[fpc-devel] Possible inlining problem

[J. Gareth Moreton]

So there is a problem!

https://gitlab.com/freepascal.org/fpc/source/-/issues/41616

It's possible to trigger an infinite loop in the compiler.

Kit


On 12/02/2026 16:25, J. Gareth Moreton via fpc-devel wrote:
>
> Hi everyone,
>
> So I recently rebased my pure function code 
> (https://gitlab.com/freepascal.org/fpc/source/-/merge_requests/645 - 
> nearly 2 years since I first made the merge request, on top of 2 years 
> of initial development!) and it now gets stuck in an infinite loop.  I 
> hadn't made any recent changes, so this was a little bit alarming.  In 
> gitlab, the following line is generated ad infinitum:
>
> |variant.inc(413,17) Note: Call to subroutine "operator :=(const 
> source:Variant):NativeInt;" marked as inline is not inlined|
>
> Locally (x86_64-win64) it gets stuck at ppc1 compiling the system 
> unit.  Using breakpoints, I found it gets stuck in the "first pass" 
> stage when it tries to expand a function call. Since I'm not getting a 
> stack error, I assume it's a vicious circle where one thing is changed 
> to another, and then that new object is changed back to the original.
>
> I'll work to try to see what's happening in the node tree, and if it's 
> my code that's causing this or if it only uncovers the fault.  Bear in 
> mind this issue only appeared when I recently rebased the merge request.
>
> Not pointing fingers (it may actually be my fault!) but be on the 
> lookout for any potential inlining issues.
>
> Kit
>
>
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