[Sema] Note that the missing import is added automatically

Author: xymus

include/swift/AST/DiagnosticsSema.def

@@ -5849,6 +5849,10 @@ ERROR(inlinable_typealias_desugars_to_type_from_hidden_module,
       "%4 was not imported by this file}5",
       (DeclName, StringRef, StringRef, unsigned, Identifier, unsigned))
 
+NOTE(missing_import_inserted,
+     none, "The missing import of module %0 will be added implicitly",
+     (Identifier))
+
 ERROR(availability_macro_in_inlinable, none,
       "availability macro cannot be used in " FRAGILE_FUNC_KIND "0",
       (unsigned))

lib/Sema/ResilienceDiagnostics.cpp

@@ -144,6 +144,11 @@ static bool diagnoseTypeAliasDeclRefExportability(SourceLoc loc,
   }
   D->diagnose(diag::kind_declared_here, DescriptiveDeclKind::Type);
 
+  if (originKind == DisallowedOriginKind::ImplicitlyImported &&
+      !ctx.LangOpts.isSwiftVersionAtLeast(6))
+    ctx.Diags.diagnose(loc, diag::missing_import_inserted,
+                       definingModule->getName());
+
   return true;
 }
 
@@ -190,7 +195,13 @@ static bool diagnoseValueDeclRefExportability(SourceLoc loc, const ValueDecl *D,
                        D->getDescriptiveKind(), D->getName(),
                        fragileKind.getSelector(), definingModule->getName(),
                        static_cast<unsigned>(originKind));
+
+    if (originKind == DisallowedOriginKind::ImplicitlyImported &&
+        downgradeToWarning == DowngradeToWarning::Yes)
+      ctx.Diags.diagnose(loc, diag::missing_import_inserted,
+                         definingModule->getName());
   }
+
   return true;
 }
 
@@ -244,5 +255,10 @@ TypeChecker::diagnoseConformanceExportability(SourceLoc loc,
       .warnUntilSwiftVersionIf(useConformanceAvailabilityErrorsOption &&
                                !ctx.LangOpts.EnableConformanceAvailabilityErrors,
                                6);
+
+    if (originKind == DisallowedOriginKind::ImplicitlyImported &&
+        !ctx.LangOpts.isSwiftVersionAtLeast(6))
+      ctx.Diags.diagnose(loc, diag::missing_import_inserted,
+                         M->getName());
   return true;
 }

test/Sema/implicit-import-in-inlinable-code.swift

@@ -53,11 +53,13 @@ import libA
 @inlinable public func bar() {
   let a = ImportedType()
   a.implicitlyImportedMethod() // expected-warning {{instance method 'implicitlyImportedMethod()' cannot be used in an '@inlinable' function because 'libB' was not imported by this file; this is an error in Swift 6}}
+  // expected-note@-1 {{The missing import of module 'libB' will be added implicitly}}
 
   // Expected implicit imports are still fine
   a.localModuleMethod()
 
   conformanceUse(a) // expected-warning {{cannot use conformance of 'ImportedType' to 'SomeProtocol' here; 'libB' was not imported by this file; this is an error in Swift 6}}
+  // expected-note@-1 {{The missing import of module 'libB' will be added implicitly}}
 }
 
 // BEGIN clientFileA-OldCheck.swift
@@ -72,6 +74,7 @@ import libA
   a.localModuleMethod()
 
   conformanceUse(a) // expected-warning {{cannot use conformance of 'ImportedType' to 'SomeProtocol' here; 'libB' was not imported by this file; this is an error in Swift 6}}
+  // expected-note@-1 {{The missing import of module 'libB' will be added implicitly}}
 }
 
 // BEGIN clientFileA-Swift6.swift

test/Sema/implicit-import-typealias.swift

@@ -60,23 +60,28 @@ public typealias WrapperAlias = Wrapper
 
 import Aliases
 
-// expected-warning@+1 {{'ClazzAlias' aliases 'Original.Clazz' and cannot be used here because 'Original' was not imported by this file; this is an error in Swift 6}}
+// expected-warning@+2 {{'ClazzAlias' aliases 'Original.Clazz' and cannot be used here because 'Original' was not imported by this file; this is an error in Swift 6}}
+// expected-note@+1 {{The missing import of module 'Original' will be added implicitly}}
 public class InheritsFromClazzAlias: ClazzAlias {}
 
 @inlinable public func inlinableFunc() {
-  // expected-warning@+1 {{'StructAlias' aliases 'Original.Struct' and cannot be used in an '@inlinable' function because 'Original' was not imported by this file; this is an error in Swift 6}}
+  // expected-warning@+2 {{'StructAlias' aliases 'Original.Struct' and cannot be used in an '@inlinable' function because 'Original' was not imported by this file; this is an error in Swift 6}}
+  // expected-note@+1 {{The missing import of module 'Original' will be added implicitly}}
   _ = StructAlias.self
 }
 
-// expected-warning@+1 {{'ProtoAlias' aliases 'Original.Proto' and cannot be used here because 'Original' was not imported by this file; this is an error in Swift 6}}
+// expected-warning@+2 {{'ProtoAlias' aliases 'Original.Proto' and cannot be used here because 'Original' was not imported by this file; this is an error in Swift 6}}
+// expected-note@+1 {{The missing import of module 'Original' will be added implicitly}}
 public func takesGeneric<T: ProtoAlias>(_ t: T) {}
 
 public struct HasMembers {
-  // expected-warning@+1 {{'WrapperAlias' aliases 'Original.Wrapper' and cannot be used as property wrapper here because 'Original' was not imported by this file; this is an error in Swift 6}}
+  // expected-warning@+2 {{'WrapperAlias' aliases 'Original.Wrapper' and cannot be used as property wrapper here because 'Original' was not imported by this file; this is an error in Swift 6}}
+ // expected-note@+1 {{The missing import of module 'Original' will be added implicitly}}
   @WrapperAlias public var wrapped: Int
 }
 
-// expected-warning@+1 {{'StructAlias' aliases 'Original.Struct' and cannot be used in an extension with public or '@usableFromInline' members because 'Original' was not imported by this file; this is an error in Swift 6}}
+// expected-warning@+2 {{'StructAlias' aliases 'Original.Struct' and cannot be used in an extension with public or '@usableFromInline' members because 'Original' was not imported by this file; this is an error in Swift 6}}
+// expected-note@+1 {{The missing import of module 'Original' will be added implicitly}}
 extension StructAlias {
   public func someFunc() {}
 }