[clang-tidy] Fix the potential infinite loop in recordIsTriviallyDefaultConstructible.

[hokein]

Summary

The recordIsTriviallyDefaultConstructible may cause an infinite loop when
running on an ill-formed decl.

[hokein]

Add newline at end of tile.

[gribozavr]

clang-tools-extra/clang-tidy/utils/TypeTraits.cpp

57 ↗

(On Diff #217617)

I'd suggest to not mention the infinite loop. Just say that it is impossible to determine whether the decl is trivially constructible if there was an error.

[hokein]

Tweak the comment

clang-tools-extra/trunk/clang-tidy/utils/TypeTraits.cpp

 }
 
 bool recordIsTriviallyDefaultConstructible(const RecordDecl &RecordDecl,
                                            const ASTContext &Context) {
   const auto *ClassDecl = dyn_cast<CXXRecordDecl>(&RecordDecl);
   // Non-C++ records are always trivially constructible.
   if (!ClassDecl)
     return true;
+  // It is impossible to detemine whether an ill-formed decl is trivially
+  // constructible.
+  if (RecordDecl.isInvalidDecl())
+    return false;
   // A class with a user-provided default constructor is not trivially
   // constructible.
   if (ClassDecl->hasUserProvidedDefaultConstructor())
     return false;
   // A polymorphic class is not trivially constructible
   if (ClassDecl->isPolymorphic())
     return false;
   // A class is trivially constructible if it has a trivial default constructor.

clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-type-member-init-no-crash.cpp

+// RUN: %check_clang_tidy -expect-clang-tidy-error %s cppcoreguidelines-pro-type-member-init %t
+
+struct X {
+  X x;
+  // CHECK-MESSAGES: :[[@LINE-1]]:5: error: field has incomplete type 'X' [clang-diagnostic-error]
+  int a = 10;
+};