[FrontendOptions] Remove the -enable-explicit-existential-types flag.

Author: hborla

include/swift/AST/DiagnosticsSema.def

@@ -4707,10 +4707,6 @@ ERROR(any_not_existential,none,
 ERROR(existential_requires_any,none,
       "protocol %0 as a type must be explicitly marked as 'any'",
       (Identifier))
-ERROR(explicit_existential_not_supported,none,
-       "explicit 'any' not supported; use frontend flag "
-       "-enable-explicit-existential-types to enable this feature",
-       ())
 
 ERROR(nonisolated_let,none,
       "'nonisolated' is meaningless on 'let' declarations because "

include/swift/Basic/LangOptions.h

@@ -313,10 +313,6 @@ namespace swift {
     /// `func f() -> <T> T`.
     bool EnableExperimentalNamedOpaqueTypes = false;
 
-    /// Enable support for explicit existential types via the \c any
-    /// keyword.
-    bool EnableExplicitExistentialTypes = true;
-
     /// Enable support for protocol types parameterized by primary
     /// associated type.
     bool EnableParameterizedProtocolTypes = false;

lib/AST/ASTContext.cpp

@@ -4256,9 +4256,6 @@ ProtocolType::ProtocolType(ProtocolDecl *TheDecl, Type Parent,
 
 Type ExistentialType::get(Type constraint) {
   auto &C = constraint->getASTContext();
-  if (!C.LangOpts.EnableExplicitExistentialTypes)
-    return constraint;
-
   // FIXME: Any and AnyObject don't yet use ExistentialType.
   if (constraint->isAny() || constraint->isAnyObject())
     return constraint;

lib/Frontend/CompilerInvocation.cpp

@@ -445,9 +445,6 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
   Opts.EnableExperimentalNamedOpaqueTypes |=
       Args.hasArg(OPT_enable_experimental_named_opaque_types);
 
-  Opts.EnableExplicitExistentialTypes |=
-      Args.hasArg(OPT_enable_explicit_existential_types);
-
   Opts.EnableParameterizedProtocolTypes |=
       Args.hasArg(OPT_enable_parameterized_protocol_types);
 

lib/IRGen/IRGenDebugInfo.cpp

@@ -98,9 +98,6 @@ class EqualUpToClangTypes
 };
 
 static bool equalWithoutExistentialTypes(Type t1, Type t2) {
-  if (!t1->getASTContext().LangOpts.EnableExplicitExistentialTypes)
-    return false;
-
   auto withoutExistentialTypes = [](Type type) -> Type {
     return type.transform([](Type type) -> Type {
       if (auto existential = type->getAs<ExistentialType>())

lib/SIL/Verifier/SILVerifier.cpp

@@ -2989,8 +2989,7 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
     // metatype with the same constraint type as its existential operand.
     auto formalInstanceTy
       = MI->getType().castTo<ExistentialMetatypeType>().getInstanceType();
-    if (M->getASTContext().LangOpts.EnableExplicitExistentialTypes &&
-        formalInstanceTy->isConstraintType() &&
+    if (formalInstanceTy->isConstraintType() &&
         !(formalInstanceTy->isAny() || formalInstanceTy->isAnyObject())) {
       require(MI->getOperand()->getType().is<ExistentialType>(),
               "existential_metatype operand must be an existential type");

lib/Sema/TypeCheckType.cpp

@@ -2142,11 +2142,6 @@ NeverNullType TypeResolver::resolveType(TypeRepr *repr,
   }
 
   case TypeReprKind::Existential: {
-    if (!getASTContext().LangOpts.EnableExplicitExistentialTypes &&
-        !(options & TypeResolutionFlags::SilenceErrors)) {
-      diagnose(repr->getLoc(), diag::explicit_existential_not_supported);
-    }
-
     auto *existential = cast<ExistentialTypeRepr>(repr);
     return resolveExistentialType(existential, options);
   }
@@ -4145,7 +4140,7 @@ class ExistentialTypeVisitor
   }
 
   void visitIdentTypeRepr(IdentTypeRepr *T) {
-    if (T->isInvalid() || !Ctx.LangOpts.EnableExplicitExistentialTypes)
+    if (T->isInvalid())
       return;
 
     auto comp = T->getComponentRange().back();

test/ClangImporter/objc_bridging_generics.swift

@@ -1,5 +1,4 @@
 // RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -typecheck -parse-as-library -verify -swift-version 4 -I %S/Inputs/custom-modules %s
-// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -typecheck -parse-as-library -enable-explicit-existential-types -verify -swift-version 4 -I %S/Inputs/custom-modules %s
 
 // REQUIRES: objc_interop
 

test/Constraints/common_type_objc.swift

@@ -1,9 +1,6 @@
 // RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -typecheck -verify %s -debug-constraints 2>%t.err
 // RUN: %FileCheck %s < %t.err
 
-// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -typecheck -verify -enable-explicit-existential-types %s -debug-constraints 2>%t.err
-// RUN: %FileCheck %s < %t.err
-
 // REQUIRES: objc_interop
 
 import Foundation

test/Constraints/openExistential.swift

@@ -1,5 +1,4 @@
 // RUN: %target-typecheck-verify-swift
-// RUN: %target-typecheck-verify-swift -enable-explicit-existential-types
 
 protocol P { }
 

test/Constraints/protocols.swift

@@ -1,5 +1,4 @@
 // RUN: %target-typecheck-verify-swift
-// RUN: %target-typecheck-verify-swift -enable-explicit-existential-types
 
 protocol Fooable { func foo() }
 protocol Barable { func bar() }

test/SILGen/protocol_with_superclass.swift

@@ -1,9 +1,6 @@
 // RUN: %target-swift-emit-silgen %s | %FileCheck %s
 // RUN: %target-swift-frontend -emit-ir %s
 
-// RUN: %target-swift-emit-silgen -enable-explicit-existential-types %s | %FileCheck %s
-// RUN: %target-swift-frontend -emit-ir -enable-explicit-existential-types %s
-
 // Protocols with superclass-constrained Self.
 
 class Concrete {

test/SILGen/subclass_existentials.swift

@@ -2,9 +2,6 @@
 // RUN: %target-swift-emit-silgen -module-name subclass_existentials -Xllvm -sil-full-demangle -parse-as-library -primary-file %s -verify | %FileCheck %s
 // RUN: %target-swift-emit-ir -module-name subclass_existentials -parse-as-library -primary-file %s
 
-// RUN: %target-swift-emit-silgen -module-name subclass_existentials -Xllvm -sil-full-demangle -parse-as-library -enable-explicit-existential-types -primary-file %s -verify | %FileCheck %s
-// RUN: %target-swift-emit-ir -module-name subclass_existentials -parse-as-library -enable-explicit-existential-types -primary-file %s
-
 // Note: we pass -verify above to ensure there are no spurious
 // compiler warnings relating to casts.
 

test/Sema/type_join.swift

@@ -1,5 +1,4 @@
 // RUN: %target-typecheck-verify-swift -parse-stdlib
-// RUN: %target-typecheck-verify-swift -parse-stdlib -enable-explicit-existential-types
 
 import Swift
 

test/TypeDecoder/explicit_existentials.swift

@@ -1,4 +1,4 @@
-// RUN: %target-typecheck-verify-swift -enable-explicit-existential-types
+// RUN: %target-typecheck-verify-swift
 
 protocol HasSelfRequirements {
   func foo(_ x: Self)