Re: master 888ff3755d4 1/3: New function internal--c-header-file-path

["Björn Bidar" <bjorn.bidar@thaodan.de>]

Stefan Kangas <stefankangas@gmail.com> writes:

> Eli Zaretskii <eliz@gnu.org> writes:
>
>> Stefan,
>>
>> Thanks for adding this function.  However, the method it uses to find
>> the include directories is incorrect and unportable.  On most systems
>> it will produce the default "/usr/include", which is most probably
>> wrong.
>>
>> The way to ask GCC to show the list of directories where it looks for
>> header files is like this:
>>
>>    (call-process "gcc" nil BUFFER nil "-v" "-E" "-")
>>
>> and then look in BUFFER for text that begins with "#include <...>
>> search starts here:" and ends with "End of search list."  What's
>> in-between is the list of include directories, one directory per line,
>> which GCC searches for header file, in the order it searches them.
>
> Thanks for helping improve this.  How about the attached patch?
>
> From c8aac6531fbf228d004b15498fd0758e080c784e Mon Sep 17 00:00:00 2001
> From: Stefan Kangas <stefankangas@gmail.com>
> Date: Mon, 6 Jan 2025 22:37:51 +0100
> Subject: [PATCH] Make internal--c-header-file-path more portable
>
> * lisp/subr.el (internal--c-header-file-path): Make more portable.
> Problem reported by Eli Zaretskii <eliz@gnu.org>.
> * test/lisp/subr-tests.el
> (subr-tests-internal--c-header-file-path)
> (subr-tests-internal--c-header-file-path/gcc-mocked)
> (subr-tests-internal--c-header-file-path/clang-mocked): Adjust tests.
> ---
>  lisp/subr.el            | 57 +++++++++++++++------------------------
>  test/lisp/subr-tests.el | 60 ++++++++++++++++++++++++++---------------
>  2 files changed, 59 insertions(+), 58 deletions(-)
>
> diff --git a/lisp/subr.el b/lisp/subr.el
> index 5be8d8f52d4..e0f5542a011 100644
> --- a/lisp/subr.el
> +++ b/lisp/subr.el
> @@ -7574,41 +7574,26 @@ internal--c-header-file-path
>    ;; See also (Bug#10702):
>    ;; cc-search-directories, semantic-c-dependency-system-include-path,
>    ;; semantic-gcc-setup
> -  (delete-dups
> -   (let ((base '("/usr/include" "/usr/local/include")))
> -     (cond ((or (internal--gcc-is-clang-p)
> -                (and (executable-find "clang")
> -                     (not (executable-find "gcc"))))
> -            ;; This is either macOS, or a system with clang only.
> -            (with-temp-buffer
> -              (ignore-errors
> -                (call-process (if (internal--gcc-is-clang-p) "gcc" "clang")
> -                              nil t nil
> -                              "-v" "-E" "-"))
> -              (goto-char (point-min))
> -              (narrow-to-region
> -               (save-excursion
> -                 (re-search-forward
> -                  "^#include <\\.\\.\\.> search starts here:\n" nil t)
> -                 (point))
> -               (save-excursion
> -                 (re-search-forward "^End of search list.$" nil t)
> -                 (pos-bol)))
> -              (while (search-forward "(framework directory)" nil t)
> -                (delete-line))
> -              (append base
> -                      (reverse
> -                       (split-string (buffer-substring-no-properties
> -                                      (point-min) (point-max)))))))
> -           ;; Prefer GCC.
> -           ((let ((arch (with-temp-buffer
> -                          (when (eq 0 (ignore-errors
> -                                        (call-process "gcc" nil '(t nil) nil
> -                                                      "-print-multiarch")))
> -                            (goto-char (point-min))
> -                            (buffer-substring (point) (line-end-position))))))
> -              (if (zerop (length arch))
> -                  base
> -                (append base (list (expand-file-name arch "/usr/include"))))))))))
> +  (if (or (executable-find "gcc")
> +          (executable-find "clang"))
why not use if-let here and fallback to cc?
> +      (with-temp-buffer
> +        (ignore-errors
> +          (call-process (if (executable-find "gcc") "gcc" "clang")
> +                        nil t nil
> +                        "-v" "-E" "-"))
> +        (goto-char (point-min))
> +        (narrow-to-region
> +         (save-excursion
> +           (re-search-forward
> +            "^#include <\\.\\.\\.> [[:word:] ]+:\n" nil t)
> +           (point))
> +         (save-excursion
> +           (re-search-forward "^[[:word:] ]+\\.$" nil t)
> +           (pos-bol)))
> +        (while (search-forward "(framework directory)" nil t)
> +          (delete-line))
> +        (split-string (buffer-substring-no-properties
> +                       (point-min) (point-max))))
> +    '("/usr/include" "/usr/include/local")))