[6.2][Frontend] Add a way to print features supported by the compiler

include/swift/AST/DiagnosticsFrontend.def

@@ -59,9 +59,9 @@ GROUPED_WARNING(cannot_disable_feature_with_mode, StrictLanguageFeatures, none,
                 "'%0' argument '%1' cannot specify a mode",
                 (StringRef, StringRef))
 
-GROUPED_WARNING(feature_does_not_support_adoption_mode, StrictLanguageFeatures,
+GROUPED_WARNING(feature_does_not_support_migration_mode, StrictLanguageFeatures,
                 none,
-                "feature '%0' does not support adoption mode",
+                "feature '%0' does not support migration mode",
                 (StringRef))
 
 ERROR(error_unknown_library_level, none,

include/swift/Basic/Feature.h

@@ -10,8 +10,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef SWIFT_BASIC_FEATURES_H
-#define SWIFT_BASIC_FEATURES_H
+#ifndef SWIFT_BASIC_FEATURE_H
+#define SWIFT_BASIC_FEATURE_H
+
+#include "swift/Basic/LLVM.h"
 
 #include "llvm/ADT/StringRef.h"
 #include <optional>
@@ -21,53 +23,72 @@ namespace swift {
 class LangOptions;
 
 /// Enumeration describing all of the named features.
-enum class Feature : uint16_t {
+struct Feature {
+  enum class InnerKind : uint16_t {
 #define LANGUAGE_FEATURE(FeatureName, SENumber, Description) FeatureName,
 #include "swift/Basic/Features.def"
-};
+  };
+
+  InnerKind kind;
 
-constexpr unsigned numFeatures() {
-  enum Features {
+  constexpr Feature(InnerKind kind) : kind(kind) {}
+  constexpr Feature(unsigned inputKind) : kind(InnerKind(inputKind)) {}
+
+  constexpr operator InnerKind() const { return kind; }
+  constexpr explicit operator unsigned() const { return unsigned(kind); }
+  constexpr explicit operator size_t() const { return size_t(kind); }
+
+  static constexpr unsigned getNumFeatures() {
+    enum Features {
 #define LANGUAGE_FEATURE(FeatureName, SENumber, Description) FeatureName,
 #include "swift/Basic/Features.def"
-    NumFeatures
-  };
-  return NumFeatures;
-}
+      NumFeatures
+    };
+    return NumFeatures;
+  }
 
-/// Check whether the given feature is available in production compilers.
-bool isFeatureAvailableInProduction(Feature feature);
+#define LANGUAGE_FEATURE(FeatureName, SENumber, Description)                   \
+  static const Feature FeatureName;
+#include "swift/Basic/Features.def"
 
-/// Determine the in-source name of the given feature.
-llvm::StringRef getFeatureName(Feature feature);
+  /// Check whether the given feature is available in production compilers.
+  bool isAvailableInProduction() const;
 
-/// Determine whether the first feature is more recent (and thus implies
-/// the existence of) the second feature.  Only meaningful for suppressible
-/// features.
-inline bool featureImpliesFeature(Feature feature, Feature implied) {
-  // Suppressible features are expected to be listed in order of
-  // addition in Features.def.
-  return (unsigned) feature < (unsigned) implied;
-}
+  /// Determine the in-source name of the given feature.
+  llvm::StringRef getName() const;
 
-/// Get the feature corresponding to this "future" feature, if there is one.
-std::optional<Feature> getUpcomingFeature(llvm::StringRef name);
+  /// Determine whether the given feature supports migration mode.
+  bool isMigratable() const;
 
-/// Get the feature corresponding to this "experimental" feature, if there is
-/// one.
-std::optional<Feature> getExperimentalFeature(llvm::StringRef name);
+  /// Determine whether this feature should be included in the
+  /// module interface
+  bool includeInModuleInterface() const;
 
-/// Get the major language version in which this feature was introduced, or
-/// \c None if it does not have such a version.
-std::optional<unsigned> getFeatureLanguageVersion(Feature feature);
+  /// Determine whether the first feature is more recent (and thus implies
+  /// the existence of) the second feature.  Only meaningful for suppressible
+  /// features.
+  constexpr bool featureImpliesFeature(Feature implied) const {
+    // Suppressible features are expected to be listed in order of
+    // addition in Features.def.
+    return (unsigned)kind < (unsigned)implied.kind;
+  }
 
-/// Determine whether the given feature supports adoption mode.
-bool isFeatureAdoptable(Feature feature);
+  /// Get the feature corresponding to this "future" feature, if there is one.
+  static std::optional<Feature> getUpcomingFeature(StringRef name);
 
-/// Determine whether this feature should be included in the
-/// module interface
-bool includeInModuleInterface(Feature feature);
+  /// Get the feature corresponding to this "experimental" feature, if there is
+  /// one.
+  static std::optional<Feature> getExperimentalFeature(StringRef name);
 
+  /// Get the major language version in which this feature was introduced, or
+  /// \c None if it does not have such a version.
+  std::optional<unsigned> getLanguageVersion() const;
+};
+
+#define LANGUAGE_FEATURE(FeatureName, SENumber, Description)                   \
+  constexpr inline Feature Feature::FeatureName =                              \
+      Feature::InnerKind::FeatureName;
+#include "swift/Basic/Features.def"
 }
 
 #endif // SWIFT_BASIC_FEATURES_H

include/swift/Basic/Features.def

@@ -121,36 +121,36 @@
     LANGUAGE_FEATURE(FeatureName, SENumber, Description)
 #endif
 
-// An upcoming feature that supports adoption mode.
+// An upcoming feature that supports migration mode.
 //
 // If the feature is source-breaking and provides for a
-// mechanical code migration, it should implement adoption mode.
+// mechanical code migration, it should implement migration mode.
 //
-// Adoption mode is a feature-oriented code migration mechanism: a mode
+// Migration mode is a feature-oriented code migration mechanism: a mode
 // of operation that should produce compiler warnings with attached
 // fix-its that can be applied to preserve the behavior of the code once
 // the upcoming feature is enacted.
 // These warnings must belong to a diagnostic group named after the
-// feature. Adoption mode itself *and* the fix-its it produces must be
+// feature. Migration mode itself *and* the fix-its it produces must be
 // source and binary compatible with how the code is compiled when the
 // feature is disabled.
-#ifndef ADOPTABLE_UPCOMING_FEATURE
+#ifndef MIGRATABLE_UPCOMING_FEATURE
   #if defined(UPCOMING_FEATURE)
-    #define ADOPTABLE_UPCOMING_FEATURE(FeatureName, SENumber, Version)         \
+    #define MIGRATABLE_UPCOMING_FEATURE(FeatureName, SENumber, Version)         \
       UPCOMING_FEATURE(FeatureName, SENumber, Version)
   #else
-    #define ADOPTABLE_UPCOMING_FEATURE(FeatureName, SENumber, Version)         \
+    #define MIGRATABLE_UPCOMING_FEATURE(FeatureName, SENumber, Version)         \
       LANGUAGE_FEATURE(FeatureName, SENumber, #FeatureName)
   #endif
 #endif
 
-// See `ADOPTABLE_UPCOMING_FEATURE`.
-#ifndef ADOPTABLE_EXPERIMENTAL_FEATURE
+// See `MIGRATABLE_UPCOMING_FEATURE`.
+#ifndef MIGRATABLE_EXPERIMENTAL_FEATURE
   #if defined(EXPERIMENTAL_FEATURE)
-    #define ADOPTABLE_EXPERIMENTAL_FEATURE(FeatureName, AvailableInProd)       \
+    #define MIGRATABLE_EXPERIMENTAL_FEATURE(FeatureName, AvailableInProd)       \
       EXPERIMENTAL_FEATURE(FeatureName, AvailableInProd)
   #else
-    #define ADOPTABLE_EXPERIMENTAL_FEATURE(FeatureName, AvailableInProd)       \
+    #define MIGRATABLE_EXPERIMENTAL_FEATURE(FeatureName, AvailableInProd)       \
       LANGUAGE_FEATURE(FeatureName, 0, #FeatureName)
   #endif
 #endif
@@ -278,11 +278,11 @@ UPCOMING_FEATURE(NonfrozenEnumExhaustivity, 192, 6)
 UPCOMING_FEATURE(GlobalActorIsolatedTypesUsability, 0434, 6)
 
 // Swift 7
-ADOPTABLE_UPCOMING_FEATURE(ExistentialAny, 335, 7)
+MIGRATABLE_UPCOMING_FEATURE(ExistentialAny, 335, 7)
 UPCOMING_FEATURE(InternalImportsByDefault, 409, 7)
 UPCOMING_FEATURE(MemberImportVisibility, 444, 7)
 UPCOMING_FEATURE(InferIsolatedConformances, 470, 7)
-ADOPTABLE_UPCOMING_FEATURE(NonisolatedNonsendingByDefault, 461, 7)
+MIGRATABLE_UPCOMING_FEATURE(NonisolatedNonsendingByDefault, 461, 7)
 
 // Optional language features / modes
 
@@ -518,8 +518,8 @@ EXPERIMENTAL_FEATURE(CopyBlockOptimization, true)
 #undef EXPERIMENTAL_FEATURE_EXCLUDED_FROM_MODULE_INTERFACE
 #undef EXPERIMENTAL_FEATURE
 #undef UPCOMING_FEATURE
-#undef ADOPTABLE_UPCOMING_FEATURE
-#undef ADOPTABLE_EXPERIMENTAL_FEATURE
+#undef MIGRATABLE_UPCOMING_FEATURE
+#undef MIGRATABLE_EXPERIMENTAL_FEATURE
 #undef BASELINE_LANGUAGE_FEATURE
 #undef OPTIONAL_LANGUAGE_FEATURE
 #undef CONDITIONALLY_SUPPRESSIBLE_EXPERIMENTAL_FEATURE

include/swift/Basic/FileTypes.def

@@ -78,8 +78,8 @@ TYPE("fine-module-trace",   FineModuleTrace,           "",                "")
 // Complete dependency information for the given Swift files as JSON.
 TYPE("json-dependencies",   JSONDependencies,          "dependencies.json",      "")
 
-// Complete feature information for the given Swift compiler.
-TYPE("json-features",       JSONFeatures,              "features.json",   "")
+// Complete supported argument information for the given Swift compiler.
+TYPE("json-arguments",      JSONArguments,            "arguments.json",   "")
 
 // Gathered compile-time-known value information for the given Swift input file as JSON.
 TYPE("const-values",       ConstValues,              "swiftconstvalues",   "")

include/swift/Basic/LangOptions.h

@@ -830,7 +830,7 @@ namespace swift {
 
     /// A wrapper around the feature state enumeration.
     struct FeatureState {
-      enum class Kind : uint8_t { Off, EnabledForAdoption, Enabled };
+      enum class Kind : uint8_t { Off, EnabledForMigration, Enabled };
 
     private:
       Feature feature;
@@ -843,9 +843,9 @@ namespace swift {
       /// Returns whether the feature is enabled.
       bool isEnabled() const;
 
-      /// Returns whether the feature is enabled in adoption mode. Should only
+      /// Returns whether the feature is enabled in migration mode. Should only
       /// be called if the feature is known to support this mode.
-      bool isEnabledForAdoption() const;
+      bool isEnabledForMigration() const;
 
       operator Kind() const { return state; }
     };
@@ -878,9 +878,9 @@ namespace swift {
     /// `false` if a feature by this name is not known.
     bool hasFeature(llvm::StringRef featureName) const;
 
-    /// Enables the given feature (enables in adoption mode if `forAdoption` is
-    /// `true`).
-    void enableFeature(Feature feature, bool forAdoption = false);
+    /// Enables the given feature (enables in migration mode if `forMigration`
+    /// is `true`).
+    void enableFeature(Feature feature, bool forMigration = false);
 
     /// Disables the given feature.
     void disableFeature(Feature feature);

include/swift/Basic/SupportedFeatures.h

@@ -0,0 +1,28 @@
+//===--- SupportedFeatures.h - Supported Features Output --------*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides a high-level API for supported features info
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SWIFT_SUPPORTEDFEATURES_H
+#define SWIFT_SUPPORTEDFEATURES_H
+
+#include "swift/Basic/LLVM.h"
+
+namespace swift {
+namespace features {
+void printSupportedFeatures(llvm::raw_ostream &out);
+} // namespace features
+} // namespace swift
+
+#endif

include/swift/Frontend/FrontendOptions.h

@@ -201,7 +201,7 @@ class FrontendOptions {
 
     ScanDependencies, ///< Scan dependencies of Swift source files
     PrintVersion,     ///< Print version information.
-    PrintFeature,     ///< Print supported feature of this compiler
+    PrintArguments,   ///< Print supported arguments of this compiler
   };
 
   /// Indicates the action the user requested that the frontend perform.
@@ -314,6 +314,10 @@ class FrontendOptions {
   /// exit.
   bool PrintTargetInfo = false;
 
+  /// Indicates that the frontend should print the supported features and then
+  /// exit.
+  bool PrintSupportedFeatures = false;
+
   /// See the \ref SILOptions.EmitVerboseSIL flag.
   bool EmitVerboseSIL = false;
 

include/swift/Option/Options.td

@@ -1530,6 +1530,10 @@ def print_target_info : Flag<["-"], "print-target-info">,
     Flags<[FrontendOption]>,
     HelpText<"Print target information for the given target <triple>, such as x86_64-apple-macos10.9">, MetaVarName<"<triple>">;
 
+def print_supported_features : Flag<["-"], "print-supported-features">,
+    Flags<[FrontendOption]>,
+    HelpText<"Print information about features supported by the compiler">;
+
 def target_cpu : Separate<["-"], "target-cpu">, Flags<[FrontendOption, ModuleInterfaceOption]>,
   HelpText<"Generate code for a particular CPU variant">;
 
@@ -1646,9 +1650,13 @@ def scan_dependencies : Flag<["-"], "scan-dependencies">,
   HelpText<"Scan dependencies of the given Swift sources">, ModeOpt,
   Flags<[FrontendOption, NoInteractiveOption, DoesNotAffectIncrementalBuild]>;
 
-def emit_supported_features : Flag<["-"], "emit-supported-features">,
-  HelpText<"Emit a JSON file including all supported compiler features">, ModeOpt,
+def emit_supported_arguments : Flag<["-"], "emit-supported-arguments">,
+  HelpText<"Emit a JSON file including all supported compiler arguments">, ModeOpt,
   Flags<[FrontendOption, NoInteractiveOption, DoesNotAffectIncrementalBuild]>;
+def emit_supported_features : Flag<["-"], "emit-supported-features">,
+  HelpText<"This is a compatibility alias for '-emit-supported-arguments'">, ModeOpt,
+  Flags<[FrontendOption, NoInteractiveOption, DoesNotAffectIncrementalBuild, HelpHidden]>,
+  Alias<emit_supported_arguments>;
 
 def enable_incremental_imports :
   Flag<["-"], "enable-incremental-imports">,

include/swift/SILOptimizer/OptimizerBridgingImpl.h

@@ -560,7 +560,7 @@ bool BridgedPassContext::enableMergeableTraps() const {
 
 bool BridgedPassContext::hasFeature(BridgedFeature feature) const {
   swift::SILModule *mod = invocation->getPassManager()->getModule();
-  return mod->getASTContext().LangOpts.hasFeature((swift::Feature)feature);
+  return mod->getASTContext().LangOpts.hasFeature(swift::Feature(feature));
 }
 
 bool BridgedPassContext::enableMoveInoutStackProtection() const {

lib/AST/ASTPrinter.cpp

@@ -3338,7 +3338,7 @@ static void printCompatibilityCheckIf(ASTPrinter &printer, bool isElseIf,
     } else {
       first = false;
     }
-    printer << "$" << getFeatureName(feature);
+    printer << "$" << Feature(feature).getName();
   }
 
 #ifndef NDEBUG

lib/AST/FeatureSet.cpp

@@ -626,7 +626,7 @@ void FeatureSet::collectRequiredFeature(Feature feature,
 
 void FeatureSet::collectSuppressibleFeature(Feature feature,
                                             InsertOrRemove operation) {
-  suppressible.insertOrRemove(numFeatures() - size_t(feature),
+  suppressible.insertOrRemove(Feature::getNumFeatures() - size_t(feature),
                               operation == Insert);
 }
 

lib/AST/FeatureSet.h

@@ -19,7 +19,8 @@
 
 namespace swift {
 
-using BasicFeatureSet = FixedBitSet<numFeatures(), Feature>;
+using BasicFeatureSet =
+    FixedBitSet<Feature::getNumFeatures(), Feature::InnerKind>;
 
 class FeatureSet {
   BasicFeatureSet required;
@@ -30,7 +31,7 @@ class FeatureSet {
   // This is the easiest way of letting us iterate from largest to
   // smallest, i.e. from the newest to the oldest feature, which is
   // the order in which we need to emit #if clauses.
-  using SuppressibleFeatureSet = FixedBitSet<numFeatures(), size_t>;
+  using SuppressibleFeatureSet = FixedBitSet<Feature::getNumFeatures(), size_t>;
   SuppressibleFeatureSet suppressible;
 
 public:
@@ -42,7 +43,7 @@ class FeatureSet {
 
   public:
     bool empty() const { return i == e; }
-    Feature next() { return Feature(numFeatures() - *i++); }
+    Feature next() { return Feature(Feature::getNumFeatures() - *i++); }
   };
 
   bool empty() const { return required.empty() && suppressible.empty(); }

lib/Basic/CMakeLists.txt

@@ -75,6 +75,7 @@ add_swift_host_library(swiftBasic STATIC
   StableHasher.cpp
   Statistic.cpp
   StringExtras.cpp
+  SupportedFeatures.cpp
   TargetInfo.cpp
   TaskQueue.cpp
   ThreadSafeRefCounted.cpp