[clang-tidy] Add check 'bugprone-invalid-enum-default-initialization'

clang-tools-extra/clang-tidy/bugprone/InvalidEnumDefaultInitializationCheck.cpp

@@ -7,8 +7,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "InvalidEnumDefaultInitializationCheck.h"
-// #include "../utils/Matchers.h"
-// #include "../utils/OptionsUtils.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include <algorithm>
@@ -21,7 +19,7 @@ namespace {
 
 AST_MATCHER(EnumDecl, isCompleteAndHasNoZeroValue) {
   const EnumDecl *Definition = Node.getDefinition();
-  return Definition && Node.isComplete() &&
+  return Definition && Node.isComplete() && !Node.enumerators().empty() &&
          std::none_of(Definition->enumerator_begin(),
                       Definition->enumerator_end(),
                       [](const EnumConstantDecl *Value) {

clang-tools-extra/clang-tidy/bugprone/InvalidEnumDefaultInitializationCheck.h

@@ -17,7 +17,7 @@ namespace clang::tidy::bugprone {
 /// the enum has no enumerator with value of 0.
 ///
 /// For the user-facing documentation see:
-/// http://clang.llvm.org/extra/clang-tidy/checks/bugprone/.html
+/// http://clang.llvm.org/extra/clang-tidy/checks/bugprone/invalid-enum-default-initialization.html
 class InvalidEnumDefaultInitializationCheck : public ClangTidyCheck {
 public:
   InvalidEnumDefaultInitializationCheck(StringRef Name,

clang-tools-extra/docs/ReleaseNotes.rst

@@ -125,6 +125,12 @@ New checks
   Finds potentially erroneous calls to ``reset`` method on smart pointers when
   the pointee type also has a ``reset`` method.
 
+- New :doc:`bugprone-invalid-enum-default-initialization
+  <clang-tidy/checks/bugprone/invalid-enum-default-initialization>` check.
+
+  Detect default initialization (to 0) of variables with ``enum`` type where
+  the enum has no enumerator with value of 0.
+
 New check aliases
 ^^^^^^^^^^^^^^^^^
 

clang-tools-extra/docs/clang-tidy/checks/bugprone/invalid-enum-default-initialization.rst

@@ -3,7 +3,7 @@
 bugprone-invalid-enum-default-initialization
 ============================================
 
-Detect default initialization (to 0) of variables with `enum` type where
+Detect default initialization (to 0) of variables with ``enum`` type where
 the enum has no enumerator with value of 0.
 
 In C++ a default initialization is performed if a variable is initialized with

clang-tools-extra/test/clang-tidy/checkers/bugprone/invalid-enum-default-initialization.cpp

@@ -114,3 +114,20 @@ S4 VarS4{};
 // CHECK-NOTES: :8:12: note: enum is defined here
 // CHECK-NOTES: :[[@LINE-3]]:10: warning: enum value of type 'Enum2' initialized with invalid value of 0
 // CHECK-NOTES: :13:6: note: enum is defined here
+
+enum class EnumFwd;
+
+EnumFwd Fwd{};
+
+enum class EnumEmpty {};
+
+EnumEmpty Empty{};
+
+template<typename T>
+struct Templ {
+  T Mem1{};
+  // CHECK-NOTES: :[[@LINE-1]]:9: warning: enum value of type 'Enum1' initialized with invalid value of 0
+  // CHECK-NOTES: :8:12: note: enum is defined here
+};
+
+Templ<Enum1> TemplVar;