patch 8.2.4510: Vim9: shortening commands leads to confusing script

Problem:    Vim9: shortening commands leads to confusing script.
Solution:   In Vim9 script require at least ":cont" for ":continue", "const"
            instead of "cons", "break" instead of "brea", "catch" instead of
            "cat", "else" instead of "el" "elseif" instead of "elsei" "endfor"
            instead of "endfo" "endif" instead of "en" "endtry" instead of
            "endt", "finally" instead of "fina", "throw" instead of "th",
            "while" instead of "wh".

src/errors.h

@@ -2761,9 +2761,9 @@ EXTERN char e_type_mismatch_for_v_variable[]
 #endif
 EXTERN char e_yank_register_changed_while_using_it[]
 	INIT(= N_("E1064: Yank register changed while using it"));
+EXTERN char e_command_cannot_be_shortened[]
+	INIT(= N_("E1065: Command cannot be shortened: %s"));
 #ifdef FEAT_EVAL
-EXTERN char e_must_use_var_instead_of_va[]
-	INIT(= N_("E1065: Must use :var instead of :va"));
 EXTERN char e_cannot_declare_a_register_str[]
 	INIT(= N_("E1066: Cannot declare a register: %s"));
 EXTERN char e_separator_mismatch_str[]

src/evalvars.c

@@ -768,11 +768,6 @@ ex_var(exarg_T *eap)
 	emsg(_(e_cannot_declare_variable_on_command_line));
 	return;
     }
-    if (eap->arg > eap->cmd && !has_var)
-    {
-	emsg(_(e_must_use_var_instead_of_va));
-	return;
-    }
     ex_let(eap);
 }
 

src/ex_cmds.h

@@ -58,6 +58,7 @@
 #define EX_NONWHITE_OK 0x2000000  // command can be followed by non-white
 #define EX_KEEPSCRIPT  0x4000000  // keep sctx of where command was invoked
 #define EX_EXPR_ARG    0x8000000  // argument is an expression
+#define EX_WHOLE      0x10000000  // command name cannot be shortened in Vim9
 
 #define EX_FILES (EX_XFILE | EX_EXTRA)	// multiple extra files allowed
 #define EX_FILE1 (EX_FILES | EX_NOSPC)	// 1 file, defaults to current file
@@ -221,7 +222,7 @@ EXCMD(CMD_brewind,	"brewind",	ex_brewind,
 	EX_BANG|EX_RANGE|EX_CMDARG|EX_TRLBAR,
 	ADDR_OTHER),
 EXCMD(CMD_break,	"break",	ex_break,
-	EX_TRLBAR|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
+	EX_TRLBAR|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK|EX_WHOLE,
 	ADDR_NONE),
 EXCMD(CMD_breakadd,	"breakadd",	ex_breakadd,
 	EX_EXTRA|EX_TRLBAR|EX_CMDWIN|EX_LOCK_OK,
@@ -281,7 +282,7 @@ EXCMD(CMD_call,		"call",		ex_call,
 	EX_RANGE|EX_NEEDARG|EX_EXTRA|EX_NOTRLCOM|EX_EXPR_ARG|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
 	ADDR_LINES),
 EXCMD(CMD_catch,	"catch",	ex_catch,
-	EX_EXTRA|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
+	EX_EXTRA|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK|EX_WHOLE,
 	ADDR_NONE),
 EXCMD(CMD_cbuffer,	"cbuffer",	ex_cbuffer,
 	EX_BANG|EX_RANGE|EX_WORD1|EX_TRLBAR,
@@ -413,7 +414,7 @@ EXCMD(CMD_confirm,	"confirm",	ex_wrongmodifier,
 	EX_NEEDARG|EX_EXTRA|EX_NOTRLCOM|EX_CMDWIN|EX_LOCK_OK,
 	ADDR_NONE),
 EXCMD(CMD_const,	"const",	ex_let,
-	EX_EXTRA|EX_BANG|EX_NOTRLCOM|EX_EXPR_ARG|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
+	EX_EXTRA|EX_BANG|EX_NOTRLCOM|EX_EXPR_ARG|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK|EX_WHOLE,
 	ADDR_NONE),
 EXCMD(CMD_copen,	"copen",	ex_copen,
 	EX_RANGE|EX_COUNT|EX_TRLBAR,
@@ -548,16 +549,16 @@ EXCMD(CMD_echon,	"echon",	ex_echo,
 	EX_EXTRA|EX_NOTRLCOM|EX_EXPR_ARG|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
 	ADDR_NONE),
 EXCMD(CMD_else,		"else",		ex_else,
-	EX_TRLBAR|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
+	EX_TRLBAR|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK|EX_WHOLE,
 	ADDR_NONE),
 EXCMD(CMD_elseif,	"elseif",	ex_else,
-	EX_EXTRA|EX_NOTRLCOM|EX_EXPR_ARG|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
+	EX_EXTRA|EX_NOTRLCOM|EX_EXPR_ARG|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK|EX_WHOLE,
 	ADDR_NONE),
 EXCMD(CMD_emenu,	"emenu",	ex_emenu,
 	EX_NEEDARG|EX_EXTRA|EX_TRLBAR|EX_NOTRLCOM|EX_RANGE|EX_CMDWIN|EX_LOCK_OK,
 	ADDR_OTHER),
 EXCMD(CMD_endif,	"endif",	ex_endif,
-	EX_TRLBAR|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
+	EX_TRLBAR|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK|EX_WHOLE,
 	ADDR_NONE),
 EXCMD(CMD_endinterface,	"endinterface",	ex_ni,
 	EX_EXTRA|EX_TRLBAR|EX_CMDWIN|EX_LOCK_OK,
@@ -575,13 +576,13 @@ EXCMD(CMD_endfunction,	"endfunction",	ex_endfunction,
 	EX_TRLBAR|EX_CMDWIN|EX_LOCK_OK,
 	ADDR_NONE),
 EXCMD(CMD_endfor,	"endfor",	ex_endwhile,
-	EX_TRLBAR|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
+	EX_TRLBAR|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK|EX_WHOLE,
 	ADDR_NONE),
 EXCMD(CMD_endtry,	"endtry",	ex_endtry,
-	EX_TRLBAR|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
+	EX_TRLBAR|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK|EX_WHOLE,
 	ADDR_NONE),
 EXCMD(CMD_endwhile,	"endwhile",	ex_endwhile,
-	EX_TRLBAR|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
+	EX_TRLBAR|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK|EX_WHOLE,
 	ADDR_NONE),
 EXCMD(CMD_enew,		"enew",		ex_edit,
 	EX_BANG|EX_TRLBAR,
@@ -623,10 +624,10 @@ EXCMD(CMD_find,		"find",		ex_find,
 	EX_RANGE|EX_BANG|EX_FILE1|EX_CMDARG|EX_ARGOPT|EX_TRLBAR|EX_NEEDARG,
 	ADDR_OTHER),
 EXCMD(CMD_final,	"final",	ex_let,
-	EX_EXTRA|EX_NOTRLCOM|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
+	EX_EXTRA|EX_NOTRLCOM|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK|EX_WHOLE,
 	ADDR_NONE),
 EXCMD(CMD_finally,	"finally",	ex_finally,
-	EX_TRLBAR|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
+	EX_TRLBAR|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK|EX_WHOLE,
 	ADDR_NONE),
 EXCMD(CMD_finish,	"finish",	ex_finish,
 	EX_TRLBAR|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
@@ -1601,7 +1602,7 @@ EXCMD(CMD_tfirst,	"tfirst",	ex_tag,
 	EX_RANGE|EX_BANG|EX_TRLBAR|EX_ZEROR,
 	ADDR_OTHER),
 EXCMD(CMD_throw,	"throw",	ex_throw,
-	EX_EXTRA|EX_NEEDARG|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
+	EX_EXTRA|EX_NEEDARG|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK|EX_WHOLE,
 	ADDR_NONE),
 EXCMD(CMD_tjump,	"tjump",	ex_tag,
 	EX_BANG|EX_TRLBAR|EX_WORD1,
@@ -1694,7 +1695,7 @@ EXCMD(CMD_vglobal,	"vglobal",	ex_global,
 	EX_RANGE|EX_WHOLEFOLD|EX_EXTRA|EX_DFLALL|EX_CMDWIN|EX_LOCK_OK|EX_NONWHITE_OK,
 	ADDR_LINES),
 EXCMD(CMD_var,		"var",		ex_var,
-	EX_EXTRA|EX_NOTRLCOM|EX_EXPR_ARG|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
+	EX_EXTRA|EX_NOTRLCOM|EX_EXPR_ARG|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK|EX_WHOLE,
 	ADDR_NONE),
 EXCMD(CMD_version,	"version",	ex_version,
 	EX_EXTRA|EX_TRLBAR|EX_CMDWIN|EX_LOCK_OK,
@@ -1763,7 +1764,7 @@ EXCMD(CMD_wall,		"wall",		do_wqall,
 	EX_BANG|EX_TRLBAR|EX_CMDWIN|EX_LOCK_OK,
 	ADDR_NONE),
 EXCMD(CMD_while,	"while",	ex_while,
-	EX_EXTRA|EX_NOTRLCOM|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK,
+	EX_EXTRA|EX_NOTRLCOM|EX_SBOXOK|EX_CMDWIN|EX_LOCK_OK|EX_WHOLE,
 	ADDR_NONE),
 EXCMD(CMD_winsize,	"winsize",	ex_winsize,
 	EX_EXTRA|EX_NEEDARG|EX_TRLBAR,

src/ex_docmd.c

@@ -3745,16 +3745,27 @@ find_ex_command(
 							    (size_t)len) == 0)
 	    {
 #ifdef FEAT_EVAL
-		if (full != NULL
-			   && cmdnames[(int)eap->cmdidx].cmd_name[len] == NUL)
+		if (full != NULL && cmdnames[eap->cmdidx].cmd_name[len] == NUL)
 		    *full = TRUE;
 #endif
 		break;
 	    }
 
-	// :Print and :mode are not supported in Vim9 script
-	if (vim9 && (eap->cmdidx == CMD_mode || eap->cmdidx == CMD_Print))
-	    eap->cmdidx = CMD_SIZE;
+	// :Print and :mode are not supported in Vim9 script.
+	// Some commands cannot be shortened in Vim9 script.
+	// ":continue" needs at least ":cont", since ":con" looks weird.
+	if (vim9 && eap->cmdidx != CMD_SIZE)
+	{
+	    if (eap->cmdidx == CMD_mode || eap->cmdidx == CMD_Print)
+		eap->cmdidx = CMD_SIZE;
+	    else if (((cmdnames[eap->cmdidx].cmd_argt & EX_WHOLE)
+			  && len < (int)STRLEN(cmdnames[eap->cmdidx].cmd_name))
+		      || (eap->cmdidx == CMD_continue && len < 4))
+	    {
+		semsg(_(e_command_cannot_be_shortened), eap->cmd);
+		eap->cmdidx = CMD_SIZE;
+	    }
+	}
 
 	// Do not recognize ":*" as the star command unless '*' is in
 	// 'cpoptions'.
@@ -3775,8 +3786,8 @@ find_ex_command(
 	    eap->cmdidx = CMD_SIZE;
     }
 
-    // ":fina" means ":finally" for backwards compatibility.
-    if (eap->cmdidx == CMD_final && p - eap->cmd == 4)
+    // ":fina" means ":finally" in legacy script, for backwards compatibility.
+    if (eap->cmdidx == CMD_final && p - eap->cmd == 4 && !vim9)
 	eap->cmdidx = CMD_finally;
 
 #ifdef FEAT_EVAL

src/testdir/test_vim9_script.vim

@@ -460,7 +460,7 @@ def Test_try_catch_throw()
     endtry
   catch /wrong/
     add(l, 'caught')
-  fina
+  finally
     add(l, 'finally')
   endtry
   assert_equal(['1', 'caught', 'finally'], l)
@@ -1004,7 +1004,7 @@ enddef
 def s:ReturnFinally(): string
   try
     return 'intry'
-  finall
+  finally
     g:in_finally = 'finally'
   endtry
   return 'end'
@@ -3374,6 +3374,37 @@ def Run_test_reject_declaration()
   g:StopVimInTerminal(buf)
 enddef
 
+def Test_minimal_command_name_length()
+  var names = [
+       'cons',
+       'brea',
+       'cat',
+       'catc',
+       'con',
+       'el',
+       'els',
+       'elsei',
+       'endfo',
+       'en',
+       'end',
+       'endi',
+       'endw',
+       'endt',
+       'endtr',
+       'fina',
+       'finall',
+       'th',
+       'thr',
+       'thro',
+       'wh',
+       'whi',
+       'whil',
+      ]
+  for name in names
+    v9.CheckDefAndScriptFailure([name .. ' '], 'E1065:')
+  endfor
+enddef
+
 def Test_unset_any_variable()
   var lines =<< trim END
     var name: any

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4510,
 /**/
     4509,
 /**/

src/vim9compile.c

@@ -1883,13 +1883,6 @@ compile_assignment(char_u *arg, exarg_T *eap, cmdidx_T cmdidx, cctx_T *cctx)
     lhs_T	lhs;
     long	start_lnum = SOURCING_LNUM;
 
-    p = eap->cmd;
-    if (eap->cmdidx == CMD_var && arg > p && !checkforcmd_noparen(&p, "var", 3))
-    {
-	emsg(_(e_must_use_var_instead_of_va));
-	return NULL;
-    }
-
     // Skip over the "varname" or "[varname, varname]" to get to any "=".
     p = skip_var_list(arg, TRUE, &var_count, &semicolon, TRUE);
     if (p == NULL)