[cfe-dev] Clang generates invalid code when lambdas call lambdas.

[Richard Smith]

On Wed, Mar 13, 2013 at 3:37 PM, Ian Stewart <Ian.Stewart at autodesk.com>wrote:

> Hello,
>
> I have created a simple program that crashes when running the resulting
> code generated by Clang.
>
>         int main( int argc, char *argv[])
>         {
>                 auto first = [&]() { return argc; };
>                 auto second = [&]() { return first(); };
>                 return second();
>         }
>
> I have investigated a little, and what I have found is that Clang
> mistakenly thinks that 'first' and 'second' should have the same
> implementation, only generates code for one of them, yet calls it for both.
> If I change the resulting type of 'first' to differ from 'second', it
> works:
>
>         int main( int argc, char *argv[])
>         {
>                 auto first = [&]() -> unsigned int { return argc; };
>                 auto second = [&]() -> int { return first(); };
>                 return second();
>         }
>
> LLVM 3.3 @ SVN 176884
> clang++.exe -Xclang -cxx-abi -Xclang microsoft -S -emit-llvm
> lambdafail.cpp -o lambdafail.cpp.bc
> lli.exe lambdafail.cpp.bc x y
>

The implementation of the Microsoft ABI is incomplete. It's quite likely
that it does not correctly mangle lambdas yet.


> expected result: 3
>
> Thank you,
> Ian
>
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