https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84906
Bug ID: 84906
Summary: [8 Regression] Ambiguous conversion not diagnosed,
causes entire selection-statement to be omitted
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Keywords: accepts-invalid, wrong-code
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: redi at gcc dot gnu.org
Target Milestone: ---
extern "C" int puts(const char*);
struct aa {
operator auto() {
puts("auto");
return false;
}
explicit operator bool() {
puts("bool");
return true;
}
};
int main() {
aa x;
if (x)
puts("here");
else
puts("there");
}
This compiles and runs, but doesn't print anything (neither here not there, and
neither auto nor bool).
This seems to be a regression, as GCC 7 prints:
auto
there
Clang and EDG correctly diagnose it as ill-formed:
odd.cc:17:9: error: conversion from 'aa' to 'bool' is ambiguous
if (x)
^
odd.cc:4:5: note: candidate function
operator auto() {
^
odd.cc:8:14: note: candidate function
explicit operator bool() {
^
1 error generated.
"odd.cc", line 17: error: more than one conversion function from "aa" to a
built-in type applies:
function "aa::operator bool()"
function "aa::operator bool()"
if (x)
^
1 error detected in the compilation of "odd.cc".
