简单的std :: regex_search()代码不会编译与苹果clang ++ -std = c ++ 14 [英] Simple std::regex_search() code won't compile with Apple clang++ -std=c++14
问题描述
以下是MCVE:
#include <iostream>
#include <regex>
std::string s()
{
return "test";
}
int main()
{
static const std::regex regex(R"(\w)");
std::smatch smatch;
if (std::regex_search(s(), smatch, regex)) {
std::cout << smatch[0] << std::endl;
}
return 0;
}
它编译正确:
$ clang ++ -std = c ++ 11 main.cpp
$ clang++ -std=c++11 main.cpp
$ clang ++ -std = c ++ 14 main.cpp
$ clang++ -std=c++14 main.cpp
在后一种情况下的错误消息(带有-std = c ++ 14):
Error message in the later case (with -std=c++14):
main.cpp:14:9: error: call to deleted function 'regex_search'
if (std::regex_search(s(), smatch, regex)) {
^~~~~~~~~~~~~~~~~
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/regex:5998:1: note:
candidate function [with _ST = std::__1::char_traits<char>, _SA = std::__1::allocator<char>,
_Ap = std::__1::allocator<std::__1::sub_match<std::__1::__wrap_iter<const char *> > >, _Cp =
char, _Tp = std::__1::regex_traits<char>] has been explicitly deleted
regex_search(const basic_string<_Cp, _ST, _SA>&& __s,
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/regex:2876:5: note:
candidate function [with _ST = std::__1::char_traits<char>, _SA = std::__1::allocator<char>,
_Ap = std::__1::allocator<std::__1::sub_match<std::__1::__wrap_iter<const char *> > >, _Cp =
char, _Tp = std::__1::regex_traits<char>]
regex_search(const basic_string<_Cp, _ST, _SA>& __s,
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/regex:2851:5: note:
candidate template ignored: deduced conflicting types for parameter '_Bp'
('std::__1::basic_string<char>' vs. 'std::__1::match_results<std::__1::__wrap_iter<const char
*>, std::__1::allocator<std::__1::sub_match<std::__1::__wrap_iter<const char *> > > >')
regex_search(_Bp, _Bp, const basic_regex<_Cp, _Tp>&,
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/regex:2857:5: note:
candidate template ignored: could not match 'const _Cp *' against 'std::string' (aka
'basic_string<char, char_traits<char>, allocator<char> >')
regex_search(const _Cp*, const _Cp*,
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/regex:2863:5: note:
candidate template ignored: could not match 'const _Cp *' against 'std::string' (aka
'basic_string<char, char_traits<char>, allocator<char> >')
regex_search(const _Cp*, match_results<const _Cp*, _Ap>&, const basic_regex<_Cp, _Tp>&,
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/regex:2869:5: note:
candidate template ignored: could not match 'basic_regex' against 'match_results'
regex_search(const basic_string<_Cp, _ST, _SA>& __s,
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/regex:5963:1: note:
candidate template ignored: could not match 'const _CharT *' against 'std::string' (aka
'basic_string<char, char_traits<char>, allocator<char> >')
regex_search(const _CharT* __str, const basic_regex<_CharT, _Traits>& __e,
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/regex:2839:5: note:
candidate function template not viable: requires at least 4 arguments, but 3 were provided
regex_search(_Bp, _Bp, match_results<_Bp, _Ap>&, const basic_regex<_Cp, _Tp>&,
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/regex:2845:5: note:
candidate function template not viable: requires at least 4 arguments, but 3 were provided
regex_search(const _Cp*, const _Cp*, match_results<const _Cp*, _Ap>&,
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/regex:2884:5: note:
candidate function template not viable: requires at least 4 arguments, but 3 were provided
regex_search(__wrap_iter<_Iter> __first,
^
1 error generated.
编译器版本信息:
$ clang++ -v
Apple LLVM version 7.0.0 (clang-700.0.72)
Target: x86_64-apple-darwin15.0.0
Thread model: posix
那么,有什么问题?
推荐答案
从C ++ 11到C ++ 14有一个变化, std :: regex_search
不再允许使用r值
There was a change going from C++11 to C++14 where std::regex_search
is no longer allowed to take a r-value
template< class STraits, class SAlloc,
class Alloc, class CharT, class Traits >
bool regex_search( const std::basic_string<CharT,STraits,SAlloc>&&,
std::match_results<
typename std::basic_string<CharT,STraits,SAlloc>::const_iterator,
Alloc>&,
const std::basic_regex<CharT, Traits>&,
std::regex_constants::match_flag_type flags =
std::regex_constants::match_default ) = delete;
这是添加为重载,需要一个 const std :: string&
This was added as the overload that takes a const std::string&
禁止接受临时字符串,否则此函数填充match_results m
is prohibited from accepting temporary strings, otherwise this function populates match_results m with string iterators that become invalid immediately.
所以你不能再传递一个临时变量到 std :: regex_search 自C ++ 14开始
So you can no longer pass a temporary to std::regex_search
as of C++14
为了修复代码,我们只需存储 code>转换为main中的变量并使用它调用
std :: regex_search
。
To fix your code we would simply store the return from s()
into a variable in main and use that to call std::regex_search
.
#include <iostream>
#include <regex>
std::string s()
{
return "test";
}
int main()
{
static const std::regex regex(R"(\w)");
std::smatch smatch;
auto search = s();
if (std::regex_search(search, smatch, regex)) {
std::cout << smatch[0] << std::endl;
}
return 0;
}
这篇关于简单的std :: regex_search()代码不会编译与苹果clang ++ -std = c ++ 14的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!