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From: "konstantin.vladimirov at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/97220] New: Overload resolution works wrong when implicit
 conversion not exists
Date: Sun, 27 Sep 2020 21:41:45 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D97220

            Bug ID: 97220
           Summary: Overload resolution works wrong when implicit
                    conversion not exists
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: konstantin.vladimirov at gmail dot com
  Target Milestone: ---

Minimal reproducer is here: https://godbolt.org/z/rd4e9a

struct S {
  explicit S(int, int, int) {}
};

struct T {
  T(int, int, int) {}
};

void foo(struct S) {} // 1
void foo(struct T) {} // 2

int main() {
  S s{1, 2, 3};

  foo({1, 2, 3});
}

By C++ standard, [over.match.viable], "for F to be a viable function, there
shall exist for each argument an implicit conversion sequence (12.4.3.1) th=
at
converts that argument to the corresponding parameter of F"

So 1 is not viable overload and resolution shall peek 2

But in reality now error produced:

error: call of overloaded 'foo(<brace-enclosed initializer list>)' is ambig=
uous=