diag-sema: plain protocol suggests some or any

Author: saehejkang

include/swift/AST/DiagnosticsSema.def

@@ -5792,6 +5792,15 @@ ERROR(incorrect_optional_any,none,
 ERROR(existential_requires_any,none,
       "use of %select{protocol |}2%0 as a type must be written %1",
       (Type, Type, bool))
+ERROR(existential_requires_any_or_some,none,
+      "use of %select{protocol |}3%0 as a type must be written %1 or %2",
+      (Type, Type, StringRef, bool))
+NOTE(replace_with_any,none,
+     "replace %0 with %1",
+     (Type, Type))
+NOTE(replace_with_some,none,
+     "replace %0 with %1",
+     (Type, StringRef))
 ERROR(inverse_requires_any,none,
       "constraint that suppresses conformance requires 'any'", ())
 

lib/Sema/TypeCheckType.cpp

@@ -6284,6 +6284,25 @@ class ExistentialTypeSyntaxChecker : public ASTWalker {
     }
 
     if (auto *proto = dyn_cast<ProtocolDecl>(decl)) {
+      if (proto->existentialRequiresAny()) {
+        //Emit fixit to add any keyword
+        Ctx.Diags.diagnose(T->getNameLoc(), diag::replace_with_any,
+                            proto->getDeclaredInterfaceType(),
+                            proto->getDeclaredExistentialType())
+        .fixItReplace(T->getSourceRange(), "any " + proto->getDeclaredInterfaceType()->getString());
+        //Emit fixit to add some keyword
+        Ctx.Diags.diagnose(T->getNameLoc(), diag::replace_with_some,
+                            proto->getDeclaredInterfaceType(),
+                            ("'some " + proto->getDeclaredInterfaceType()->getString() + "'"))
+        .fixItReplace(T->getSourceRange(), "some " + proto->getDeclaredInterfaceType()->getString());
+        auto diag =
+          Ctx.Diags.diagnose(T->getNameLoc(), diag::existential_requires_any_or_some,
+                            proto->getDeclaredInterfaceType(),
+                            proto->getDeclaredExistentialType(),
+                            ("'some " + proto->getDeclaredInterfaceType()->getString() + "'"),
+                            /*isAlias=*/false);
+        emitInsertAnyFixit(diag, T);
+      }
       if (proto->existentialRequiresAny() && isAnyOrSomeMissing()) {
         auto diag =
             Ctx.Diags.diagnose(T->getNameLoc(), diag::existential_requires_any,

test/decl/nested/protocol.swift

@@ -356,3 +356,11 @@ struct Outer {
     }
   }
 }
+
+// https://github.com/apple/swift/issues/68284
+protocol P {
+  associatedtype A
+}
+func generic(value: P) {}   // expected-error {{use of protocol 'P' as a type must be written 'any P' or 'some P'}}
+                            // expected-note@-1 {{replace 'P' with 'any P'}} {{21-22=any P}}
+                            // expected-note@-2 {{replace 'P' with 'some P'}} {{21-22=some P}}