[Sema] Allow unrecognized platforms in @backDeployed and @_originallyDefinedIn

Don't emit attr_availability_need_platform_version for a @backDeployed or @_originallyDefinedIn that have a single unrecognized platform name.

include/swift/Parse/Parser.h

@@ -2104,12 +2104,15 @@ public:
 
   using PlatformAndVersion = std::pair<PlatformKind, llvm::VersionTuple>;
 
-  /// Parse a platform and version tuple (e.g. "macOS 12.0") and append it to the
-  /// given vector. Wildcards ('*') parse successfully but are ignored. Assumes
-  /// that the tuples are part of a comma separated list ending with a trailing
-  /// ')'.
-  ParserStatus parsePlatformVersionInList(StringRef AttrName,
-      llvm::SmallVector<PlatformAndVersion, 4> &PlatformAndVersions);
+  /// Parse a platform and version tuple (e.g. "macOS 12.0") and append it to
+  /// the given vector. Wildcards ('*') parse successfully but are ignored.
+  /// Unrecognized platform names also parse successfully but are ignored.
+  /// Assumes that the tuples are part of a comma separated list ending with a
+  /// trailing ')'.
+  ParserStatus parsePlatformVersionInList(
+      StringRef AttrName,
+      llvm::SmallVector<PlatformAndVersion, 4> & PlatformAndVersions,
+      bool &ParsedUnrecognizedPlatformName);
 
   //===--------------------------------------------------------------------===//
   // Code completion second pass.

lib/Parse/ParseDecl.cpp

@@ -2189,7 +2189,8 @@ void Parser::parseAllAvailabilityMacroArguments() {
 }
 
 ParserStatus Parser::parsePlatformVersionInList(StringRef AttrName,
-    llvm::SmallVector<PlatformAndVersion, 4> &PlatformAndVersions) {
+    llvm::SmallVector<PlatformAndVersion, 4> &PlatformAndVersions,
+    bool &ParsedUnrecognizedPlatformName) {
   // Check for availability macros first.
   if (peekAvailabilityMacroName()) {
     SmallVector<AvailabilitySpec *, 4> Specs;
@@ -2226,6 +2227,7 @@ ParserStatus Parser::parsePlatformVersionInList(StringRef AttrName,
   // Parse the platform name.
   StringRef platformText = Tok.getText();
   auto MaybePlatform = platformFromString(platformText);
+  ParsedUnrecognizedPlatformName = !MaybePlatform.has_value();
   SourceLoc PlatformLoc = Tok.getLoc();
   consumeToken();
 
@@ -2288,6 +2290,7 @@ bool Parser::parseBackDeployedAttribute(DeclAttributes &Attributes,
   SourceLoc RightLoc;
   ParserStatus Status;
   bool SuppressLaterDiags = false;
+  bool ParsedUnrecognizedPlatformName = false;
   llvm::SmallVector<PlatformAndVersion, 4> PlatformAndVersions;
 
   {
@@ -2306,12 +2309,12 @@ bool Parser::parseBackDeployedAttribute(DeclAttributes &Attributes,
     if (!Tok.is(tok::r_paren)) {
       ParseListItemResult Result;
       do {
-        Result = parseListItem(Status, tok::r_paren, LeftLoc, RightLoc,
-                               /*AllowSepAfterLast=*/false,
-                               [&]() -> ParserStatus {
-                                 return parsePlatformVersionInList(
-                                     AtAttrName, PlatformAndVersions);
-                               });
+        Result = parseListItem(
+            Status, tok::r_paren, LeftLoc, RightLoc,
+            /*AllowSepAfterLast=*/false, [&]() -> ParserStatus {
+              return parsePlatformVersionInList(AtAttrName, PlatformAndVersions,
+                                                ParsedUnrecognizedPlatformName);
+            });
       } while (Result == ParseListItemResult::Continue);
     }
   }
@@ -2324,12 +2327,11 @@ bool Parser::parseBackDeployedAttribute(DeclAttributes &Attributes,
     return false;
   }
 
-  if (PlatformAndVersions.empty()) {
+  if (PlatformAndVersions.empty() && !ParsedUnrecognizedPlatformName) {
     diagnose(Loc, diag::attr_availability_need_platform_version, AtAttrName);
     return false;
   }
 
-  assert(!PlatformAndVersions.empty());
   auto AttrRange = SourceRange(Loc, RightLoc);
   for (auto &Item : PlatformAndVersions) {
     Attributes.add(new (Context) BackDeployedAttr(AtLoc, AttrRange, Item.first,
@@ -3445,6 +3447,7 @@ ParserStatus Parser::parseNewDeclAttribute(DeclAttributes &Attributes,
 
     StringRef AttrName = "@_originallyDefinedIn";
     bool SuppressLaterDiags = false;
+    bool ParsedUnrecognizedPlatformName = false;
     if (parseList(tok::r_paren, LeftLoc, RightLoc, false,
                   diag::originally_defined_in_missing_rparen,
                   [&]() -> ParserStatus {
@@ -3484,8 +3487,8 @@ ParserStatus Parser::parseNewDeclAttribute(DeclAttributes &Attributes,
       }
       // Parse 'OSX 13.13'.
       case NextSegmentKind::PlatformVersion: {
-        ParserStatus ListItemStatus =
-            parsePlatformVersionInList(AttrName, PlatformAndVersions);
+        ParserStatus ListItemStatus = parsePlatformVersionInList(
+            AttrName, PlatformAndVersions, ParsedUnrecognizedPlatformName);
         if (ListItemStatus.isErrorOrHasCompletion())
           SuppressLaterDiags = true;
         return ListItemStatus;
@@ -3499,13 +3502,13 @@ ParserStatus Parser::parseNewDeclAttribute(DeclAttributes &Attributes,
       diagnose(AtLoc, diag::originally_defined_in_need_nonempty_module_name);
       return makeParserSuccess();
     }
-    if (PlatformAndVersions.empty()) {
+
+    if (PlatformAndVersions.empty() && !ParsedUnrecognizedPlatformName) {
       diagnose(AtLoc, diag::attr_availability_need_platform_version, AttrName);
       return makeParserSuccess();
     }
 
     assert(!OriginalModuleName.empty());
-    assert(!PlatformAndVersions.empty());
     assert(NK == NextSegmentKind::PlatformVersion);
     AttrRange = SourceRange(Loc, RightLoc);
     for (auto &Item: PlatformAndVersions) {

test/Sema/diag_originally_definedin.swift

@@ -34,30 +34,24 @@ public func macroUnknown() {}
 
 @available(macOS 10.9, *)
 @_originallyDefinedIn(module: "original", macos 10.13) // expected-warning {{unknown platform 'macos' for attribute '@_originallyDefinedIn'; did you mean 'macOS'?}} {{43-48=macOS}}
-// expected-error@-1 {{expected at least one platform version in '@_originallyDefinedIn' attribute}}
 public func incorrectPlatformCase() {}
 
 @available(macOS 10.9, *)
 @_originallyDefinedIn(module: "original", mscos 10.13) // expected-warning {{unknown platform 'mscos' for attribute '@_originallyDefinedIn'; did you mean 'macOS'?}} {{43-48=macOS}}
-// expected-error@-1 {{expected at least one platform version in '@_originallyDefinedIn' attribute}}
 public func incorrectPlatformSimilar1() {}
 
 @available(macOS 10.9, *)
 @_originallyDefinedIn(module: "original", macoss 10.13) // expected-warning {{unknown platform 'macoss' for attribute '@_originallyDefinedIn'; did you mean 'macOS'?}} {{43-49=macOS}}
-// expected-error@-1 {{expected at least one platform version in '@_originallyDefinedIn' attribute}}
 public func incorrectPlatformSimilar2() {}
 
 @available(macOS 10.9, *)
 @_originallyDefinedIn(module: "original", mac 10.13) // expected-warning {{unknown platform 'mac' for attribute '@_originallyDefinedIn'; did you mean 'macOS'?}} {{43-46=macOS}}
-// expected-error@-1 {{expected at least one platform version in '@_originallyDefinedIn' attribute}}
 public func incorrectPlatformSimilar3() {}
 
 @available(macOS 10.9, *)
 @_originallyDefinedIn(module: "original", notValid 10.13) // expected-warning {{unknown platform 'notValid' for attribute '@_originallyDefinedIn'}} {{none}}
-// expected-error@-1 {{expected at least one platform version in '@_originallyDefinedIn' attribute}}
 public func incorrectPlatformNotSimilar() {}
 
 @available(macOS 10.9, *)
 @_originallyDefinedIn(module: "original", swift 5.1) // expected-warning {{unknown platform 'swift' for attribute '@_originallyDefinedIn'}}
-// expected-error@-1 {{expected at least one platform version in '@_originallyDefinedIn' attribute}}
 public func swiftVersionMacro() {}

test/attr/Inputs/SymbolMove/LowLevel.swift

@@ -5,7 +5,9 @@ public func printMessageMoved() {
 }
 
 @available(OSX 10.7, iOS 7.0, *)
+@available(unrecognizedOS 1.0, *)
 @_originallyDefinedIn(module: "HighLevel", OSX 10.9, iOS 13.0)
+@_originallyDefinedIn(module: "HighLevel", unrecognizedOS 2.0)
 public struct Entity {
     public let value = "LowLevel"
     public init() {}

test/attr/attr_backDeployed.swift

@@ -367,7 +367,11 @@ public func incorrectPlatformCaseFunc() {}
 public func incorrectPlatformSimilarFunc() {}
 
 @backDeployed(before: macOS 12.0, unknownOS 1.0) // expected-warning {{unknown platform 'unknownOS' for attribute '@backDeployed'}}
-public func unknownOSFunc() {}
+public func unknownOSFunc1() {}
+
+@backDeployed(before: macOS 12.0)
+@backDeployed(before: unknownOS 1.0) // expected-warning {{unknown platform 'unknownOS' for attribute '@backDeployed'}}
+public func unknownOSFunc2() {}
 
 @backDeployed(before: @) // expected-error {{expected platform in '@backDeployed' attribute}}
 public func badPlatformFunc1() {}
@@ -414,7 +418,6 @@ public func missingMacroVersion() {}
 public func unknownMacroMissingVersion() {}
 
 @backDeployed(before: _unknownMacro 1.0) // expected-warning {{unknown platform '_unknownMacro' for attribute '@backDeployed'}}
-// expected-error@-1 {{expected at least one platform version in '@backDeployed' attribute}}
 public func unknownMacroVersioned() {}
 
 @backDeployed(before: _unknownMacro 1.0, _myProject 2.0) // expected-warning {{unknown platform '_unknownMacro' for attribute '@backDeployed'}}