[PATCH] D147844: Emit warning when implicit cast to bool happens in an conditional operator expression when used inside an overloaded shift operator expression

[NagaChaitanya Vellanki via Phabricator via cfe-commits]

chaitanyav added a comment.

In D147844#4281288 <https://reviews.llvm.org/D147844#4281288>, @aaron.ballman wrote:

> In D147844#4278384 <https://reviews.llvm.org/D147844#4278384>, @chaitanyav wrote:
>
>> @aaron.ballman am looking into this. If i change it back to
>>  `operation int();`
>> and add
>> `Stream& operator<<(bool)`
>> i get 
>> `
>> error: 'warning' diagnostics expected but not seen:
>>
>>   File /usr/home/nvellanki/explore/llvm-project/clang/test/Sema/parentheses.cpp Line 68: operator '?:' has lower precedence than '<<'
>>
>> error: 'note' diagnostics expected but not seen:
>>
>>   File /usr/home/nvellanki/explore/llvm-project/clang/test/Sema/parentheses.cpp Line 68: place parentheses around the '<<' expression to silence this warning
>>   File /usr/home/nvellanki/explore/llvm-project/clang/test/Sema/parentheses.cpp Line 68: place parentheses around the '?:' expression to evaluate it first
>>
>> 3 errors generated.
>> `
>> But it works correctly with std::cout
>>
>> `
>> test.cpp:7:30: warning: operator '?:' has lower precedence than '<<'; '<<' will be evaluated first [-Wparentheses]
>>
>>   std::cout << "Test" << a ? 1 : 0;
>>   ~~~~~~~~~~~~~~~~~~~~~~~~ ^
>>
>> test.cpp:7:30: note: place parentheses around the '<<' expression to silence this warning
>>
>>   std::cout << "Test" << a ? 1 : 0;
>>                            ^
>>   (                       )
>>
>> test.cpp:7:30: note: place parentheses around the '?:' expression to evaluate it first
>>
>>   std::cout << "Test" << a ? 1 : 0;
>>                            ^
>>                          (        )
>
> I would expect to get the same diagnostic with either `operator int()` or `operator bool()` as the precedence is the same either way. I think what might be happening here is that `ExprLooksBoolean` is getting tricked into thinking the expression isn't boolean when it actually is (I think this might be the `FIXME` comment in that function needing to be addressed).

Thanks @aaron.ballman, will look into the FIXME.


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https://reviews.llvm.org/D147844