arphaman created this revision.
arphaman added a reviewer: aaron.ballman.
arphaman added a subscriber: cfe-commits.
arphaman set the repository for this revision to rL LLVM.
This patch adds a bit of documentation for the `transparent_union` attribute.
Repository:
rL LLVM
https://reviews.llvm.org/D25995
Files:
include/clang/Basic/Attr.td
include/clang/Basic/AttrDocs.td
Index: include/clang/Basic/AttrDocs.td
===================================================================
--- include/clang/Basic/AttrDocs.td
+++ include/clang/Basic/AttrDocs.td
@@ -2649,3 +2649,21 @@
If a function has neither of these attributes, they become subject to the XRay
heuristics used to determine whether a function should be instrumented or
otherwise.
}];
}
+
+def TransparentUnionDocs : Documentation {
+ let Category = DocCatType;
+ let Content = [{
+This attribute can be applied to a union to change the behaviour of calls to
+functions that have an argument with a transparent union type. The compiler
+behaviour is changed in the following manner:
+
+- A value whose type is any member of the transparent union can be passed as an
+argument without the need to cast that value.
+
+- The argument is passed to the function using the calling convention of the
+first member of the transparent union. Consequently, all the members of the
+transparent union should have the same calling convention as its first member.
+
+Transparent unions are not supported in C++.
+ }];
+}
Index: include/clang/Basic/Attr.td
===================================================================
--- include/clang/Basic/Attr.td
+++ include/clang/Basic/Attr.td
@@ -1542,7 +1542,7 @@
def TransparentUnion : InheritableAttr {
let Spellings = [GCC<"transparent_union">];
// let Subjects = SubjectList<[Record, TypedefName]>;
- let Documentation = [Undocumented];
+ let Documentation = [TransparentUnionDocs];
let LangOpts = [COnly];
}
Index: include/clang/Basic/AttrDocs.td
===================================================================
--- include/clang/Basic/AttrDocs.td
+++ include/clang/Basic/AttrDocs.td
@@ -2649,3 +2649,21 @@
If a function has neither of these attributes, they become subject to the XRay heuristics used to determine whether a function should be instrumented or otherwise.
}];
}
+
+def TransparentUnionDocs : Documentation {
+ let Category = DocCatType;
+ let Content = [{
+This attribute can be applied to a union to change the behaviour of calls to
+functions that have an argument with a transparent union type. The compiler
+behaviour is changed in the following manner:
+
+- A value whose type is any member of the transparent union can be passed as an
+argument without the need to cast that value.
+
+- The argument is passed to the function using the calling convention of the
+first member of the transparent union. Consequently, all the members of the
+transparent union should have the same calling convention as its first member.
+
+Transparent unions are not supported in C++.
+ }];
+}
Index: include/clang/Basic/Attr.td
===================================================================
--- include/clang/Basic/Attr.td
+++ include/clang/Basic/Attr.td
@@ -1542,7 +1542,7 @@
def TransparentUnion : InheritableAttr {
let Spellings = [GCC<"transparent_union">];
// let Subjects = SubjectList<[Record, TypedefName]>;
- let Documentation = [Undocumented];
+ let Documentation = [TransparentUnionDocs];
let LangOpts = [COnly];
}
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