[5.6][SymbolGraph] consider underscored symbols as private if they're internal

lib/SymbolGraphGen/SymbolGraph.cpp

@@ -582,9 +582,23 @@ bool SymbolGraph::isImplicitlyPrivate(const Decl *D,
   }
 
   // Don't record effectively internal declarations if specified
-  if (Walker.Options.MinimumAccessLevel > AccessLevel::Internal &&
-      D->hasUnderscoredNaming()) {
-    return true;
+  if (D->hasUnderscoredNaming()) {
+    AccessLevel symLevel = AccessLevel::Public;
+    if (const ValueDecl *VD = dyn_cast<ValueDecl>(D)) {
+      symLevel = VD->getFormalAccess();
+    }
+
+    // Underscored symbols should be treated as `internal`, unless they're already
+    // marked that way - in that case, treat them as `private`
+    AccessLevel effectiveLevel;
+    if (symLevel > AccessLevel::Internal) {
+      effectiveLevel = AccessLevel::Internal;
+    } else {
+      effectiveLevel = AccessLevel::Private;
+    }
+
+    if (Walker.Options.MinimumAccessLevel > effectiveLevel)
+      return true;
   }
 
   // Don't include declarations with the @_spi attribute unless the

test/SymbolGraph/Symbols/SkipsPublicUnderscore.swift

@@ -1,29 +1,49 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-build-swift %s -module-name SkipsPublicUnderscore -emit-module -emit-module-path %t/
 // RUN: %target-swift-symbolgraph-extract -module-name SkipsPublicUnderscore -I %t -pretty-print -output-dir %t
-// RUN: %FileCheck %s --input-file %t/SkipsPublicUnderscore.symbols.json
+// RUN: %FileCheck %s --input-file %t/SkipsPublicUnderscore.symbols.json --check-prefix PUBLIC
+
+// RUN: %target-swift-symbolgraph-extract -module-name SkipsPublicUnderscore -I %t -pretty-print -output-dir %t -minimum-access-level internal
+// RUN: %FileCheck %s --input-file %t/SkipsPublicUnderscore.symbols.json --check-prefix INTERNAL
+
+// RUN: %target-swift-symbolgraph-extract -module-name SkipsPublicUnderscore -I %t -pretty-print -output-dir %t -minimum-access-level private
+// RUN: %FileCheck %s --input-file %t/SkipsPublicUnderscore.symbols.json --check-prefix PRIVATE
 
 public protocol PublicProtocol {}
 
-// CHECK-NOT: precise:{{.*}}_ProtocolShouldntAppear
-// CHECK-NOT: precise:{{.*}}PublicProtocol
+public class SomeClass {
+  // underscored names marked `internal` or tighter should be considered `private`
+
+  // PUBLIC-NOT: "precise": "s:21SkipsPublicUnderscore9SomeClassC12_InternalVarSSvp"
+  // INTERNAL-NOT: "precise": "s:21SkipsPublicUnderscore9SomeClassC12_InternalVarSSvp"
+  // PRIVATE: "precise": "s:21SkipsPublicUnderscore9SomeClassC12_InternalVarSSvp"
+  internal var _InternalVar: String = ""
+}
+
+// PUBLIC-NOT: precise:{{.*}}_ProtocolShouldntAppear
+// PUBLIC-NOT: precise:{{.*}}PublicProtocol
 @_show_in_interface
 public protocol _ProtocolShouldntAppear {}
 
-// CHECK-NOT: _ShouldntAppear
+// PUBLIC-NOT: _ShouldntAppear
+// INTERNAL-DAG: _ShouldntAppear
 
+// INTERNAL-DAG: "precise": "s:21SkipsPublicUnderscore23_ProtocolShouldntAppearP"
 public struct _ShouldntAppear: PublicProtocol, _ProtocolShouldntAppear {
   // Although these are public and not underscored,
   // they are inside an underscored type,
   // so shouldn't be allowed through.
 
-  // CHECK-NOT: shouldntAppear
+  // PUBLIC-NOT: shouldntAppear
+  // INTERNAL-DAG: shouldntAppear
   public var shouldntAppear: Int
 
-  // CHECK-NOT: InnerShouldntAppear
+  // PUBLIC-NOT: InnerShouldntAppear
+  // INTERNAL-DAG: InnerShouldntAppear
   public struct InnerShouldntAppear {
 
-  // CHECK-NOT: InnerInnerShouldntAppear
+  // PUBLIC-NOT: InnerInnerShouldntAppear
+  // INTERNAL-DAG: InnerInnerShouldntAppear
   public struct InnerInnerShouldntAppear {}
   }
 }
@@ -34,22 +54,27 @@ public struct ShouldAppear: _ProtocolShouldntAppear {}
 
 public struct PublicOuter {
   // Nor should an "internal" type's relationship to a "public" protocol.
-  // CHECK-NOT: _InnerShouldntAppear
+  // PUBLIC-NOT: _InnerShouldntAppear
+  // INTERNAL-DAG: _InnerShouldntAppear
   public struct _InnerShouldntAppear: PublicProtocol {}
 }
 
 extension PublicOuter {
-  // CHECK-NOT: _FromExtension
+  // PUBLIC-NOT: _FromExtension
+  // INTERNAL-DAG: _FromExtension
   public struct _FromExtension: PublicProtocol {
-    // CHECK-NOT: shouldntAppear
+    // PUBLIC-NOT: shouldntAppear
+    // INTERNAL-DAG: shouldntAppear
     public var shouldntAppear: Int
   }
 }
 
 extension _ShouldntAppear {
-  // CHECK-NOT: FromExtension
+  // PUBLIC-NOT: FromExtension
+  // INTERNAL-DAG: FromExtension
   public struct FromExtension: PublicProtocol {
-    // CHECK-NOT: shouldntAppear
+    // PUBLIC-NOT: shouldntAppear
+    // INTERNAL-DAG: shouldntAppear
     public var shouldntAppear: Int
   }
 }
@@ -60,4 +85,4 @@ extension _ShouldntAppear.InnerShouldntAppear {
 
 extension _ShouldntAppear.InnerShouldntAppear: Equatable {}
 
-// CHECK: "relationships": []
+// PUBLIC: "relationships": []