[Bug c++/69970] New: Surprising warning with -Wnonnull-compare - 'this' compared to NULL

["larsbj at gullik dot net" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69970

            Bug ID: 69970
           Summary: Surprising warning with -Wnonnull-compare - 'this'
                    compared to NULL
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: larsbj at gullik dot net
  Target Milestone: ---

Compiling this snippet:

class Foo {
public:
        explicit Foo(bool)
        {}
};

class Bar {
public:
        Bar()
        : foo_(new Foo(this))
        {}
private:
        Foo * foo_; 
};

int main()
{
        Bar bar;
        return 0;
}


With:
g++ -c -Wnonnull-compare nonnull.cpp

Gives:
nonnull.cpp: In constructor âBar::Bar()â:
nonnull.cpp:10:21: warning: nonnull argument âthisâ compared to NULL
[-Wnonnull-compare]
  : foo_(new Foo(this))


Removing explict makes no difference.

g++ -v
Using built-in specs.
COLLECT_GCC=/opt/gcc/gcc-6/bin/g++
COLLECT_LTO_WRAPPER=/opt/gcc/gcc-6/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc/configure --prefix=/opt/gcc/gcc-6
--enable-checking=release --enable-languages=c,c++,lto
Thread model: posix
gcc version 6.0.0 20160225 (experimental) (GCC)