr79986.C b/gcc/testsuite/g++.dg/pr79986.C
new file mode 100644
index 0000000..d179cf6
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr79986.C
@@ -0,0 +1,10 @@
+/* PR c++/79986 - [CHKP] ICE in fold_convert_loc with a flexible array
+ { dg-do compile { target { { i?86-*-* x86_64-*-* } && { ! x32 } } } }
+ { dg-options "-fcheck-pointer-bounds -mmpx" } */
+
+int f (int i)
+{
+ struct A { int n; char a[]; };
+
+ return ((struct A){ 1, "" }).a[i]; // { dg-error "invalid use of array" }
+}
diff --git a/gcc/tree-chkp.c b/gcc/tree-chkp.c
index b1ff218..780d18f 100644
--- a/gcc/tree-chkp.c
+++ b/gcc/tree-chkp.c
@@ -4092,6 +4092,10 @@ chkp_process_stmt (gimple_stmt_iterator *iter, tree node,
expression to compute it. */
if (!addr_last)
{
+ /* C++ flexible array members have a null size. */
+ if (!size)
+ return;
+
addr_last = fold_build_pointer_plus_loc (loc, addr_first, size);
addr_last = fold_build_pointer_plus_hwi_loc (loc, addr_last, -1);
}
