Merge pull request swiftlang#31508 from mdiep/incomplete-computed-properties-in-extensions

[Diags] Don't error twice for incomplete computed properties in extensions

Author: xedin

lib/Sema/TypeCheckStorage.cpp

@@ -3064,6 +3064,13 @@ StorageImplInfoRequest::evaluate(Evaluator &evaluator,
       readImpl = ReadImplKind::Stored;
     }
 
+  // Extensions can't have stored properties. If there are braces, assume
+  // this is an incomplete computed property. This avoids an "extensions
+  // must not contain stored properties" error later on.
+  } else if (isa<ExtensionDecl>(storage->getDeclContext()) &&
+             storage->getBracesRange().isValid()) {
+    readImpl = ReadImplKind::Get;
+
   // Otherwise, it's stored.
   } else {
     readImpl = ReadImplKind::Stored;

test/decl/var/properties.swift

@@ -380,6 +380,12 @@ var x12: X {
 
 var x13: X {} // expected-error {{computed property must have accessors specified}}
 
+struct X14 {}
+extension X14 {
+  var x14: X {
+  } // expected-error {{computed property must have accessors specified}}
+}
+
 // Type checking problems
 struct Y { }
 var y: Y