patch 8.2.1416: Vim9: boolean evaluation does not work as intended

Problem:    Vim9: boolean evaluation does not work as intended.
Solution:   Use tv2bool() in Vim9 script. (closes #6681)

src/eval.c

@@ -192,6 +192,9 @@ eval_to_bool(
 	*error = FALSE;
 	if (!skip)
 	{
+	    if (in_vim9script())
+		retval = tv2bool(&tv);
+	    else
 		retval = (tv_get_number_chk(&tv, error) != 0);
 	    clear_tv(&tv);
 	}
@@ -3098,7 +3101,8 @@ eval7(
 
 		// Apply prefixed "-" and "+" now.  Matters especially when
 		// "->" follows.
-		if (ret == OK && evaluate && end_leader > start_leader)
+		if (ret == OK && evaluate && end_leader > start_leader
+						  && rettv->v_type != VAR_BLOB)
 		    ret = eval7_leader(rettv, TRUE, start_leader, &end_leader);
 		break;
 
@@ -3281,6 +3285,9 @@ eval7_leader(
 	f = rettv->vval.v_float;
     else
 #endif
+	if (in_vim9script() && end_leader[-1] == '!')
+	    val = tv2bool(rettv);
+	else
 	    val = tv_get_number_chk(rettv, &error);
     if (error)
     {

src/testdir/test_vim9_expr.vim

@@ -1750,6 +1750,7 @@ enddef
 
 
 def Test_expr7_not()
+  let lines =<< trim END
       assert_equal(true, !'')
       assert_equal(true, ![])
       assert_equal(false, !'asdf')
@@ -1775,6 +1776,9 @@ def Test_expr7_not()
 
       assert_equal(true, !test_void())
       assert_equal(true, !test_unknown())
+  END
+  CheckDefSuccess(lines)
+  CheckScriptSuccess(['vim9script'] + lines)
 enddef
 
 func Test_expr7_fails()

src/testdir/vim9.vim

@@ -1,5 +1,13 @@
 " Utility functions for testing vim9 script
 
+" Check that "lines" inside ":def" has no error.
+func CheckDefSuccess(lines)
+  call writefile(['def Func()'] + a:lines + ['enddef', 'defcompile'], 'Xdef')
+  so Xdef
+  call Func()
+  call delete('Xdef')
+endfunc
+
 " Check that "lines" inside ":def" results in an "error" message.
 func CheckDefFailure(lines, error)
   call writefile(['def Func()'] + a:lines + ['enddef', 'defcompile'], 'Xdef')

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1416,
 /**/
     1415,
 /**/