Hi Jason,
On 6 Nov 2024, at 20:47, Jason Merrill wrote:
> On 11/6/24 2:23 PM, Simon Martin wrote:
>> Even though this PR is very close to PR117101, it's not addressed by
>> the
>> fix I made through r15-4958-g5821f5c8c89a05 because
>> cxx_placement_new_fn
>> has the very same issue as std_placement_new_fn_p used to have.
>>
>> This patch fixes the issue exactly the same, by checking the first
>> parameter against NULL_TREE. I considered somehow sharing code
>> between
>> the two *_placement_new_fn* static functions, but it looked pointless
>> since the shared part ("the second parameter is the last one, and a
>> pointer") is unlikely to be useful elsewhere.
>
> It seems those two functions are intended to test the exact same
> thing: whether the argument is ::operator new(size_t, void*).
>
> I think cxx_placement_new_fn should just be
>
> return (cxx_dialect >= cxx20 && std_placement_new_fn_p (fndecl));
>
> and some of the tests in cxx_placement_new_fn move into
> std_placement_new_fn_p to accommodate callers that e.g. don't already
> know we're dealing with operator new.
Thanks for the suggestion, makes sense.
I did not realise that some of the tests in those functions were
actually redundant (like the tree code or global namespace ones, implied
by DECL_NAMESPACE_SCOPE_P and IDENTIFIER_NEW_OP_P) and made them look
more different than they really are.
The attached patch has been successfully tested on x86_64-pc-linux-gnu.
OK for trunk?
Thanks, SimonFrom 65c73e12cb25ccfa8dd06fa8d765d993f973aecf Mon Sep 17 00:00:00 2001
From: Simon Martin <si...@nasilyan.com>
Date: Wed, 6 Nov 2024 15:39:23 +0100
Subject: [PATCH] c++: Fix another crash with invalid new operators [PR117463]
Even though this PR is very close to PR117101, it's not addressed by the
fix I made through r15-4958-g5821f5c8c89a05 because cxx_placement_new_fn
has the very same issue as std_placement_new_fn_p used to have.
As suggested by Jason, this patch changes both functions so that
cxx_placement_new_fn leverages std_placement_new_fn_p which reduces code
duplication and fixes the PR.
Successfully tested on x86_64-pc-linux-gnu.
PR c++/117463
gcc/cp/ChangeLog:
* constexpr.cc (cxx_placement_new_fn): Implement in terms of
std_placement_new_fn_p.
* cp-tree.h (std_placement_new_fn_p): Declare.
* init.cc (std_placement_new_fn_p): Add missing checks to ensure
that fndecl is a non-replaceable ::operator new.
gcc/testsuite/ChangeLog:
* g++.dg/init/new54.C: New test.
---
gcc/cp/constexpr.cc | 13 +------------
gcc/cp/cp-tree.h | 1 +
gcc/cp/init.cc | 6 ++++--
gcc/testsuite/g++.dg/init/new54.C | 14 ++++++++++++++
4 files changed, 20 insertions(+), 14 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/init/new54.C
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 71e6dc4ef32..c097860e655 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -2327,18 +2327,7 @@ cxx_replaceable_global_alloc_fn (tree fndecl)
static inline bool
cxx_placement_new_fn (tree fndecl)
{
- if (cxx_dialect >= cxx20
- && IDENTIFIER_NEW_OP_P (DECL_NAME (fndecl))
- && CP_DECL_CONTEXT (fndecl) == global_namespace
- && !DECL_IS_REPLACEABLE_OPERATOR_NEW_P (fndecl)
- && TREE_CODE (TREE_TYPE (fndecl)) == FUNCTION_TYPE)
- {
- tree first_arg = TREE_CHAIN (TYPE_ARG_TYPES (TREE_TYPE (fndecl)));
- if (TREE_VALUE (first_arg) == ptr_type_node
- && TREE_CHAIN (first_arg) == void_list_node)
- return true;
- }
- return false;
+ return (cxx_dialect >= cxx20 && std_placement_new_fn_p (fndecl));
}
/* Return true if FNDECL is std::construct_at. */
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 92d1dba6a5c..fb04b6f1ae0 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -7281,6 +7281,7 @@ extern tree build_offset_ref (tree,
tree, bool,
extern tree throw_bad_array_new_length (void);
extern bool type_has_new_extended_alignment (tree);
extern unsigned malloc_alignment (void);
+extern bool std_placement_new_fn_p (tree);
extern tree build_new_constexpr_heap_type (tree, tree, tree);
extern tree build_new (location_t,
vec<tree, va_gc> **, tree,
diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index 62b3d6f6ce9..a11701002c8 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -2976,10 +2976,12 @@ malloc_alignment ()
/* Determine whether an allocation function is a namespace-scope
non-replaceable placement new function. See DR 1748. */
-static bool
+bool
std_placement_new_fn_p (tree alloc_fn)
{
- if (DECL_NAMESPACE_SCOPE_P (alloc_fn))
+ if (DECL_NAMESPACE_SCOPE_P (alloc_fn)
+ && IDENTIFIER_NEW_OP_P (DECL_NAME (alloc_fn))
+ && !DECL_IS_REPLACEABLE_OPERATOR_NEW_P (alloc_fn))
{
tree first_arg = TREE_CHAIN (TYPE_ARG_TYPES (TREE_TYPE (alloc_fn)));
if (first_arg
diff --git a/gcc/testsuite/g++.dg/init/new54.C
b/gcc/testsuite/g++.dg/init/new54.C
new file mode 100644
index 00000000000..fdff1b55f0d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/init/new54.C
@@ -0,0 +1,14 @@
+// PR c++/117463
+// { dg-do "compile" { target c++20 } }
+
+struct S {};
+void *operator new[] (unsigned long, // { dg-bogus "first parameter" "" {
xfail *-*-* } }
+ void void *volatile p); // { dg-error "two or more" }
+S *fun(void *p) {
+ return new(p) S[10];
+}
+
+void *operator new (decltype(sizeof(0)), // { dg-bogus "first parameter" "" {
xfail *-*-* } }
+ void void * p); // { dg-error "two or more" }
+void *p;
+auto t = new(p) int;
--
2.44.0
