Parse attributes on generic type parameter declarations and check availability.

Author: DougGregor

lib/Parse/ParseGeneric.cpp

@@ -43,10 +43,22 @@ ParserResult<GenericParamList> Parser::parseGenericParameters(SourceLoc LAngleLo
   SmallVector<GenericTypeParamDecl *, 4> GenericParams;
   bool Invalid = false;
   do {
+    // Note that we're parsing a declaration.
+    StructureMarkerRAII ParsingDecl(*this, Tok.getLoc(),
+                                    StructureMarkerKind::Declaration);
+
+    // Parse attributes.
+    DeclAttributes attributes;
+    if (Tok.hasComment())
+      attributes.add(new (Context) RawDocCommentAttr(Tok.getCommentRange()));
+    bool foundCCTokenInAttr;
+    parseDeclAttributeList(attributes, foundCCTokenInAttr);
+
     // Parse the name of the parameter.
     Identifier Name;
     SourceLoc NameLoc;
-    if (parseIdentifier(Name, NameLoc, diag::expected_generics_parameter_name)) {
+    if (parseIdentifier(Name, NameLoc,
+                        diag::expected_generics_parameter_name)) {
       Invalid = true;
       break;
     }
@@ -83,6 +95,9 @@ ParserResult<GenericParamList> Parser::parseGenericParameters(SourceLoc LAngleLo
       Param->setInherited(Context.AllocateCopy(Inherited));
     GenericParams.push_back(Param);
 
+    // Attach attributes.
+    Param->getAttrs() = attributes;
+
     // Add this parameter to the scope.
     addToScope(Param);
 

lib/Sema/TypeCheckType.cpp

@@ -1171,6 +1171,15 @@ static bool diagnoseAvailability(Type ty, IdentTypeRepr *IdType, SourceLoc Loc,
       return true;
   }
 
+  if (auto *GPT = dyn_cast<GenericTypeParamType>(ty.getPointer())) {
+    if (auto GP = GPT->getDecl()) {
+      if (checkTypeDeclAvailability(GP, IdType, Loc, DC, TC,
+                                    AllowPotentiallyUnavailableProtocol)) {
+        return true;
+      }
+    }
+  }
+
   // Look through substituted types to diagnose when the original
   // type is marked unavailable.
   if (auto *ST = dyn_cast<SubstitutedType>(ty.getPointer())) {

test/attr/attr_availability.swift

@@ -200,3 +200,7 @@ func OutputStreamTest(message: String, inout to: OutputStreamType) {
   print(message, &to)  // expected-error {{'print' is unavailable: Please use the 'toStream' label for the target stream: 'print((...), toStream: &...)'}}
 }
 
+// expected-note@+1{{'T' has been explicitly marked unavailable here}}
+struct UnavailableGenericParam<@available(*, unavailable, message="nope") T> {
+  func f(t: T) { } // expected-error{{'T' is unavailable: nope}}
+}