[CodeCompletion] Delete expr type state after getting expr completions

lib/IDE/CodeCompletion.cpp

@@ -3591,6 +3591,7 @@ class CompletionLookup final : public swift::VisibleDeclConsumer {
                                         bool IncludeTopLevel = false,
                                         bool RequestCache = true,
                                         bool LiteralCompletions = true) {
+    ExprType = Type();
     Kind = LookupKind::ValueInDeclContext;
     NeedLeadingDot = false;
     FilteredDeclConsumer Consumer(*this, Filter);

test/IDE/complete_with_visible_members.swift

@@ -0,0 +1,52 @@
+// RUN: %swift-ide-test -code-completion -code-completion-token=A -source-filename %s
+// RUN: %swift-ide-test -code-completion -code-completion-token=B -source-filename %s
+// RUN: %swift-ide-test -code-completion -code-completion-token=C -source-filename %s
+// RUN: %swift-ide-test -code-completion -code-completion-token=D -source-filename %s
+// RUN: %swift-ide-test -code-completion -code-completion-token=E -source-filename %s
+// RUN: %swift-ide-test -code-completion -code-completion-token=F -source-filename %s
+
+// Make sure that visible members don't mess up code completion,
+// having seen a constructor for an incompatible declaration.
+
+class CompeteInMethod {
+  // Here, the method foo is actually visible at the
+  // point of code-completion.
+  func foo() {
+    String(#^A^#
+  }
+}
+
+class CompleteInVar {
+  // Same here - var decls are added to code completion results
+  // in a different but similarly shaped code path. So here,
+  // the var x is actually visible at the point of code-completion.
+  var x: Int {
+    String(#^B^#
+  }
+}
+
+class CompleteOutsideMethod {
+  func foo() {}
+  init() {
+    String(#^C^#
+  }
+}
+
+class CompleteOutsideVar {
+  var x: Int { return 1 }
+  init() {
+    String(#^D^#
+  }
+}
+
+class CompleteInsideGenericFunc {
+  func foo<S: Sequence>(x: S) {
+    String(#^E^#
+  }
+}
+
+class CompleteInsideGenericClass<S: Sequence> {
+  func foo(x: S) {
+    String(#^F^#
+  }
+}