[Bug c/63421] New: GCC generates a very misleading warning when looking at an erroneously-overloaded type

[gccbugs at dima dot secretsauce.net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63421

            Bug ID: 63421
           Summary: GCC generates a very misleading warning when looking
                    at an erroneously-overloaded type
           Product: gcc
           Version: 4.9.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gccbugs at dima dot secretsauce.net

Hi. I'm running gcc-4.9.1 from Debian/sid. This is built off of r214759. When
building source that had a mistake GCC produced a very misleading warning that
masked the underlying issue. A minimized test case:

typedef struct
{
    int x, y, z;
} S;

struct S
{
    int x;
};

S s;

void g(struct S *);

void f()
{
    g(&s);
}


Here the error is that S is defined both as a struct and a typedef struct. g()
expects a 'struct S *', but I'm giving it a S*. When gcc builds this I see:

dima@shorty:/tmp/recorder$ /usr/bin/gcc-4.9 -g -O0 -Wall -Wextra -std=gnu99 -I.
 -c -o dbtest.o dbtest.c
dbtest.c: In function 'f':
dbtest.c:17:5: warning: passing argument 1 of 'g' from incompatible pointer
type
     g(&s);
     ^
dbtest.c:13:6: note: expected 'struct S *' but argument is of type 'struct S *'
 void g(struct S *);
      ^

So it tells me that the function is getting a type mismatch, but it says that
both what it wants and what it got was 'struct S *'. This makes the complaint
look redundant.