Add runtime availability checking for value generics

Author: Azoy

include/swift/AST/DiagnosticsSema.def

@@ -8026,6 +8026,9 @@ ERROR(missing_value_generic_type,none,
       "value generic %0 must have an explicit value type declared", (Identifier))
 ERROR(value_generics_missing_feature,none,
       "value generics require '-enable-experimental-feature ValueGenerics'", ())
+ERROR(availability_value_generic_type_only_version_newer, none,
+      "values in generic types are only available in %0 %1 or newer",
+      (StringRef, llvm::VersionTuple))
 
 #define UNDEFINE_DIAGNOSTIC_MACROS
 #include "DefineDiagnosticMacros.h"

include/swift/AST/FeatureAvailability.def

@@ -72,12 +72,13 @@ FEATURE(SwiftExceptionPersonality,                      (6, 0))
 FEATURE(IsolatedAny,                                    (6, 0))
 
 FEATURE(NoncopyableGenerics,                            (6, 0))
+FEATURE(InitRawStructMetadata,                          (6, 0))
 
 FEATURE(TaskExecutor,                                   FUTURE)
 FEATURE(Differentiation,                                FUTURE)
-FEATURE(InitRawStructMetadata,                          FUTURE)
 FEATURE(ClearSensitive,                                 FUTURE)
 FEATURE(UpdatePureObjCClassMetadata,                    FUTURE)
+FEATURE(ValueGenericType,                               FUTURE)
 
 #undef FEATURE
 #undef FUTURE

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -588,6 +588,17 @@ static void checkGenericParams(GenericContext *ownerCtx) {
       hasPack = true;
     }
 
+    if (gp->isValue()) {
+      // Value generic nominal types require runtime support.
+      if (isa<NominalTypeDecl>(decl)) {
+        TypeChecker::checkAvailability(
+          gp->getSourceRange(),
+          ownerCtx->getASTContext().getValueGenericTypeAvailability(),
+          diag::availability_value_generic_type_only_version_newer,
+          ownerCtx);
+      }
+    }
+
     TypeChecker::checkDeclAttributes(gp);
     checkInheritanceClause(gp);
   }

test/Interpreter/value_generics.swift

@@ -1,4 +1,4 @@
-// RUN: %target-run-simple-swift(-enable-experimental-feature ValueGenerics) | %FileCheck %s
+// RUN: %target-run-simple-swift(-enable-experimental-feature ValueGenerics -Xfrontend  -disable-availability-checking) | %FileCheck %s
 
 // REQUIRES: executable_test
 

test/ModuleInterface/value_generics.swift

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
-// RUN: %target-swift-emit-module-interface(%t.swiftinterface) %s -module-name ValueGeneric -enable-experimental-feature ValueGenerics
-// RUN: %target-swift-typecheck-module-from-interface(%t.swiftinterface) -module-name ValueGeneric
+// RUN: %target-swift-emit-module-interface(%t.swiftinterface) %s -module-name ValueGeneric -enable-experimental-feature ValueGenerics -disable-availability-checking
+// RUN: %target-swift-typecheck-module-from-interface(%t.swiftinterface) -module-name ValueGeneric -disable-availability-checking
 // RUN: %FileCheck %s < %t.swiftinterface
 
 // CHECK: public struct Vector<Element, let N : Swift.Int>

test/SILGen/closures.swift

@@ -1,6 +1,6 @@
 
-// RUN: %target-swift-emit-silgen -module-name closures -parse-stdlib -parse-as-library %s -enable-experimental-feature ValueGenerics | %FileCheck %s
-// RUN: %target-swift-emit-silgen -module-name closures -parse-stdlib -parse-as-library %s -enable-experimental-feature ValueGenerics | %FileCheck %s --check-prefix=GUARANTEED
+// RUN: %target-swift-emit-silgen -module-name closures -parse-stdlib -parse-as-library %s -enable-experimental-feature ValueGenerics -disable-availability-checking | %FileCheck %s
+// RUN: %target-swift-emit-silgen -module-name closures -parse-stdlib -parse-as-library %s -enable-experimental-feature ValueGenerics -disable-availability-checking | %FileCheck %s --check-prefix=GUARANTEED
 
 import Swift
 

test/Sema/value_generics.swift

@@ -1,4 +1,4 @@
-// RUN: %target-typecheck-verify-swift -enable-experimental-feature ValueGenerics -enable-experimental-feature NonescapableTypes
+// RUN: %target-typecheck-verify-swift -enable-experimental-feature ValueGenerics -enable-experimental-feature NonescapableTypes -disable-availability-checking
 
 protocol P {}
 

test/Sema/value_generics_availability.swift

@@ -0,0 +1,14 @@
+// RUN: %target-typecheck-verify-swift -enable-experimental-feature ValueGenerics -enable-experimental-feature NonescapableTypes
+
+// REQUIRES: OS=macosx
+
+struct A<let N: Int> {} // expected-error {{values in generic types are only available in macOS 99.99.0 or newer}}
+                        // expected-note@-1 {{add @available attribute to enclosing generic struct}}
+
+class B<let N: Int> {} // expected-error {{values in generic types are only available in macOS 99.99.0 or newer}}
+                       // expected-note@-1 {{add @available attribute to enclosing generic class}}
+
+enum C<let N: Int> {} // expected-error {{values in generic types are only available in macOS 99.99.0 or newer}}
+                      // expected-note@-1 {{add @available attribute to enclosing generic enum}}
+
+func something<let N: Int>(_: A<N>) {} // OK, because A can't reference value generics.

test/Serialization/value_generics.swift

@@ -1,5 +1,5 @@
 // RUN: %empty-directory(%t)
-// RUN: %target-swift-frontend %s -emit-module -enable-experimental-feature ValueGenerics -enable-experimental-feature RawLayout -parse-as-library -o %t
+// RUN: %target-swift-frontend %s -emit-module -enable-experimental-feature ValueGenerics -enable-experimental-feature RawLayout -disable-availability-checking -parse-as-library -o %t
 // RUN: %target-sil-opt -enable-sil-verify-all %t/value_generics.swiftmodule -o - | %FileCheck %s
 
 // CHECK: @_rawLayout(likeArrayOf: Element, count: Count) struct Vector<Element, let Count : Int> : ~Copyable where Element : ~Copyable {