Merge pull request #24926 from xedin/rdar-50668864

[CSDiag] Adjust assert to account for changes in `filterContextualMem…

Author: xedin

lib/Sema/CSDiag.cpp

@@ -6491,16 +6491,20 @@ bool FailureDiagnosis::visitUnresolvedMemberExpr(UnresolvedMemberExpr *E) {
 
     // Depending on how we matched, produce tailored diagnostics.
     switch (candidateInfo.closeness) {
+    case CC_SelfMismatch:         // Self argument mismatches.
+      llvm_unreachable("These aren't produced by filterContextualMemberList");
+      return false;
+
     case CC_NonLValueInOut: // First argument is inout but no lvalue present.
     case CC_OneArgumentMismatch: // All arguments except one match.
     case CC_OneArgumentNearMismatch:
     case CC_OneGenericArgumentMismatch:
     case CC_OneGenericArgumentNearMismatch:
     case CC_GenericNonsubstitutableMismatch:
-    case CC_SelfMismatch:         // Self argument mismatches.
     case CC_ArgumentNearMismatch: // Argument list mismatch.
     case CC_ArgumentMismatch:     // Argument list mismatch.
-      llvm_unreachable("These aren't produced by filterContextualMemberList");
+      // Candidate filtering can produce these now, but they can't
+      // be properly diagnosed here at the moment.
       return false;
 
     case CC_ExactMatch: { // This is a perfect match for the arguments.

test/Constraints/construction.swift

@@ -209,3 +209,14 @@ func rdar_45535925() {
     // expected-error@-1 {{'bar' is inaccessible due to 'private' protection level}}
   }
 }
+
+// rdar://problem/50668864
+func rdar_50668864() {
+  struct Foo {
+    init(anchors: [Int]) {
+      // TODO: This would be improved when argument conversions are diagnosed via new diagnostic framework,
+      // actual problem here is that `[Int]` cannot be converted to function type represented by a closure.
+      self = .init { _ in [] } // expected-error {{type of expression is ambiguous without more context}}
+    }
+  }
+}