sema: diagnose bad interactions between @available and @_originallyDefinedIn

Author: nkcsgexi

include/swift/AST/DiagnosticsSema.def

@@ -1466,6 +1466,15 @@ NOTE(option_set_empty_set_init,none,
 ERROR(originally_defined_in_dupe_platform,none,
       "duplicate version number for platform %0", (StringRef))
 
+ERROR(originally_definedin_topleve_decl,none,
+      "@%0 is only applicable to top-level decl", (StringRef))
+
+ERROR(originally_definedin_need_available,none,
+      "need @available attribute for @%0", (StringRef))
+
+ERROR(originally_definedin_must_after_available_version,none,
+      "moved version from @%0 must after introduced OS version", (StringRef))
+
 // Alignment attribute
 ERROR(alignment_not_power_of_two,none,
       "alignment value must be a power of two", ())

lib/Sema/TypeCheckAttr.cpp

@@ -252,7 +252,7 @@ class AttributeChecker : public AttributeVisitor<AttributeChecker> {
 
   void visitImplementationOnlyAttr(ImplementationOnlyAttr *attr);
   void visitNonEphemeralAttr(NonEphemeralAttr *attr);
-  void checkOriginalDefinedInAttrs(ArrayRef<OriginallyDefinedInAttr*> Attrs);
+  void checkOriginalDefinedInAttrs(Decl *D, ArrayRef<OriginallyDefinedInAttr*> Attrs);
 };
 } // end anonymous namespace
 
@@ -1070,7 +1070,7 @@ void TypeChecker::checkDeclAttributes(Decl *D) {
     else
       Checker.diagnoseAndRemoveAttr(attr, diag::invalid_decl_attribute, attr);
   }
-  Checker.checkOriginalDefinedInAttrs(ODIAttrs);
+  Checker.checkOriginalDefinedInAttrs(D, ODIAttrs);
 }
 
 /// Returns true if the given method is an valid implementation of a
@@ -2631,21 +2631,48 @@ void TypeChecker::checkParameterAttributes(ParameterList *params) {
   }
 }
 
-void
-AttributeChecker::checkOriginalDefinedInAttrs(
+void AttributeChecker::checkOriginalDefinedInAttrs(Decl *D,
     ArrayRef<OriginallyDefinedInAttr*> Attrs) {
-  llvm::SmallSet<PlatformKind, 4> AllPlatforms;
+  if (Attrs.empty())
+    return;
+  auto &Ctx = D->getASTContext();
+  OriginallyDefinedInAttr* theAttr = nullptr;
   // Attrs are in the reverse order of the source order. We need to visit them
   // in source order to diagnose the later attribute.
-  for (auto It = Attrs.rbegin(), End = Attrs.rend(); It != End; ++ It) {
-    auto *Attr = *It;
-    auto CurPlat = Attr->Platform;
-    if (!AllPlatforms.insert(CurPlat).second) {
+  for (auto *Attr: Attrs) {
+    if (!Attr->isActivePlatform(Ctx))
+      continue;
+    if (theAttr) {
       // Only one version number is allowed for one platform name.
-      diagnose(Attr->AtLoc, diag::originally_defined_in_dupe_platform,
+      diagnose(theAttr->AtLoc, diag::originally_defined_in_dupe_platform,
                platformString(Attr->Platform));
+      return;
+    } else {
+      theAttr = Attr;
     }
   }
+  if (!theAttr)
+    return;
+  assert(theAttr);
+  static StringRef AttrName = "_originallyDefinedIn";
+  auto AtLoc = theAttr->AtLoc;
+  if (!D->getDeclContext()->isModuleScopeContext()) {
+    diagnose(AtLoc, diag::originally_definedin_topleve_decl, AttrName);
+    return;
+  }
+  auto AvailRange = AvailabilityInference::availableRange(D, Ctx);
+  if (!AvailRange.getOSVersion().hasLowerEndpoint()) {
+    diagnose(AtLoc, diag::originally_definedin_need_available,
+             AttrName);
+    return;
+  }
+  auto AvailBegin = AvailRange.getOSVersion().getLowerEndpoint();
+  if (AvailBegin >= theAttr->MovedVersion) {
+    diagnose(AtLoc,
+             diag::originally_definedin_must_after_available_version,
+             AttrName);
+    return;
+  }
 }
 
 Type TypeChecker::checkReferenceOwnershipAttr(VarDecl *var, Type type,

test/Sema/diag_originally_definedin.swift

@@ -0,0 +1,12 @@
+// RUN: %target-typecheck-verify-swift
+// REQUIRES: OS=macosx
+
+@_originallyDefinedIn(module: "original", OSX 10.13) // expected-error {{need @available attribute for @_originallyDefinedIn}}
+public func foo() {}
+
+@available(macOS 10.13, *)
+@_originallyDefinedIn(module: "original", OSX 10.12) // expected-error {{moved version from @_originallyDefinedIn must after introduced OS version}}
+public class C {
+  @_originallyDefinedIn(module: "original", OSX 10.13) // expected-error {{@_originallyDefinedIn is only applicable to top-level decl}}
+  public func foo() {}
+}