Index: clang-tools-extra/clang-tidy/misc/CMakeLists.txt
===================================================================
--- clang-tools-extra/clang-tidy/misc/CMakeLists.txt
+++ clang-tools-extra/clang-tidy/misc/CMakeLists.txt
@@ -22,6 +22,7 @@
   ConfusableIdentifierCheck.cpp
   HeaderIncludeCycleCheck.cpp
   IncludeCleanerCheck.cpp
+  IncompleteSwitchCheck.cpp
   MiscTidyModule.cpp
   MisleadingBidirectional.cpp
   MisleadingIdentifier.cpp
Index: clang-tools-extra/clang-tidy/misc/IncompleteSwitchCheck.h
===================================================================
--- /dev/null
+++ clang-tools-extra/clang-tidy/misc/IncompleteSwitchCheck.h
@@ -0,0 +1,29 @@
+//===--- IncompleteSwitchCheck.h - clang-tidy --------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_INCOMPLETESWITCHCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_INCOMPLETESWITCHCHECK_H
+
+#include "../ClangTidyCheck.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+
+namespace clang::tidy::misc {
+
+class IncompleteSwitchCheck : public ClangTidyCheck {
+public:
+  IncompleteSwitchCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace clang::tidy::misc
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_INCOMPLETESWITCHCHECK_H
Index: clang-tools-extra/clang-tidy/misc/IncompleteSwitchCheck.cpp
===================================================================
--- /dev/null
+++ clang-tools-extra/clang-tidy/misc/IncompleteSwitchCheck.cpp
@@ -0,0 +1,36 @@
+//===--- IncompleteSwitchCheck.cpp - clang-tidy ---------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "IncompleteSwitchCheck.h"
+#include "clang/AST/ASTContext.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::misc {
+
+void IncompleteSwitchCheck::registerMatchers(
+    ast_matchers::MatchFinder *Finder) {
+  Finder->addMatcher(
+      switchStmt(has(implicitCastExpr().bind("cast")),
+                 unless(hasAncestor(switchStmt(has(defaultStmt())))))
+          .bind("switch"),
+      this);
+}
+
+void IncompleteSwitchCheck::check(
+    const ast_matchers::MatchFinder::MatchResult &Result) {
+  const auto *c = Result.Nodes.getNodeAs<ImplicitCastExpr>("cast");
+  if (c->getCastKind() == CK_IntegralCast)
+    return;
+
+  const auto *s = Result.Nodes.getNodeAs<SwitchStmt>("switch");
+  diag(s->getSwitchLoc(), "switching on non-enum value without "
+                          "default case may not cover all cases");
+}
+
+} // namespace clang::tidy::misc
Index: clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp
===================================================================
--- clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp
+++ clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp
@@ -14,6 +14,7 @@
 #include "DefinitionsInHeadersCheck.h"
 #include "HeaderIncludeCycleCheck.h"
 #include "IncludeCleanerCheck.h"
+#include "IncompleteSwitchCheck.h"
 #include "MisleadingBidirectional.h"
 #include "MisleadingIdentifier.h"
 #include "MisplacedConstCheck.h"
@@ -46,6 +47,8 @@
     CheckFactories.registerCheck<HeaderIncludeCycleCheck>(
         "misc-header-include-cycle");
     CheckFactories.registerCheck<IncludeCleanerCheck>("misc-include-cleaner");
+    CheckFactories.registerCheck<IncompleteSwitchCheck>(
+        "misc-incomplete-switch");
     CheckFactories.registerCheck<MisleadingBidirectionalCheck>(
         "misc-misleading-bidirectional");
     CheckFactories.registerCheck<MisleadingIdentifierCheck>(
Index: clang-tools-extra/docs/ReleaseNotes.rst
===================================================================
--- clang-tools-extra/docs/ReleaseNotes.rst
+++ clang-tools-extra/docs/ReleaseNotes.rst
@@ -219,6 +219,11 @@
   Enforces consistent token representation for invoked binary, unary and
   overloaded operators in C++ code.
 
+- New :doc:`misc-incomplete-switch
+  <clang-tidy/checks/misc/incomplete-switch>` check.
+
+  Detects incomplete switch statements without a default case.
+
 New check aliases
 ^^^^^^^^^^^^^^^^^
 
Index: clang-tools-extra/test/clang-tidy/checkers/misc/incomplete-switch.cpp
===================================================================
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/checkers/misc/incomplete-switch.cpp
@@ -0,0 +1,27 @@
+// RUN: clang-tidy --checks='-*,misc-incomplete-switch' %s -- | FileCheck -implicit-check-not="{{warning|error}}:" %s
+
+void Positive() {
+  int i = 0;
+  // CHECK: [[@LINE+1]]:11: warning: switching on non-enum value without default case may not cover all cases [misc-incomplete-switch]
+  switch (i) {
+  case 0:
+    break;
+  }
+}
+
+void Negative() {
+  enum E { eE1 };
+  E e = eE1;
+  switch (e) { // no-warning
+  case eE1:
+    break;
+  }
+
+  int i = 0;
+  switch (i) { // no-warning
+  case 0:
+    break;
+  default:
+    break;
+  }
+}