Close https://github.com/llvm/llvm-project/issues/71034
See
https://discourse.llvm.org/t/rfc-c-20-modules-introduce-thin-bmi-and-decls-hash/74755
This patch introduces reduced BMI, which doesn't contain the definitions
of functions and variables if its definitions won't contribute to the
ABI.
Testing is a big part of the patch. We want to make sure the reduced BMI
contains the same behavior with the existing and relatively stable
fatBMI. This is pretty helpful for further reduction.
The user interfaces part it left to following patches to ease the
reviewing.
Close https://github.com/llvm/llvm-project/issues/79240
Cite the comment from @mizvekov in
//github.com/llvm/llvm-project/issues/79240:
> There are two kinds of bugs / issues relevant here:
>
> Clang bugs that this change hides
> Here we can add a Frontend flag that disables the GMF ODR check, just
> so
> we can keep tracking, testing and fixing these issues.
> The Driver would just always pass that flag.
> We could add that flag in this current issue.
> Bugs in user code:
> I don't think it's worth adding a corresponding Driver flag for
> controlling the above Frontend flag, since we intend it's behavior to
> become default as we fix the problems, and users interested in testing
> the more strict behavior can just use the Frontend flag directly.
This patch follows the suggestion:
- Introduce the CC1 flag `-fskip-odr-check-in-gmf` which is by default
off, so that the every existing test will still be tested with checking
ODR violations.
- Passing `-fskip-odr-check-in-gmf` in the driver to keep the behavior
we intended.
- Edit the document to tell the users who are still interested in more
strict checks can use `-Xclang -fno-skip-odr-check-in-gmf` to get the
existing behavior.
Close https://github.com/llvm/llvm-project/issues/79240.
See the linked issue for details. Given the frequency of issue reporting
about false positive ODR checks (I received private issue reports too),
I'd like to backport this to 18.x too.
parameters.
The current implementation to judge the similarity of TypeConstraint in
ASTContext::isSameTemplateParameter is problematic, it couldn't handle
the following case:
```C++
template <__integer_like _Tp, C<_Tp> Sentinel>
constexpr _Tp operator()(_Tp &&__t, Sentinel &&last) const {
return __t;
}
```
When we see 2 such declarations from different modules, we would judge
their similarity by `ASTContext::isSame*` methods. But problems come for
the TypeConstraint. Originally, we would profile each argument one by
one. But it is not right. Since the profiling result of `_Tp` would
refer to two different template type declarations. So it would get
different results. It is right since the `_Tp` in different modules
refers to different declarations indeed. So the same declaration in
different modules would meet incorrect our-checking results.
It is not the thing we want. We want to know if the TypeConstraint have
the same expression.
Reviewer: vsapsai, ilya-biryukov
Differential Revision: https://reviews.llvm.org/D129068
When we do profiling in ASTContext::getAutoType, it wouldn't think about
the canonical declaration for the type constraint. It is bad since it
would cause a negative ODR mismatch while we already know the type
constraint declaration is a redeclaration for the previous one. Also it shouldn't be
bad to use the canonical declaration here.
The compiler would judge two concepts is same by their addresses.
However, when we use modules, the addresses wouldn't be the same all the
time since one is parsed in their TU and another is imported in another
TU.
This patch fixes this by using isSameEntity to judge the two concepts.
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D114769
