-Wdangling-field detects view members initalized from a by-value owner parameter

Description

struct Foo {};
struct Bar {
  const Foo& foo;
  Bar(Foo f ) : foo(f) {} // good, clang warn on this case
};


struct C {
    string_view s;
    C(std::string c) : s(c) {} // bad, clang doesn't warn on this case. support it
};

Contributor guide

Tech stack

cpp

Domain

toolingdeveloper experience

Issue type

feature

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

4

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

3-5 days

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

fresh

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

clear

Prerequisites

C++LLVM/clang development environment setup

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

25

Research direction

Investigate how clang's Wdangling field warning currently detects member initialization from temporary owners. The relevant code is likely in clang/lib/Sema/SemaChecking.cpp or similar diagnostic implementation. Extending the warning to cover std::string view and similar view types when initialized from a by value parameter requires adding logic to recognize view types (e.g., std::string view, std::span) that hold references to temporary strings. Look at existing patterns for detecting dangling references and consider adding a new check for view member init from by value std::string parameters. Review comments on the issue for any suggested approach.