Merge pull request #3440 from devincoughlin/suppress-availability-useless-deployment

[Sema] Remove 'deployment target ensures guard will always be true'

Author: devincoughlin

include/swift/AST/DiagnosticsSema.def

@@ -2946,10 +2946,6 @@ ERROR(availability_inout_accessor_only_version_newer, none,
 ERROR(availability_query_required_for_platform, none,
       "condition required for target platform '%0'", (StringRef))
 
-WARNING(availability_query_useless_min_deployment, none,
-        "unnecessary check for '%0'; minimum deployment target ensures guard "
-        "will always be true", (StringRef))
-
 WARNING(availability_query_useless_enclosing_scope, none,
         "unnecessary check for '%0'; enclosing scope ensures guard "
         "will always be true", (StringRef))

lib/Sema/TypeChecker.cpp

@@ -1316,19 +1316,15 @@ class TypeRefinementContextBuilder : private ASTWalker {
       // spec is useless. If so, report this.
       if (CurrentInfo.isContainedIn(NewConstraint)) {
         DiagnosticEngine &Diags = TC.Diags;
-        if (CurrentTRC->getReason() == TypeRefinementContext::Reason::Root) {
-          // Diagnose for checks that are useless because the minimum deployment
-          // target ensures they will never be false. We suppress this warning
-          // when compiling for playgrounds because the developer cannot
-          // cannot explicitly set the minimum deployment target to silence
-          // the alarm. We also suppress in script mode (where setting the
-          // minimum deployment target requires a target triple).
-          if (!TC.getLangOpts().Playground && !TC.getInImmediateMode()) {
-            Diags.diagnose(Query->getLoc(),
-                           diag::availability_query_useless_min_deployment,
-                           platformString(targetPlatform(TC.getLangOpts())));
-          }
-        } else {
+        // Some availability checks will always pass because the minimum
+        // deployment target gurantees they will never be false. We don't
+        // diagnose these checks as useless because the source file may
+        // be shared with other projects/targets having older deployment
+        // targets. We don't currently have a mechanism for the user to
+        // suppress these warnings (for example, by indicating when the
+        // required compatibility version is different than the deployment
+        // target).
+        if (CurrentTRC->getReason() != TypeRefinementContext::Reason::Root) {
           Diags.diagnose(Query->getLoc(),
                          diag::availability_query_useless_enclosing_scope,
                          platformString(targetPlatform(TC.getLangOpts())));

test/SILGen/availability_query.swift

@@ -42,15 +42,15 @@ if #available(macOS 10.52, *) {
 // CHECK: [[PATCH:%.*]] = integer_literal $Builtin.Word, 0
 // CHECK: [[QUERY_FUNC:%.*]] = function_ref @_TFs26_stdlib_isOSVersionAtLeastFTBwBwBw_Bi1_ : $@convention(thin) (Builtin.Word, Builtin.Word, Builtin.Word) -> Builtin.Int1
 // CHECK: [[QUERY_RESULT:%.*]] = apply [[QUERY_FUNC]]([[MAJOR]], [[MINOR]], [[PATCH]]) : $@convention(thin) (Builtin.Word, Builtin.Word, Builtin.Word) -> Builtin.Int1
-if #available(OSX 10, *) { // expected-warning {{minimum deployment target ensures guard will always be true}}
+if #available(OSX 10, *) {
 }
 
 // CHECK: }
 
 func doThing() {}
 
 func testUnreachableVersionAvailable(condition: Bool) {
-  if #available(OSX 10.0, *) { // expected-warning {{minimum deployment target ensures guard will always be true}}
+  if #available(OSX 10.0, *) {
     doThing() // no-warning
     return
   } else {

test/Sema/availability_versions.swift

@@ -1011,7 +1011,7 @@ func useUnavailableExtension() {
 func functionWithDefaultAvailabilityAndUselessCheck(_ p: Bool) {
 // Default availability reflects minimum deployment: 10.9 and up
 
-  if #available(OSX 10.9, *) { // expected-warning {{unnecessary check for 'OSX'; minimum deployment target ensures guard will always be true}}
+  if #available(OSX 10.9, *) { // no-warning
     let _ = globalFuncAvailableOn10_9()
   }
 
@@ -1023,7 +1023,7 @@ func functionWithDefaultAvailabilityAndUselessCheck(_ p: Bool) {
     }
   }
 
-  if #available(OSX 10.9, *) { // expected-note {{enclosing scope here}} expected-warning {{unnecessary check for 'OSX'; minimum deployment target ensures guard will always be true}}
+  if #available(OSX 10.9, *) { // expected-note {{enclosing scope here}}
   } else {
     // Make sure we generate a warning about an unnecessary check even if the else branch of if is dead.
     if #available(OSX 10.51, *) { // expected-warning {{unnecessary check for 'OSX'; enclosing scope ensures guard will always be true}}
@@ -1032,7 +1032,7 @@ func functionWithDefaultAvailabilityAndUselessCheck(_ p: Bool) {
 
   // This 'if' is strictly to limit the scope of the guard fallthrough
   if p {
-    guard #available(OSX 10.9, *) else { // expected-note {{enclosing scope here}} expected-warning {{unnecessary check for 'OSX'; minimum deployment target ensures guard will always be true}}
+    guard #available(OSX 10.9, *) else { // expected-note {{enclosing scope here}}
       // Make sure we generate a warning about an unnecessary check even if the else branch of guard is dead.
       if #available(OSX 10.51, *) { // expected-warning {{unnecessary check for 'OSX'; enclosing scope ensures guard will always be true}}
       }

test/Sema/deprecation_osx.swift

@@ -156,7 +156,7 @@ func functionWithDeprecatedMethodInDeadElseBranch() {
     let _ = ClassDeprecatedIn10_9()  // no-warning
   }
 
-  if #available(OSX 10.9, *) { // expected-warning {{unnecessary check for 'OSX'; minimum deployment target ensures guard will always be true}}
+  if #available(OSX 10.9, *) { // no-warning
   } else {
     // This branch is dead because our minimum deployment target is 10.51.
     let _ = ClassDeprecatedIn10_9()  // no-warning

test/attr/attr_availability_tvos.swift

@@ -70,7 +70,7 @@ if #available(iOS 9.1, tvOS 9.2, *) {
 if #available(iOS 8.0, tvOS 9.2, *) {
 }
 
-if #available(iOS 9.2, tvOS 8.0, *) { // expected-warning {{unnecessary check for 'tvOS'; minimum deployment target ensures guard will always be true}}
+if #available(iOS 9.2, tvOS 8.0, *) { // no-warning
 }
 
 

test/attr/attr_availability_watchos.swift

@@ -70,7 +70,7 @@ if #available(iOS 9.1, watchOS 2.2, *) {
 if #available(iOS 8.0, watchOS 2.2, *) {
 }
 
-if #available(iOS 9.2, watchOS 1.0, *) { // expected-warning {{unnecessary check for 'watchOS'; minimum deployment target ensures guard will always be true}}
+if #available(iOS 9.2, watchOS 1.0, *) { // no-warning
 }