3 files changed, 24 insertions, 7 deletions
diff --git a/src/testdir/test_vim9_builtin.vim b/src/testdir/test_vim9_builtin.vim
index 547a2132a4..43b9d3373b 100644
--- a/src/testdir/test_vim9_builtin.vim
+++ b/src/testdir/test_vim9_builtin.vim
@@ -1241,6 +1241,15 @@ enddef
 
 def Test_filter()
   CheckDefAndScriptFailure(['filter(1.1, "1")'], ['E1013: Argument 1: type mismatch, expected list<any> but got float', 'E1251: List, Dictionary, Blob or String required for argument 1'])
+
+  var lines =<< trim END
+    def F(i: number, v: any): string
+      return 'bad'
+    enddef
+    echo filter([1, 2, 3], F)
+  END
+  CheckDefAndScriptFailure(lines, ['E1013: Argument 2: type mismatch, expected func(...): bool', 'E1135: Using a String as a Bool:'])
+
   assert_equal([], filter([1, 2, 3], '0'))
   assert_equal([1, 2, 3], filter([1, 2, 3], '1'))
   assert_equal({b: 20}, filter({a: 10, b: 20}, 'v:val == 20'))
@@ -2141,6 +2150,14 @@ def Test_map_function_arg()
       range(3)->map((a, b, c, d) => a + b + c + d)
   END
   CheckDefExecAndScriptFailure(lines, 'E1190: 2 arguments too few')
+
+  lines =<< trim END
+    def Map(i: number, v: number): string
+      return 'bad'
+    enddef
+    echo map([1, 2, 3], Map)
+  END
+  CheckDefAndScriptFailure(lines, ['E1013: Argument 2: type mismatch, expected func(...): number but got func(number, number): string', 'E1012: Type mismatch; expected number but got string in map()'])
 enddef
 
 def Test_map_item_type()
@@ -2155,19 +2172,19 @@ def Test_map_item_type()
     var l: list<number> = [0]
     echo map(l, (_, v) => [])
   END
-  CheckDefExecAndScriptFailure(lines, 'E1012: Type mismatch; expected number but got list<unknown> in map()', 2)
+  CheckDefAndScriptFailure(lines, ['E1013: Argument 2: type mismatch, expected func(...): number but got func(any, any): list<unknown>', 'E1012: Type mismatch; expected number but got list<unknown> in map()'], 2)
 
   lines =<< trim END
     var l: list<number> = range(2)
     echo map(l, (_, v) => [])
   END
-  CheckDefExecAndScriptFailure(lines, 'E1012: Type mismatch; expected number but got list<unknown> in map()', 2)
+  CheckDefAndScriptFailure(lines, ['E1013: Argument 2: type mismatch, expected func(...): number but got func(any, any): list<unknown>', 'E1012: Type mismatch; expected number but got list<unknown> in map()'], 2)
 
   lines =<< trim END
     var d: dict<number> = {key: 0}
     echo map(d, (_, v) => [])
   END
-  CheckDefExecAndScriptFailure(lines, 'E1012: Type mismatch; expected number but got list<unknown> in map()', 2)
+  CheckDefAndScriptFailure(lines, ['E1013: Argument 2: type mismatch, expected func(...): number but got func(any, any): list<unknown>', 'E1012: Type mismatch; expected number but got list<unknown> in map()'], 2)
 enddef
 
 def Test_maparg()
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index 9cf035a618..01b4538508 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -2077,7 +2077,7 @@ def Test_expr7_lambda()
             )
       assert_equal([111, 222, 111], ll)
 
-      var dl = [{key: 0}, {key: 22}]->filter(( _, v) => v['key'] )
+      var dl = [{key: 0}, {key: 22}]->filter(( _, v) => !!v['key'] )
       assert_equal([{key: 22}], dl)
 
       dl = [{key: 12}, {['foo']: 34}]
@@ -2236,7 +2236,7 @@ def Test_expr7_new_lambda()
             )
       assert_equal([111, 222, 111], ll)
 
-      var dl = [{key: 0}, {key: 22}]->filter(( _, v) => v['key'] )
+      var dl = [{key: 0}, {key: 22}]->filter(( _, v) => !!v['key'] )
       assert_equal([{key: 22}], dl)
 
       dl = [{key: 12}, {['foo']: 34}]
@@ -2308,7 +2308,7 @@ def Test_expr7_lambda_vim9script()
   lines =<< trim END
       search('"', 'cW', 0, 0, () =>
 	synstack('.', col('.'))
-          ->map((_, v) => synIDattr(v, 'name'))->len())
+          ->mapnew((_, v) => synIDattr(v, 'name'))->len())
   END
   CheckDefAndScriptSuccess(lines)
 enddef
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index dcfe888646..8975e1bf38 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -2048,7 +2048,7 @@ def Test_vim9script_funcref_other_script()
       return idx % 2 == 1
     enddef
     export def FastFilter(): list<number>
-      return range(10)->filter('FilterFunc')
+      return range(10)->filter('FilterFunc(v:key, v:val)')
     enddef
     export def FastFilterDirect(): list<number>
       return range(10)->filter(FilterFunc)