我有这段代码可以用clang编译好(即使是-Weverything),但gcc会发出错误。
#include <iostream>
#include <vector>
#include <fstream>
using namespace std;
class PhonebookWriter
{
public:
PhonebookWriter(const string& fname):
fname_(fname), names_(), numbers_() {}
PhonebookWriter& operator()(const string& name,
const string& number)
{
names_.push_back(name);
numbers_.push_back(number);
return *this;
}
~PhonebookWriter(void)
{
ofstream f(fname_.c_str());
for(size_t i=0;i<names_.size();++i)
f << names_[i] << " " << numbers_[i] << "\n";
f.close();
}
private:
const string fname_;
vector<string> names_;
vector<string> numbers_;
};
namespace {
void write_guests_data(const string& fname)
{
PhonebookWriter(fname)("Mr Foo Bar","12345")("Mrs Bar Foo","54321");
}
}
int main(void)
{
write_guests_data("phone_book.txt");
return 0;
}
这是我尝试编译代码时得到的结果:
$ g++ ./test.cpp
./test.cpp: In function ‘void {anonymous}::write_guests_data(const string&)’:
./test.cpp:39:27: error: declaration of ‘PhonebookWriter fname’ shadows a parameter
PhonebookWriter(fname)("Mr Foo Bar","12345")("Mrs Bar Foo","54321");
^
./test.cpp:39:48: error: no matching function for call to ‘PhonebookWriter::PhonebookWriter(const char [11], const char [6])’
PhonebookWriter(fname)("Mr Foo Bar","12345")("Mrs Bar Foo","54321");
^
./test.cpp:39:48: note: candidates are:
./test.cpp:11:3: note: PhonebookWriter::PhonebookWriter(const string&)
PhonebookWriter(const string& fname):
^
./test.cpp:11:3: note: candidate expects 1 argument, 2 provided
./test.cpp:7:7: note: PhonebookWriter::PhonebookWriter(const PhonebookWriter&)
class PhonebookWriter
^
./test.cpp:7:7: note: candidate expects 1 argument, 2 provided
./test.cpp:39:49: error: expected ‘,’ or ‘;’ before ‘(’ token
PhonebookWriter(fname)("Mr Foo Bar","12345")("Mrs Bar Foo","54321");
^
我的gcc版本是4.9.1,我的clang版本是3.5.0。 我不明白为什么甚至会出现阴影问题。即使有,也应该被clang拾取。
答案 0 :(得分:8)
变化:
PhonebookWriter(fname)("Mr Foo Bar","12345")("Mrs Bar Foo","54321");
为:
(PhonebookWriter(fname))("Mr Foo Bar","12345")("Mrs Bar Foo","54321");
<强>说明强>
由于某种原因,gcc会移除fname
周围的大括号,这会将该行转换为:
PhonebookWriter fname ("Mr Foo Bar","12345")("Mrs Bar Foo","54321");
现在错误是有道理的。