Fix a crash in cppcoreguidelines-pro-type-member-init related to missing constructor bodies.

[michael_miller]

Summary

Fixes a crash in cppcoreguidelines-pro-type-member-init when checking some record types with a constructor without a body. We now check to make sure the constructor has a body before looking for missing members and base initializers.

[aaron.ballman]

LGTM!

[alexfh]

LG. Do you need me to submit the patch?

[michael_miller]

In D19270#405805, @alexfh wrote:

LG. Do you need me to submit the patch?

Yeah, that's be awesome—thanks!

[hokein]

LGTM. Thanks.

[hokein]

@michael_miller

You fixing is not completed. The crash still happens, the test case see https://llvm.org/bugs/show_bug.cgi?id=27419.

Could you please take a look on it? Thanks very much.

clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProTypeMemberInitCheck.cpp

Finder->addMatcher(
               hasType(recordDecl(has(fieldDecl()),
                                  isTriviallyDefaultConstructible())))
           .bind("var"),
       this);
 }
 
 void ProTypeMemberInitCheck::check(const MatchFinder::MatchResult &Result) {
   if (const auto *Ctor = Result.Nodes.getNodeAs<CXXConstructorDecl>("ctor")) {
+    // Skip declarations delayed by late template parsing without a body.
+    if (!Ctor->getBody())
+      return;
     checkMissingMemberInitializer(*Result.Context, Ctor);
     checkMissingBaseClassInitializer(*Result.Context, Ctor);
   } else if (const auto *Var = Result.Nodes.getNodeAs<VarDecl>("var")) {
     checkUninitializedTrivialType(*Result.Context, Var);
   }
 }
 
 void ProTypeMemberInitCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
   Options.store(Opts, "IgnoreArrays", IgnoreArrays);
 }
 
 void ProTypeMemberInitCheck::checkMissingMemberInitializer(
     ASTContext &Context, const CXXConstructorDecl *Ctor) {
   const CXXRecordDecl *ClassDecl = Ctor->getParent();
   bool IsUnion = ClassDecl->isUnion();
 
   if (IsUnion && ClassDecl->hasInClassInitializer())
     return;
 
-  // Skip declarations delayed by late template parsing without a body.
-  const Stmt *Body = Ctor->getBody();
-  if (!Body)
-    return;
-
   SmallPtrSet<const FieldDecl *, 16> FieldsToInit;
   fieldsRequiringInit(ClassDecl->fields(), Context, FieldsToInit);
   if (FieldsToInit.empty())
     return;
 
   for (const CXXCtorInitializer *Init : Ctor->inits()) {
     // Remove any fields that were explicitly written in the initializer list
     // or in-class.
     if (Init->isAnyMemberInitializer() && Init->isWritten()) {
       if (IsUnion)
         return; // We can only initialize one member of a union.
       FieldsToInit.erase(Init->getMember());
     }
   }
-  removeFieldsInitializedInBody(*Body, Context, FieldsToInit);
+  removeFieldsInitializedInBody(*Ctor->getBody(), Context, FieldsToInit);
 
   // Collect all fields in order, both direct fields and indirect fields from
   // anonmyous record types.
   SmallVector<const FieldDecl *, 16> OrderedFields;
   forEachField(ClassDecl, ClassDecl->fields(), false,
                [&](const FieldDecl *F) { OrderedFields.push_back(F); });
 
   // Collect all the fields we need to initialize, including indirect fields.

clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-type-member-init.cpp

union {
       long E;
       // CHECK-FIXES: long E{};
       float F;
     };
   };
   int X;
   // CHECK-FIXES: int X{};
 };
+
+// This check results in a CXXConstructorDecl with no body.
+struct NegativeDeletedConstructor : NegativeAggregateType {
+  NegativeDeletedConstructor() = delete;
+
+  Template<int> F;
+};