patch 8.2.3137: Vim9: no error when a line only has a variable namev8.2.3137

Problem:    Vim9: no error when a line only has a variable name.
Solution:   Give an error when an expression is evaluated without an effect.
            (closes #8538)

3 files changed, 21 insertions, 6 deletions

diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index 1e99e9568d..79a4ea36e5 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -647,7 +647,7 @@ def Test_expr4_equal()
   CheckDefFailure(["var x = 'a' == "], 'E1097:', 3)
   CheckScriptFailure(['vim9script', "var x = 'a' == "], 'E15:', 2)
 
-  CheckDefExecAndScriptFailure2(['var items: any', 'eval 1', 'eval 2', 'if items == []', 'endif'], 'E691:', 'E1072:', 4)
+  CheckDefExecAndScriptFailure2(['var items: any', 'eval 1 + 1', 'eval 2 + 2', 'if items == []', 'endif'], 'E691:', 'E1072:', 4)
 
   CheckDefExecAndScriptFailure(['var x: any = "a"', 'echo x == true'], 'E1072: Cannot compare string with bool', 2)
   CheckDefExecAndScriptFailure(["var x: any = true", 'echo x == ""'], 'E1072: Cannot compare bool with string', 2)
diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index 89cdee7437..08e68d147c 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -2538,7 +2538,7 @@ def Test_restore_modifiers()
       set eventignore=
       autocmd QuickFixCmdPost * copen
       def AutocmdsDisabled()
-        eval 0
+        eval 1 + 2
       enddef
       func Func()
         noautocmd call s:AutocmdsDisabled()
@@ -2551,8 +2551,8 @@ def Test_restore_modifiers()
 enddef
 
 def StackTop()
-  eval 1
-  eval 2
+  eval 1 + 2
+  eval 2 + 3
   # call not on fourth line
   StackBot()
 enddef
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index 66b0c740fe..b21b63cbe0 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -691,7 +691,7 @@ enddef
 def Test_cnext_works_in_catch()
   var lines =<< trim END
       vim9script
-      au BufEnter * eval 0
+      au BufEnter * eval 1 + 2
       writefile(['text'], 'Xfile1')
       writefile(['text'], 'Xfile2')
       var items = [
@@ -1754,6 +1754,21 @@ def Test_script_var_shadows_function()
   CheckScriptFailure(lines, 'E1041:', 5)
 enddef
 
+def Test_script_var_shadows_command()
+  var lines =<< trim END
+      var undo = 1
+      undo = 2
+      assert_equal(2, undo)
+  END
+  CheckDefAndScriptSuccess(lines)
+
+  lines =<< trim END
+      var undo = 1
+      undo
+  END
+  CheckDefAndScriptFailure(lines, 'E1207:', 2)
+enddef
+
 def s:RetSome(): string
   return 'some'
 enddef
@@ -2270,7 +2285,7 @@ def Test_if_const_expr()
   assert_equal(false, res)
 
   # with constant "false" expression may be invalid so long as the syntax is OK
-  if false | eval 0 | endif
+  if false | eval 1 + 2 | endif
   if false | eval burp + 234 | endif
   if false | echo burp 234 'asd' | endif
   if false