llvm-project

3eba28d1 - [clang] Extend lifetime analysis to support assignments for pointer-like objects. (#99032)

[clang] Extend lifetime analysis to support assignments for pointer-like objects. (#99032) This is a follow-up patch to #96475 to detect dangling assignments for C++ pointer-like objects (classes annotated with the `[[gsl::Pointer]]`). Fixes #63310. Similar to the behavior for built-in pointer types, if a temporary owner (`[[gsl::Owner]]`) object is assigned to a pointer-like class object, and this temporary object is destroyed at the end of the full assignment expression, the assignee pointer is considered dangling. In such cases, clang will emit a warning: ``` /tmp/t.cpp:7:20: warning: object backing the pointer my_string_view will be destroyed at the end of the full-expression [-Wdangling-assignment-gsl] 7 | my_string_view = CreateString(); | ^~~~~~~~~~~~~~ 1 warning generated. ``` This new warning is `-Wdangling-assignment-gsl`. It is initially disabled, but I intend to enable it by default in clang 20. I have initially tested this patch on our internal codebase, and it has identified many use-after-free bugs, primarily related to `string_view`.