ChuanqiXu added a comment.
In D137787#3921673 <https://reviews.llvm.org/D137787#3921673>, @Hahnfeld wrote:
> I've trimmed the failing code down to
>
> #include <string>
> #include <string_view>
> #include <vector>
>
> template <typename T>
> struct SO {
> void a() {
> struct SI {
> std::vector<int> v;
> };
> SI s;
> SI m(std::move(s));
> }
>
> void g() {
> std::vector<std::string_view> v{"a"};
> }
> };
>
> in a header / module and
>
> SO<int> s;
> s.a();
> s.g();
>
> in the calling code. Sadly this works fine in standalone Clang...
>
> All of the above code seems to be important, starting from the outer
> `template`, having two functions, moving a `std::vector` from a default
> generated move constructor and then constructing a
> `std::vector<std::string_view>` with at least one element. If this rings a
> bell for anybody or anybody has an idea where to go from here, please let me
> know. I'm out of depth how to produce the exact failing conditions in a test.
> I would argue that relaxing the `assert` is fine regardless because it still
> tests that the `DtorDecl` belongs to this type, but I can't articulate why an
> exact pointer comparison fails in very rare circumstances...
So the code look like:
// foo.h
#include <string>
#include <string_view>
#include <vector>
template <typename T>
struct SO {
void a() {
struct SI {
std::vector<int> v;
};
SI s;
SI m(std::move(s));
}
void g() {
std::vector<std::string_view> v{"a"};
}
};
// foo.cpp
import "foo.h";
void func() {
SO<int> s;
s.a();
s.g();
}
Is it the reproducer? If it is, my suggestion would be:
- Preprocess `foo.h` into `foo.ii` then replace `import "foo.h";`
- Then reduce `foo.ii` step by step. There should be many things that can be
removed.
- Then we found there is no things we can reduce, then it should be the test.
I know it sounds too hard at first. But I tried and it works although it would
take one whole day. Here is an example for the reduced test case:
https://github.com/llvm/llvm-project/commit/1aaba40dcbe8fdc93d825d1f4e22edaa3e9aa5b1,
which is reduced from 2 system headers which contains 30,000+ lines of code.
> I would argue that relaxing the `assert` is fine regardless
Yes, I understood. But we hope it can land with a test case really. Otherwise,
the same use case may be broken some time again without being noticed by any
one.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D137787/new/
https://reviews.llvm.org/D137787
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