AST: Use -verify-emitted-module-interface in test case the emits a swiftinterface containing a back-deployed decl. Also leave a FIXME to stop using -merge-modules in the future and fix a diagnostic typo.

Author: tshortli

include/swift/AST/DiagnosticsParse.def

@@ -1537,7 +1537,7 @@ WARNING(attr_availability_wildcard_ignored,none,
         "* as platform name has no effect in '%0' attribute", (StringRef))
 
 ERROR(attr_availability_need_platform_version,none,
-     "expected at least one platform version in in '%0' attribute", (StringRef))
+     "expected at least one platform version in '%0' attribute", (StringRef))
 
 WARNING(attr_availability_platform_version_major_minor_only,none,
         "'%0' only uses major and minor version number", (StringRef))

test/ModuleInterface/back-deploy-attr.swift

@@ -2,9 +2,12 @@
 
 // Ensure @_backDeploy attributes and function bodies are printed in
 // swiftinterface files.
-// RUN: %target-swift-frontend -emit-module -o %t/Test.swiftmodule -emit-module-interface-path %t/Test.swiftinterface -module-name Test %s
+// RUN: %swiftc_driver -emit-module -o %t/Test.swiftmodule -emit-module-interface-path %t/Test.swiftinterface -enable-library-evolution -verify-emitted-module-interface -module-name Test %s
 // RUN: %FileCheck %s --check-prefix FROMSOURCE --check-prefix CHECK < %t/Test.swiftinterface
 
+// FIXME(backDeploy): Remove this step in favor of a test that exercises using
+// a back deployed API from a test library so that we can avoid -merge-modules
+
 // Ensure @_backDeploy attributes and function bodies are present after
 // deserializing .swiftmodule files.
 // RUN: %target-swift-frontend -emit-module -o /dev/null -merge-modules %t/Test.swiftmodule -disable-objc-attr-requires-foundation-module -emit-module-interface-path %t/TestFromModule.swiftinterface -module-name Test

test/attr/backDeploy.swift

@@ -118,7 +118,7 @@ public func duplicatePlatformsFunc1() {}
 public func duplicatePlatformsFunc2() {}
 
 @available(macOS 12.0, *)
-@_backDeploy() // expected-error {{expected at least one platform version in in '@_backDeploy' attribute}}
+@_backDeploy() // expected-error {{expected at least one platform version in '@_backDeploy' attribute}}
 public func zeroPlatformVersionsFunc() {}
 
 @available(macOS 12.0, *)