patch 8.2.2239: Vim9: concatenating lines with backslash is inconvenient

Problem:    Vim9: concatenating lines with backslash is inconvenient.
Solution:   Support concatenating lines starting with '|', useful for
            :autocmd, :command, etc. (closes #6702)

runtime/doc/vim9.txt

@@ -6,7 +6,7 @@
 
 THIS IS STILL UNDER DEVELOPMENT - ANYTHING CAN BREAK - ANYTHING CAN CHANGE
 
-Vim9 script commands and expressions.			*Vim9*
+Vim9 script commands and expressions.			*Vim9* *vim9*
 
 Most expression help is in |eval.txt|.  This file is about the new syntax and
 features in Vim9 script.
@@ -113,11 +113,12 @@ In Vi # is a command to list text with numbers.  In Vim9 script you can use
 
 To improve readability there must be a space between a command and the #
 that starts a comment: >
-	var = value # comment
-	var = value# error!
+	var name = value # comment
+	var name = value# error!
 
-In legacy script # is also used for the alternate file name.  In Vim9 script
-you need to use %% instead.  Instead of ## use %%% (stands for all arguments).
+In legacy Vim script # is also used for the alternate file name.  In Vim9
+script you need to use %% instead.  Instead of ## use %%% (stands for all
+arguments).
 
 
 Vim9 functions ~
@@ -209,13 +210,13 @@ if you are developing a plugin and want to try a new version.  If you renamed
 something you don't have to worry about the old name still hanging around.
 
 If you do want to keep items, use: >
-	vimscript noclear
+	vim9script noclear
 
 You want to use this in scripts that use a `finish` command to bail out at
 some point when loaded again.  E.g. when a buffer local option is set: >
-	vimscript noclear
+	vim9script noclear
 	setlocal completefunc=SomeFunc
-	if exists('*SomeFunc') | finish | endif
+	if exists('*g:SomeFunc') | finish | endif
 	def g:SomeFunc()
 	....
 
@@ -385,9 +386,13 @@ No line break is allowed in the arguments of a lambda up to and including the
 This does not work: >
 	filter(list, (k, v)
 			=> v > 0)
-This also does not work:
+This also does not work: >
 	filter(list, (k,
 			v) => v > 0)
+But you can use a backslash to concatenate the lines before parsing: >
+	filter(list, (k,
+		\	v)
+		\	=> v > 0)
 
 Additionally, a lambda can contain statements in {}: >
 	var Lambda = (arg) => {
@@ -404,8 +409,8 @@ wrap it in parenthesis: >
 Automatic line continuation ~
 
 In many cases it is obvious that an expression continues on the next line.  In
-those cases there is no need to prefix the line with a backslash
-|line-continuation|.  For example, when a list spans multiple lines: >
+those cases there is no need to prefix the line with a backslash (see
+|line-continuation|).  For example, when a list spans multiple lines: >
 	var mylist = [
 		'one',
 		'two',
@@ -442,6 +447,12 @@ before it: >
 	var result = MyDict
 			.member
 
+For commands that have an argument that is a list of commands, the | character
+at the start of the line indicates line continuation: >
+	autocmd BufNewFile *.match if condition
+		|   echo 'match'
+		| endif
+
 <							*E1050*
 To make it possible for the operator at the start of the line to be
 recognized, it is required to put a colon before a range.  This will add
@@ -941,7 +952,7 @@ that you don't do that.
 
 
 Namespace ~
-							*:vim9script* *:vim9*
+							*vim9-namespace*
 To recognize a file that can be imported the `vim9script` statement must
 appear as the first statement in the file.  It tells Vim to interpret the
 script in its own namespace, instead of the global namespace.  If a file

src/proto/vim9compile.pro

@@ -5,7 +5,6 @@ int use_typecheck(type_T *actual, type_T *expected);
 int get_script_item_idx(int sid, char_u *name, int check_writable, cctx_T *cctx);
 imported_T *find_imported(char_u *name, size_t len, cctx_T *cctx);
 imported_T *find_imported_in_script(char_u *name, size_t len, int sid);
-int vim9_comment_start(char_u *p);
 char_u *peek_next_line_from_context(cctx_T *cctx);
 char_u *next_line_from_context(cctx_T *cctx, int skip_comment);
 char_u *to_name_end(char_u *arg, int use_namespace);
@@ -15,7 +14,7 @@ void error_white_both(char_u *op, int len);
 int assignment_len(char_u *p, int *heredoc);
 void vim9_declare_error(char_u *name);
 int check_vim9_unlet(char_u *name);
-int compile_def_function(ufunc_T *ufunc, int set_return_type, cctx_T *outer_cctx);
+int compile_def_function(ufunc_T *ufunc, int check_return_type, cctx_T *outer_cctx);
 void set_function_type(ufunc_T *ufunc);
 void delete_instr(isn_T *isn);
 void unlink_def_function(ufunc_T *ufunc);

src/proto/vim9script.pro

@@ -2,6 +2,7 @@
 int in_vim9script(void);
 void ex_vim9script(exarg_T *eap);
 int not_in_vim9(exarg_T *eap);
+int vim9_comment_start(char_u *p);
 void ex_export(exarg_T *eap);
 void free_imports_and_script_vars(int sid);
 void mark_imports_for_reload(int sid);

src/scriptfile.c

@@ -1739,6 +1739,10 @@ getsourceline(
     struct source_cookie *sp = (struct source_cookie *)cookie;
     char_u		*line;
     char_u		*p;
+    int			do_vim9_all = in_vim9script()
+					      && options == GETLINE_CONCAT_ALL;
+    int			do_vim9_cont = do_vim9_all
+					 || options == GETLINE_CONCAT_CONTDEF;
 
 #ifdef FEAT_EVAL
     // If breakpoints have been added/deleted need to check for it.
@@ -1785,17 +1789,15 @@ getsourceline(
 	// backslash. We always need to read the next line, keep it in
 	// sp->nextline.
 	/* Also check for a comment in between continuation lines: "\ */
-	// Also check for a Vim9 comment and empty line.
+	// Also check for a Vim9 comment, empty line, line starting with '|',
+	// but not "||".
 	sp->nextline = get_one_sourceline(sp);
 	if (sp->nextline != NULL
 		&& (*(p = skipwhite(sp->nextline)) == '\\'
 			      || (p[0] == '"' && p[1] == '\\' && p[2] == ' ')
-#ifdef FEAT_EVAL
-			      || (in_vim9script()
-				      && options == GETLINE_CONCAT_ALL
-				      && (*p == NUL || vim9_comment_start(p)))
-#endif
-			      ))
+			      || (do_vim9_all && (*p == NUL
+						     || vim9_comment_start(p)))
+			      || (do_vim9_cont && p[0] == '|' && p[1] != '|')))
 	{
 	    garray_T    ga;
 
@@ -1803,6 +1805,11 @@ getsourceline(
 	    ga_concat(&ga, line);
 	    if (*p == '\\')
 		ga_concat(&ga, p + 1);
+	    else if (*p == '|')
+	    {
+		ga_concat(&ga, (char_u *)" ");
+		ga_concat(&ga, p);
+	    }
 	    for (;;)
 	    {
 		vim_free(sp->nextline);
@@ -1810,7 +1817,7 @@ getsourceline(
 		if (sp->nextline == NULL)
 		    break;
 		p = skipwhite(sp->nextline);
-		if (*p == '\\')
+		if (*p == '\\' || (do_vim9_cont && p[0] == '|' && p[1] != '|'))
 		{
 		    // Adjust the growsize to the current length to speed up
 		    // concatenating many lines.
@@ -1821,15 +1828,16 @@ getsourceline(
 			else
 			    ga.ga_growsize = ga.ga_len;
 		    }
+		    if (*p == '\\')
 			ga_concat(&ga, p + 1);
+		    else
+		    {
+			ga_concat(&ga, (char_u *)" ");
+			ga_concat(&ga, p);
+		    }
 		}
 		else if (!(p[0] == '"' && p[1] == '\\' && p[2] == ' ')
-#ifdef FEAT_EVAL
-			&& !(in_vim9script()
-				&& options == GETLINE_CONCAT_ALL
-				&& (*p == NUL || vim9_comment_start(p)))
-#endif
-			)
+		     && !(do_vim9_all && (*p == NUL || vim9_comment_start(p))))
 		    break;
 		/* drop a # comment or "\ comment line */
 	    }

src/structs.h

@@ -1565,7 +1565,8 @@ typedef void (*cfunc_free_T)(void *state);
 // type of getline() last argument
 typedef enum {
     GETLINE_NONE,	    // do not concatenate any lines
-    GETLINE_CONCAT_CONT,    // concatenate continuation lines
+    GETLINE_CONCAT_CONT,    // concatenate continuation lines in Vim9 script
+    GETLINE_CONCAT_CONTDEF, // concatenate continuation lines always
     GETLINE_CONCAT_ALL	    // concatenate continuation and Vim9 # comment lines
 } getline_opt_T;
 

src/testdir/test_vim9_cmd.vim

@@ -548,13 +548,33 @@ def Test_command_modifier_other()
   bwipe!
 
   au BufNewFile Xfile g:readFile = 1
+      | g:readExtra = 2
   g:readFile = 0
+  g:readExtra = 0
   edit Xfile
   assert_equal(1, g:readFile)
+  assert_equal(2, g:readExtra)
   bwipe!
   g:readFile = 0
   noautocmd edit Xfile
   assert_equal(0, g:readFile)
+  au! BufNewFile
+
+  au BufNewFile Xfile g:readFile = 1
+      | g:readExtra = 2
+      | g:readMore = 3
+  g:readFile = 0
+  g:readExtra = 0
+  g:readMore = 0
+  edit Xfile
+  assert_equal(1, g:readFile)
+  assert_equal(2, g:readExtra)
+  assert_equal(3, g:readMore)
+  bwipe!
+  au! BufNewFile
+  unlet g:readFile
+  unlet g:readExtra
+  unlet g:readMore
 
   noswapfile edit XnoSwap
   assert_equal(0, &l:swapfile)

src/userfunc.c

@@ -2960,7 +2960,7 @@ define_function(exarg_T *eap, char_u *name_arg)
     static int	func_nr = 0;	    // number for nameless function
     int		paren;
     hashitem_T	*hi;
-    getline_opt_T getline_options = GETLINE_CONCAT_CONT;
+    getline_opt_T getline_options;
     linenr_T	sourcing_lnum_off;
     linenr_T	sourcing_lnum_top;
     int		is_heredoc = FALSE;
@@ -3291,6 +3291,8 @@ define_function(exarg_T *eap, char_u *name_arg)
     indent = 2;
     nesting = 0;
     nesting_def[nesting] = (eap->cmdidx == CMD_def);
+    getline_options = eap->cmdidx == CMD_def
+				? GETLINE_CONCAT_CONTDEF : GETLINE_CONCAT_CONT;
     for (;;)
     {
 	if (KeyTyped)
@@ -3365,7 +3367,8 @@ define_function(exarg_T *eap, char_u *name_arg)
 		{
 		    VIM_CLEAR(skip_until);
 		    VIM_CLEAR(heredoc_trimmed);
-		    getline_options = GETLINE_CONCAT_CONT;
+		    getline_options = eap->cmdidx == CMD_def
+				? GETLINE_CONCAT_CONTDEF : GETLINE_CONCAT_CONT;
 		    is_heredoc = FALSE;
 		}
 	    }

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2239,
 /**/
     2238,
 /**/

src/vim9compile.c

@@ -2164,15 +2164,6 @@ free_imported(cctx_T *cctx)
     ga_clear(&cctx->ctx_imports);
 }
 
-/*
- * Return TRUE if "p" points at a "#".  Does not check for white space.
- */
-    int
-vim9_comment_start(char_u *p)
-{
-    return p[0] == '#';
-}
-
 /*
  * Return a pointer to the next line that isn't empty or only contains a
  * comment. Skips over white space.

src/vim9script.c

@@ -103,6 +103,15 @@ not_in_vim9(exarg_T *eap)
     return OK;
 }
 
+/*
+ * Return TRUE if "p" points at a "#".  Does not check for white space.
+ */
+    int
+vim9_comment_start(char_u *p)
+{
+    return p[0] == '#';
+}
+
 #if defined(FEAT_EVAL) || defined(PROTO)
 
 /*