[PATCH] D88345: [CUDA] Allow local `static const {__constant__, __device__}` variables.

[Justin Lebar via Phabricator via cfe-commits]

jlebar added a comment.

OK, now I'm starting to I understand this change..

Before, in function scope, we allow static const/non-const `__shared__`, and allow static const so long as it's not `__device__` or `__constant__`.

- `static` -> error?  (I understood us saying above that it is, but now that I read the code, isn't it saying it's an error?)
- `static const` -> allowed
- `static __device__` -> error
- `static const __device__` -> error
- `static __constant__` -> error
- `static const __constant__` -> error

After, in function scope, the rule is, allow static const/non-const `__shared__` or anything that's `static const`.

- `static` -> error, must be const
- `static const` -> allowed
- `static __device__` -> error, must be const
- `static const __device__` -> allowed
- `static __constant__` -> error, must be const
- `static const __constant__` -> allowed

I guess my question when I write out this table is, why shouldn't it be like this?

- `static` -> allowed
- `static const` -> allowed
- `static __device__` -> allowed
- `const static __device__` -> allowed
- `static __constant__` -> error, must be const
- `const static __constant__` -> allowed

This makes some sense to me because we're saying, "`__constant__` must be const", otherwise, anything goes.

Or here's another way of thinking about it.  You're saying that `static` and `static __device__` in function scope are the same as a `__device__` variable in block scope.  And a `__device__` variable in block scope doesn't have to be const (right?).  So why the extra restriction on function-scope static?



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Comment at: clang/lib/Sema/SemaDecl.cpp:13161
       // without device memory qualifier is implemented, therefore only static
       // const variable without device memory qualifier is allowed.
       [&]() {
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