[cfe-dev] bool type is represented as "_Bool" in the AST

[Aaron Ballman via cfe-dev]

On Tue, Jul 23, 2019 at 7:59 PM Pradeep Kumar <pradeepisro49 at gmail.com> wrote:
>
> Dear Aaron,
>    For the sake of clarity, I have detailed about the case in here. I just want to know is this the expected behavior from the tool.

Expected: no. Explainable: yes.

var_decl->getType().dump(); calls the default dumper on QualType. This
creates an ASTDumper object from llvm::errs() and two null pointers
(see ASTDumper.cpp:164). This ASTDumper constructor constructs a
PrintingPolicy object from a default-constructed LangOptions object
rather than using the one from the ASTContext (see ASTDumper.h:32),
which is why you're getting the behavior you are.

There is no QualType::dump() interface that lets you pass in a
printing policy. I would have expected the QualType dumper to use the
correct printing policy, like the Decl dumper does, which is why I
think this is unexpected.

~Aaron

>
> Regards,
> Pradeep
>
>
> Gist link: https://gist.github.com/schwarzschild-radius/8986bd5dc734183727291b3f3aae4c53
>
> On Tue, Jul 23, 2019 at 10:01 PM Aaron Ballman <aaron at aaronballman.com> wrote:
>>
>> On Tue, Jul 23, 2019 at 12:24 PM Pradeep Kumar <pradeepisro49 at gmail.com> wrote:
>> >
>> > Dear Aaron,
>> >    How do I set it from command line? I am remeber setting the language standard as -std=c++17 in the clangTool.
>>
>> You don't change it via the command line. If you set the language mode
>> to C++ in Clang, it should always print as bool automatically. See
>> CompilerInvocation::setLangDefaults(), where it sets the values for
>> the LangOptions object used to make printing policies. If you're not
>> executing Clang, we need more information about how you are setting up
>> the tool to be able to help.
>>
>> ~Aaron
>>
>> >
>> > Regards,
>> > Pradeep
>> >
>> > On Tue, Jul 23, 2019 at 8:48 PM Aaron Ballman <aaron at aaronballman.com> wrote:
>> >>
>> >> On Tue, Jul 23, 2019 at 11:12 AM Pradeep Kumar <pradeepisro49 at gmail.com> wrote:
>> >> >
>> >> > Dear Aaron,
>> >> >     Why is it set to "_Bool" by default?
>> >>
>> >> It seems to get its default value from LangOptions::Bool, which I
>> >> believe is set automatically by the language standard mode.
>> >>
>> >> > How do I change it?
>> >>
>> >> Usually you do this by making a copy of an existing PrintingPolicy
>> >> object and modifying it.
>> >>
>> >> PrintingPolicy PP(WhateverPrintingPolicyYouWereUsing);
>> >> PP.Bool = 1;
>> >>
>> >> Then pass PP into the call to getAsString().
>> >>
>> >> ~Aaron
>> >>
>> >> >
>> >> > Regards,
>> >> > Pradeep
>> >> >
>> >> > On Tue, Jul 23, 2019 at 8:32 PM Aaron Ballman <aaron at aaronballman.com> wrote:
>> >> >>
>> >> >> On Tue, Jul 23, 2019 at 10:47 AM Pradeep Kumar via cfe-dev
>> >> >> <cfe-dev at lists.llvm.org> wrote:
>> >> >> >
>> >> >> > Dear Clang-developer community,
>> >> >> >     I am using libTooling to query information about the source. While querying the string representation of the bool type, I get "_Bool" string. I got the string from QualType::getAsString(). Should I be using another function to query the actual type or is it an expected behavior?
>> >> >> >
>> >> >> >     I don't get _Bool when dumping the ast except when I dump the QualType Node.
>> >> >>
>> >> >> The PrintingPolicy::Bool member dictates this behavior.
>> >> >>
>> >> >> ~Aaron
>> >> >>
>> >> >> >
>> >> >> > clang Version: 9.0
>> >> >> > LLVM Version: 9.0
>> >> >> >
>> >> >> > Regards,
>> >> >> > Pradeep
>> >> >> > _______________________________________________
>> >> >> > cfe-dev mailing list
>> >> >> > cfe-dev at lists.llvm.org
>> >> >> > https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev