93 lines
2.9 KiB
Diff
93 lines
2.9 KiB
Diff
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From de31f5445b12fd9ab9969dc536d821fe6f0edad0 Mon Sep 17 00:00:00 2001
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From: Patrick Palka <ppalka@redhat.com>
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Date: Mon, 21 Jun 2021 07:54:26 -0400
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Subject: [PATCH] c++: conversion to base of vbase in NSDMI [PR80431]
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The delayed processing of conversions to a virtual base in an NSDMI
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assumes the target base type is a (possibly indirect) virtual base of
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the current class, but the target base type could also be a base of a
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virtual base, as in the testcase below. Since such a base isn't a part
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of CLASSTYPE_VBASECLASSES, we end up miscompiling the testcase due to
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the call to build_base_path (with binfo=NULL_TREE) silently returning
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error_mark_node. Fix this by using convert_to_base to build the
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conversion instead.
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PR c++/80431
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gcc/cp/ChangeLog:
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* tree.c (bot_replace): Use convert_to_base to build the
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conversion to the (morally) virtual base.
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gcc/testsuite/ChangeLog:
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* g++.dg/cpp0x/nsdmi-virtual1a.C: New test.
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---
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gcc/cp/tree.c | 14 ++++------
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gcc/testsuite/g++.dg/cpp0x/nsdmi-virtual1a.C | 28 ++++++++++++++++++++
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2 files changed, 33 insertions(+), 9 deletions(-)
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create mode 100644 gcc/testsuite/g++.dg/cpp0x/nsdmi-virtual1a.C
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diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c
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index fec5afaa2be..297da2b1550 100644
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--- a/gcc/cp/tree.c
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+++ b/gcc/cp/tree.c
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@@ -3242,15 +3242,11 @@ bot_replace (tree* t, int* /*walk_subtrees*/, void* data_)
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else if (TREE_CODE (*t) == CONVERT_EXPR
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&& CONVERT_EXPR_VBASE_PATH (*t))
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{
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- /* In an NSDMI build_base_path defers building conversions to virtual
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- bases, and we handle it here. */
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- tree basetype = TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (*t)));
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- vec<tree, va_gc> *vbases = CLASSTYPE_VBASECLASSES (current_class_type);
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- int i; tree binfo;
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- FOR_EACH_VEC_SAFE_ELT (vbases, i, binfo)
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- if (BINFO_TYPE (binfo) == basetype)
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- break;
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- *t = build_base_path (PLUS_EXPR, TREE_OPERAND (*t, 0), binfo, true,
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+ /* In an NSDMI build_base_path defers building conversions to morally
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+ virtual bases, and we handle it here. */
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+ tree basetype = TREE_TYPE (*t);
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+ *t = convert_to_base (TREE_OPERAND (*t, 0), basetype,
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+ /*check_access=*/false, /*nonnull=*/true,
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tf_warning_or_error);
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}
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diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-virtual1a.C b/gcc/testsuite/g++.dg/cpp0x/nsdmi-virtual1a.C
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new file mode 100644
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index 00000000000..dc847cc16e5
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--- /dev/null
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+++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-virtual1a.C
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@@ -0,0 +1,28 @@
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+// PR c++/80431
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+// { dg-do run { target c++11 } }
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+
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+// A variant of nsdmi-virtual1.C where A is only a morally virtual base of B.
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+
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+struct A
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+{
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+ A(): i(42) { }
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+ int i;
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+ int f() { return i; }
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+};
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+
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+struct D : A { int pad; };
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+
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+struct B : virtual D
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+{
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+ int j = i + f();
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+ int k = A::i + A::f();
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+};
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+
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+struct C: B { int pad; };
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+
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+int main()
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+{
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+ C c;
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+ if (c.j != 84 || c.k != 84)
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+ __builtin_abort();
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+}
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--
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2.31.1
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