[PATCH] D49911: Summary:Add clang::reinitializes attribute

[Martin Böhme via Phabricator via cfe-commits]

mboehme created this revision.
Herald added a subscriber: cfe-commits.

This is for use by clang-tidy's bugprone-use-after-move check -- see
corresponding clang-tidy patch at https://reviews.llvm.org/D49910.


Repository:
  rC Clang

https://reviews.llvm.org/D49911

Files:
  include/clang/Basic/Attr.td
  include/clang/Basic/AttrDocs.td
  lib/Sema/SemaDeclAttr.cpp
  test/SemaCXX/attr-reinitializes.cpp


Index: test/SemaCXX/attr-reinitializes.cpp
===================================================================
--- /dev/null
+++ test/SemaCXX/attr-reinitializes.cpp
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
+
+[[clang::reinitializes]] int a; // expected-error {{only applies to}}
+
+[[clang::reinitializes]] void f(); // expected-error {{only applies to}}
+
+struct A {
+  [[clang::reinitializes]] void foo();
+  [[clang::reinitializes]] void bar() const; // expected-error {{only applies to non-static non-const}}
+  [[clang::reinitializes]] static void baz(); // expected-error {{only applies to}}
+  [[clang::reinitializes]] int a; // expected-error {{only applies to}}
+};
Index: lib/Sema/SemaDeclAttr.cpp
===================================================================
--- lib/Sema/SemaDeclAttr.cpp
+++ lib/Sema/SemaDeclAttr.cpp
@@ -6539,6 +6539,11 @@
   case ParsedAttr::AT_XRayLogArgs:
     handleXRayLogArgsAttr(S, D, AL);
     break;
+
+  // Move semantics attribute.
+  case ParsedAttr::AT_Reinitializes:
+    handleSimpleAttribute<ReinitializesAttr>(S, D, AL);
+    break;
   }
 }
 
Index: include/clang/Basic/AttrDocs.td
===================================================================
--- include/clang/Basic/AttrDocs.td
+++ include/clang/Basic/AttrDocs.td
@@ -3419,3 +3419,31 @@
 corresponding line within the inlined callee.
   }];
 }
+
+def ReinitializesDocs : Documentation {
+  let Category = DocCatFunction;
+  let Content = [{
+The ``reinitializes`` attribute can be applied to a non-static, non-const C++
+member function to indicate that this member function reinitializes the entire
+object to a known state, independent of the previous state of the object.
+
+This attribute can be interpreted by static analyzers that warn about uses of an
+object that has been left in an indeterminate state by a move operation. If a
+member function marked with the ``reinitializes`` attribute is called on a
+moved-from object, the analyzer can conclude that the object is no longer in an
+indeterminate state.
+
+A typical example where this attribute would be used is on functions that clear
+a container class:
+
+.. code-block:: c++
+
+  template <class T>
+  class Container {
+  public:
+    ...
+    [[clang::reinitializes]] void Clear();
+    ...
+  };
+  }];
+}
Index: include/clang/Basic/Attr.td
===================================================================
--- include/clang/Basic/Attr.td
+++ include/clang/Basic/Attr.td
@@ -90,6 +90,11 @@
                                 [{!S->isBitField()}],
                                 "non-bit-field non-static data members">;
 
+def NonStaticNonConstCXXMethod
+    : SubsetSubject<CXXMethod,
+                    [{!S->isStatic() && !S->isConst()}],
+                    "non-static non-const member functions">;
+
 def ObjCInstanceMethod : SubsetSubject<ObjCMethod,
                                        [{S->isInstanceMethod()}],
                                        "Objective-C instance methods">;
@@ -2935,3 +2940,9 @@
   let Subjects = SubjectList<[Var, Function, CXXRecord]>;
   let Documentation = [InternalLinkageDocs];
 }
+
+def Reinitializes : InheritableAttr {
+  let Spellings = [CXX11<"clang", "reinitializes">];
+  let Subjects = SubjectList<[NonStaticNonConstCXXMethod], ErrorDiag>;
+  let Documentation = [ReinitializesDocs];
+}


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