isuckatcs wrote:
> I think this might be working around the issue rather than fixing it. It
> looks to me like the bug is in `Decl::printGroup`:
>
> https://github.com/llvm/llvm-project/blob/f4023d4d5d6a6f35ef2315f1b1ce7dd35f24e901/clang/lib/AST/DeclPrinter.cpp#L223
>
> We are printing the tag _definition_ here if the tag _declaration_ is part of
> the `DeclGroup`. I think that the `if(TD)` on the line above that one should
> instead be something like:
>
> ```c++
> if (TD && (TD->isThisDeclarationADefinition() ||
> TD->isThisDeclarationADemotedDefinition()))
> ```
>
> (That is: print the tag definition if the tag declaration in the decl group
> was written as a definition.)
Initially I was thinking about tweaking `Decl::printGroup` but I wasn't
entirely sure about it. Now that I'm experimenting with your proposed solution,
it seems there is an edge case, which we need to handle explicitly.
```c++
enum __attribute__((aligned(16))) T *p0;
```
```c++
EnumDecl ... T
`-AlignedAttr ... aligned
`-ConstantExpr ... 'int'
|-value: Int 16
`-IntegerLiteral ... 'int' 16
```
This enum doesn't have a definition but has attributes, which are not printed
unless `SubPolicy.IncludeTagDefinition` is set to `true`.
If we explicitly check for `TD->hasAttrs()`, we are back at the original issue.
```c++
struct A {
int x;
};
struct Class {
enum __attribute__((aligned(16))) T *(*next)(struct A *q);
};
```
```c++
struct A {
int x;
};
struct Class {
enum __attribute__((aligned(16))) T *(*next)(struct A {
int x;
} *);
};
```
At this point we either ignore the implicitly generated `TagDecl`, or we can
tweak the attribute printing, so that they are printed even if we only print
the declaration, though when I tried that 10 test cases failed, so I'm not sure
we want to pursue that solution.
https://github.com/llvm/llvm-project/pull/69971
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