llvm dev - Sep 2021 - Disabling inline compilation (Clang with VS2019)

On 23/09/2021 15:18, John Emmas via llvm-dev wrote:
>
> I've used MSVC for maybe 20 years and I've never once known a DLL 
> function to be inline-able.
>
On 23/09/2021 15:07, Hans Wennborg wrote:
> Actually, MSDN
(https://docs.microsoft.com/en-us/cpp/cpp/defining-inline-cpp-functions-with-dllexport-and-dllimport)
> documents the opposite:
>
> "You can also define as inline a function declared with the dllimport
> attribute. In this case, the function can be expanded (subject to /Ob
> specifications)"
>
> Of course the reality is more complicated, but it's clear MSVC never
> excluded dllimport functions from inlining in general.
>
Ah... maybe that's the situation - perhaps a DLL function CAN be inlined 
but only if it's specifically declared as such?  That makes a lot of 
sense and it would also explain why I've never seen it here with 
ordinary DLL declarations (i.e. those not declared using inline)

John

On 23/09/2021 16:03, John Emmas wrote:
>
> perhaps a DLL function CAN be inlined but only if it's specifically 
> declared as such?  That makes a lot of sense and it would also explain 
> why I've never seen it here with ordinary DLL declarations (i.e. those 
> not declared using inline)
>
I found this Microsoft document about inlining:-

https://docs.microsoft.com/en-us/cpp/cpp/inline-functions-cpp?view=msvc-160

About half way down there are two examples and the 2nd one states that 
class member functions which get implemented in a header file are now 
regarded as being implicitly inlined.  This supports Paul's statement 
yesterday about the One Definition Rule - but what MS doesn't clarify is 
whether or not that'd also apply to DLL functions.  Paul wrote:-

On 23/09/2021 14:14, paul.robinson at sony.com wrote:
> If MSVC promises not to inline a dllimport method, that seems like
> something Clang should take into consideration in MS-compatibility
> mode.
>
Two decades of experience with MSVC suggests that where a dllimport 
method isn't also declared as 'inline' the compiler won't
attempt to
inline it. To me that makes perfect sense but frustratingly, I just 
can't find it in writing anywhere :-(

John