AST: Fix runtime unavailability for universally unavailable decls

include/swift/AST/AvailabilityConstraint.h

@@ -240,6 +240,14 @@ std::optional<AvailabilityConstraint> getAvailabilityConstraintForDeclInDomain(
     const Decl *decl, const AvailabilityContext &context,
     AvailabilityDomain domain,
     AvailabilityConstraintFlags flags = std::nullopt);
+
+/// Computes the set of constraints that indicate whether a decl is "runtime
+/// unavailable" (can never be reached at runtime) and adds the domain for each
+/// of those constraints to the \p domains vector.
+void getRuntimeUnavailableDomains(
+    const DeclAvailabilityConstraints &constraints,
+    llvm::SmallVectorImpl<AvailabilityDomain> &domains, const ASTContext &ctx);
+
 } // end namespace swift
 
 namespace llvm {

lib/AST/Availability.cpp

@@ -574,27 +574,6 @@ getRootTargetDomains(const ASTContext &ctx) {
   return domains;
 }
 
-static bool constraintIndicatesRuntimeUnavailability(
-    const AvailabilityConstraint &constraint, const ASTContext &ctx) {
-  std::optional<CustomAvailabilityDomain::Kind> customDomainKind;
-  if (auto customDomain = constraint.getDomain().getCustomDomain())
-    customDomainKind = customDomain->getKind();
-
-  switch (constraint.getReason()) {
-  case AvailabilityConstraint::Reason::UnavailableUnconditionally:
-    if (customDomainKind)
-      return customDomainKind == CustomAvailabilityDomain::Kind::Enabled;
-    return true;
-  case AvailabilityConstraint::Reason::UnavailableObsolete:
-  case AvailabilityConstraint::Reason::UnavailableUnintroduced:
-    return false;
-  case AvailabilityConstraint::Reason::Unintroduced:
-    if (customDomainKind)
-      return customDomainKind == CustomAvailabilityDomain::Kind::Disabled;
-    return false;
-  }
-}
-
 /// Returns true if a decl that is unavailable in the given domain must still be
 /// emitted to preserve load time ABI compatibility.
 static bool
@@ -633,10 +612,7 @@ computeDeclRuntimeAvailability(const Decl *decl) {
 
   // First, collect the unavailable domains from the constraints.
   llvm::SmallVector<AvailabilityDomain, 8> unavailableDomains;
-  for (auto constraint : constraints) {
-    if (constraintIndicatesRuntimeUnavailability(constraint, ctx))
-      unavailableDomains.push_back(constraint.getDomain());
-  }
+  getRuntimeUnavailableDomains(constraints, unavailableDomains, ctx);
 
   // Check whether there are any available attributes that would make the
   // decl available in descendants of the unavailable domains.
@@ -647,6 +623,10 @@ computeDeclRuntimeAvailability(const Decl *decl) {
       continue;
 
     llvm::erase_if(unavailableDomains, [domain](auto unavailableDomain) {
+      // Unavailability in '*' cannot be superseded by an @available attribute
+      // for a more specific availability domain.
+      if (unavailableDomain.isUniversal())
+        return false;
       return unavailableDomain.contains(domain);
     });
   }

lib/AST/AvailabilityConstraint.cpp

@@ -322,3 +322,33 @@ swift::getAvailabilityConstraintForDeclInDomain(
 
   return std::nullopt;
 }
+
+static bool constraintIndicatesRuntimeUnavailability(
+    const AvailabilityConstraint &constraint, const ASTContext &ctx) {
+  std::optional<CustomAvailabilityDomain::Kind> customDomainKind;
+  if (auto customDomain = constraint.getDomain().getCustomDomain())
+    customDomainKind = customDomain->getKind();
+
+  switch (constraint.getReason()) {
+  case AvailabilityConstraint::Reason::UnavailableUnconditionally:
+    if (customDomainKind)
+      return customDomainKind == CustomAvailabilityDomain::Kind::Enabled;
+    return true;
+  case AvailabilityConstraint::Reason::UnavailableObsolete:
+  case AvailabilityConstraint::Reason::UnavailableUnintroduced:
+    return false;
+  case AvailabilityConstraint::Reason::Unintroduced:
+    if (customDomainKind)
+      return customDomainKind == CustomAvailabilityDomain::Kind::Disabled;
+    return false;
+  }
+}
+
+void swift::getRuntimeUnavailableDomains(
+    const DeclAvailabilityConstraints &constraints,
+    llvm::SmallVectorImpl<AvailabilityDomain> &domains, const ASTContext &ctx) {
+  for (auto constraint : constraints) {
+    if (constraintIndicatesRuntimeUnavailability(constraint, ctx))
+      domains.push_back(constraint.getDomain());
+  }
+}

test/SILGen/unavailable_decl_custom_domain.swift

@@ -3,23 +3,15 @@
 // RUN:   -define-enabled-availability-domain EnabledDomain \
 // RUN:   -define-disabled-availability-domain DisabledDomain \
 // RUN:   -define-dynamic-availability-domain DynamicDomain \
-// RUN:   | %FileCheck %s
-
-// RUN: %target-swift-emit-silgen -module-name Test %s -verify \
-// RUN:   -enable-experimental-feature CustomAvailability \
-// RUN:   -define-enabled-availability-domain EnabledDomain \
-// RUN:   -define-disabled-availability-domain DisabledDomain \
-// RUN:   -define-dynamic-availability-domain DynamicDomain \
-// RUN:   -unavailable-decl-optimization=stub \
-// RUN:   | %FileCheck %s
+// RUN:   | %FileCheck %s --check-prefixes=CHECK,CHECK-NOOPT
 
 // RUN: %target-swift-emit-silgen -module-name Test %s -verify \
 // RUN:   -enable-experimental-feature CustomAvailability \
 // RUN:   -define-enabled-availability-domain EnabledDomain \
 // RUN:   -define-disabled-availability-domain DisabledDomain \
 // RUN:   -define-dynamic-availability-domain DynamicDomain \
 // RUN:   -unavailable-decl-optimization=complete \
-// RUN:   | %FileCheck %s
+// RUN:   | %FileCheck %s --check-prefixes=CHECK,CHECK-OPT
 
 // REQUIRES: swift_feature_CustomAvailability
 
@@ -84,3 +76,25 @@ public func availableInEnabledAndDisabledDomain() { }
 @available(DisabledDomain)
 @available(EnabledDomain)
 public func availableInDisabledAndEnabledDomain() { }
+
+// CHECK-NOOPT: s4Test49availableInEnabledDomainAndUnavailableUniversallyyyF
+// CHECK-OPT-NOT: s4Test49availableInEnabledDomainAndUnavailableUniversallyyyF
+@available(*, unavailable)
+@available(EnabledDomain)
+public func availableInEnabledDomainAndUnavailableUniversally() { }
+
+// CHECK-NOT: s4Test40unavailableInEnabledDomainAndUniversallyyyF
+@available(*, unavailable)
+@available(EnabledDomain, unavailable)
+public func unavailableInEnabledDomainAndUniversally() { }
+
+// CHECK-NOT: s4Test50availableInDisabledDomainAndUnavailableUniversallyyyF
+@available(*, unavailable)
+@available(DisabledDomain)
+public func availableInDisabledDomainAndUnavailableUniversally() { }
+
+// CHECK-NOOPT: s4Test41unavailableInDisabledDomainAndUniversallyyyF
+// CHECK-OPT-NOT: s4Test41unavailableInDisabledDomainAndUniversallyyyF
+@available(*, unavailable)
+@available(DisabledDomain, unavailable)
+public func unavailableInDisabledDomainAndUniversally() { }

test/SILGen/unavailable_decl_optimization_stub.swift

@@ -12,6 +12,14 @@ public func unavailableFunc() -> S {
   return S()
 }
 
+// CHECK-LABEL: sil{{.*}}@$s4Test33unavailableFuncIntroducedInSwift5yyF
+// CHECK:         [[FNREF:%.*]] = function_ref @$[[DIAGNOSEFN:(ss31_diagnoseUnavailableCodeReacheds5NeverOyF|ss31_diagnoseUnavailableCodeReacheds5NeverOyFTwb)]] : $@convention(thin) () -> Never
+// CHECK-NEXT:    [[APPLY:%.*]] = apply [[FNREF]]()
+// CHECK:       } // end sil function '$s4Test33unavailableFuncIntroducedInSwift5yyF'
+@available(*, unavailable)
+@available(swift 5)
+public func unavailableFuncIntroducedInSwift5() { }
+
 // CHECK-LABEL: sil{{.*}}@$s4Test025unavailableFuncWithNestedC0yyF
 // CHECK:         [[FNREF:%.*]] = function_ref @$[[DIAGNOSEFN:(ss31_diagnoseUnavailableCodeReacheds5NeverOyF|ss31_diagnoseUnavailableCodeReacheds5NeverOyFTwb)]] : $@convention(thin) () -> Never
 // CHECK-NEXT:    [[APPLY:%.*]] = apply [[FNREF]]()

test/SILGen/unavailable_decl_optimization_stub_macos.swift

@@ -24,6 +24,14 @@ public func unavailableFunc() {}
 @available(macOS, unavailable)
 public func unavailableOnMacOSFunc() {}
 
+// CHECK-LABEL:     sil{{.*}}@$s4Test36unavailableFuncWithMacOSIntroductionyyF
+// CHECK:             [[FNREF:%.*]] = function_ref @$ss31_diagnoseUnavailableCodeReacheds5NeverOyFTwb : $@convention(thin) () -> Never
+// CHECK-NEXT:        [[APPLY:%.*]] = apply [[FNREF]]()
+// CHECK:           } // end sil function '$s4Test36unavailableFuncWithMacOSIntroductionyyF'
+@available(*, unavailable)
+@available(macOS 12.0, *)
+public func unavailableFuncWithMacOSIntroduction() {}
+
 // CHECK-LABEL:     sil{{.*}}@$s4Test31unavailableOnMacOSExtensionFuncyyF
 // CHECK-NOT:         _diagnoseUnavailableCodeReached
 // CHECK:           } // end sil function '$s4Test31unavailableOnMacOSExtensionFuncyyF'