[Bug c++/95085] New: diagnostic on designated-initializer from braced-init-list could be better

barry.revzin at gmail dot com gcc-bugzilla@gcc.gnu.org
Tue May 12 13:59:54 GMT 2020


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95085

            Bug ID: 95085
           Summary: diagnostic on designated-initializer from
                    braced-init-list could be better
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: barry.revzin at gmail dot com
  Target Milestone: ---

In this program (note the typo in the call to f):

struct A {
    int width, height;
};

void f(A);
void g() {
    f(A{.width=1, .hieght=2});
}

gcc's diagnostic is absolutely excellent:

<source>:7:20: error: field designator 'hieght' does not refer to any field in
type 'A'; did you mean 'height'?
    f(A{.width=1, .hieght=2});
                   ^~~~~~
                   height
<source>:2:16: note: 'height' declared here
    int width, height;
               ^

However, if instead of calling f(A{...}) we instead just call f({...}) (as is
common to do if the type name is meaningless and is just used as a proxy for
named function arguments):

struct A {
    int width, height;
};

void f(A);
void g() {
    f({.width=1, .hieght=2});
}

then we get a much worse diagnostic:

<source>:7:5: error: no matching function for call to 'f'
    f({.width=1, .hieght=2});
    ^
<source>:5:6: note: candidate function not viable: cannot convert initializer
list argument to 'A'
void f(A);
     ^

Basically just: "error". Would it be possible to get the same quality of
diagnostic from the named call case as it is in the just-a-braced-init-list
case?


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