Merge pull request #36880 from ahoppen/pr/cursor-info-protocol-var

[ASTPrinter] Don't transform type if current type can't have members

Author: ahoppen

lib/AST/ASTPrinter.cpp

@@ -924,6 +924,18 @@ class PrintAST : public ASTVisitor<PrintAST> {
     if (Options.TransformContext) {
       Type CurrentType = Options.TransformContext->getBaseType();
       if (CurrentType && CurrentType->hasArchetype()) {
+        // OpenedArchetypeTypes get replaced by a GenericTypeParamType without a
+        // name in mapTypeOutOfContext. The GenericTypeParamType has no children
+        // so we can't use it for TypeTransformContext.
+        // To work around this, replace the OpenedArchetypeType with the type of
+        // the protocol itself.
+        CurrentType = CurrentType.transform([](Type T) -> Type {
+          if (auto *Opened = T->getAs<OpenedArchetypeType>()) {
+            return Opened->getOpenedExistentialType();
+          } else {
+            return T;
+          }
+        });
         CurrentType = CurrentType->mapTypeOutOfContext();
       }
       setCurrentType(CurrentType);

test/SourceKit/CursorInfo/cursor_info_existential_var.swift

@@ -0,0 +1,13 @@
+protocol MyError {
+    var myVar: String { get }
+}
+
+func foo(error: MyError) {
+    _ = error.myVar
+}
+
+// RUN: %sourcekitd-test -req=cursor -pos=6:15 %s -- %s | %FileCheck %s
+// CHECK: myVar
+// CHECK-NEXT: s:27cursor_info_existential_var7MyErrorP5myVarSSvp
+// CHECK-NEXT: source.lang.swift
+// CHECK-NEXT: String