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author | Jonathan Wakely <jwakely@redhat.com> | 2021-10-01 21:27:24 +0100 |
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committer | Jonathan Wakely <jwakely@redhat.com> | 2021-10-04 15:23:28 +0100 |
commit | cf876562c592193732f869e9f96034a42d0fad89 (patch) | |
tree | bea69f3de5d35fa5396f00ad388640f2b82748d2 | |
parent | fa3ccf8bfe9940b439d6cc2c38ee8da134b0ff2d (diff) | |
download | gcc-cf876562c592193732f869e9f96034a42d0fad89.zip gcc-cf876562c592193732f869e9f96034a42d0fad89.tar.gz gcc-cf876562c592193732f869e9f96034a42d0fad89.tar.bz2 |
libstdc++: Disable std::string{,_view} construction from nullptr (P2166R1)
Implement this C++23 feature. Because construction from a null pointer
is undefined, we can implement it for C++11 and up, turning undefined
behaviour into a compilation error.
libstdc++-v3/ChangeLog:
* include/bits/basic_string.h (basic_string(nullptr_t)): Define
as deleted.
(operator=(nullptr_t)): Likewise.
* include/bits/cow_string.h (basic_string(nullptr_t)): Likewise.
(operator=(nullptr_t)): Likewise.
* include/std/string_view (basic_string_view(nullptr_t)):
Likewise.
* testsuite/21_strings/basic_string/cons/char/nullptr.cc: New test.
* testsuite/21_strings/basic_string_view/cons/char/nonnull.cc:
Change dg-warning to dg-error.
* testsuite/21_strings/basic_string_view/cons/wchar_t/nonnull.cc:
Likewise.
6 files changed, 13 insertions, 2 deletions
diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h index 24c454d..68c3884 100644 --- a/libstdc++-v3/include/bits/basic_string.h +++ b/libstdc++-v3/include/bits/basic_string.h @@ -623,6 +623,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11 _M_construct(__str.begin(), __str.end()); } + basic_string(nullptr_t) = delete; + basic_string& operator=(nullptr_t) = delete; #endif // C++11 /** diff --git a/libstdc++-v3/include/bits/cow_string.h b/libstdc++-v3/include/bits/cow_string.h index ba4a8cc..f054012 100644 --- a/libstdc++-v3/include/bits/cow_string.h +++ b/libstdc++-v3/include/bits/cow_string.h @@ -667,6 +667,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION else _M_dataplus._M_p = _S_construct(__str.begin(), __str.end(), __a); } + + basic_string(nullptr_t) = delete; + basic_string& operator=(nullptr_t) = delete; #endif // C++11 /** diff --git a/libstdc++-v3/include/std/string_view b/libstdc++-v3/include/std/string_view index d8cbee9..996b03f 100644 --- a/libstdc++-v3/include/std/string_view +++ b/libstdc++-v3/include/std/string_view @@ -168,6 +168,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION #endif // C++23 #endif // C++20 + basic_string_view(nullptr_t) = delete; + constexpr basic_string_view& operator=(const basic_string_view&) noexcept = default; diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/nullptr.cc b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/nullptr.cc new file mode 100644 index 0000000..fdb24ae --- /dev/null +++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/nullptr.cc @@ -0,0 +1,4 @@ +// { dg-do compile { target c++11 } } +#include <string> + +std::string s = nullptr; // { dg-error "deleted" "P2166R1" } diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/nonnull.cc b/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/nonnull.cc index b33af08..f42f95e 100644 --- a/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/nonnull.cc +++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/nonnull.cc @@ -25,5 +25,5 @@ test01() { std::string_view s((const char*)nullptr); // { dg-warning "\\\[-Wnonnull" } std::string_view t((char*)nullptr); // { dg-warning "\\\[-Wnonnull" } - std::string_view u(nullptr); // { dg-warning "\\\[-Wnonnull" } + std::string_view u(nullptr); // { dg-error "deleted" } } diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/wchar_t/nonnull.cc b/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/wchar_t/nonnull.cc index 4c10131..e480f7c 100644 --- a/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/wchar_t/nonnull.cc +++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/wchar_t/nonnull.cc @@ -25,5 +25,5 @@ test01() { std::wstring_view s((const wchar_t*)nullptr); // { dg-warning "\\\[-Wnonnull" } std::wstring_view t((wchar_t*)nullptr); // { dg-warning "\\\[-Wnonnull" } - std::wstring_view u(nullptr); // { dg-warning "\\\[-Wnonnull" } + std::wstring_view u(nullptr); // { dg-error "deleted" } } |