SILGen: Fix if #available miscompile with -disable-availabilty-checking.

Author: tshortli

include/swift/AST/Stmt.h

@@ -504,8 +504,7 @@ class alignas(8) PoundAvailableInfo final :
                      ArrayRef<AvailabilitySpec *> queries, SourceLoc RParenLoc,
                      bool isUnavailability)
       : PoundLoc(PoundLoc), LParenLoc(LParenLoc), RParenLoc(RParenLoc),
-        NumQueries(queries.size()), AvailableRange(VersionRange::empty()),
-        VariantAvailableRange(VersionRange::empty()), Flags() {
+        NumQueries(queries.size()), Flags() {
     Flags.isInvalid = false;
     Flags.isUnavailability = isUnavailability;
     std::uninitialized_copy(queries.begin(), queries.end(),

test/SILGen/availability_disabled.swift

@@ -0,0 +1,16 @@
+// RUN: %target-swift-emit-silgen -disable-availability-checking %s -verify
+// RUN: %target-swift-emit-silgen -disable-availability-checking %s | %FileCheck %s
+
+// CHECK-LABEL: // available()
+func available() {
+  // CHECK: [[TRUE:%.*]] = integer_literal $Builtin.Int1, -1
+  // CHECK: cond_br [[TRUE]]
+  if #available(macOS 10.15, *) {}
+}
+
+// CHECK-LABEL: // unavailable()
+func unavailable() {
+  // CHECK: [[FALSE:%.*]] = integer_literal $Builtin.Int1, 0
+  // CHECK: cond_br [[FALSE]]
+  if #unavailable(macOS 10.15) {}
+}

test/SILGen/availability_disabled_zippered.swift

@@ -0,0 +1,21 @@
+// RUN: %target-swift-emit-silgen -target %target-cpu-apple-macosx13 -target-variant %target-cpu-apple-ios16-macabi -disable-availability-checking %s -verify
+// RUN: %target-swift-emit-silgen -target-variant %target-cpu-apple-macosx13 -target %target-cpu-apple-ios16-macabi -disable-availability-checking %s -verify
+
+// RUN: %target-swift-emit-silgen -target %target-cpu-apple-macosx13 -target-variant %target-cpu-apple-ios16-macabi -disable-availability-checking %s | %FileCheck %s
+// RUN: %target-swift-emit-silgen -target-variant %target-cpu-apple-macosx13 -target %target-cpu-apple-ios16-macabi -disable-availability-checking %s | %FileCheck %s
+
+// REQUIRES: OS=macosx || OS=maccatalyst
+
+// CHECK-LABEL: // available()
+func available() {
+  // CHECK: [[TRUE:%.*]] = integer_literal $Builtin.Int1, -1
+  // CHECK: cond_br [[TRUE]]
+  if #available(macOS 10.15, *) {}
+}
+
+// CHECK-LABEL: // unavailable()
+func unavailable() {
+  // CHECK: [[FALSE:%.*]] = integer_literal $Builtin.Int1, 0
+  // CHECK: cond_br [[FALSE]]
+  if #unavailable(macOS 10.15) {}
+}