[cfe-dev] Find Type by name

[Roman Popov via cfe-dev]

Well, from what I'm seeing non-type argument printer is actually untyped.
It uses APInt, which looks like "generic" arbitrary precision integer, that
knows nothing about C++ type system.

So solution is to print APInt value without type postfix, and then generate
type postfix based on template parameter type.

I'm not really familiar with Clang yet, so it will take a time to fix this.
But I will try.

Another option would be using mangled type names in AST Matcher.  This way
it will be even better: you wan't need to demangle names from LLVM IR.



2018-02-28 18:07 GMT-08:00 Roman Popov <ripopov at gmail.com>:

> Ok, let me run the code in debugger to understand how it makes decision
> when to print U.
>
> 2018-02-28 18:05 GMT-08:00 Artem Dergachev <noqnoqneo at gmail.com>:
>
>> Huh, nice one. It means that the problem is somewhere in
>> QualType::getQualifiedNameAsString(). No, it doesn't seem to be fixed in
>> trunk. This might be an easy and welcomed patch.
>>
>> On 28/02/2018 5:56 PM, Roman Popov wrote:
>>
>>> Btw, I'm using Clang 5.0, probably it is already fixed in trunk?
>>>
>>> 2018-02-28 17:54 GMT-08:00 Roman Popov <ripopov at gmail.com <mailto:
>>> ripopov at gmail.com>>:
>>>
>>>     Yes, it matches indeed vs my_nm::my_type<int, 10>.
>>>
>>>     I think this is a bug in*asString() *matcher: Here is reproducer:
>>>
>>>     *namespace my_nm {*
>>>     *template<typename T, unsigned U>*
>>>     *struct my_type {  };*
>>>     *}*
>>>     *
>>>     *
>>>     *my_nm::my_type<int, 10> m1;*
>>>     *my_nm::my_type<int, 11u> m2;*
>>>
>>>     LLVM IR  generator correctly generates both types with unsigned
>>>     second parameter. But AST Matcher thinks that m1 has signed
>>>     parameter, and m2 has unsigned:
>>>
>>>     m1 matches vs *my_nm::my_type<int, 10>*
>>>     m2 matches vs *my_nm::my_type<int, 11U> *(notice capital U)
>>>
>>>     In LLVM IR types are *my_nm::my_type<int, 10u> and
>>>     *my_nm::my_type<int, 11u> **
>>>
>>>
>>>     Thanks, Roman
>>>
>>>
>>>
>>>     2018-02-28 17:37 GMT-08:00 Artem Dergachev <noqnoqneo at gmail.com
>>>     <mailto:noqnoqneo at gmail.com>>:
>>>
>>>
>>>         Sorry i don't have a quick way of trying this at the moment;
>>>         Does it work with "struct my_nm::my_type<int, 10>"? - because
>>>         that's what i see in clang's -ast-dump. Does
>>>         varDecl(hasType(asString(...))) work? If you match qualType()
>>>         and dump .getAsString() on all results, what do you see?
>>>
>>>         Cause i think it should ultimately work.
>>>
>>>         On 28/02/2018 2:12 PM, Roman Popov wrote:
>>>
>>>             Thanks Artem. This is what I've tried before writing
>>>             original mail. However it does not work, I got zero matches.
>>>
>>>             Here is reproducer:
>>>
>>>             *namespace my_nm {*
>>>             *template<typename T, unsigned U>*
>>>             *struct my_type {  };*
>>>             *}*
>>>             *
>>>             *
>>>             *my_nm::my_type<int, 10> m;
>>>             *
>>>
>>>
>>>             I got types from LLVM IR analysis, and then want to find
>>>             them in Clang AST.
>>>
>>>             From LLVM I got mangled name:
>>>             *N5my_nm7my_typeIiLj10EEE*
>>>
>>>             Demangled to:
>>>             *my_nm::my_type<int, 10u>*
>>>
>>>             However I can't find it by any matcher:
>>>
>>>             auto matches =
>>>             match(qualType(asString("*my_nm::my_type<int,
>>>             10u>*")).bind("types"), astCtx);  // Zero matches
>>>
>>>             auto matches =
>>>             match(qualType(asString("*N5my_nm7my_typeIiLj10EEE*")).bind(
>>> "types"),
>>>             astCtx);  // Zero matches
>>>
>>>             Probably there is some other way to go back from LLVM IR
>>>             to Clang AST?
>>>
>>>
>>>             Thanks,
>>>             Roman
>>>
>>>
>>>             2018-02-28 12:36 GMT-08:00 Artem Dergachev
>>>             <noqnoqneo at gmail.com <mailto:noqnoqneo at gmail.com>
>>>             <mailto:noqnoqneo at gmail.com <mailto:noqnoqneo at gmail.com>>>:
>>>
>>>                 I don't think it's possible via straightforward lookup
>>>             - you might
>>>                 need to scan the AST to do this.
>>>
>>>                 Eg. using ASTMatchers:
>>>
>>>                     qualType(asString("my_nm::my_type<int, 10u>"))
>>>
>>>                 Or, if you're not using ASTMatchers (likely), you can
>>>             do the same
>>>                 with a RecursiveASTVisitor. Or manually.
>>>
>>>
>>>                 On 27/02/2018 10:56 AM, Roman Popov via cfe-dev wrote:
>>>
>>>                     Hello,
>>>
>>>                     Is it possible to find type in AST by it's
>>>             qualified type?
>>>
>>>                     For example I have string "my_nm::my_type<int,
>>>             10u>", how can
>>>                     I get clang::QualType if type is present in
>>>             translation unit?
>>>
>>>                     Thanks,
>>>                     Roman
>>>
>>>
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>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>
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