Hello,The attached patch fixes a compile error when converting a weak_ptr of array type to a compatible type, for instance:
std::weak_ptr<int [42]> wptr; std::weak_ptr<int []> wptr2 = wptr; // ERROR https://gcc.godbolt.org/z/EWYb73MvfThe reason seems to be a typo: the inner __weak_ptr class has a lock() implementation which doesn't work with arrays because it accidentally uses `element_type` instead of `_Tp`. That lock() (and *not* std::weak_ptr::lock(), which is instead fine) is called by the converting constructors of __weak_ptr and that causes the compile error.
I'm not sure if this has been already reported somewhere. Tested on x86-64 Linux. Thanks, -- Giuseppe D'Angelo
From 2636a2be91fe5a82472068121382a569e0676865 Mon Sep 17 00:00:00 2001
From: Giuseppe D'Angelo <giuseppe.dang...@kdab.com>
Date: Tue, 10 Dec 2024 00:56:13 +0100
Subject: [PATCH] libstdc++: fix compile error when converting
std::weak_ptr<T[]>
A std::weak_ptr<T[]> can be converted to a compatible
std::weak_ptr<U[]>. This is implemented by having suitable converting
constructors to std::weak_ptr which dispatch to the __weak_ptr base
class (implementation detail).
In __weak_ptr<T[]>, lock() is supposed to return a __shared_ptr<T[]>,
not a __shared_ptr<element_type> (that is, __shared_ptr<T>).
Unfortunately the return type of lock() and the type of the returned
__shared_ptr were mismatching and that was causing a compile error:
when converting a __weak_ptr<T[]> to a __weak_ptr<U[]> through a
converting constructor, the code calls lock(), and that simply failed to
build.
Fix it by removing the usage of element_type inside lock(), and using
_Tp instead.
Note that std::weak_ptr::lock() itself was already correct; the one in
__weak_ptr was faulty (and that is the one called by __weak_ptr's
converting constructors).
libstdc++-v3/ChangeLog:
* include/bits/shared_ptr_base.h: Fixed a compile error when
calling lock() on a weak_ptr<T[]>, by removing an erroneous
usage of element_type from within lock().
* testsuite/20_util/shared_ptr/requirements/explicit_instantiation/1.cc:
Add more tests for array types.
* testsuite/20_util/weak_ptr/requirements/explicit_instantiation/1.cc:
Likewise.
* testsuite/20_util/shared_ptr/requirements/1.cc: New test.
* testsuite/20_util/weak_ptr/requirements/1.cc: New test.
Signed-off-by: Giuseppe D'Angelo <giuseppe.dang...@kdab.com>
---
libstdc++-v3/include/bits/shared_ptr_base.h | 2 +-
.../20_util/shared_ptr/requirements/1.cc | 33 +++++++++++++++++++
.../requirements/explicit_instantiation/1.cc | 12 +++++++
.../20_util/weak_ptr/requirements/1.cc | 33 +++++++++++++++++++
.../requirements/explicit_instantiation/1.cc | 12 +++++++
5 files changed, 91 insertions(+), 1 deletion(-)
create mode 100644 libstdc++-v3/testsuite/20_util/shared_ptr/requirements/1.cc
create mode 100644 libstdc++-v3/testsuite/20_util/weak_ptr/requirements/1.cc
diff --git a/libstdc++-v3/include/bits/shared_ptr_base.h b/libstdc++-v3/include/bits/shared_ptr_base.h
index ee01594ce0c..bc87c402afb 100644
--- a/libstdc++-v3/include/bits/shared_ptr_base.h
+++ b/libstdc++-v3/include/bits/shared_ptr_base.h
@@ -2076,7 +2076,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__shared_ptr<_Tp, _Lp>
lock() const noexcept
- { return __shared_ptr<element_type, _Lp>(*this, std::nothrow); }
+ { return __shared_ptr<_Tp, _Lp>(*this, std::nothrow); }
long
use_count() const noexcept
diff --git a/libstdc++-v3/testsuite/20_util/shared_ptr/requirements/1.cc b/libstdc++-v3/testsuite/20_util/shared_ptr/requirements/1.cc
new file mode 100644
index 00000000000..8ddb5d220ac
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/shared_ptr/requirements/1.cc
@@ -0,0 +1,33 @@
+// { dg-do compile { target c++11 } }
+// { dg-require-effective-target hosted }
+
+#include <memory>
+#include <testsuite_tr1.h>
+
+using namespace __gnu_test;
+
+void
+test01()
+{
+ std::shared_ptr<ClassType> ptr;
+ std::shared_ptr<const ClassType> ptr2 = ptr;
+
+#if __cpp_lib_shared_ptr_arrays >= 201611L
+ std::shared_ptr<ClassType[10]> ptr_array;
+ std::shared_ptr<ClassType[]> ptr_array2 = ptr_array;
+ std::shared_ptr<ClassType const []> ptr_array3 = ptr_array;
+#endif
+}
+
+void
+test02()
+{
+ std::shared_ptr<IncompleteClass> ptr;
+ std::shared_ptr<const IncompleteClass> ptr2 = ptr;
+
+#if __cpp_lib_shared_ptr_arrays >= 201611L
+ std::shared_ptr<IncompleteClass[10]> ptr_array;
+ std::shared_ptr<IncompleteClass[]> ptr_array2 = ptr_array;
+ std::shared_ptr<IncompleteClass const []> ptr_array3 = ptr_array;
+#endif
+}
diff --git a/libstdc++-v3/testsuite/20_util/shared_ptr/requirements/explicit_instantiation/1.cc b/libstdc++-v3/testsuite/20_util/shared_ptr/requirements/explicit_instantiation/1.cc
index 94bc8c7adfe..48f162d4072 100644
--- a/libstdc++-v3/testsuite/20_util/shared_ptr/requirements/explicit_instantiation/1.cc
+++ b/libstdc++-v3/testsuite/20_util/shared_ptr/requirements/explicit_instantiation/1.cc
@@ -28,3 +28,15 @@ template class std::shared_ptr<int>;
template class std::shared_ptr<void>;
template class std::shared_ptr<ClassType>;
template class std::shared_ptr<IncompleteClass>;
+
+#if __cpp_lib_shared_ptr_arrays >= 201611L
+template class std::shared_ptr<ClassType []>;
+template class std::shared_ptr<ClassType [42]>;
+template class std::shared_ptr<ClassType const []>;
+template class std::shared_ptr<ClassType const [42]>;
+
+template class std::shared_ptr<IncompleteClass []>;
+template class std::shared_ptr<IncompleteClass [42]>;
+template class std::shared_ptr<IncompleteClass const []>;
+template class std::shared_ptr<IncompleteClass const [42]>;
+#endif
diff --git a/libstdc++-v3/testsuite/20_util/weak_ptr/requirements/1.cc b/libstdc++-v3/testsuite/20_util/weak_ptr/requirements/1.cc
new file mode 100644
index 00000000000..04ea837d85a
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/weak_ptr/requirements/1.cc
@@ -0,0 +1,33 @@
+// { dg-do compile { target c++11 } }
+// { dg-require-effective-target hosted }
+
+#include <memory>
+#include <testsuite_tr1.h>
+
+using namespace __gnu_test;
+
+void
+test01()
+{
+ std::weak_ptr<ClassType> ptr;
+ std::weak_ptr<const ClassType> ptr2 = ptr;
+
+#if __cpp_lib_shared_ptr_arrays >= 201611L
+ std::weak_ptr<ClassType[10]> ptr_array;
+ std::weak_ptr<ClassType[]> ptr_array2 = ptr_array;
+ std::weak_ptr<ClassType const []> ptr_array3 = ptr_array;
+#endif
+}
+
+void
+test02()
+{
+ std::weak_ptr<IncompleteClass> ptr;
+ std::weak_ptr<const IncompleteClass> ptr2 = ptr;
+
+#if __cpp_lib_shared_ptr_arrays >= 201611L
+ std::weak_ptr<IncompleteClass[10]> ptr_array;
+ std::weak_ptr<IncompleteClass[]> ptr_array2 = ptr_array;
+ std::weak_ptr<IncompleteClass const []> ptr_array3 = ptr_array;
+#endif
+}
diff --git a/libstdc++-v3/testsuite/20_util/weak_ptr/requirements/explicit_instantiation/1.cc b/libstdc++-v3/testsuite/20_util/weak_ptr/requirements/explicit_instantiation/1.cc
index b32ff6ea284..b51a614693c 100644
--- a/libstdc++-v3/testsuite/20_util/weak_ptr/requirements/explicit_instantiation/1.cc
+++ b/libstdc++-v3/testsuite/20_util/weak_ptr/requirements/explicit_instantiation/1.cc
@@ -28,3 +28,15 @@ template class std::weak_ptr<int>;
template class std::weak_ptr<void>;
template class std::weak_ptr<ClassType>;
template class std::weak_ptr<IncompleteClass>;
+
+#if __cpp_lib_shared_ptr_arrays >= 201611L
+template class std::weak_ptr<ClassType []>;
+template class std::weak_ptr<ClassType [42]>;
+template class std::weak_ptr<ClassType const []>;
+template class std::weak_ptr<ClassType const [42]>;
+
+template class std::weak_ptr<IncompleteClass []>;
+template class std::weak_ptr<IncompleteClass [42]>;
+template class std::weak_ptr<IncompleteClass const []>;
+template class std::weak_ptr<IncompleteClass const [42]>;
+#endif
--
2.34.1
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