[clang][NFC] Use constructor instead of factory function in `CFGStmtMap` (#172530)

`CFGStmtMap::Build` accepts pointers and returns a pointer to
dynamically allocated memory. In the one location where the type is
actually constructed, the pointers are guaranteed to be non-null. By
accepting references to statically enforce this, we can remove the only
way for the construction to fail.

By making this change, we also allow our user to decide how they want to
own the memory (either directly or indirectly). The user does not
actually need dynamic allocation here, so we replace the
`std::unique_ptr` with `std::optional`.

This simplifies the code by requiring fewer checks, makes comments on
what happens redundant because the code can obviously do only one thing,
avoids potential bugs, and improves performance by allocating less.

GitOrigin-RevId: 1eea63811aa00ed2cc402c783ca67e1ac2a74121
5 files changed
tree: 28d2b472cb044fcb20ff7a84ca01557380033bd1
  1. bindings/
  2. cmake/
  3. docs/
  4. examples/
  5. include/
  6. lib/
  7. runtime/
  8. test/
  9. tools/
  10. unittests/
  11. utils/
  12. www/
  13. .clang-format
  14. .clang-tidy
  15. .gitignore
  16. AreaTeamMembers.txt
  17. CMakeLists.txt
  18. INSTALL.txt
  19. LICENSE.TXT
  20. Maintainers.rst
  21. NOTES.txt
  22. README.md
README.md

C language Family Front-end

Welcome to Clang.

This is a compiler front-end for the C family of languages (C, C++ and Objective-C) which is built as part of the LLVM compiler infrastructure project.

Unlike many other compiler frontends, Clang is useful for a number of things beyond just compiling code: we intend for Clang to be host to a number of different source-level tools. One example of this is the Clang Static Analyzer.

If you're interested in more (including how to build Clang) it is best to read the relevant websites. Here are some pointers: