Teach ClangImporter to handle effective Swift version with minor release.

Needed to support Swift 4.2.
2025-12-14 20:36:38 +01:00 · 2018-03-23 00:30:44 -07:00
parent fa730db1c2
commit 3da51018b6
11 changed files with 195 additions and 19 deletions
--- a/include/swift/Basic/Version.h
+++ b/include/swift/Basic/Version.h
@@ -119,6 +119,9 @@ public:
  /// Return this Version struct with minor and sub-minor components stripped
  Version asMajorVersion() const;

+  /// Return this Version struct as the appropriate version string for APINotes.
+  std::string asAPINotesVersionString() const;
+
  /// Parse a version in the form used by the _compiler_version \#if condition.
  static Optional<Version> parseCompilerVersionString(StringRef VersionString,
                                                      SourceLoc Loc,
--- a/lib/Basic/Version.cpp
+++ b/lib/Basic/Version.cpp
@@ -17,6 +17,7 @@
 #include "clang/Basic/CharInfo.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringExtras.h"
 #include "swift/AST/DiagnosticsParse.h"
 #include "swift/Basic/LLVM.h"
 #include "swift/Basic/Version.h"
@@ -302,8 +303,13 @@ Optional<Version> Version::getEffectiveLanguageVersion() const {
  case 0:
    return None;
  case 1:
-  case 2:
    break;
+  case 2:
+    // The only valid explicit language version with a minor
+    // component is 4.2.
+    if (Components[0] == 4 && Components[1] == 2)
+      break;
+    return None;
  default:
    // We do not want to permit users requesting more precise effective language
    // versions since accepting such an argument promises more than we're able
@@ -327,9 +333,9 @@ Optional<Version> Version::getEffectiveLanguageVersion() const {
  case 4:
    static_assert(SWIFT_VERSION_MAJOR == 4,
                  "getCurrentLanguageVersion is no longer correct here");
-    // Version '4' on its own implies '4.1'.
+    // Version '4' on its own implies '4.1.50'.
    if (size() == 1)
-      return Version{4, 1};
+      return Version{4, 1, 50};
    return Version::getCurrentLanguageVersion();
  case 5:
    return Version{5, 0};
@@ -346,6 +352,16 @@ Version Version::asMajorVersion() const {
  return res;
 }

+std::string Version::asAPINotesVersionString() const {
+  // Other than for "4.2.x", map the Swift major version into
+  // the API notes version for Swift. This has the effect of allowing
+  // API notes to effect changes only on Swift major versions,
+  // not minor versions.
+  if (size() >= 2 && Components[0] == 4 && Components[1] == 2)
+    return "4.2";
+  return llvm::itostr(Components[0]);
+}
+
 bool operator>=(const class Version &lhs,
                const class Version &rhs) {

--- a/lib/ClangImporter/ClangImporter.cpp
+++ b/lib/ClangImporter/ClangImporter.cpp
@@ -611,12 +611,8 @@ getNormalInvocationArguments(std::vector<std::string> &invocationArgStrs,
  }
  invocationArgStrs.push_back("-iapinotes-modules");
  invocationArgStrs.push_back(searchPathOpts.RuntimeLibraryImportPath);
-
-  // Map the Swift major version into the API notes version for Swift. This
-  // has the effect of allowing API notes to effect changes only on Swift
-  // major versions, not minor versions.
  invocationArgStrs.push_back("-fapinotes-swift-version=" +
-                              llvm::itostr(languageVersion[0]));
+      languageVersion.asAPINotesVersionString());
 }

 static void
--- a/lib/ClangImporter/ImportName.cpp
+++ b/lib/ClangImporter/ImportName.cpp
@@ -578,6 +578,8 @@ checkVersionedSwiftName(VersionedSwiftNameInfo info,
  if (!bestSoFar.empty() && bestSoFar <= info.Version)
    return VersionedSwiftNameAction::Ignore;

+  auto requestedClangVersion = requestedVersion.asClangVersionTuple();
+
  if (info.IsReplacedByActive) {
    // We know that there are no versioned names between the active version and
    // a replacement version, because otherwise /that/ name would be active.
@@ -586,7 +588,7 @@ checkVersionedSwiftName(VersionedSwiftNameInfo info,
    // new value that is now active. (Special case: replacement = 0 means that
    // a header annotation was replaced by an unversioned API notes annotation.)
    if (info.Version.empty() ||
-        info.Version.getMajor() >= requestedVersion.majorVersionNumber()) {
+        info.Version >= requestedClangVersion) {
      return VersionedSwiftNameAction::ResetToActive;
    }
    if (bestSoFar.empty())
@@ -594,7 +596,7 @@ checkVersionedSwiftName(VersionedSwiftNameInfo info,
    return VersionedSwiftNameAction::Ignore;
  }

-  if (info.Version.getMajor() < requestedVersion.majorVersionNumber())
+  if (info.Version < requestedClangVersion)
    return VersionedSwiftNameAction::Ignore;
  return VersionedSwiftNameAction::Use;
 }
--- a/lib/ClangImporter/ImportName.h
+++ b/lib/ClangImporter/ImportName.h
@@ -56,12 +56,35 @@ class ImportNameVersion : public RelationalOperationsBase<ImportNameVersion> {
 public:
  /// Map a language version into an import name version.
  static ImportNameVersion fromOptions(const LangOptions &langOpts) {
-    return ImportNameVersion(langOpts.EffectiveLanguageVersion[0]);
+    // We encode the 'rawValue' as just major version numbers with the
+    // exception of '4.2', which is a special minor version that can impact
+    // importing of names.  We treat that with a rawValue of 5, and treat
+    // all major values of 5 or higher as being rawValue = majorversion + 1.
+    const auto &version = langOpts.EffectiveLanguageVersion;
+    if (version.size() > 1 && version[0] == 4 && version[1] == 2) {
+      return ImportNameVersion::swift4_2();
+    }
+    unsigned major = version[0];
+    return ImportNameVersion(major >= 5 ? major + 1 : major);
  }

  unsigned majorVersionNumber() const {
    assert(*this != ImportNameVersion::raw());
-    return rawValue;
+    if (*this == ImportNameVersion::swift4_2())
+      return 4;
+    return rawValue < 5 ? rawValue : rawValue - 1;
+  }
+
+  unsigned minorVersionNumber() const {
+    assert(*this != ImportNameVersion::raw());
+    if (*this == ImportNameVersion::swift4_2())
+      return 2;
+    return 0;
+  }
+
+  clang::VersionTuple asClangVersionTuple() const {
+    assert(*this != ImportNameVersion::raw());
+    return clang::VersionTuple(majorVersionNumber(), minorVersionNumber());    
  }

  bool operator==(ImportNameVersion other) const {
@@ -105,12 +128,17 @@ public:
    return ImportNameVersion{2, AsConstExpr};
  }

+  /// Names as they appeared in Swift 4.2 family.
+  static constexpr inline ImportNameVersion swift4_2() {
+    return ImportNameVersion{5, AsConstExpr};
+  }
+
  /// The latest supported version.
  ///
  /// FIXME: All other version information is in Version.h. Can this go there
  /// instead?
  static constexpr inline ImportNameVersion maxVersion() {
-    return ImportNameVersion{5, AsConstExpr};
+    return ImportNameVersion{6, AsConstExpr};
  }

  /// The version which should be used for importing types, which need to have
--- a/test/APINotes/Inputs/custom-frameworks/APINotesFrameworkTest.framework/Headers/APINotesFrameworkTest.apinotes
+++ b/test/APINotes/Inputs/custom-frameworks/APINotesFrameworkTest.framework/Headers/APINotesFrameworkTest.apinotes
@@ -259,7 +259,7 @@ SwiftVersions:
        SwiftName: multiVersionedGlobal45Notes_5
      - Name: multiVersionedGlobal45Both
        SwiftName: multiVersionedGlobal45Both_5
-  - Version: 4 # Versions are deliberately ordered as "3, 5, 4" to catch bugs.
+  - Version: 4 # Versions are deliberately ordered as "3, 5, 4.2, 4" to catch bugs.
    Globals:
      - Name: multiVersionedGlobal34
        SwiftName: multiVersionedGlobal34_4
@@ -293,3 +293,37 @@ SwiftVersions:
        SwiftName: multiVersionedGlobal45Notes_4
      - Name: multiVersionedGlobal45Both
        SwiftName: multiVersionedGlobal45Both_4
+  - Version: 4.2
+    Globals:
+      - Name: multiVersionedGlobal34
+        SwiftName: multiVersionedGlobal34_4_2
+      - Name: multiVersionedGlobal34Header
+        SwiftName: multiVersionedGlobal34Header_4_2
+      - Name: multiVersionedGlobal34Notes
+        SwiftName: multiVersionedGlobal34Notes_4_2
+      - Name: multiVersionedGlobal34Both
+        SwiftName: multiVersionedGlobal34Both_4_2
+      - Name: multiVersionedGlobal345
+        SwiftName: multiVersionedGlobal345_4_2
+      - Name: multiVersionedGlobal345Header
+        SwiftName: multiVersionedGlobal345Header_4_2
+      - Name: multiVersionedGlobal345Notes
+        SwiftName: multiVersionedGlobal345Notes_4_2
+      - Name: multiVersionedGlobal345Both
+        SwiftName: multiVersionedGlobal345Both_4_2
+      - Name: multiVersionedGlobal4
+        SwiftName: multiVersionedGlobal4_4_2
+      - Name: multiVersionedGlobal4Header
+        SwiftName: multiVersionedGlobal4Header_4_2
+      - Name: multiVersionedGlobal4Notes
+        SwiftName: multiVersionedGlobal4Notes_4_2
+      - Name: multiVersionedGlobal4Both
+        SwiftName: multiVersionedGlobal4Both_4_2
+      - Name: multiVersionedGlobal45
+        SwiftName: multiVersionedGlobal45_4_2
+      - Name: multiVersionedGlobal45Header
+        SwiftName: multiVersionedGlobal45Header_4_2
+      - Name: multiVersionedGlobal45Notes
+        SwiftName: multiVersionedGlobal45Notes_4_2
+      - Name: multiVersionedGlobal45Both
+        SwiftName: multiVersionedGlobal45Both_4_2
--- a/test/APINotes/versioned-multi.swift
+++ b/test/APINotes/versioned-multi.swift
@@ -4,6 +4,8 @@

 // RUN: %target-swift-ide-test -F %S/Inputs/custom-frameworks -print-module -source-filename %s -module-to-print=APINotesFrameworkTest -function-definitions=false -swift-version 4 | %FileCheck -check-prefix=CHECK-SWIFT-4 %s

+// RUN: %target-swift-ide-test -F %S/Inputs/custom-frameworks -print-module -source-filename %s -module-to-print=APINotesFrameworkTest -function-definitions=false -swift-version 4.2 | %FileCheck -check-prefix=CHECK-SWIFT-4-2 %s
+
 // RUN: %target-swift-ide-test -F %S/Inputs/custom-frameworks -print-module -source-filename %s -module-to-print=APINotesFrameworkTest -function-definitions=false -swift-version 5 | %FileCheck -check-prefix=CHECK-SWIFT-5 %s

 // CHECK-SWIFT-3: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal4_4")
@@ -199,6 +201,101 @@
 // CHECK-SWIFT-4: @available(swift, introduced: 5, renamed: "multiVersionedGlobal345Both_4")
 // CHECK-SWIFT-4: var multiVersionedGlobal345Both_5: Int32

+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal4_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal4: Int32
+// CHECK-SWIFT-4-2: var multiVersionedGlobal4_4: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal4Notes_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal4Notes: Int32
+// CHECK-SWIFT-4-2: var multiVersionedGlobal4Notes_4: Int32
+// CHECK-SWIFT-4-2: @available(swift, introduced: 5, renamed: "multiVersionedGlobal4Notes_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal4Notes_NEW: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal4Header_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal4Header: Int32
+// CHECK-SWIFT-4-2: var multiVersionedGlobal4Header_4: Int32
+// CHECK-SWIFT-4-2: @available(swift, introduced: 5, renamed: "multiVersionedGlobal4Header_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal4Header_NEW: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal4Both_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal4Both: Int32
+// CHECK-SWIFT-4-2: var multiVersionedGlobal4Both_4: Int32
+// CHECK-SWIFT-4-2: @available(swift, introduced: 5, renamed: "multiVersionedGlobal4Both_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal4Both_NEW: Int32
+
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal34_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal34: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 4, renamed: "multiVersionedGlobal34_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal34_3: Int32
+// CHECK-SWIFT-4-2: var multiVersionedGlobal34_4: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal34Notes_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal34Notes: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 4, renamed: "multiVersionedGlobal34Notes_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal34Notes_3: Int32
+// CHECK-SWIFT-4-2: var multiVersionedGlobal34Notes_4: Int32
+// CHECK-SWIFT-4-2: @available(swift, introduced: 5, renamed: "multiVersionedGlobal34Notes_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal34Notes_NEW: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal34Header_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal34Header: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 4, renamed: "multiVersionedGlobal34Header_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal34Header_3: Int32
+// CHECK-SWIFT-4-2: var multiVersionedGlobal34Header_4: Int32
+// CHECK-SWIFT-4-2: @available(swift, introduced: 5, renamed: "multiVersionedGlobal34Header_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal34Header_NEW: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal34Both_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal34Both: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 4, renamed: "multiVersionedGlobal34Both_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal34Both_3: Int32
+// CHECK-SWIFT-4-2: var multiVersionedGlobal34Both_4: Int32
+// CHECK-SWIFT-4-2: @available(swift, introduced: 5, renamed: "multiVersionedGlobal34Both_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal34Both_NEW: Int32
+
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal45_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal45: Int32
+// CHECK-SWIFT-4-2: var multiVersionedGlobal45_4: Int32
+// CHECK-SWIFT-4-2: @available(swift, introduced: 5, renamed: "multiVersionedGlobal45_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal45_5: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal45Notes_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal45Notes: Int32
+// CHECK-SWIFT-4-2: var multiVersionedGlobal45Notes_4: Int32
+// CHECK-SWIFT-4-2: @available(swift, introduced: 5, renamed: "multiVersionedGlobal45Notes_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal45Notes_5: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal45Header_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal45Header: Int32
+// CHECK-SWIFT-4-2: var multiVersionedGlobal45Header_4: Int32
+// CHECK-SWIFT-4-2: @available(swift, introduced: 5, renamed: "multiVersionedGlobal45Header_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal45Header_5: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal45Both_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal45Both: Int32
+// CHECK-SWIFT-4-2: var multiVersionedGlobal45Both_4: Int32
+// CHECK-SWIFT-4-2: @available(swift, introduced: 5, renamed: "multiVersionedGlobal45Both_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal45Both_5: Int32
+
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal345_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal345: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 4, renamed: "multiVersionedGlobal345_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal345_3: Int32
+// CHECK-SWIFT-4-2: var multiVersionedGlobal345_4: Int32
+// CHECK-SWIFT-4-2: @available(swift, introduced: 5, renamed: "multiVersionedGlobal345_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal345_5: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal345Notes_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal345Notes: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 4, renamed: "multiVersionedGlobal345Notes_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal345Notes_3: Int32
+// CHECK-SWIFT-4-2: var multiVersionedGlobal345Notes_4: Int32
+// CHECK-SWIFT-4-2: @available(swift, introduced: 5, renamed: "multiVersionedGlobal345Notes_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal345Notes_5: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal345Header_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal345Header: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 4, renamed: "multiVersionedGlobal345Header_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal345Header_3: Int32
+// CHECK-SWIFT-4-2: var multiVersionedGlobal345Header_4: Int32
+// CHECK-SWIFT-4-2: @available(swift, introduced: 5, renamed: "multiVersionedGlobal345Header_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal345Header_5: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 3, renamed: "multiVersionedGlobal345Both_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal345Both: Int32
+// CHECK-SWIFT-4-2: @available(swift, obsoleted: 4, renamed: "multiVersionedGlobal345Both_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal345Both_3: Int32
+// CHECK-SWIFT-4-2: var multiVersionedGlobal345Both_4: Int32
+// CHECK-SWIFT-4-2: @available(swift, introduced: 5, renamed: "multiVersionedGlobal345Both_4_2")
+// CHECK-SWIFT-4-2: var multiVersionedGlobal345Both_5: Int32

 // CHECK-SWIFT-5: var multiVersionedGlobal4: Int32
 // CHECK-SWIFT-5: @available(swift, obsoleted: 5, renamed: "multiVersionedGlobal4")
--- a/test/Driver/swift-version.swift
+++ b/test/Driver/swift-version.swift
@@ -14,7 +14,7 @@
 // RUN: not %target-swiftc_driver -swift-version 5 -typecheck %s 2>&1 | %FileCheck --check-prefix ERROR_5 %s

 // BAD: invalid value
-// BAD: note: valid arguments to '-swift-version' are '3', '4', '5'
+// BAD: note: valid arguments to '-swift-version' are '3', '4', '4.2', '5'

 // FIXIT_3: use major version, as in '-swift-version 3'
 // FIXIT_4: use major version, as in '-swift-version 4'
--- a/test/Parse/ConditionalCompilation/language_version_explicit.swift
+++ b/test/Parse/ConditionalCompilation/language_version_explicit.swift
@@ -1,4 +1,4 @@
-// RUN: %target-typecheck-verify-swift -swift-version 4
+// RUN: %target-typecheck-verify-swift -swift-version 4.2

 #if swift(>=4)
  let w = 1
--- a/test/Serialization/Recovery/crash-recovery.swift
+++ b/test/Serialization/Recovery/crash-recovery.swift
@@ -2,7 +2,7 @@
 // RUN: %target-swift-frontend -emit-module -o %t -module-name Lib -I %S/Inputs/custom-modules -swift-version 3 %s

 // RUN: echo 'import Lib; _ = Sub.disappearingMethod' | not --crash %target-swift-frontend -typecheck -I %t -I %S/Inputs/custom-modules -swift-version 3 -disable-deserialization-recovery -Xcc -DBAD - 2>&1 | %FileCheck -check-prefix CHECK-CRASH -check-prefix CHECK-CRASH-3 %s
-// RUN: echo 'import Lib; _ = Sub.disappearingMethod' | not --crash %target-swift-frontend -typecheck -I %t -I %S/Inputs/custom-modules -swift-version 4 -disable-deserialization-recovery -Xcc -DBAD - 2>&1 | %FileCheck -check-prefix CHECK-CRASH -check-prefix CHECK-CRASH-4 %s
+// RUN: echo 'import Lib; _ = Sub.disappearingMethod' | not --crash %target-swift-frontend -typecheck -I %t -I %S/Inputs/custom-modules -swift-version 4.2 -disable-deserialization-recovery -Xcc -DBAD - 2>&1 | %FileCheck -check-prefix CHECK-CRASH -check-prefix CHECK-CRASH-4 %s

 // REQUIRES: objc_interop

--- a/test/Serialization/Recovery/types-4-to-3.swift
+++ b/test/Serialization/Recovery/types-4-to-3.swift
@@ -16,8 +16,8 @@ import Lib
 func requiresConformance(_: B_RequiresConformance<B_ConformsToProto>) {}
 func requiresConformance(_: B_RequiresConformance<C_RelyOnConformanceImpl.Assoc>) {}

-class Sub: Base {} // expected-error {{cannot inherit from class 'Base' (compiled with Swift 4.2) because it has overridable members that could not be loaded in Swift 3.4}}
-class Impl: Proto {} // expected-error {{type 'Impl' cannot conform to protocol 'Proto' (compiled with Swift 4.2) because it has requirements that could not be loaded in Swift 3.4}}
+class Sub: Base {} // expected-error {{cannot inherit from class 'Base' (compiled with Swift 4.1.50) because it has overridable members that could not be loaded in Swift 3.4}}
+class Impl: Proto {} // expected-error {{type 'Impl' cannot conform to protocol 'Proto' (compiled with Swift 4.1.50) because it has requirements that could not be loaded in Swift 3.4}}

 #else // TEST