Emacs Compile Mode: Extra characters before filename result in bad match

Question

In the compile buffer of Emacs 25.3.1, I am getting the following compilation error using Clang (the error message is given as it appears in the compile buffer line by line) :

src/platform/linux/linux.c:668:70: error: no member named 'buffer_size_' in 'struct
      OpenGL_State::(anonymous at src/platform/linux/opengl.c:8:5)'
        init_data->render_command_buffer_size_in_bytes = gl->command.buffer_size_;

Emacs correctly matches src/platform/linux/linux.c:668:70 to be a filepath in the first line; however, in the second line, it matches with OpenGL_State::(anonymous at src/platform/linux/opengl.c:8:5)' instead of src/platform/linux/opengl.c:8:5 which means that when I click on the error, Emacs can not find the file.

How can I make Emacs not start matching the file name from the beginning of the line?

Answer 1

A variable called compilation-error-regexp-alist-alist (I will call c-e-r-a-a) is a list of (<name> <regexp> <list of regexp match numbers...>).

From the output of `M-x describe-variable compilation-error-regexp-alist':

Each elt has the form (REGEXP FILE [LINE COLUMN TYPE HYPERLINK
HIGHLIGHT...]).  If REGEXP matches, the FILE’th subexpression
gives the file name, and the LINE’th subexpression gives the line
number.  The COLUMN’th subexpression gives the column number on
that line.

A variable called compilation-error-regexp-alist (I will call c-e-r-a) contains a list of entries which are names of entries in the above c-e-r-a-a variable.

So, to solve your problem, we need to create an entry in c-e-r-a-a to match OpenGL_State::(anonymous at src/platform/linux/opengl.c:8:5)'

(add-to-list 'compilation-error-regexp-alist-alist
             '(clang-anonymous
               "^.* at \\(\\([^\n:/]+/\\)+[^\n:/]+\\):\\([0-9]+\\):\\([0-9]+\\)"
               1 3 4))

and add a reference to c-e-r-a:

(add-to-list 'compilation-error-regexp-alist 'clang-anonymous)

For more information of Emacs' regular expressions, see here.