bug#46301: 28.0.50; cc-mode: add support for c++ lambda expression

[Utkarsh Singh]

Hi,

This bugs only occurs when we assign lambda expression as default
arguments in C++.  I know there are better ways of using lambda but I
was just playing with both C++ and Emacs on a hobby project.

Consider this C++ code:

template <typename T>
void bubble_sort(std :: vector<T> &v, bool cmp(T, T)=[](T a, T b){return a < 
b;})
{
    bool swapped = true;
    for(size_t i = 0; i < v.size() && swapped; i++) {
        swapped = false;
        for(size_t j = 0; j < v.size()-i; j++){
            if(cmp(v[j+1], v[j])) {
                std::swap(v[j], v[j+1]);
                swapped=true;
            }
        }
    }
}

Here cmp takes a lambda as default argument and if in c++-mode if we try
using C-M-e(c-end-of-defun) it will get trapped into lambda.

To solve this is added c-forward-to-nth

((memq where '(at-function-end outwith-function at-header in-header))
    (when (c-syntactic-re-search-forward "{" nil 'eob)
      (backward-char)
      (forward-sexp)

      ;; continue to move sexp if we are looking ) and ,
      (while (looking-at ")\\|,")
        (c-syntactic-re-search-forward "{" nil 'eob)
        (backward-char)
        (forward-sexp))

      (setq n (1- n))))

By this I am trying to move forward lambda's which are separated by ','
or ended with ')'.  I will also attaching the necessary diff to support
the issue.
--
Utkarsh Singh

cc-cmds.el.diff
Description: support c++ lambda

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