[cfe-dev] Parameters of Custom Attribute are not included in AST

[Aaron Ballman]

On Thu, Dec 18, 2014 at 7:28 AM, LUIS MIGUEL SANCHEZ GARCIA
<lmsanche at inf.uc3m.es> wrote:
> Hi everyone,
>
> I included a C++11 attribute in clang, however I cannot see its integer
> parameters in the AST.
>
> Example:
>
> int main(){
>
> int i = 0;
> int j=1;
> [[own::myattr(1,2,3)]]
> int a = i + j;
> return 0;
>
> }
>
> AST output is:
>
> clang++ test.cpp  -std=c++11 -Xclang -ast-dump -fsyntax-only
>
>
> TranslationUnitDecl 0x894a230 <<invalid sloc>> <invalid sloc>
> |-TypedefDecl 0x894a770 <<invalid sloc>> <invalid sloc> implicit __int128_t
> '__int128'
> |-TypedefDecl 0x894a7d0 <<invalid sloc>> <invalid sloc> implicit __uint128_t
> 'unsigned __int128'
> |-TypedefDecl 0x894ab90 <<invalid sloc>> <invalid sloc> implicit
> __builtin_va_list '__va_list_tag [1]'
> `-FunctionDecl 0x894ac30 <hello.cpp:3:1, line:10:1> line:3:5 main 'int
> (void)'
>   `-CompoundStmt 0x898e668 <line:4:1, line:10:1>
>     |-DeclStmt 0x894adb8 <line:5:5, col:14>
>     | `-VarDecl 0x894ad40 <col:5, col:13> col:9 used i 'int' cinit
>     |   `-IntegerLiteral 0x894ad98 <col:13> 'int' 0
>     |-DeclStmt 0x894ae58 <line:6:5, col:14>
>     | `-VarDecl 0x894ade0 <col:5, col:13> col:9 used j 'int' cinit
>     |   `-IntegerLiteral 0x894ae38 <col:13> 'int' 1
>     |-DeclStmt 0x898e610 <line:8:5, col:18>
>     | `-VarDecl 0x894aee0 <col:5, col:16> col:10 a 'int':'int' cinit
>     |   |-BinaryOperator 0x898e528 <col:14, col:16> 'int' '+'
>     |   | |-ImplicitCastExpr 0x898e4f8 <col:14> 'int' <LValueToRValue>
>     |   | | `-DeclRefExpr 0x898e4a8 <col:14> 'int' lvalue Var 0x894ad40 'i'
> 'int'
>     |   | `-ImplicitCastExpr 0x898e510 <col:16> 'int' <LValueToRValue>
>     |   |   `-DeclRefExpr 0x898e4d0 <col:16> 'int' lvalue Var 0x894ade0 'j'
> 'int'
>     |   `-OWNMyattrAttr 0x894af40 <line:7:7, col:20>//missing parameters
> 1,2,3
>     `-ReturnStmt 0x898e648 <line:9:5, col:12>
>       `-IntegerLiteral 0x898e628 <col:12> 'int' 0
>
>
>
> I modified include/clang/Basic/Attr.td like this:
>
> //own::attr
> def OWNAttr : Attr {
>   let Spellings = [CXX11<"own", "attr">];
>   let Args = [VariadicUnsignedArgument<"Args">];
>   let Documentation = [Undocumented];
> }
>
>
> Any help?

When you rerun the table generators for attributes, you should get an
AttrDump.inc file generated that has a switch statement for attr::Kind
enumerators. What does the case look like for your OWNAttr object? It
should look something like:

case attr::NonNull: {
  const NonNullAttr *SA = cast<NonNullAttr>(A);
  for (const auto &Val : SA->args())
    OS << " " << Val;
  break;
}

(This is an example of another attribute using
VariadicUnsignedArgument for its Args.)

~Aaron

>
>
> Regards,
> Luis.
>
>
> --
> --
> --
> --------------------------------------------------
> Luis Miguel Sánchez García
> Computer Architecture and Technology Area.
> Office 2.2.B08
> Computer Science Department. UNIVERSIDAD CARLOS III DE MADRID
> Universidad Carlos III de Madrid
> Avda. de la Universidad, 30
> 28911 Leganés - Madrid - Spain
> e-mail: lmsan at arcos.inf.uc3m.es
>         luismiguel.sanchez at uc3m.es
>
> Phone: (+34) 91 624 5951
>
> Linked-In: http://es.linkedin.com/in/lmsan
> Twitter: http://twitter.com/lmsanchezgarcia
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