AST: Simplify AvailabilitySpec subclasses further.

Remove methods that are specific to AvailabilitySpec subclasses and replace
them with methods on the superclass if necessary.

NFC.

Author: tshortli

include/swift/AST/AvailabilitySpec.h

@@ -76,10 +76,15 @@ class AvailabilitySpec : public ASTAllocated<AvailabilitySpec> {
   AvailabilitySpecKind getKind() const { return Kind; }
 
   SourceRange getSourceRange() const { return SrcRange; }
+  SourceLoc getStartLoc() const { return SrcRange.Start; }
 
   std::optional<AvailabilityDomain> getDomain() const { return Domain; }
 
-  std::optional<PlatformKind> getPlatform() const;
+  PlatformKind getPlatform() const {
+    if (auto domain = getDomain())
+      return domain->getPlatformKind();
+    return PlatformKind::none;
+  }
 
   // The platform version to compare against.
   llvm::VersionTuple getVersion() const;
@@ -114,22 +119,6 @@ class PlatformVersionConstraintAvailabilitySpec : public AvailabilitySpec {
                          getDomainForPlatform(Platform),
                          SourceRange(PlatformLoc, VersionSrcRange.End), Version,
                          VersionSrcRange.Start) {}
-
-  /// The required platform.
-  PlatformKind getPlatform() const {
-    if (auto domain = getDomain())
-      return domain->getPlatformKind();
-    return PlatformKind::none;
-  }
-  SourceLoc getPlatformLoc() const { return getSourceRange().Start; }
-
-  /// Returns true when the constraint is for a platform that was not
-  /// recognized. This enables better recovery during parsing but should never
-  /// be true after parsing is completed.
-  bool isUnrecognizedPlatform() const {
-    return getPlatform() == PlatformKind::none;
-  }
-
   // The version to be used in codegen for version comparisons at run time.
   // This is required to support beta versions of macOS Big Sur that
   // report 10.16 at run time.
@@ -180,14 +169,6 @@ class PlatformAgnosticVersionConstraintAvailabilitySpec
            AvailabilitySpecKind == AvailabilitySpecKind::PackageDescriptionVersionConstraint);
   }
 
-  SourceLoc getPlatformAgnosticNameLoc() const {
-    return getSourceRange().Start;
-  }
-
-  bool isLanguageVersionSpecific() const {
-      return getKind() == AvailabilitySpecKind::LanguageVersionConstraint;
-  }
-
   void print(raw_ostream &OS, unsigned Indent) const;
 
   static bool classof(const AvailabilitySpec *Spec) {
@@ -220,8 +201,6 @@ class OtherPlatformAvailabilitySpec : public AvailabilitySpec {
                          /*Version=*/{},
                          /*VersionStartLoc=*/{}) {}
 
-  SourceLoc getStarLoc() const { return getSourceRange().Start; }
-
   void print(raw_ostream &OS, unsigned Indent) const;
 
   static bool classof(const AvailabilitySpec *Spec) {

lib/AST/ASTDumper.cpp

@@ -1118,7 +1118,7 @@ namespace {
               printHead("platform_agnostic_version_constraint_"
                         "availability_spec",
                         PatternColor, label);
-              printField(agnostic->isLanguageVersionSpecific()
+              printField(agnostic->getDomain()->isSwiftLanguage()
                              ? "swift"
                              : "package_description",
                          Label::always("kind"));

lib/AST/AvailabilitySpec.cpp

@@ -21,20 +21,6 @@
 
 using namespace swift;
 
-std::optional<PlatformKind> AvailabilitySpec::getPlatform() const {
-  switch (getKind()) {
-  case AvailabilitySpecKind::PlatformVersionConstraint: {
-    auto spec = cast<PlatformVersionConstraintAvailabilitySpec>(this);
-    return spec->getPlatform();
-  }
-  case AvailabilitySpecKind::LanguageVersionConstraint:
-  case AvailabilitySpecKind::PackageDescriptionVersionConstraint:
-  case AvailabilitySpecKind::OtherPlatform:
-    return std::nullopt;
-  }
-  llvm_unreachable("bad AvailabilitySpecKind");
-}
-
 llvm::VersionTuple AvailabilitySpec::getVersion() const {
   switch (getKind()) {
   case AvailabilitySpecKind::PlatformVersionConstraint: {
@@ -77,7 +63,7 @@ void PlatformAgnosticVersionConstraintAvailabilitySpec::print(raw_ostream &OS,
   OS.indent(Indent) << '('
                     << "platform_agnostic_version_constraint_availability_spec"
                     << " kind='"
-                    << (isLanguageVersionSpecific() ?
+                    << (getDomain()->isSwiftLanguage() ?
                          "swift" : "package_description")
                     << "'"
                     << " version='" << getVersion() << "'"

lib/AST/Bridging/AvailabilityBridging.cpp

@@ -101,10 +101,7 @@ BridgedAvailabilitySpec_getDomain(BridgedAvailabilitySpec spec) {
 
 BridgedPlatformKind
 BridgedAvailabilitySpec_getPlatform(BridgedAvailabilitySpec spec) {
-  auto platform = spec.unbridged()->getPlatform();
-  if (platform)
-    return bridge(*platform);
-  return BridgedPlatformKind_None;
+  return bridge(spec.unbridged()->getPlatform());
 }
 
 BridgedVersionTuple

lib/Parse/ParseDecl.cpp

@@ -1877,15 +1877,15 @@ ParserStatus Parser::parsePlatformVersionInList(StringRef AttrName,
       auto Platform = Spec->getPlatform();
       // Since peekAvailabilityMacroName() only matches defined availability
       // macros, we only expect platform specific constraints here.
-      assert(Platform && "Unexpected AvailabilitySpec kind");
+      DEBUG_ASSERT(Platform != PlatformKind::none);
 
       auto Version = Spec->getVersion();
       if (Version.getSubminor().has_value() || Version.getBuild().has_value()) {
         diagnose(Spec->getVersionSrcRange().Start,
                  diag::attr_availability_platform_version_major_minor_only,
                  AttrName);
       }
-      PlatformAndVersions.emplace_back(*Platform, Version);
+      PlatformAndVersions.emplace_back(Platform, Version);
     }
 
     return makeParserSuccess();

lib/Parse/ParseStmt.cpp

@@ -1306,24 +1306,25 @@ validateAvailabilitySpecList(Parser &P,
   for (auto *Spec : Specs) {
     RecognizedSpecs.push_back(Spec);
     if (auto *OtherPlatSpec = dyn_cast<OtherPlatformAvailabilitySpec>(Spec)) {
-      OtherPlatformSpecLoc = OtherPlatSpec->getStarLoc();
+      OtherPlatformSpecLoc = OtherPlatSpec->getStartLoc();
       continue;
     }
 
     if (auto *PlatformAgnosticSpec =
          dyn_cast<PlatformAgnosticVersionConstraintAvailabilitySpec>(Spec)) {
-      P.diagnose(PlatformAgnosticSpec->getPlatformAgnosticNameLoc(),
+      bool isLanguageVersionSpecific = PlatformAgnosticSpec->getDomain()->isSwiftLanguage();
+      P.diagnose(PlatformAgnosticSpec->getStartLoc(),
                  diag::availability_must_occur_alone,
-                 PlatformAgnosticSpec->isLanguageVersionSpecific() 
-                   ? "swift" 
-                   : "_PackageDescription");
+                 isLanguageVersionSpecific
+                     ? "swift"
+                     : "_PackageDescription");
       continue;
     }
 
     auto *VersionSpec = cast<PlatformVersionConstraintAvailabilitySpec>(Spec);
     // We keep specs for unrecognized platforms around for error recovery
     // during parsing but remove them once parsing is completed.
-    if (VersionSpec->isUnrecognizedPlatform()) {
+    if (!VersionSpec->getDomain().has_value()) {
       RecognizedSpecs.pop_back();
       continue;
     }
@@ -1334,7 +1335,7 @@ validateAvailabilitySpecList(Parser &P,
       // For example, we emit an error for
       /// #available(OSX 10.10, OSX 10.11, *)
       PlatformKind Platform = VersionSpec->getPlatform();
-      P.diagnose(VersionSpec->getPlatformLoc(),
+      P.diagnose(VersionSpec->getStartLoc(),
                  diag::availability_query_repeated_platform,
                  platformString(Platform));
     }
@@ -1404,8 +1405,9 @@ ParserResult<PoundAvailableInfo> Parser::parseStmtConditionPoundAvailable() {
   for (auto *Spec : Specs) {
     if (auto *PlatformAgnostic =
           dyn_cast<PlatformAgnosticVersionConstraintAvailabilitySpec>(Spec)) {
-      diagnose(PlatformAgnostic->getPlatformAgnosticNameLoc(),
-               PlatformAgnostic->isLanguageVersionSpecific()
+      bool isLanguageVersionSpecific = PlatformAgnostic->getDomain()->isSwiftLanguage();
+      diagnose(PlatformAgnostic->getStartLoc(),
+               isLanguageVersionSpecific
                    ? diag::pound_available_swift_not_allowed
                    : diag::pound_available_package_description_not_allowed,
                getTokenText(MainToken));
@@ -1551,11 +1553,10 @@ Parser::parseAvailabilitySpecList(SmallVectorImpl<AvailabilitySpec *> &Specs,
             auto *PlatformSpec =
                 cast<PlatformVersionConstraintAvailabilitySpec>(Previous);
 
-            auto PlatformNameEndLoc =
-              Lexer::getLocForEndOfToken(SourceManager,
-                                         PlatformSpec->getPlatformLoc());
+            auto PlatformNameEndLoc = Lexer::getLocForEndOfToken(
+                SourceManager, PlatformSpec->getStartLoc());
 
-            diagnose(PlatformSpec->getPlatformLoc(),
+            diagnose(PlatformSpec->getStartLoc(),
                      diag::avail_query_meant_introduced)
                 .fixItInsert(PlatformNameEndLoc, ", introduced:");
           }