| Issue |
143325
|
| Summary |
relocation diagnostics asserts in response to code that is broken for unrelated reasons #awesome
|
| Labels |
good first issue
|
| Assignees |
cor3ntin
|
| Reporter |
ojhunt
|
I made an error in one of my test cases and got a crash due to a null value. After much confusion I realized the problem is actually that I had redefined the same struct multiple times, and that's what caused the unexpected state.
The test case:
```cpp
struct Foo {
Foo(const Foo&);
~Foo();
};
struct Foo {
Foo();
int;
};
struct Wrapper {
union {
Foo p;
} u;
};
static_assert(__builtin_is_cpp_trivially_relocatable(Wrapper));
```
The assertion is triggered under `DiagnoseNonTriviallyRelocatableReason` in this code:
```cpp
if (!D->hasSimpleMoveConstructor() && !D->hasSimpleCopyConstructor()) {
const auto *Decl = cast<CXXConstructorDecl>(
LookupSpecialMemberFromXValue(SemaRef, D, /*Assign=*/false));
if (Decl && Decl->isUserProvided())
SemaRef.Diag(Loc, diag::note_unsatisfied_trait_reason)
<< diag::TraitNotSatisfiedReason::UserProvidedCtr
<< Decl->isMoveConstructor() << Decl->getSourceRange();
}
```
The issue is the `cast< CXXConstructorDecl >` as `LookupSpecialMemberFromXValue` can return null. The `cast<>` is followed by a null check so it's presumably expected that `LookupSpecialMemberFromXValue` returns null, in which case the fix is likely just to replace `cast` with `cast_or_null`. If it's expected that the cast itself may fail then I assume there's `dyn_cast_or_null` that should be used.
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