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author | Marek Polacek <polacek@redhat.com> | 2023-07-21 17:48:37 -0400 |
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committer | Marek Polacek <polacek@redhat.com> | 2023-07-25 11:30:19 -0400 |
commit | 6e424febfbcb27c21a7fe3a137e614765f9cf9d2 (patch) | |
tree | 259529bacee7d36cdd54ea94abc9164727744f27 /gcc/cp | |
parent | 09dda270380fe13e7b4722305cb1122df1f779a0 (diff) | |
download | gcc-6e424febfbcb27c21a7fe3a137e614765f9cf9d2.zip gcc-6e424febfbcb27c21a7fe3a137e614765f9cf9d2.tar.gz gcc-6e424febfbcb27c21a7fe3a137e614765f9cf9d2.tar.bz2 |
c++: fix ICE with constexpr ARRAY_REF [PR110382]
This code in cxx_eval_array_reference has been hard to get right.
In r12-2304 I added some code; in r13-5693 I removed some of it.
Here the problematic line is "S s = arr[0];" which causes a crash
on the assert in verify_ctor_sanity:
gcc_assert (!ctx->object || !DECL_P (ctx->object)
|| ctx->global->get_value (ctx->object) == ctx->ctor);
ctx->object is the VAR_DECL 's', which is correct here. The second
line points to the problem: we replaced ctx->ctor in
cxx_eval_array_reference:
new_ctx.ctor = build_constructor (elem_type, NULL); // #1
which I think we shouldn't have; the CONSTRUCTOR we created in
cxx_eval_constant_expression/DECL_EXPR
new_ctx.ctor = build_constructor (TREE_TYPE (r), NULL);
had the right type.
We still need #1 though. E.g., in constexpr-96241.C, we never
set ctx.ctor/object before calling cxx_eval_array_reference, so
we have to build a CONSTRUCTOR there. And in constexpr-101371-2.C
we have a ctx.ctor, but it has the wrong type, so we need a new one.
We can fix the problem by always clearing the object, and, as an
optimization, only create/free a new ctor when actually needed.
PR c++/110382
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_array_reference): Create a new constructor
only when we don't already have a matching one. Clear the object
when the type is non-scalar.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1y/constexpr-110382.C: New test.
Diffstat (limited to 'gcc/cp')
-rw-r--r-- | gcc/cp/constexpr.cc | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc index fb94f3c..5e0fe93 100644 --- a/gcc/cp/constexpr.cc +++ b/gcc/cp/constexpr.cc @@ -4291,15 +4291,24 @@ cxx_eval_array_reference (const constexpr_ctx *ctx, tree t, else val = build_value_init (elem_type, tf_warning_or_error); - if (!SCALAR_TYPE_P (elem_type)) + /* Create a new constructor only if we don't already have a suitable one. */ + const bool new_ctor = (!SCALAR_TYPE_P (elem_type) + && (!ctx->ctor + || !same_type_ignoring_top_level_qualifiers_p + (elem_type, TREE_TYPE (ctx->ctor)))); + if (new_ctor) { new_ctx = *ctx; + /* We clear the object here. We used to replace it with T, but that + caused problems (101371, 108158); and anyway, T is the initializer, + not the target object. */ + new_ctx.object = NULL_TREE; new_ctx.ctor = build_constructor (elem_type, NULL); ctx = &new_ctx; } t = cxx_eval_constant_expression (ctx, val, lval, non_constant_p, overflow_p); - if (!SCALAR_TYPE_P (elem_type) && t != ctx->ctor) + if (new_ctor && t != ctx->ctor) free_constructor (ctx->ctor); return t; } |