https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118178
Bug ID: 118178
Summary: No overload resolution feedback for
copy-initialization which fails to call a converting
constructor
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: janschultke at googlemail dot com
Target Milestone: ---
Assuming this is a bug, GCC gives you no feedback on why a converting
constructor cannot be called:
> struct awoo {
> awoo(int);
> };
>
> struct baka {};
>
> awoo r = baka{};
For this, GCC simply outputs (https://godbolt.org/z/hTfoG4h3c):
> <source>:7:10: error: conversion from 'baka' to non-scalar type 'awoo'
> requested
> 7 | awoo r = baka{};
> | ^~~~~~
There is no feedback whatsoever as to why the converting constructor couldn't
be called. This is very low-quality output. On the contrary, when using
direct-initialization such as 'awoo r{baka{}}', the output is:
> <source>:7:14: error: no matching function for call to
> 'awoo::awoo(<brace-enclosed initializer list>)'
> 7 | awoo r{baka{}};
> | ^
> <source>:7:14: note: there are 3 candidates
> <source>:2:5: note: candidate 1: 'awoo::awoo(int)'
> 2 | awoo(int);
> | ^~~~
> <source>:2:10: note: no known conversion for argument 1 from 'baka' to 'int'
> 2 | awoo(int);
> | ^~~
> <source>:1:8: note: candidate 2: 'constexpr awoo::awoo(const awoo&)'
> 1 | struct awoo {
> | ^~~~
> <source>:1:8: note: no known conversion for argument 1 from 'baka' to 'const
> awoo&'
> <source>:1:8: note: candidate 3: 'constexpr awoo::awoo(awoo&&)'
> <source>:1:8: note: no known conversion for argument 1 from 'baka' to 'awoo&&'
Clang does give overload resolution feedback for both copy-initialization and
direct-initialization.
