[autoantwort]

Trac: https://trac.cppcheck.net/ticket/15197

Follow-up to #15080: a class without constructors that has a member whose type has no default constructor cannot be default-initialized. Every instance initializes all members, so uninitMemberVarNoCtor is a false positive:

struct N {
    explicit N(int);
};

struct S {
    N n;
    int i;          // FP: Member variable 'S::i' has no initializer. [uninitMemberVarNoCtor]
    bool b = true;
};

Cause: CheckClass::constructors() marks a class without constructors as not default-constructible only for reference members and const members of non-class type.

Fix: also mark it for a (non-pointer) member whose class type has constructors but none callable without arguments. A deleted default constructor doesn't count. A variadic constructor counts as default constructor if only the parameter pack or ellipsis is left.

Limitations (still reported as before):

• library types without default constructor, e.g. std::reference_wrapper (std.cfg has no such information)
• base classes without default constructor
• members of aggregates that are themselves not default-constructible, and private default constructors
• member types cppcheck does not resolve to a scope (e.g. decltype(...))

This PR was created by Claude Code (an AI coding agent) on behalf of @autoantwort.

🤖 Generated with Claude Code

[dmcppcheck]

AI review

I found no problems with this change. Classes with no constructors now count as not default-constructible when they have a non-pointer member whose class type has constructors but none that can be called without arguments. I tested about 30 variations. Every result was correct except the limitations that the PR description already lists (for example, inherited constructors without a default constructor are still reported). The variadic rule minArgCount() == 1 works the way the PR says: F(int = 0, ...) and V(A&&...) count as default constructors, while E(int, ...) and template<class... A> V(int, A...) don't. comments.md has no earlier comments.

Testing

• Built cppcheck and testrunner in pr/ and cppcheck in base/.
• ./testrunner TestConstructors TestClass: 0 failures. The full ./testrunner -q also had 0 failures.
• I wrote scratch files and compared pr/cppcheck with base/cppcheck, running both as cppcheck -q --enable=warning --std=c++17 t*.cpp.
• No longer reported (correct):
  • a member type whose only constructors are deleted (X() = delete; X(int) = delete;)
  • a member type with only a defaulted copy constructor
  • a member type with only a deleted copy constructor
  • a nested member type S::N with N(int)
  • E(int, ...)
  • template<class... A> V(int, A...)
• Still reported (correct):
  • std::vector<N>
  • a template wrapper that has a default constructor (Opt<N>)
  • a type that has both P(int) and P()
  • DD() = default
  • H(void)
  • F(int = 0, ...)
  • I(std::initializer_list<int> = {})
  • a template constructor with defaulted parameters
  • a static member whose type has no default constructor
  • a namespace-local type that has the same name as a global one
  • an explicit specialization B<int> that has no constructors, while the primary template has B(T)
• Known limitation: struct K : N { using N::N; }; is still reported. This falls under the base-class limitation in the PR description.
• I found no crashes, hangs or new false positives.

---

Automated review of eb7b004 by Claude. The pull request was built and tested locally.