AST: Introduce AvailabilityContext::forDeploymentTarget().

Author: tshortli

include/swift/AST/AvailabilityContext.h

@@ -44,19 +44,28 @@ class AvailabilityContext {
 
   AvailabilityContext(const Storage *info) : Info(info) { assert(info); };
 
-  /// Retrieves a uniqued `AvailabilityContext` with the given platform
-  /// availability parameters.
+  /// Retrieves an `AvailabilityContext` with the given platform availability
+  /// parameters.
   static AvailabilityContext
   get(const AvailabilityRange &platformAvailability,
       std::optional<PlatformKind> unavailablePlatform, bool deprecated,
       ASTContext &ctx);
 
 public:
+  /// Retrieves an `AvailabilityContext` constrained by the given platform
+  /// availability range.
+  static AvailabilityContext forPlatformRange(const AvailabilityRange &range,
+                                              ASTContext &ctx);
+
   /// Retrieves the maximally available `AvailabilityContext` for the
   /// compilation. The platform availability range will be set to the minimum
   /// inlining target (which may just be the deployment target).
   static AvailabilityContext forInliningTarget(ASTContext &ctx);
 
+  /// Retrieves an `AvailabilityContext` with the platform availability range
+  /// set to the deployment target.
+  static AvailabilityContext forDeploymentTarget(ASTContext &ctx);
+
   /// Returns the range of platform versions which may execute code in the
   /// availability context, starting at its introduction version.
   AvailabilityRange getPlatformRange() const;

lib/AST/AvailabilityContext.cpp

@@ -124,15 +124,26 @@ void AvailabilityContext::Storage::Profile(llvm::FoldingSetNodeID &id) const {
   Platform.Profile(id);
 }
 
-AvailabilityContext AvailabilityContext::forInliningTarget(ASTContext &ctx) {
-  PlatformInfo platformInfo{AvailabilityRange::forInliningTarget(ctx),
-                            PlatformKind::none,
+AvailabilityContext
+AvailabilityContext::forPlatformRange(const AvailabilityRange &range,
+                                      ASTContext &ctx) {
+  PlatformInfo platformInfo{range, PlatformKind::none,
                             /*IsUnavailable*/ false,
                             /*IsUnavailableInEmbedded*/ false,
                             /*IsDeprecated*/ false};
   return AvailabilityContext(Storage::get(platformInfo, ctx));
 }
 
+AvailabilityContext AvailabilityContext::forInliningTarget(ASTContext &ctx) {
+  return AvailabilityContext::forPlatformRange(
+      AvailabilityRange::forInliningTarget(ctx), ctx);
+}
+
+AvailabilityContext AvailabilityContext::forDeploymentTarget(ASTContext &ctx) {
+  return AvailabilityContext::forPlatformRange(
+      AvailabilityRange::forDeploymentTarget(ctx), ctx);
+}
+
 AvailabilityContext
 AvailabilityContext::get(const AvailabilityRange &platformAvailability,
                          std::optional<PlatformKind> unavailablePlatform,