diff options
| author | Douglas Gregor <dgregor@apple.com> | 2012-03-11 17:21:03 +0000 |
|---|---|---|
| committer | Douglas Gregor <dgregor@apple.com> | 2012-03-11 17:21:03 +0000 |
| commit | 594f8419349d4131216e9296bfba0c5e8d2be950 (patch) | |
| tree | 69d92eb880c8632bf795a92ec353c5d9b75d4393 /docs | |
| parent | 74d2a9cfc9ef9bf0e02eedd4ba0befedeca4d713 (diff) | |
Document the weak-linking behavior of the availability attribute
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@152543 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/LanguageExtensions.html | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/docs/LanguageExtensions.html b/docs/LanguageExtensions.html index bdb04ac1a5..cbdebe12de 100644 --- a/docs/LanguageExtensions.html +++ b/docs/LanguageExtensions.html @@ -665,6 +665,12 @@ void f(void) __attribute__((availability(macosx,introduced=10.4,deprecated=10.6, <dd>Apple's Mac OS X operating system. The minimum deployment target is specified by the <code>-mmacosx-version-min=<i>version</i></code> command-line argument.</dd> </dl> +<p>A declaration can be used even when deploying back to a platform +version prior to when the declaration was introduced. When this +happens, the declaration is <a + href="https://developer.apple.com/library/mac/#documentation/MacOSX/Conceptual/BPFrameworks/Concepts/WeakLinking.html">weakly +linked</a>, as if the <code>weak_import</code> attribute were added to the declaration. A weakly-linked declaration may or may not be present a run-time, and a program can determine whether the declaration is present by checking whether the address of that declaration is non-NULL.</p> + <!-- ======================================================================= --> <h2 id="checking_language_features">Checks for Standard Language Features</h2> <!-- ======================================================================= --> |