Add new flag to always generate tags as absolute.

autoload/gutentags/ctags.vim

@@ -92,16 +92,23 @@ function! gutentags#ctags#generate(proj_dir, tags_file, gen_opts) abort
         endif
     endif
 
-    " Get a tags file path relative to the current directory, which 
-    " happens to be the project root in this case.
-    " Since the given tags file path is absolute, and since Vim won't
-    " change the path if it is not inside the current directory, we
-    " know that the tags file is "local" (i.e. inside the project)
-    " if the path was shortened (an absolute path will always be
-    " longer than a true relative path).
-    let l:tags_file_relative = fnamemodify(a:tags_file, ':.')
-    let l:tags_file_is_local = len(l:tags_file_relative) < len(a:tags_file)
-    let l:use_tag_relative_opt = 0
+
+    if (g:gutentags_always_absolute)
+        let l:tags_file_relative = a:tags_file
+        let l:tags_file_is_local = 2 > 1 "True
+        let l:use_tag_relative_opt = 0
+    else
+        " Get a tags file path relative to the current directory, which 
+        " happens to be the project root in this case.
+        " Since the given tags file path is absolute, and since Vim won't
+        " change the path if it is not inside the current directory, we
+        " know that the tags file is "local" (i.e. inside the project)
+        " if the path was shortened (an absolute path will always be
+        " longer than a true relative path).
+        let l:tags_file_relative = fnamemodify(a:tags_file, ':.')
+        let l:tags_file_is_local = len(l:tags_file_relative) < len(a:tags_file)
+        let l:use_tag_relative_opt = 0
+    endif
 
     if empty(g:gutentags_cache_dir) && l:tags_file_is_local
         " If we don't use the cache directory, we can pass relative paths
@@ -169,8 +176,12 @@ function! gutentags#ctags#generate(proj_dir, tags_file, gen_opts) abort
         " Omit --recursive if this project uses a file list command.
         let l:cmd += ['-o', '"' . gutentags#get_res_file('ctags_recursive.options') . '"']
     endif
-    if l:use_tag_relative_opt
-        let l:cmd += ['-O', shellescape("--tag-relative=yes")]
+    if (g:gutentags_always_absolute)
+        let l:cmd += ['-O', shellescape("--tag-relative=never")]
+    else
+        if l:use_tag_relative_opt
+            let l:cmd += ['-O', shellescape("--tag-relative=yes")]
+        endif
     endif
     for extra_arg in g:gutentags_ctags_extra_args
         let l:cmd += ['-O', shellescape(extra_arg)]

doc/gutentags.txt

@@ -396,6 +396,12 @@ g:gutentags_project_root_finder
                         behaviour by calling
                         `gutentags#default_get_project_root`.
 
+                                                *gutentags_always_absolute*
+g:gutentags_always_absolute
+                        Always resolve tags file as absolute, even if tags
+                        file is local.
+                        Defaults to 0.
+
                                                 *gutentags_generate_on_missing*
 g:gutentags_generate_on_missing
                         If set to 1, Gutentags will start generating an initial

plugin/gutentags.vim

@@ -46,6 +46,7 @@ if g:gutentags_add_default_project_roots
 endif
 
 let g:gutentags_project_root_finder = get(g:, 'gutentags_project_root_finder', '')
+let g:gutentags_always_absolute = get(g:, 'gutentags_always_absolute', 0)
 
 let g:gutentags_project_info = get(g:, 'gutentags_project_info', [])
 call add(g:gutentags_project_info, {'type': 'python', 'file': 'setup.py'})