-fanalyzer triggers on empty vector of strings and foreach loop

-fanalyzer triggers on empty vector of strings and foreach loop

[andre maute]

I wonder if this is expected behavior

this is on a recent fedora 32 x86_64 system

g++ (GCC) 10.0.1 20200328 (Red Hat 10.0.1-0.11)
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

To trigger a lengthy list of deductions, I use the following three files and
g++ -fanalyzer main.cpp line.cpp

Using only the given warning flag triggers nothing
g++ -Wanalyzer-null-dereference main.cpp line.cpp

///// begin of main.cpp ///////////
#include <string>
#include <vector>

#include "line.h"

int main()
{
	std::vector<std::string> m_Text;
	std::vector<Line> m_Lines;

	for( const auto& line : m_Text ) {
		m_Lines.emplace_back(line);
	}

	return 0;
}
///// end of main.cpp /////////////

///// begin of line.h ///////////
#ifndef LINE_H
#define LINE_H

#include <string>

class Line
{
public:
	explicit
	Line(
		const std::string& data
	);

	const std::string& data() const;

private:
	std::string m_Data;
};

#endif /* LINE_H */
///// end of line.h /////////////

///// begin of line.cpp ///////////
#include "line.h"

Line::Line(
	const std::string& data
)
: m_Data(data)
{}

const std::string&
Line::data() const
{
	return m_Data;
}
///// end of line.cpp /////////////

Re: -fanalyzer triggers on empty vector of strings and foreach loop

[Jonathan Wakely]

On Fri, 1 May 2020 at 23:59, andre maute wrote:
>
> I wonder if this is expected behavior

It's a known limitation that the analyzer doesn't support C++ yet.

Re: -fanalyzer triggers on empty vector of strings and foreach loop

[andre maute]

On 5/2/20 1:24 PM, Jonathan Wakely wrote:
> On Fri, 1 May 2020 at 23:59, andre maute wrote:
>>
>> I wonder if this is expected behavior
>
> It's a known limitation that the analyzer doesn't support C++ yet.
>

So nevertheless should these two be filed as bugs?

The first being the iteration over the empty vector.
The second the one for the warning flag given by the output of -fanalyzer
but which doesn't trigger anything if used alone.

Regards
Andre

Re: -fanalyzer triggers on empty vector of strings and foreach loop

[Jonathan Wakely]

On Sat, 2 May 2020 at 18:21, andre maute wrote:
>
> On 5/2/20 1:24 PM, Jonathan Wakely wrote:
> > On Fri, 1 May 2020 at 23:59, andre maute wrote:
> >>
> >> I wonder if this is expected behavior
> >
> > It's a known limitation that the analyzer doesn't support C++ yet.
> >
>
> So nevertheless should these two be filed as bugs?

No thank you.

> The first being the iteration over the empty vector.

The analyzer dev says "it's not worth trying -fanalyzer with C++ at
this point.  Hopefully GCC 11."

> The second the one for the warning flag given by the output of -fanalyzer
> but which doesn't trigger anything if used alone.

That's expected, -Wanalyzer-null-dereference requires -fanalyzer to do anything.





> Regards
> Andre