[Bug c++/13979] Error message about no matching function for call with derived class arguments could be improved

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=13979

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |msebor at gcc dot gnu.org
         Resolution|---                         |FIXED
      Known to fail|                            |7.0

--- Comment #11 from Martin Sebor <msebor at gcc dot gnu.org> ---
The errors printed by today's top of trunk (GCC 7.0) for the test case from
comment #9 are below.  They seem quite clear, at least as good as if not better
than Clang's which prints those below.  Resolving as fixed.

error: no matching function for call to 'foo'
int i = foo( (B*)0 );
        ^~~
note: candidate function not viable: no known conversion from 'B *' to 'B *&'
for 1st argument


$ cat t.C && gcc -S -Wall -Wextra -Wpedantic t.C

struct B {}; 
struct D : B {}; 

struct X {};

int foo(B*&);

int i = foo( (B*)0 );

int j = foo( (D*)0 );

D* pd = 0;
int k = foo( pd );

X* px = 0;
int l = foo( px );\
t.C:17:19: warning: backslash-newline at end of file
 int l = foo( px );\

t.C:9:20: error: cannot bind non-const lvalue reference of type ‘B*&’ to an
rvalue of type ‘B*’
 int i = foo( (B*)0 );
                    ^
t.C:7:5: note:   initializing argument 1 of ‘int foo(B*&)’
 int foo(B*&);
     ^~~
t.C:11:20: error: cannot bind non-const lvalue reference of type ‘B*&’ to an
rvalue of type ‘B*’
 int j = foo( (D*)0 );
                    ^
t.C:7:5: note:   initializing argument 1 of ‘int foo(B*&)’
 int foo(B*&);
     ^~~
t.C:14:17: error: cannot bind non-const lvalue reference of type ‘B*&’ to an
rvalue of type ‘B*’
 int k = foo( pd );
                 ^
t.C:7:5: note:   initializing argument 1 of ‘int foo(B*&)’
 int foo(B*&);
     ^~~
t.C:17:17: error: invalid initialization of reference of type ‘B*&’ from
expression of type ‘X*’
 int l = foo( px );\
                 ^
t.C:7:5: note: in passing argument 1 of ‘int foo(B*&)’
 int foo(B*&);
     ^~~