AST: Remove runtime version from AvailabilitySpec.

Instead of canonicalizing platform versions during parsing and storing two
versions, just canonicalize the parsed version on-demand when its requested.

Author: tshortli

include/swift/AST/ASTBridging.h

@@ -654,12 +654,12 @@ BridgedSourceRange
 BridgedAvailabilitySpec_getVersionRange(BridgedAvailabilitySpec spec);
 
 SWIFT_NAME("BridgedPlatformVersionConstraintAvailabilitySpec.createParsed(_:"
-           "platform:platformLoc:version:runtimeVersion:versionRange:)")
+           "platform:platformLoc:version:versionRange:)")
 BridgedPlatformVersionConstraintAvailabilitySpec
 BridgedPlatformVersionConstraintAvailabilitySpec_createParsed(
     BridgedASTContext cContext, BridgedPlatformKind cPlatform,
     BridgedSourceLoc cPlatformLoc, BridgedVersionTuple cVersion,
-    BridgedVersionTuple cRuntimeVersion, BridgedSourceRange cVersionSrcRange);
+    BridgedSourceRange cVersionSrcRange);
 
 SWIFT_NAME("BridgedPlatformAgnosticVersionConstraintAvailabilitySpec."
            "createParsed(_:kind:nameLoc:version:versionRange:)")

include/swift/AST/AvailabilitySpec.h

@@ -75,20 +75,6 @@ class PlatformVersionConstraintAvailabilitySpec : public AvailabilitySpec {
 
   llvm::VersionTuple Version;
 
-  // For macOS Big Sur, we canonicalize 10.16 to 11.0 for compile-time
-  // checking since clang canonicalizes availability markup. However, to
-  // support Beta versions of macOS Big Sur where the OS
-  // reports 10.16 at run time, we need to compare against 10.16,
-  //
-  // This means for:
-  //
-  // if #available(macOS 10.16, *) { ... }
-  //
-  // we need to keep around both a canonical version for use in compile-time
-  // checks and an uncanonicalized version for the version to actually codegen
-  // with.
-  llvm::VersionTuple RuntimeVersion;
-
   SourceRange VersionSrcRange;
 
   // Location of the macro expanded to create this spec.
@@ -98,13 +84,10 @@ class PlatformVersionConstraintAvailabilitySpec : public AvailabilitySpec {
   PlatformVersionConstraintAvailabilitySpec(PlatformKind Platform,
                                             SourceLoc PlatformLoc,
                                             llvm::VersionTuple Version,
-                                            llvm::VersionTuple RuntimeVersion,
                                             SourceRange VersionSrcRange)
-    : AvailabilitySpec(AvailabilitySpecKind::PlatformVersionConstraint),
-      Platform(Platform),
-      PlatformLoc(PlatformLoc), Version(Version),
-      RuntimeVersion(RuntimeVersion),
-      VersionSrcRange(VersionSrcRange) {}
+      : AvailabilitySpec(AvailabilitySpecKind::PlatformVersionConstraint),
+        Platform(Platform), PlatformLoc(PlatformLoc), Version(Version),
+        VersionSrcRange(VersionSrcRange) {}
 
   /// The required platform.
   PlatformKind getPlatform() const { return Platform; }
@@ -116,13 +99,13 @@ class PlatformVersionConstraintAvailabilitySpec : public AvailabilitySpec {
   bool isUnrecognizedPlatform() const { return Platform == PlatformKind::none; }
 
   // The platform version to compare against.
-  llvm::VersionTuple getVersion() const { return Version; }
+  llvm::VersionTuple getVersion() const;
   SourceRange getVersionSrcRange() const { return VersionSrcRange; }
 
   // 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.
-  llvm::VersionTuple getRuntimeVersion() const { return RuntimeVersion; }
+  llvm::VersionTuple getRuntimeVersion() const;
 
   SourceRange getSourceRange() const;
 

lib/AST/AvailabilitySpec.cpp

@@ -116,6 +116,27 @@ SourceRange PlatformAgnosticVersionConstraintAvailabilitySpec::getSourceRange()
   return SourceRange(PlatformAgnosticNameLoc, VersionSrcRange.End);
 }
 
+llvm::VersionTuple
+PlatformVersionConstraintAvailabilitySpec::getVersion() const {
+  // For macOS Big Sur, we canonicalize 10.16 to 11.0 for compile-time
+  // checking since clang canonicalizes availability markup. However, to
+  // support Beta versions of macOS Big Sur where the OS
+  // reports 10.16 at run time, we need to compare against 10.16,
+  //
+  // This means for:
+  //
+  // if #available(macOS 10.16, *) { ... }
+  //
+  // we need to store the uncanonicalized version for codegen and canonicalize
+  // it as necessary for compile-time checks.
+  return canonicalizePlatformVersion(Platform, Version);
+}
+
+llvm::VersionTuple
+PlatformVersionConstraintAvailabilitySpec::getRuntimeVersion() const {
+  return Version;
+}
+
 void PlatformAgnosticVersionConstraintAvailabilitySpec::print(raw_ostream &OS,
                                                       unsigned Indent) const {
   OS.indent(Indent) << '('

lib/AST/Bridging/AvailabilityBridging.cpp

@@ -135,10 +135,10 @@ BridgedPlatformVersionConstraintAvailabilitySpec
 BridgedPlatformVersionConstraintAvailabilitySpec_createParsed(
     BridgedASTContext cContext, BridgedPlatformKind cPlatform,
     BridgedSourceLoc cPlatformLoc, BridgedVersionTuple cVersion,
-    BridgedVersionTuple cRuntimeVersion, BridgedSourceRange cVersionSrcRange) {
+    BridgedSourceRange cVersionSrcRange) {
   return new (cContext.unbridged()) PlatformVersionConstraintAvailabilitySpec(
       unbridge(cPlatform), cPlatformLoc.unbridged(), cVersion.unbridged(),
-      cRuntimeVersion.unbridged(), cVersionSrcRange.unbridged());
+      cVersionSrcRange.unbridged());
 }
 
 BridgedPlatformAgnosticVersionConstraintAvailabilitySpec

lib/ASTGen/Sources/ASTGen/Availability.swift

@@ -334,7 +334,6 @@ extension ASTGenVisitor {
             platform: platform,
             platformLoc: nameLoc,
             version: version.bridged,
-            runtimeVersion: version.bridged,
             versionRange: versionRange
           )
           result.append(spec.asAvailabilitySpec)

lib/Parse/ParseExpr.cpp

@@ -3787,11 +3787,7 @@ Parser::parsePlatformVersionConstraintSpec() {
   // Register the platform name as a keyword token.
   TokReceiver->registerTokenKindChange(PlatformLoc, tok::contextual_keyword);
 
-  // Keep the original version around for run-time checks to support
-  // macOS Big Sur betas that report 10.16 at
-  // run time.
-  llvm::VersionTuple RuntimeVersion = Version;
-  Version = canonicalizePlatformVersion(*Platform, Version);
-  return makeParserResult(new (Context) PlatformVersionConstraintAvailabilitySpec(
-      Platform.value(), PlatformLoc, Version, RuntimeVersion, VersionRange));
+  return makeParserResult(
+      new (Context) PlatformVersionConstraintAvailabilitySpec(
+          Platform.value(), PlatformLoc, Version, VersionRange));
 }

lib/Sema/DerivedConformanceRawRepresentable.cpp

@@ -201,9 +201,7 @@ struct RuntimeVersionCheck {
   Stmt *createEarlyReturnStmt(ASTContext &C) const {
     // platformSpec = "\(attr.platform) \(attr.introduced)"
     auto platformSpec = new (C) PlatformVersionConstraintAvailabilitySpec(
-                            Platform, SourceLoc(),
-                            Version, Version, SourceLoc()
-                        );
+        Platform, SourceLoc(), Version, SourceLoc());
 
     // otherSpec = "*"
     auto otherSpec = new (C) OtherPlatformAvailabilitySpec(SourceLoc());