aaron.ballman added inline comments.
================
Comment at: clang/lib/AST/Interp/ByteCodeEmitter.cpp:24-31
+ bool HasBody = true;
+
+ // Function is not defined at all or not yet. We will
+ // create a Function instance but not compile the body. That
+ // will (maybe) happen later.
if (!FuncDecl->isDefined(FuncDecl) ||
(!FuncDecl->hasBody() && FuncDecl->willHaveBody()))
----------------
tbaeder wrote:
> aaron.ballman wrote:
> > tbaeder wrote:
> > > aaron.ballman wrote:
> > > > .... negating the Boolean calculation and applying deMorgan's law did
> > > > not make that code more clear, did it (assuming I did everything
> > > > right)? If you agree, then I'm fine with the more complicated form and
> > > > letting the optimizer make it faster.
> > > I can see that going either way. I think your version is a more confusing
> > > though because the two body conditions are coupled with the `isDefined`
> > > condition. E.g. `HasBody` is `true` if `isDefined() && !willHaveBody()`,
> > > which doesn't make sense to me I think.
> > >
> > > I think I just read this code too many times now. How does being defined
> > > even relate to the function having a body? Should that code just be
> > > `HasBody = hasBody() || willHaveBody()`?
> > > I can see that going either way. I think your version is a more confusing
> > > though because the two body conditions are coupled with the isDefined
> > > condition. E.g. HasBody is true if isDefined() && !willHaveBody(), which
> > > doesn't make sense to me I think.
> >
> > I'm glad we both are confused about the same thing!
> >
> > > I think I just read this code too many times now. How does being defined
> > > even relate to the function having a body? Should that code just be
> > > HasBody = hasBody() || willHaveBody()?
> >
> > I've not dug back in time to see how we got to that predicate in the first
> > place, but my *hunch* is that this may have to do with implicit function
> > definitions for things like special member functions. That's a case where
> > you can have a function definition without a body. e.g.,
> > ```
> > struct S {
> > S();
> > };
> >
> > S::S() = default;
> > ```
> Well, any sort of digging usually just gets you to the //one// commit that
> introduced all of the new constant interpreter :P
>
> `willHaveBody()` isn't even relevant here, is it?
> I think simply
>
> ```
> bool hasBody = FuncDecl->isDefined() || FuncDecl->hasBody();
>
> ```
> makes the most sense.
I think it's one or the other?
`isDefined` searches for a function that's been defined by looking for
something in the redecl chain that: is deleted as written, is defaulted, has a
body, will have a body, has a body that's skipped, or has an attribute that
causes the declaration to be a definition.
By contrast, `hasBody` searches the redecl chain looking for a declaration that
has not been defaulted and has a body or is template late parsed.
So I *think* what you want is `FuncDecl->hasBody(FuncDecl)` to do the check and
get the specific declaration with the body.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D136936/new/
https://reviews.llvm.org/D136936
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