patch 8.2.1756: Vim9: :let will soon be disallowed

Problem: Vim9: :let will soon be disallowed. Solution: Add v:disallow_let temporarily. Fix tests.
vim · Sep 27, 2020 · cfcd011 · cfcd011 · lacygoill · Sep 27, 2020
1 parent c0e2901
commit cfcd011
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Showing 7 changed files with 240 additions and 213 deletions.
diff --git a/src/errors.h b/src/errors.h
@@ -274,4 +274,6 @@ EXTERN char e_str_cannot_be_used_in_legacy_vim_script[]
 	INIT(= N_("E1124: \"%s\" cannot be used in legacy Vim script"));
 EXTERN char e_final_requires_a_value[]
 	INIT(= N_("E1125: Final requires a value"));
+EXTERN char e_cannot_use_let_in_vim9_script[]
+	INIT(= N_("E1126: Cannot use :let in Vim9 script"));
 #endif
diff --git a/src/evalvars.c b/src/evalvars.c
@@ -146,6 +146,7 @@ static struct vimvar
     {VV_NAME("echospace",	 VAR_NUMBER), VV_RO},
     {VV_NAME("argv",		 VAR_LIST), VV_RO},
     {VV_NAME("collate",		 VAR_STRING), VV_RO},
+    {VV_NAME("disallow_let",	 VAR_NUMBER), 0}, // TODO: remove
 };
 
 // shorthand
@@ -734,6 +735,12 @@ ex_let(exarg_T *eap)
 	    ex_finally(eap);
 	    return;
     }
+    if (get_vim_var_nr(VV_DISALLOW_LET)
+				      && eap->cmdidx == CMD_let && vim9script)
+    {
+	emsg(_(e_cannot_use_let_in_vim9_script));
+	return;
+    }
     if (eap->cmdidx == CMD_const && !vim9script && !eap->forceit)
 	// In legacy Vim script ":const" works like ":final".
 	eap->cmdidx = CMD_final;