SE-0193: Public default argument generators cannot reference declarations that are @usableFromInline

Author: slavapestov

include/swift/AST/DiagnosticsSema.def

@@ -3765,10 +3765,10 @@ ERROR(resilience_decl_unavailable,
 
 #undef FRAGILE_FUNC_KIND
 
-NOTE(resilience_decl_declared_here,
+NOTE(resilience_decl_declared_here_public,
      none, "%0 %1 is not public", (DescriptiveDeclKind, DeclName))
 
-NOTE(resilience_decl_declared_here_versioned,
+NOTE(resilience_decl_declared_here,
      none, "%0 %1 is not '@usableFromInline' or public", (DescriptiveDeclKind, DeclName))
 
 ERROR(class_designated_init_inlinable_resilient,none,

lib/Sema/ResilienceDiagnostics.cpp

@@ -27,8 +27,15 @@ std::pair<FragileFunctionKind, bool>
 TypeChecker::getFragileFunctionKind(const DeclContext *DC) {
   for (; DC->isLocalContext(); DC = DC->getParent()) {
     if (isa<DefaultArgumentInitializer>(DC)) {
+      // Default argument generators of public functions cannot reference
+      // @usableFromInline declarations; all other fragile function kinds
+      // can.
+      auto *VD = cast<ValueDecl>(DC->getInnermostDeclarationDeclContext());
+      auto access =
+        VD->getFormalAccessScope(/*useDC=*/nullptr,
+                                 /*treatUsableFromInlineAsPublic=*/false);
       return std::make_pair(FragileFunctionKind::DefaultArgument,
-                            /*treatUsableFromInlineAsPublic=*/true);
+                            !access.isPublic());
     }
 
     if (isa<PatternBindingInitializer>(DC))
@@ -121,21 +128,11 @@ bool TypeChecker::diagnoseInlinableDeclRef(SourceLoc loc,
            D->getFormalAccessScope().accessLevelForDiagnostics(),
            static_cast<unsigned>(Kind));
 
-  bool isDefaultArgument = false;
-  while (DC->isLocalContext()) {
-    if (isa<DefaultArgumentInitializer>(DC)) {
-      isDefaultArgument = true;
-      break;
-    }
-
-    DC = DC->getParent();
-  }
-
-  if (isDefaultArgument) {
+  if (TreatUsableFromInlineAsPublic) {
     diagnose(D, diag::resilience_decl_declared_here,
              D->getDescriptiveKind(), D->getFullName());
   } else {
-    diagnose(D, diag::resilience_decl_declared_here_versioned,
+    diagnose(D, diag::resilience_decl_declared_here_public,
              D->getDescriptiveKind(), D->getFullName());
   }
 

test/decl/func/default-values-swift4.swift

@@ -2,16 +2,27 @@
 // RUN: %target-typecheck-verify-swift -swift-version 4 -enable-testing
 
 private func privateFunction() {}
-// expected-note@-1 4{{global function 'privateFunction()' is not public}}
+// expected-note@-1 2{{global function 'privateFunction()' is not public}}
 fileprivate func fileprivateFunction() {}
-// expected-note@-1 4{{global function 'fileprivateFunction()' is not public}}
+// expected-note@-1 2{{global function 'fileprivateFunction()' is not public}}
 func internalFunction() {}
-// expected-note@-1 4{{global function 'internalFunction()' is not public}}
+// expected-note@-1 2{{global function 'internalFunction()' is not public}}
 @usableFromInline func versionedFunction() {}
+// expected-note@-1 5{{global function 'versionedFunction()' is not public}}
 public func publicFunction() {}
 
 func internalIntFunction() -> Int {}
-// expected-note@-1 2{{global function 'internalIntFunction()' is not public}}
+// expected-note@-1 {{global function 'internalIntFunction()' is not public}}
+
+private func privateFunction2() {}
+// expected-note@-1 2{{global function 'privateFunction2()' is not '@usableFromInline' or public}}
+fileprivate func fileprivateFunction2() {}
+// expected-note@-1 2{{global function 'fileprivateFunction2()' is not '@usableFromInline' or public}}
+func internalFunction2() {}
+// expected-note@-1 2{{global function 'internalFunction2()' is not '@usableFromInline' or public}}
+
+func internalIntFunction2() -> Int {}
+// expected-note@-1 {{global function 'internalIntFunction2()' is not '@usableFromInline' or public}}
 
 func internalFunctionWithDefaultValue(
     x: Int = {
@@ -44,17 +55,17 @@ func internalFunctionWithDefaultValue(
       // OK
       versionedFunction()
       // OK
-      internalFunction()
-      // expected-error@-1 2{{global function 'internalFunction()' is internal and cannot be referenced from a default argument value}}
-      fileprivateFunction()
-      // expected-error@-1 2{{global function 'fileprivateFunction()' is fileprivate and cannot be referenced from a default argument value}}
-      privateFunction()
-      // expected-error@-1 2{{global function 'privateFunction()' is private and cannot be referenced from a default argument value}}
+      internalFunction2()
+      // expected-error@-1 2{{global function 'internalFunction2()' is internal and cannot be referenced from a default argument value}}
+      fileprivateFunction2()
+      // expected-error@-1 2{{global function 'fileprivateFunction2()' is fileprivate and cannot be referenced from a default argument value}}
+      privateFunction2()
+      // expected-error@-1 2{{global function 'privateFunction2()' is private and cannot be referenced from a default argument value}}
 
       return 0
     }(),
-    y: Int = internalIntFunction()) {}
-    // expected-error@-1 {{global function 'internalIntFunction()' is internal and cannot be referenced from a default argument value}}
+    y: Int = internalIntFunction2()) {}
+    // expected-error@-1 {{global function 'internalIntFunction2()' is internal and cannot be referenced from a default argument value}}
 
 public func publicFunctionWithDefaultValue(
     x: Int = {
@@ -64,13 +75,16 @@ public func publicFunctionWithDefaultValue(
       // FIXME: Some errors below are diagnosed twice
 
       publicFunction()
-      // OK
+
       versionedFunction()
-      // OK
+      // expected-error@-1 2{{global function 'versionedFunction()' is internal and cannot be referenced from a default argument value}}
+
       internalFunction()
       // expected-error@-1 2{{global function 'internalFunction()' is internal and cannot be referenced from a default argument value}}
+
       fileprivateFunction()
       // expected-error@-1 2{{global function 'fileprivateFunction()' is fileprivate and cannot be referenced from a default argument value}}
+
       privateFunction()
       // expected-error@-1 2{{global function 'privateFunction()' is private and cannot be referenced from a default argument value}}
 
@@ -83,3 +97,16 @@ public func publicFunctionWithDefaultValue(
 public class MyClass {
   public func method<T>(_: T.Type = T.self) -> T { }
 }
+
+public func evilCode(
+  x: Int = {
+    let _ = publicFunction()
+    let _ = versionedFunction()
+    // expected-error@-1 2{{global function 'versionedFunction()' is internal and cannot be referenced from a default argument value}}
+
+    func localFunction() {
+      publicFunction()
+      versionedFunction()
+      // expected-error@-1 {{global function 'versionedFunction()' is internal and cannot be referenced from a default argument value}}
+    }
+  }()) {}