Example trivial implementation of C23 [[safe]] attribute support

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda · Feb 5, 2021 · c5d9117 · c5d9117
1 parent 43ff75f
commit c5d9117
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Showing 7 changed files with 27 additions and 1 deletion.
diff --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.h
@@ -2627,7 +2627,8 @@ enum CXCursorKind {
   CXCursor_WarnUnusedAttr = 439,
   CXCursor_WarnUnusedResultAttr = 440,
   CXCursor_AlignedAttr = 441,
-  CXCursor_LastAttr = CXCursor_AlignedAttr,
+  CXCursor_SafeAttr = 442,
+  CXCursor_LastAttr = CXCursor_SafeAttr,
 
   /* Preprocessing */
   CXCursor_PreprocessingDirective = 500,

diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
@@ -2422,6 +2422,12 @@ def ObjCRequiresPropertyDefs : InheritableAttr {
   let SimpleHandler = 1;
 }
 
+def Safe : InheritableAttr {
+  let Spellings = [C2x<"", "safe">];
+  let Subjects = SubjectList<[Function]>;
+  let Documentation = [Undocumented];
+}
+
 def Unused : InheritableAttr {
   let Spellings = [CXX11<"", "maybe_unused", 201603>, GCC<"unused">,
                    C2x<"", "maybe_unused">];

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -8212,6 +8212,8 @@ def ext_cxx17_attr : Extension<
   "use of the %0 attribute is a C++17 extension">, InGroup<CXX17>;
 def ext_cxx20_attr : Extension<
   "use of the %0 attribute is a C++20 extension">, InGroup<CXX20>;
+def ext_c2x_attr : Extension<
+  "use of the %0 attribute is a C2x extension">, InGroup<C2x>;
 
 def warn_unused_comparison : Warning<
   "%select{equality|inequality|relational|three-way}0 comparison result unused">,

diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -4018,6 +4018,7 @@ static bool IsBuiltInOrStandardCXX11Attribute(IdentifierInfo *AttrName,
   case ParsedAttr::AT_FallThrough:
   case ParsedAttr::AT_CXX11NoReturn:
   case ParsedAttr::AT_NoUniqueAddress:
+  case ParsedAttr::AT_Safe:
     return true;
   case ParsedAttr::AT_WarnUnusedResult:
     return !ScopeName && AttrName->getName().equals("nodiscard");

diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -2153,6 +2153,15 @@ static void handleDependencyAttr(Sema &S, Scope *Scope, Decl *D,
   D->addAttr(::new (S.Context) CarriesDependencyAttr(S.Context, AL));
 }
 
+static void handleSafeAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
+  // If this is spelled as the standard C2x attribute, but not in C2x, warn
+  // about using it as an extension.
+  if (!S.getLangOpts().C2x && AL.isC2xAttribute())
+    S.Diag(AL.getLoc(), diag::ext_c2x_attr) << AL;
+
+  D->addAttr(::new (S.Context) SafeAttr(S.Context, AL));
+}
+
 static void handleUnusedAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
   bool IsCXX17Attr = AL.isCXX11Attribute() && !AL.getScopeName();
 
@@ -7196,6 +7205,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_Unused:
     handleUnusedAttr(S, D, AL);
     break;
+  case ParsedAttr::AT_Safe:
+    handleSafeAttr(S, D, AL);
+    break;
   case ParsedAttr::AT_NotTailCalled:
     handleSimpleAttributeWithExclusions<NotTailCalledAttr, AlwaysInlineAttr>(
         S, D, AL);

diff --git a/clang/tools/libclang/CIndex.cpp b/clang/tools/libclang/CIndex.cpp
@@ -5637,6 +5637,8 @@ CXString clang_getCursorKindSpelling(enum CXCursorKind Kind) {
     return cxstring::createRef("FriendDecl");
   case CXCursor_ConvergentAttr:
     return cxstring::createRef("attribute(convergent)");
+  case CXCursor_SafeAttr:
+    return cxstring::createRef("attribute(safe)");
   case CXCursor_WarnUnusedAttr:
     return cxstring::createRef("attribute(warn_unused)");
   case CXCursor_WarnUnusedResultAttr:

diff --git a/clang/tools/libclang/CXCursor.cpp b/clang/tools/libclang/CXCursor.cpp
@@ -118,6 +118,8 @@ static CXCursorKind GetCursorKind(const Attr *A) {
     return CXCursor_FlagEnum;
   case attr::Convergent:
     return CXCursor_ConvergentAttr;
+  case attr::Safe:
+    return CXCursor_SafeAttr;
   case attr::WarnUnused:
     return CXCursor_WarnUnusedAttr;
   case attr::WarnUnusedResult: