Szelethus added a comment. In D79704#2034571 <https://reviews.llvm.org/D79704#2034571>, @NoQ wrote:
> In D79704#2032947 <https://reviews.llvm.org/D79704#2032947>, @Szelethus wrote: > > > In D79704#2032271 <https://reviews.llvm.org/D79704#2032271>, @NoQ wrote: > > > > > Blanket reply! `ParamRegion` is not a `DeclRegion` because it does not > > > necessarily have a corresponding `Decl`. For instance, when calling a > > > function through an unknown function pointer, you don't have the > > > declaration of a function, let alone its parameters. > > > > > > Well hold on for a second then -- how is this, if it is, different for > > member pointers? Aren't they represented with a `VarRegion`? > > > They aren't even `Loc`! > > We currently don't have a representation for an unknown pointer-to-member. A > known pointer-to-member is represented by a `FieldDecl` (not sure about > static members) but it's still a `NonLoc` and as such isn't a region at all. > Because, well, you can't dereference a pointer-to-member; you can only apply > it to a base pointer like an offset. The mental model is "an offset". > Therefore it's `NonLoc`. > > Pointers to member functions are a different thing; they're function pointers > so they're kinda regions. > > >> But for parameters of C++ object type you still need your `ParamRegion` > >> because arguments are constructed into it. > > > > Could you give a specific code example? > > > > struct S { > S() { > this; // What region does 'this' point to... > } > }; > > void foo(void (*bar)(S)) { > bar(S()); // ...in this invocation? > } > I remember this coming up so many times, and I'm an inch away from getting it but I'm not there just yet ^-^ Sorry if you have to repeat yourself too many times. The example you have shown sounds like a case we could (should?) abstract away. If we model in accordance to the AST as closely as possible, `ParamRegion` should totally be a `VarRegion`. If something tricky like this came up, the `getDecl` function should just return with a nullptr, shouldn't it? The code changes make me feel like we're doing a lot of chore (and make it super easy to forget checking for parameters explicitly). The gain, which is I guess correctness, seems negligible, and I'm not sure this is actually correct, as I mentioned in D79704#inline-730731 <https://reviews.llvm.org/D79704#inline-730731>. I don't see why the most defining feature of a `DeclRegion` is supposed to be an always existing `Decl`, rather than a mirror of the AST. CHANGES SINCE LAST ACTION https://reviews.llvm.org/D79704/new/ https://reviews.llvm.org/D79704 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
