Always load defaults.vim

This has always caused confusion, when defaults.vim is loaded and when
not. So let's always load defaults.vim even when a `.vimrc` files has
been found.

Users who don't want this slightly backwards compatible behaviour, can
opt-out of this by setting the $VIM_NO_SOURCE_DEFAULTS environment
variable

Signed-off-by: Christian Brabandt <[email protected]>

runtime/doc/starting.txt

@@ -1063,23 +1063,28 @@ giving the mapping.
 
 Defaults without a .vimrc file ~
 							*defaults.vim* *E1187*
-If Vim is started normally and no user vimrc file is found, the
-$VIMRUNTIME/defaults.vim script is loaded.  This will set 'compatible' off,
-switch on syntax highlighting and a few more things.  See the script for
-details.  NOTE: this is done since Vim 8.0, not in Vim 7.4. (it was added in
-patch 7.4.2111 to be exact).
-
-This should work well for new Vim users.  If you create your own .vimrc, it is
-recommended to add these lines somewhere near the top: >
+If Vim is started normally, the $VIMRUNTIME/defaults.vim script is loaded.
+This will set 'compatible' off, switch on syntax highlighting and a few more
+things.  See the script for details.  NOTE: this is done since Vim 8.0, not in
+Vim 7.4. (it was added in patch 7.4.2111 to be exact).
+
+This should work well for new Vim users.  If you create your own .vimrc,
+defaults.vim will always be loaded before your own .vimrc, so that you
+can revert settings that have been set. If you don't like some of the
+defaults, you can still source defaults.vim and revert individual settings.
+See the defaults.vim file for hints on how to revert each item.
+
+Note: since patch 9.1.XXXX Vim will always load the defaults.vim file even
+when a user vimrc file has been found. If you do not want this behaviour, you
+can opt-out of sourcing defaults.vim by setting the environment variable
+`$VIM_NO_SOURCE_DEFAULTS`.
+
+Previously you had to explicitly source defaults.vim by adding those lines at
+the top: >
+
 	unlet! skip_defaults_vim
 	source $VIMRUNTIME/defaults.vim
-Then Vim works like before you had a .vimrc. Copying $VIMRUNTIME/vimrc_example
-is way to do this.  Alternatively, you can copy defaults.vim to your .vimrc
-and modify it (but then you won't get updates when it changes).
-
-If you don't like some of the defaults, you can still source defaults.vim and
-revert individual settings.  See the defaults.vim file for hints on how to
-revert each item.
+<
 						*skip_defaults_vim*
 If you use a system-wide vimrc and don't want defaults.vim to change settings,
 set the "skip_defaults_vim" variable.  If this was set and you want to load

src/main.c

@@ -3261,6 +3261,7 @@ source_startup_scripts(mparm_T *parmp)
 	/*
 	 * Try to read initialization commands from the following places:
 	 * - environment variable VIMINIT
+	 * - defaults.vim unless $VIM_NO_SOURCE_DEFAULTS is set
 	 * - user vimrc file (s:.vimrc for Amiga, ~/.vimrc otherwise)
 	 * - second user vimrc file ($VIM/.vimrc for Dos)
 	 * - environment variable EXINIT
@@ -3270,6 +3271,10 @@ source_startup_scripts(mparm_T *parmp)
 	 */
 	if (process_env((char_u *)"VIMINIT", TRUE) != OK)
 	{
+	    int loaded_vimrc = NOTDONE;
+	    if (mch_getenv("VIM_NO_SOURCE_DEFAULTS") == NULL)
+		loaded_vimrc = do_source((char_u *)VIM_DEFAULTS_FILE, FALSE,
+								DOSO_NONE, NULL);
 	    if (do_source((char_u *)USR_VIMRC_FILE, TRUE,
 						      DOSO_VIMRC, NULL) == FAIL
 #ifdef USR_VIMRC_FILE2
@@ -3295,7 +3300,7 @@ source_startup_scripts(mparm_T *parmp)
 		&& do_source((char_u *)USR_EXRC_FILE2, FALSE,
 						       DOSO_NONE, NULL) == FAIL
 #endif
-		&& !has_dash_c_arg)
+		&& !has_dash_c_arg && loaded_vimrc != OK)
 	    {
 		// When no .vimrc file was found: source defaults.vim.
 		if (do_source((char_u *)VIM_DEFAULTS_FILE, FALSE, DOSO_NONE,