Do even less availability checking under -disable-availability-checking.

lib/Frontend/CompilerInvocation.cpp

@@ -727,7 +727,8 @@ static bool ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
 }
 
 static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
-                          DiagnosticEngine &Diags, bool isImmediate) {
+                          DiagnosticEngine &Diags,
+                          const FrontendOptions &FrontendOpts) {
   using namespace options;
 
   Opts.AttachCommentsToDecls |= Args.hasArg(OPT_dump_api_path);
@@ -745,6 +746,8 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
 
   Opts.DisableAvailabilityChecking |=
       Args.hasArg(OPT_disable_availability_checking);
+  if (FrontendOpts.InputKind == InputFileKind::IFK_SIL)
+    Opts.DisableAvailabilityChecking = true;
 
   if (auto A = Args.getLastArg(OPT_enable_access_control,
                                OPT_disable_access_control)) {
@@ -1327,8 +1330,7 @@ bool CompilerInvocation::parseArgs(ArrayRef<const char *> Args,
     return true;
   }
 
-  if (ParseLangArgs(LangOpts, ParsedArgs, Diags,
-                    FrontendOpts.actionIsImmediate())) {
+  if (ParseLangArgs(LangOpts, ParsedArgs, Diags, FrontendOpts)) {
     return true;
   }
 

lib/Sema/MiscDiagnostics.cpp

@@ -2045,9 +2045,6 @@ bool AvailabilityWalker::diagAvailability(const ValueDecl *D, SourceRange R,
     TC.diagnoseDeprecated(R, DC, Attr, D->getFullName(), call);
   }
 
-  if (TC.getLangOpts().DisableAvailabilityChecking)
-    return false;
-
   // Diagnose for potential unavailability
   auto maybeUnavail = TC.checkDeclarationAvailability(D, R.Start, DC);
   if (maybeUnavail.hasValue()) {
@@ -3582,7 +3579,8 @@ void swift::performSyntacticExprDiagnostics(TypeChecker &TC, const Expr *E,
   diagSyntacticUseRestrictions(TC, E, DC, isExprStmt);
   diagRecursivePropertyAccess(TC, E, DC);
   diagnoseImplicitSelfUseInClosure(TC, E, DC);
-  diagAvailability(TC, E, const_cast<DeclContext*>(DC));
+  if (!TC.getLangOpts().DisableAvailabilityChecking)
+    diagAvailability(TC, E, const_cast<DeclContext*>(DC));
   if (TC.Context.LangOpts.EnableObjCInterop)
     diagDeprecatedObjCSelectors(TC, DC, E);
 }

lib/Sema/TypeCheckType.cpp

@@ -1441,8 +1441,8 @@ Type TypeChecker::resolveIdentifierType(
   bool AllowPotentiallyUnavailableProtocol =
       options.contains(TR_InheritanceClause);
 
-  // Check the availability of the type. Skip checking for SIL.
-  if (!(options & TR_SILType) && !(options & TR_AllowUnavailable) &&
+  // Check the availability of the type.
+  if (!(options & TR_AllowUnavailable) &&
       diagnoseAvailability(result, IdType,
                            Components.back()->getIdLoc(), DC, *this,
                            AllowPotentiallyUnavailableProtocol)) {
@@ -1664,6 +1664,9 @@ Type TypeResolver::resolveType(TypeRepr *repr, TypeResolutionOptions options) {
     options -= TR_FunctionInput;
   }
 
+  if (Context.LangOpts.DisableAvailabilityChecking)
+    options |= TR_AllowUnavailable;
+
   switch (repr->getKind()) {
   case TypeReprKind::Error:
     return ErrorType::get(Context);
@@ -1782,9 +1785,8 @@ Type TypeResolver::resolveAttributedType(TypeAttributes &attrs,
 
         if (base) {
           Optional<MetatypeRepresentation> storedRepr;
-          // The instance type is not a SIL type. We still want to allow
-          // unavailable references, though.
-          auto instanceOptions = options - TR_SILType | TR_AllowUnavailable;
+          // The instance type is not a SIL type.
+          auto instanceOptions = options - TR_SILType;
           auto instanceTy = resolveType(base, instanceOptions);
           if (!instanceTy || instanceTy->is<ErrorType>())
             return instanceTy;

test/Sema/availability_versions.swift

@@ -1068,15 +1068,12 @@ func functionWithUnavailableInDeadBranch() {
 
     localFuncAvailableOn10_51() // no-warning
 
-    // We still want to error on references to explicitly unavailable symbols
-    // CHECK:error: 'explicitlyUnavailable()' is unavailable
     explicitlyUnavailable() // expected-error {{'explicitlyUnavailable()' is unavailable}}
   }
 
   guard #available(iOS 8.0, *) else {
     _ = globalFuncAvailableOn10_51() // no-warning
 
-    // CHECK:error: 'explicitlyUnavailable()' is unavailable
     explicitlyUnavailable() // expected-error {{'explicitlyUnavailable()' is unavailable}}
   }
 }
@@ -1624,6 +1621,5 @@ func useShortFormAvailable() {
       // expected-note@-1 {{add @available attribute to enclosing global function}}
       // expected-note@-2 {{add 'if #available' version check}}
 
-    // CHECK:error: 'unavailableWins()' is unavailable
   unavailableWins() // expected-error {{'unavailableWins()' is unavailable}}
 }

tools/sil-extract/SILExtract.cpp

@@ -163,6 +163,7 @@ int main(int argc, char **argv) {
     Invocation.setRuntimeResourcePath(ResourceDir);
   Invocation.getClangImporterOptions().ModuleCachePath = ModuleCachePath;
   Invocation.setParseStdlib();
+  Invocation.getLangOptions().DisableAvailabilityChecking = true;
   Invocation.getLangOptions().EnableAccessControl = false;
   Invocation.getLangOptions().EnableObjCAttrRequiresFoundation = false;
 

tools/sil-opt/SILOpt.cpp

@@ -210,6 +210,7 @@ int main(int argc, char **argv) {
   // cache.
   Invocation.getClangImporterOptions().ModuleCachePath = ModuleCachePath;
   Invocation.setParseStdlib();
+  Invocation.getLangOptions().DisableAvailabilityChecking = true;
   Invocation.getLangOptions().EnableAccessControl = false;
   Invocation.getLangOptions().EnableObjCAttrRequiresFoundation = false;