[libc++][istream] P3223R2: Making std::istream::ignore less surprising by H-G-Hristov · Pull Request #147007 · llvm/llvm-project (original) (raw)

@llvm/pr-subscribers-libcxx

Author: Hristo Hristov (H-G-Hristov)

Changes

Implements P3223R2

References

• P3223R2 Making std::istream::ignore less surprising cplusplus/draft#7996

Full diff: https://github.com/llvm/llvm-project/pull/147007.diff

4 Files Affected:

• (modified) libcxx/docs/ReleaseNotes/21.rst (+1)
• (modified) libcxx/include/istream (+9)
• (added) libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore.char_type.pass.cpp (+37)
• (added) libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore.verify.cpp (+27)

diff --git a/libcxx/docs/ReleaseNotes/21.rst b/libcxx/docs/ReleaseNotes/21.rst index 08b32bb508dc1..34735ca515d53 100644 --- a/libcxx/docs/ReleaseNotes/21.rst +++ b/libcxx/docs/ReleaseNotes/21.rst @@ -51,6 +51,7 @@ Implemented Papers - P2441R2: views::join_with (Github <https://github.com/llvm/llvm-project/issues/105185>) - P2711R1: Making multi-param constructors of views explicit (Github <https://github.com/llvm/llvm-project/issues/105252>) - P2770R0: Stashing stashing iterators for proper flattening (Github <https://github.com/llvm/llvm-project/issues/105250>__) +- P3223R2: Making std::istream::ignore less surprising Improvements and New Features

diff --git a/libcxx/include/istream b/libcxx/include/istream index 02546902494e3..83ba1799cae91 100644 --- a/libcxx/include/istream +++ b/libcxx/include/istream @@ -70,6 +70,7 @@ public: basic_istream& getline(char_type* s, streamsize n, char_type delim);

 basic_istream& ignore(streamsize n = 1, int_type delim = traits_type::eof());

• basic_istream& ignore(streamsize n, char_type delim); // Since C++26 int_type peek(); basic_istream& read (char_type* s, streamsize n); streamsize readsome(char_type* s, streamsize n); @@ -171,6 +172,7 @@ template <class Stream, class T>

include <__type_traits/conjunction.h>

include <__type_traits/enable_if.h>

include <__type_traits/is_base_of.h>

+# include <__type_traits/is_same.h>

include <__type_traits/make_unsigned.h>

include <__utility/declval.h>

include <__utility/forward.h>

@@ -291,6 +293,13 @@ public: basic_istream& getline(char_type* __s, streamsize __n, char_type __dlm);

basic_istream& ignore(streamsize __n = 1, int_type __dlm = traits_type::eof()); +# if _LIBCPP_STD_VER >= 26

• _LIBCPP_HIDE_FROM_ABI basic_istream& ignore(streamsize __n, char_type __delim)
• requires is_same_v<char_type, char>
• {
• return this->ignore(__n, _Traits::to_int_type(__delim));
• } +# endif int_type peek(); basic_istream& read(char_type* __s, streamsize __n); streamsize readsome(char_type* __s, streamsize __n); diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore.char_type.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore.char_type.pass.cpp new file mode 100644 index 0000000000000..9d83a7ea15027 --- /dev/null +++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore.char_type.pass.cpp @@ -0,0 +1,37 @@ +//===----------------------------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===//
• +// REQUIRES: std-at-least-c++26
• +// Requires 396145d in the built library. +// XFAIL: using-built-library-before-llvm-9
• +//
• +// basic_istream& ignore(streamsize n, char_type delim);
• +#include

+#include +#include + +#include "test_macros.h" + +int main(int, char**) {

• std::istringstream in("\xF0\x9F\xA4\xA1 Clown Face");
• in.ignore(100, '\xA1'); // ignore up to '\xA1' delimiter,

•                      // previously might have ignored to EOF

• assert(in.gcount() == 4); // 4 bytes were ignored
• assert(in.peek() == ' '); // next character is a space
• std::string str; // read the next word
• in >> str;
• assert(str == "Clown");
• return 0; +} diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore.verify.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore.verify.cpp new file mode 100644 index 0000000000000..54d13cac69b94 --- /dev/null +++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore.verify.cpp @@ -0,0 +1,27 @@ +//===----------------------------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===//
• +// REQUIRES: std-at-least-c++26
• +// Requires 396145d in the built library. +// XFAIL: using-built-library-before-llvm-9
• +//
• +// basic_istream& ignore(streamsize n, char_type delim);
• +#include

+#include +#include + +#include "test_macros.h" + +void test() {

• std::istringstream in("\xF0\x9F\xA4\xA1 Clown Face");
• in.ignore(100, -1L); // expected-error {{call to member function 'ignore' is ambiguous}} +}