diff options
Diffstat (limited to 'libcxx/docs/DesignDocs')
| -rw-r--r-- | libcxx/docs/DesignDocs/VisibilityMacros.rst | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/libcxx/docs/DesignDocs/VisibilityMacros.rst b/libcxx/docs/DesignDocs/VisibilityMacros.rst index f45d67b17ea..67886e392ae 100644 --- a/libcxx/docs/DesignDocs/VisibilityMacros.rst +++ b/libcxx/docs/DesignDocs/VisibilityMacros.rst @@ -112,14 +112,15 @@ Visibility Macros Mark a symbol as being exported by the libc++ library. This macro must be applied to all `operator new` and `operator delete` overloads. - **Windows Behavior**: When using the Microsoft CRT, all the `operator new` and - `operator delete` overloads are defined statically in `msvcrt.lib`. Marking - them as `dllimport` in the libc++ `<new>` header is therefore undesirable: if - we were to mark them as `dllimport` and then link against libc++, source files - which included `<new>` would end up linking against libc++'s `operator new` - and `operator delete`, while source files which did not include `<new>` would - end up linking against msvcrt's `operator new` and `operator delete`, which - would be a confusing and potentially error-prone inconsistency. + **Windows Behavior**: The `operator new` and `operator delete` overloads + should not be marked as `dllimport`; if they were, source files including the + `<new>` header (either directly or transitively) would lose the ability to use + local overloads of `operator new` and `operator delete`. On Windows, this + macro therefore expands to `__declspec(dllexport)` when building the library + and has an empty definition otherwise. A related caveat is that libc++ must be + included on the link line before `msvcrt.lib`, otherwise Microsoft's + definitions of `operator new` and `operator delete` inside `msvcrt.lib` will + end up being used instead of libc++'s. Links ===== |
