patch 8.2.3365: Vim9: cannot use option for all operations

Problem:    Vim9: cannot use option for all operations.
Solution:   Recognize more operations. (closes #8779)

Author: brammool

src/ex_docmd.c

@@ -3425,12 +3425,26 @@ find_ex_command(
     {
 	char_u *pskip = skip_option_env_lead(eap->cmd);
 
-	if (vim_strchr((char_u *)"{('[\"@", *p) != NULL
+	if (vim_strchr((char_u *)"{('[\"@&", *p) != NULL
 	       || ((p = to_name_const_end(pskip)) > eap->cmd && *p != NUL))
 	{
 	    int	    oplen;
 	    int	    heredoc;
-	    char_u  *swp = skipwhite(p);
+	    char_u  *swp;
+
+	    if (*eap->cmd == '&')
+	    {
+		p = to_name_end(eap->cmd + 1, FALSE);
+		if (ends_excmd(*skipwhite(p)))
+		{
+		    // "&option <NL>" is the start of an expression.
+		    eap->cmdidx = CMD_eval;
+		    return eap->cmd;
+		}
+		// "&option" can be followed by "->" or "=", check below
+	    }
+
+	    swp = skipwhite(p);
 
 	    if (
 		// "(..." is an expression.
@@ -3530,10 +3544,14 @@ find_ex_command(
 
 	    // Recognize an assignment if we recognize the variable name:
 	    // "g:var = expr"
+	    // "@r = expr"
+	    // "&opt = expr"
 	    // "var = expr"  where "var" is a variable name or we are skipping
 	    // (variable declaration might have been skipped).
 	    if (*eap->cmd == '@')
 		p = eap->cmd + 2;
+	    else if (*eap->cmd == '&')
+		p = skiptowhite_esc(eap->cmd + 1);
 	    oplen = assignment_len(skipwhite(p), &heredoc);
 	    if (oplen > 0)
 	    {

src/proto/vim9compile.pro

@@ -8,6 +8,7 @@ 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);
 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);
 char_u *to_name_const_end(char_u *arg);
 int get_lambda_tv_and_compile(char_u **arg, typval_T *rettv, int types_optional, evalarg_T *evalarg);
 exprtype_T get_compare_type(char_u *p, int *len, int *type_is);

src/testdir/test_vim9_cmd.vim

@@ -521,6 +521,22 @@ def Test_method_and_user_command()
   CheckScriptSuccess(lines)
 enddef
 
+def Test_option_use_linebreak()
+  var lines =<< trim END
+      new
+      &matchpairs = '(:)'
+      &matchpairs->setline(1)
+      &matchpairs = '[:]'
+      &matchpairs   ->setline(2)
+      &matchpairs = '{:}'
+      &matchpairs  
+          ->setline(3)
+      assert_equal(['(:)', '[:]', '{:}'], getline(1, '$'))
+      bwipe!
+  END
+  CheckDefAndScriptSuccess(lines)
+enddef
+
 def Test_skipped_expr_linebreak()
   if 0
     var x = []

src/version.c

@@ -755,6 +755,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3365,
 /**/
     3364,
 /**/

src/vim9compile.c

@@ -3579,7 +3579,7 @@ compile_call(
  * Return a pointer to just after the name.  Equal to "arg" if there is no
  * valid name.
  */
-    static char_u *
+    char_u *
 to_name_end(char_u *arg, int use_namespace)
 {
     char_u	*p;