[libc++] Introduce `_LIBCPP_OVERRIDABLE_FUNC_VIS`
This is a generalization of `_LIBCPP_NEW_DELETE_VIS`; the new macro name
captures the semantics better, and also allows us to get rid of the
`_WIN32` check in `include/new`. No functional change.
Differential Revision: https://reviews.llvm.org/D26702
llvm-svn: 287164
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: dce4218df7baa24f11a28611f3cc11fc34898e87
diff --git a/docs/DesignDocs/VisibilityMacros.rst b/docs/DesignDocs/VisibilityMacros.rst
index 861cc04..2ee0714 100644
--- a/docs/DesignDocs/VisibilityMacros.rst
+++ b/docs/DesignDocs/VisibilityMacros.rst
@@ -22,6 +22,18 @@
Mark a symbol as being exported by the libc++ library. This attribute must
be applied to the declaration of all functions exported by the libc++ dylib.
+**_LIBCPP_OVERRIDABLE_FUNC_VIS**
+ Mark a symbol as being exported by the libc++ library, but allow it to be
+ overridden locally. On non-Windows, this is equivalent to `_LIBCPP_FUNC_VIS`.
+ This macro is applied to all `operator new` and `operator delete` overloads.
+
+ **Windows Behavior**: Any symbol marked `dllimport` cannot be overridden
+ locally, since `dllimport` indicates the symbol should be bound to a separate
+ DLL. All `operator new` and `operator delete` overloads are required to be
+ locally overridable, and therefore must not be marked `dllimport`. On Windows,
+ this macro therefore expands to `__declspec(dllexport)` when building the
+ library and has an empty definition otherwise.
+
**_LIBCPP_INLINE_VISIBILITY**
Mark a function as hidden and force inlining whenever possible.
@@ -107,20 +119,6 @@
versioning namespace. This allows throwing and catching some exception types
between libc++ and libstdc++.
-**_LIBCPP_NEW_DELETE_VIS**
- 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**: 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
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