[cfe-dev] AST for expresions in array sizes

[Dávid Bolvanský via cfe-dev]

Great! Thanks

po 1. 10. 2018 o 20:55 David Blaikie <dblaikie at gmail.com> napísal(a):

> I chatted with Richard Smith about this and he pointed out that the extra
> info for MAX * 3 is stored in the TypeLocInfo (which can be retrieved from
> the VarDecl), rather than the Type itself.
>
> For example, in gdb, once I've found the VarDecl (pointer stored in the
> GDB temporary expression $10), I could retrieve the expression:
>
> p
> ((clang::ArrayTypeLoc)((VarDecl*)$10)->getTypeSourceInfo()->getTypeLoc()).getSizeExpr()->dump()
> BinaryOperator 0xcc8f7c8 'int' '*'
> |-IntegerLiteral 0xcc8f788 'int' 10
> `-IntegerLiteral 0xcc8f7a8 'int' 3
>
> You can find the macro details by looking at the source location stuff - I
> don't know that piece in detail, but should work as well/in the same way
> here as in the rest of the AST.
>
> Hope that helps!
> - Dave
>
> On Mon, Oct 1, 2018 at 3:35 AM Dávid Bolvanský via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
>
>> Hello,
>>
>> #define MAX 10
>>
>> int main() // (int n)
>> {
>> char arr[MAX * 3]; // arr[n + 3]
>> }
>>
>> I expected that AST would be more detailed (e.g. Binary Operator) but
>> Clang seems to fold it:
>> TranslationUnitDecl
>> `-FunctionDecl <line:11:1, line:14:1> line:11:5 main 'int ()'
>> `-CompoundStmt <line:12:1, line:14:1>
>> `-DeclStmt <line:13:3, col:20>
>> `-VarDecl <col:3, col:19> col:8 arr 'char [30]'
>>
>> or raw output
>> `-VarDecl <col:3, col:15> col:8 a 'char [n * 3]'
>>
>> So with the current AST output we are unable to determine overflowing in
>> array sizes, as requested in https://bugs.llvm.org/show_bug.cgi?id=27439,
>> right?
>>
>> Is it possible to disable that folding / enhance VarDecl for arrays?
>> _______________________________________________
>> cfe-dev mailing list
>> cfe-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20181001/9199e9ec/attachment.html>