| Issue |
99825
|
| Summary |
Unexpected internal linkage of const/constexpr variable within extern "C++"
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
kamrann
|
clang rejects the following with `error: declaration of 'x' with internal linkage cannot be exported`:
```
export module mod;
extern "C++"
{
export constexpr auto x = 10;
}
```
Compiler explorer: https://godbolt.org/z/a6nhazoKr
According to [[basic.link] 3.2](https://eel.is/c++draft/basic.link#3.2), `const` (or `constexpr` ) implies internal linkage for a namespace scope variable, with some exceptions, and 3.2.1 states that one such exception is if the declaration is in the purview of a module interface. clang appears to respect this generally, but in the case of `extern "C++"` it seems to not apply this exception, as if it considers the contents of such a block to not be part of the module's purview. This feels like a corner case, since obviously the symbols are not attached to the module; but the purview is nonetheless defined as all tokens following the module declaration and I can't see anywhere that states a linkage block is exempt.
Note that MSVC accepts the code.
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