[SourceKit] Add accessibility in extension structure (SR-4823)

Author: marcelofabri

test/SourceKit/DocumentStructure/access_parse.swift.response

@@ -538,6 +538,7 @@
     },
     {
       key.kind: source.lang.swift.decl.extension,
+      key.accessibility: source.lang.swift.accessibility.internal,
       key.name: "DefAccess",
       key.offset: 1399,
       key.length: 43,
@@ -561,6 +562,7 @@
     },
     {
       key.kind: source.lang.swift.decl.extension,
+      key.accessibility: source.lang.swift.accessibility.internal,
       key.name: "PubAccess",
       key.offset: 1443,
       key.length: 43,
@@ -584,6 +586,7 @@
     },
     {
       key.kind: source.lang.swift.decl.extension,
+      key.accessibility: source.lang.swift.accessibility.internal,
       key.name: "IntAccess",
       key.offset: 1487,
       key.length: 43,
@@ -607,6 +610,7 @@
     },
     {
       key.kind: source.lang.swift.decl.extension,
+      key.accessibility: source.lang.swift.accessibility.internal,
       key.name: "PrivAccess",
       key.offset: 1531,
       key.length: 44,
@@ -630,6 +634,7 @@
     },
     {
       key.kind: source.lang.swift.decl.extension,
+      key.accessibility: source.lang.swift.accessibility.private,
       key.name: "PubAccess",
       key.offset: 1584,
       key.length: 47,

test/SourceKit/DocumentStructure/structure.swift.invalid.response

@@ -5,6 +5,7 @@
   key.substructure: [
     {
       key.kind: source.lang.swift.decl.extension,
+      key.accessibility: source.lang.swift.accessibility.internal,
       key.name: "OuterCls",
       key.offset: 0,
       key.length: 43,

test/SourceKit/DocumentStructure/structure.swift.response

@@ -213,6 +213,7 @@
     },
     {
       key.kind: source.lang.swift.decl.extension,
+      key.accessibility: source.lang.swift.accessibility.internal,
       key.name: "OuterCls",
       key.offset: 377,
       key.length: 45,
@@ -528,6 +529,7 @@
     },
     {
       key.kind: source.lang.swift.decl.extension,
+      key.accessibility: source.lang.swift.accessibility.internal,
       key.name: "Foo",
       key.offset: 999,
       key.length: 58,

test/SourceKit/InterfaceGen/gen_clang_module.swift.response

@@ -5600,6 +5600,7 @@ public class FooOverlayClassDerived : Foo.FooOverlayClassBase {
   },
   {
     key.kind: source.lang.swift.decl.extension,
+    key.accessibility: source.lang.swift.accessibility.internal,
     key.name: "FooClassBase",
     key.offset: 5429,
     key.length: 66,
@@ -5621,6 +5622,7 @@ public class FooOverlayClassDerived : Foo.FooOverlayClassBase {
   },
   {
     key.kind: source.lang.swift.decl.extension,
+    key.accessibility: source.lang.swift.accessibility.internal,
     key.name: "FooClassBase",
     key.offset: 5542,
     key.length: 107,
@@ -5651,6 +5653,7 @@ public class FooOverlayClassDerived : Foo.FooOverlayClassBase {
   },
   {
     key.kind: source.lang.swift.decl.extension,
+    key.accessibility: source.lang.swift.accessibility.internal,
     key.name: "FooClassBase",
     key.offset: 5651,
     key.length: 66,

tools/SourceKit/lib/SwiftLang/SwiftEditor.cpp

@@ -1025,6 +1025,8 @@ class SwiftDocumentStructureWalker: public ide::SyntaxModelWalker {
     if (Node.Kind != SyntaxStructureKind::Parameter) {
       if (auto *VD = dyn_cast_or_null<ValueDecl>(Node.Dcl)) {
         AccessLevel = getAccessibilityUID(inferAccessibility(VD));
+      } else if (auto *ED = dyn_cast_or_null<ExtensionDecl>(Node.Dcl)) {
+        AccessLevel = getAccessibilityUID(inferDefaultAccessibility(ED));
       }
       if (auto *ASD = dyn_cast_or_null<AbstractStorageDecl>(Node.Dcl)) {
         Optional<Accessibility> SetAccess = inferSetterAccessibility(ASD);