Merge pull request #27668 from CodaFi/disqualified-lookup

[DiagnosticsQoI] Strike VarDecls in Pattern Binding Initializers From Overloads

Author: CodaFi

lib/Sema/CSSimplify.cpp

@@ -20,6 +20,7 @@
 #include "swift/AST/ExistentialLayout.h"
 #include "swift/AST/GenericEnvironment.h"
 #include "swift/AST/GenericSignature.h"
+#include "swift/AST/Initializer.h"
 #include "swift/AST/ParameterList.h"
 #include "swift/AST/PropertyWrappers.h"
 #include "swift/AST/ProtocolConformance.h"
@@ -4864,7 +4865,19 @@ performMemberLookup(ConstraintKind constraintKind, DeclName memberName,
   // reasonable choice.
   auto addChoice = [&](OverloadChoice candidate) {
     auto decl = candidate.getDecl();
-    
+
+    // In a pattern binding initializer, immediately reject all of its bound
+    // variables. These would otherwise allow circular references.
+    if (auto *PBI = dyn_cast<PatternBindingInitializer>(DC)) {
+      if (auto *VD = dyn_cast<VarDecl>(decl)) {
+        if (PBI->getBinding() == VD->getParentPatternBinding()) {
+          result.addUnviable(candidate,
+                             MemberLookupResult::UR_InstanceMemberOnType);
+          return;
+        }
+      }
+    }
+
     // If the result is invalid, skip it.
     // FIXME(InterfaceTypeRequest): isInvalid() should be based on the interface type.
     (void)decl->getInterfaceType();

test/NameBinding/name_lookup.swift

@@ -616,12 +616,15 @@ struct PatternBindingWithTwoVars1 { var x = 3, y = x }
 // expected-error@-1 {{cannot use instance member 'x' within property initializer; property initializers run before 'self' is available}}
 
 struct PatternBindingWithTwoVars2 { var x = y, y = 3 }
-// expected-error@-1 {{type 'PatternBindingWithTwoVars2' has no member 'y'}}
+// expected-error@-1 {{property 'y' references itself}}
+// expected-error@-2 {{cannot use instance member 'y' within property initializer; property initializers run before 'self' is available}}
 
 // This one should be accepted, but for now PatternBindingDecl validation
 // circularity detection is not fine grained enough.
 struct PatternBindingWithTwoVars3 { var x = y, y = x }
-// expected-error@-1 {{type 'PatternBindingWithTwoVars3' has no member 'y'}}
+// expected-error@-1 {{cannot use instance member 'x' within property initializer; property initializers run before 'self' is available}}
+// expected-error@-2 {{cannot use instance member 'y' within property initializer; property initializers run before 'self' is available}}
+// expected-error@-3 {{property 'y' references itself}}
 
 // https://bugs.swift.org/browse/SR-9015
 func sr9015() {

test/decl/overload.swift

@@ -571,23 +571,23 @@ enum SR_10084_E_8 {
 }
 
 enum SR_10084_E_9 {
-  case A // expected-note {{found this candidate}} // expected-note {{'A' previously declared here}}
-  static let A: SR_10084_E_9 = .A // expected-note {{found this candidate}} // expected-error {{invalid redeclaration of 'A'}} // expected-error {{ambiguous use of 'A'}}
+  case A // expected-note {{'A' previously declared here}}
+  static let A: SR_10084_E_9 = .A // expected-error {{invalid redeclaration of 'A'}}
 }
 
 enum SR_10084_E_10 {
-  static let A: SR_10084_E_10 = .A // expected-note {{found this candidate}} // expected-note {{'A' previously declared here}} // expected-error {{ambiguous use of 'A'}}
-  case A // expected-note {{found this candidate}} // expected-error {{invalid redeclaration of 'A'}}
+  static let A: SR_10084_E_10 = .A // expected-note {{'A' previously declared here}}
+  case A // expected-error {{invalid redeclaration of 'A'}}
 }
 
 enum SR_10084_E_11 {
-  case A // expected-note {{found this candidate}} // expected-note {{'A' previously declared here}}
-  static var A: SR_10084_E_11 = .A // expected-note {{found this candidate}} // expected-error {{invalid redeclaration of 'A'}} // expected-error {{ambiguous use of 'A'}}
+  case A // expected-note {{'A' previously declared here}}
+  static var A: SR_10084_E_11 = .A // expected-error {{invalid redeclaration of 'A'}}
 }
 
 enum SR_10084_E_12 {
-  static var A: SR_10084_E_12 = .A // expected-note {{found this candidate}} // expected-note {{'A' previously declared here}} // expected-error {{ambiguous use of 'A'}}
-  case A // expected-note {{found this candidate}} // expected-error {{invalid redeclaration of 'A'}}
+  static var A: SR_10084_E_12 = .A // expected-note {{'A' previously declared here}}
+  case A // expected-error {{invalid redeclaration of 'A'}}
 }
 
 enum SR_10084_E_13 {
@@ -609,3 +609,11 @@ enum SR_10084_E_16 {
   typealias Z = Int // expected-note {{'Z' previously declared here}}
   case Z // expected-error {{invalid redeclaration of 'Z'}}
 }
+
+// N.B. Validating the pattern binding initializer for `raw` used to cause
+// recursive validation of the VarDecl. Check that we don't regress now that
+// this isn't the case.
+public struct Cyclic {
+  static func pickMe(please: Bool) -> Int { return 42 }
+  public static let pickMe = Cyclic.pickMe(please: true)
+}